11.2.0.1

./transform_all_sql.sh < input_file > output_file

/**
* The main entry point to create indexes via parallel threads / AQ
* @param p_directory_name The directory where the file resides that contains the CREATE INDEX DDLs
* @param p_file_name The file name in the directory above
* @param p_parallel_degree_set_1 The number threads to start for the worker thread 1 which usually
represents the SERIAL_INDEX threads - G_AUTO_PARALLEL_DEGREE means use the CPU_COUNT and
CLUSTER_DATABASE_INSTANCES parameter to determine number of threads automatically
* @param p_parallel_degree_set_2 The number threads to start for the worker thread 2 which usually
represents the PARALLEL_INDEX threads - G_AUTO_PARALLEL_DEGREE means get the CPU_COUNT and
CLUSTER_DATABASE_INSTANCES parameter to determine number of threads automatically,
however 1 is the default here since we assume that these indexes use parallel DDL
* @param p_job_submit_delay The number of seconds each job will be delayed to allow Oracle
proper load balancing in a cluster, default 30 seconds (commented out at present due to
odd locking issues on the queue table in RAC environments)
* @param p_sleep_seconds The number of seconds to wait for the threads to startup
before attempting to teardown the AQ infrastructure again
* @param p_optional_init Optionally a SQL can be passed usually used to initialize the session
for example forcing a particular parallel degree
* @param p_worker_set_id_1
The character identifier used to identify the indexes to process by the first worker thread set
Default value is "SERIAL_INDEX"
* @param p_worker_set_id_2
The character identifier used to identify the indexes to process by the second worker thread set
Default value is "PARALLEL_INDEX"
**/
procedure create_index_concurrent(
p_directory_name in varchar2
, p_file_name in varchar2
, p_parallel_degree_set_1 in integer default G_AUTO_PARALLEL_DEGREE
, p_parallel_degree_set_2 in integer default 1
, p_job_submit_delay in integer default 30
, p_sleep_seconds in integer default 10
, p_optional_init in varchar2 default null
, p_worker_set_id_1 in varchar2 default G_WORKER_SET_ID_1
, p_worker_set_id_2 in varchar2 default G_WORKER_SET_ID_2
);

select
to_char(log_timestamp, 'DD-MON-YYYY HH24:MI:SS.FF') as log_timestamp
, sql_statement
, message
from
create_index_concurrent_log
order by
log_timestamp desc;

select
to_char(log_timestamp, 'DD-MON-YYYY HH24:MI:SS.FF') as log_timestamp
, cast(substr(sql_statement, 1, 30) as varchar2(30)) as index_name
, cast(substr(message, 1, 128) as varchar2(128)) as worker_set_id
from
create_index_concurrent_log
order by
log_timestamp desc;

set echo on timing on linesize 130 tab off trimspool on

alter session set nls_date_format = 'DD.MM.YYYY HH24:MI:SS';

drop table t purge;

create table t
as
select * from all_objects
where rownum <= 1000;

exec dbms_stats.set_global_prefs('PUBLISH', 'TRUE')

select dbms_stats.get_prefs('PUBLISH', null, 'T') from dual;

-- Our baseline, no histograms, basic column statistics for all columns
exec dbms_stats.gather_table_stats(null, 'T', estimate_percent => null, cascade => false, method_opt => 'FOR ALL COLUMNS SIZE 1')

-- Verify the result
select
num_distinct
, density
, last_analyzed
, num_buckets
, user_stats
from
user_tab_col_statistics
where
table_name = 'T'
and column_name = 'OBJECT_NAME';

-- Enable pending statistics for table T
-- You can try these different calls
--
-- The GATHER_*_STATS procedures seem to behave correctly
-- only when setting the GLOBAL PREFS to FALSE
--
-- "Correctly" means that the results are reflected in the
-- pending area only but not in the dictionary statistics
--
-- Note that the SET_*_STATS procedures seem to ignore the setting
-- always and publish directly to the dictionary
-- no matter what the PUBLISH setting is on any level (TABLE, GLOBAL)
--
-- exec dbms_stats.set_global_prefs('PUBLISH', 'FALSE')
exec dbms_stats.set_table_prefs(null, 'T', 'PUBLISH', 'FALSE')
-- exec dbms_stats.set_schema_prefs(user, 'PUBLISH', 'FALSE')

-- Verify the current setting, statistics will not be published
select dbms_stats.get_prefs('PUBLISH', null, 'T') from dual;

-- Wait for two seconds to make the LAST_ANALYZED column meaningful
exec dbms_lock.sleep(2)

-- This is supposed to go to the pending statistics area
exec dbms_stats.gather_table_stats(null, 'T', estimate_percent => null, cascade => false, method_opt => 'FOR ALL COLUMNS SIZE 254')

-- Yes, it worked, the dictionary statistics are not modified
select
num_distinct
, density
, last_analyzed
, num_buckets
, user_stats
from
user_tab_col_statistics
where
table_name = 'T'
and column_name = 'OBJECT_NAME';

-- The pending statistics area contains now the new statistics including histograms
select
num_distinct
, density
, last_analyzed
from
user_col_pending_stats
where
table_name = 'T'
and column_name = 'OBJECT_NAME';

select
count(*)
from
user_tab_histgrm_pending_stats
where
table_name = 'T'
and column_name = 'OBJECT_NAME';

select
count(*)
from
user_tab_histograms
where
table_name = 'T'
and column_name = 'OBJECT_NAME';

-- Wait for two seconds to make the LAST_ANALYZED column meaningful
exec dbms_lock.sleep(2)

-- Let's gather statistics only for the OBJECT_NAME column
exec dbms_stats.gather_table_stats(null, 'T', estimate_percent => null, cascade => false, method_opt => 'FOR COLUMNS OBJECT_NAME SIZE 1')

-- Oops, why do my dictionary statistics reflect that change (Note the LAST_ANALYZED column)
-- Except for you set the GLOBAL preferences for PUBLISH to FALSE
select
num_distinct
, density
, last_analyzed
, num_buckets
, user_stats
from
user_tab_col_statistics
where
table_name = 'T'
and column_name = 'OBJECT_NAME';

-- I do have now the statistics updated in both, pending statistics and dictionary statistics
-- Except for you set the GLOBAL preferences for PUBLISH to FALSE
select
num_distinct
, density
, last_analyzed
from
user_col_pending_stats
where
table_name = 'T'
and column_name = 'OBJECT_NAME';

select
count(*)
from
user_tab_histgrm_pending_stats
where
table_name = 'T'
and column_name = 'OBJECT_NAME';

select
count(*)
from
user_tab_histograms
where
table_name = 'T'
and column_name = 'OBJECT_NAME';

-- Wait for two seconds to make the LAST_ANALYZED column meaningful
exec dbms_lock.sleep(2)

-- Let's recreate the histogram only on the OBJECT_NAME column
exec dbms_stats.gather_table_stats(null, 'T', estimate_percent => null, cascade => false, method_opt => 'FOR COLUMNS OBJECT_NAME SIZE 254')

-- Oops, I did it again...
-- Except for you set the GLOBAL preferences for PUBLISH to FALSE
select
num_distinct
, density
, last_analyzed
, num_buckets
, user_stats
from
user_tab_col_statistics
where
table_name = 'T'
and column_name = 'OBJECT_NAME';

select
num_distinct
, density
, last_analyzed
from
user_col_pending_stats
where
table_name = 'T'
and column_name = 'OBJECT_NAME';

select
count(*)
from
user_tab_histgrm_pending_stats
where
table_name = 'T'
and column_name = 'OBJECT_NAME';

select
count(*)
from
user_tab_histograms
where
table_name = 'T'
and column_name = 'OBJECT_NAME';

-- Wait for two seconds to make the LAST_ANALYZED column meaningful
exec dbms_lock.sleep(2)

-- Let's define a manually crafted NDV and DENSITY value
-- Again I expect this to go to the pending statistics area
declare
srec dbms_stats.statrec;
novals dbms_stats.numarray;
distcnt number;
avgclen number;
nullcnt number;
density number;
begin
dbms_stats.get_column_stats(null, 't', 'object_name', distcnt => distcnt, avgclen => avgclen, nullcnt => nullcnt, density => density, srec => srec);
dbms_stats.set_column_stats(
ownname=>null,
tabname=>'t',
colname=>'object_name',
distcnt=>distcnt*100,
nullcnt=>nullcnt,
srec=>srec,
avgclen=>avgclen,
density=>density/100
);
end;
/

-- Nope, no change here
select
num_distinct
, density
, last_analyzed
from
user_col_pending_stats
where
table_name = 'T'
and column_name = 'OBJECT_NAME';

-- But I just changed it in the dictionary statistics
-- Even in case of setting the GLOBAL preference to FALSE
select
num_distinct
, density
, last_analyzed
, num_buckets
, user_stats
from
user_tab_col_statistics
where
table_name = 'T'
and column_name = 'OBJECT_NAME';

-- And what is even worse: The statistics history does not reflect all these changes to the dictionary statistics
select table_name, stats_update_time from USER_TAB_STATS_HISTORY where table_name = 'T';

exec dbms_stats.restore_table_stats(null, 'T', systimestamp)

-- But which statistics have been restored now?
-- It looks like this actually restored the PENDING statistics
-- according to the LAST_ANALYZED information??
select
num_distinct
, density
, last_analyzed
, num_buckets
, user_stats
from
user_tab_col_statistics
where
table_name = 'T'
and column_name = 'OBJECT_NAME';

select
count(*)
from
user_tab_histgrm_pending_stats
where
table_name = 'T'
and column_name = 'OBJECT_NAME';

select
count(*)
from
user_tab_histograms
where
table_name = 'T'
and column_name = 'OBJECT_NAME';

exec dbms_stats.set_global_prefs('PUBLISH', 'TRUE')

Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options

SQL>
SQL> alter session set nls_date_format = 'DD.MM.YYYY HH24:MI:SS';

Session altered.

Elapsed: 00:00:00.00
SQL>
SQL> drop table t purge;

Table dropped.

Elapsed: 00:00:00.20
SQL>
SQL> create table t
2 as
3 select * from all_objects
4 where rownum <= 1000;

Table created.

Elapsed: 00:00:00.35
SQL>
SQL> exec dbms_stats.set_global_prefs('PUBLISH', 'TRUE')

PL/SQL procedure successfully completed.

Elapsed: 00:00:00.03
SQL>
SQL> select dbms_stats.get_prefs('PUBLISH', null, 'T') from dual;

DBMS_STATS.GET_PREFS('PUBLISH',NULL,'T')
----------------------------------------------------------------------------------------------------------------------------------
TRUE

Elapsed: 00:00:00.00
SQL>
SQL> -- Our baseline, no histograms, basic column statistics for all columns
SQL> exec dbms_stats.gather_table_stats(null, 'T', estimate_percent => null, cascade => false, method_opt => 'FOR ALL COLUMNS SIZE 1')

PL/SQL procedure successfully completed.

Elapsed: 00:00:00.09
SQL>
SQL> -- Verify the result
SQL> select
2 num_distinct
3 , density
4 , last_analyzed
5 , num_buckets
6 , user_stats
7 from
8 user_tab_col_statistics
9 where
10 table_name = 'T'
11 and column_name = 'OBJECT_NAME';

NUM_DISTINCT DENSITY LAST_ANALYZED NUM_BUCKETS USE
------------ ---------- ------------------- ----------- ---
995 .001005025 18.01.2011 18:58:24 1 NO

Elapsed: 00:00:00.01
SQL>
SQL> -- Enable pending statistics for table T
SQL> -- You can try these different calls
SQL> --
SQL> -- The GATHER_*_STATS procedures seem to behave correctly
SQL> -- only when setting the GLOBAL PREFS to FALSE
SQL> --
SQL> -- "Correctly" means that the results are reflected in the
SQL> -- pending area only but not in the dictionary statistics
SQL> --
SQL> -- Note that the SET_*_STATS procedures seem to ignore the setting
SQL> -- always and publish directly to the dictionary
SQL> -- no matter what the PUBLISH setting is on any level (TABLE, GLOBAL)
SQL> --
SQL> -- exec dbms_stats.set_global_prefs('PUBLISH', 'FALSE')
SQL> exec dbms_stats.set_table_prefs(null, 'T', 'PUBLISH', 'FALSE')

PL/SQL procedure successfully completed.

Elapsed: 00:00:00.01
SQL> -- exec dbms_stats.set_schema_prefs(user, 'PUBLISH', 'FALSE')
SQL>
SQL> -- Verify the current setting, statistics will not be published
SQL> select dbms_stats.get_prefs('PUBLISH', null, 'T') from dual;

DBMS_STATS.GET_PREFS('PUBLISH',NULL,'T')
----------------------------------------------------------------------------------------------------------------------------------
FALSE

Elapsed: 00:00:00.01
SQL>
SQL> -- Wait for two seconds to make the LAST_ANALYZED column meaningful
SQL> exec dbms_lock.sleep(2)

PL/SQL procedure successfully completed.

Elapsed: 00:00:02.01
SQL>
SQL> -- This is supposed to go to the pending statistics area
SQL> exec dbms_stats.gather_table_stats(null, 'T', estimate_percent => null, cascade => false, method_opt => 'FOR ALL COLUMNS SIZE 254')

PL/SQL procedure successfully completed.

Elapsed: 00:00:00.99
SQL>
SQL> -- Yes, it worked, the dictionary statistics are not modified
SQL> select
2 num_distinct
3 , density
4 , last_analyzed
5 , num_buckets
6 , user_stats
7 from
8 user_tab_col_statistics
9 where
10 table_name = 'T'
11 and column_name = 'OBJECT_NAME';

NUM_DISTINCT DENSITY LAST_ANALYZED NUM_BUCKETS USE
------------ ---------- ------------------- ----------- ---
995 .001005025 18.01.2011 18:58:24 1 NO

Elapsed: 00:00:00.01
SQL>
SQL> -- The pending statistics area contains now the new statistics including histograms
SQL> select
2 num_distinct
3 , density
4 , last_analyzed
5 from
6 user_col_pending_stats
7 where
8 table_name = 'T'
9 and column_name = 'OBJECT_NAME';

NUM_DISTINCT DENSITY LAST_ANALYZED
------------ ---------- -------------------
995 .00101 18.01.2011 18:58:26

Elapsed: 00:00:00.01
SQL>
SQL> select
2 count(*)
3 from
4 user_tab_histgrm_pending_stats
5 where
6 table_name = 'T'
7 and column_name = 'OBJECT_NAME';

COUNT(*)
----------
255

Elapsed: 00:00:00.01
SQL>
SQL> select
2 count(*)
3 from
4 user_tab_histograms
5 where
6 table_name = 'T'
7 and column_name = 'OBJECT_NAME';

COUNT(*)
----------
2

Elapsed: 00:00:00.01
SQL>
SQL> -- Wait for two seconds to make the LAST_ANALYZED column meaningful
SQL> exec dbms_lock.sleep(2)

PL/SQL procedure successfully completed.

Elapsed: 00:00:02.01
SQL>
SQL> -- Let's gather statistics only for the OBJECT_NAME column
SQL> exec dbms_stats.gather_table_stats(null, 'T', estimate_percent => null, cascade => false, method_opt => 'FOR COLUMNS OBJECT_NAME SIZE 1')

PL/SQL procedure successfully completed.

Elapsed: 00:00:00.14
SQL>
SQL> -- Oops, why do my dictionary statistics reflect that change (Note the LAST_ANALYZED column)
SQL> -- Except for you set the GLOBAL preferences for PUBLISH to FALSE
SQL> select
2 num_distinct
3 , density
4 , last_analyzed
5 , num_buckets
6 , user_stats
7 from
8 user_tab_col_statistics
9 where
10 table_name = 'T'
11 and column_name = 'OBJECT_NAME';

NUM_DISTINCT DENSITY LAST_ANALYZED NUM_BUCKETS USE
------------ ---------- ------------------- ----------- ---
995 .001005025 18.01.2011 18:58:29 1 NO

Elapsed: 00:00:00.01
SQL>
SQL> -- I do have now the statistics updated in both, pending statistics and dictionary statistics
SQL> -- Except for you set the GLOBAL preferences for PUBLISH to FALSE
SQL> select
2 num_distinct
3 , density
4 , last_analyzed
5 from
6 user_col_pending_stats
7 where
8 table_name = 'T'
9 and column_name = 'OBJECT_NAME';

NUM_DISTINCT DENSITY LAST_ANALYZED
------------ ---------- -------------------
995 .001005025 18.01.2011 18:58:29

Elapsed: 00:00:00.01
SQL>
SQL> select
2 count(*)
3 from
4 user_tab_histgrm_pending_stats
5 where
6 table_name = 'T'
7 and column_name = 'OBJECT_NAME';

COUNT(*)
----------
0

Elapsed: 00:00:00.01
SQL>
SQL> select
2 count(*)
3 from
4 user_tab_histograms
5 where
6 table_name = 'T'
7 and column_name = 'OBJECT_NAME';

COUNT(*)
----------
2

Elapsed: 00:00:00.01
SQL>
SQL> -- Wait for two seconds to make the LAST_ANALYZED column meaningful
SQL> exec dbms_lock.sleep(2)

PL/SQL procedure successfully completed.

Elapsed: 00:00:02.01
SQL>
SQL> -- Let's recreate the histogram only on the OBJECT_NAME column
SQL> exec dbms_stats.gather_table_stats(null, 'T', estimate_percent => null, cascade => false, method_opt => 'FOR COLUMNS OBJECT_NAME SIZE 254')

PL/SQL procedure successfully completed.

Elapsed: 00:00:00.34
SQL>
SQL> -- Oops, I did it again...
SQL> -- Except for you set the GLOBAL preferences for PUBLISH to FALSE
SQL> select
2 num_distinct
3 , density
4 , last_analyzed
5 , num_buckets
6 , user_stats
7 from
8 user_tab_col_statistics
9 where
10 table_name = 'T'
11 and column_name = 'OBJECT_NAME';

NUM_DISTINCT DENSITY LAST_ANALYZED NUM_BUCKETS USE
------------ ---------- ------------------- ----------- ---
995 .00101 18.01.2011 18:58:32 254 NO

Elapsed: 00:00:00.01
SQL>
SQL> select
2 num_distinct
3 , density
4 , last_analyzed
5 from
6 user_col_pending_stats
7 where
8 table_name = 'T'
9 and column_name = 'OBJECT_NAME';

NUM_DISTINCT DENSITY LAST_ANALYZED
------------ ---------- -------------------
995 .00101 18.01.2011 18:58:32

Elapsed: 00:00:00.01
SQL>
SQL> select
2 count(*)
3 from
4 user_tab_histgrm_pending_stats
5 where
6 table_name = 'T'
7 and column_name = 'OBJECT_NAME';

COUNT(*)
----------
255

Elapsed: 00:00:00.01
SQL>
SQL> select
2 count(*)
3 from
4 user_tab_histograms
5 where
6 table_name = 'T'
7 and column_name = 'OBJECT_NAME';

COUNT(*)
----------
255

Elapsed: 00:00:00.01
SQL>
SQL> -- Wait for two seconds to make the LAST_ANALYZED column meaningful
SQL> exec dbms_lock.sleep(2)

PL/SQL procedure successfully completed.

Elapsed: 00:00:02.01
SQL>
SQL> -- Let's define a manually crafted NDV and DENSITY value
SQL> -- Again I expect this to go to the pending statistics area
SQL> declare
2 srec dbms_stats.statrec;
3 novals dbms_stats.numarray;
4 distcnt number;
5 avgclen number;
6 nullcnt number;
7 density number;
8 begin
9 dbms_stats.get_column_stats(null, 't', 'object_name', distcnt => distcnt, avgclen => avgclen, nullcnt => nullcnt, density => density, srec => srec);
10 dbms_stats.set_column_stats(
11 ownname=>null,
12 tabname=>'t',
13 colname=>'object_name',
14 distcnt=>distcnt*100,
15 nullcnt=>nullcnt,
16 srec=>srec,
17 avgclen=>avgclen,
18 density=>density/100
19 );
20 end;
21 /

PL/SQL procedure successfully completed.

Elapsed: 00:00:00.17
SQL>
SQL> -- Nope, no change here
SQL> select
2 num_distinct
3 , density
4 , last_analyzed
5 from
6 user_col_pending_stats
7 where
8 table_name = 'T'
9 and column_name = 'OBJECT_NAME';

NUM_DISTINCT DENSITY LAST_ANALYZED
------------ ---------- -------------------
995 .00101 18.01.2011 18:58:32

Elapsed: 00:00:00.01
SQL>
SQL> -- But I just changed it in the dictionary statistics
SQL> -- Even in case of setting the GLOBAL preference to FALSE
SQL> select
2 num_distinct
3 , density
4 , last_analyzed
5 , num_buckets
6 , user_stats
7 from
8 user_tab_col_statistics
9 where
10 table_name = 'T'
11 and column_name = 'OBJECT_NAME';

NUM_DISTINCT DENSITY LAST_ANALYZED NUM_BUCKETS USE
------------ ---------- ------------------- ----------- ---
99500 .0000101 18.01.2011 18:58:34 254 YES

Elapsed: 00:00:00.01
SQL>
SQL> -- And what is even worse: The statistics history does not reflect all these changes to the dictionary statistics
SQL> select table_name, stats_update_time from USER_TAB_STATS_HISTORY where table_name = 'T';

TABLE_NAME STATS_UPDATE_TIME
------------------------------ ---------------------------------------------------------------------------
T 18-JAN-11 06.58.24.391000 PM +01:00

Elapsed: 00:00:00.01
SQL>
SQL> exec dbms_stats.restore_table_stats(null, 'T', systimestamp)

PL/SQL procedure successfully completed.

Elapsed: 00:00:00.29
SQL>
SQL> -- But which statistics have been restored now?
SQL> -- It looks like this actually restored the PENDING statistics
SQL> -- according to the LAST_ANALYZED information??
SQL> select
2 num_distinct
3 , density
4 , last_analyzed
5 , num_buckets
6 , user_stats
7 from
8 user_tab_col_statistics
9 where
10 table_name = 'T'
11 and column_name = 'OBJECT_NAME';

NUM_DISTINCT DENSITY LAST_ANALYZED NUM_BUCKETS USE
------------ ---------- ------------------- ----------- ---
995 .00101 18.01.2011 18:58:32 254 NO

Elapsed: 00:00:00.01
SQL>
SQL> select
2 count(*)
3 from
4 user_tab_histgrm_pending_stats
5 where
6 table_name = 'T'
7 and column_name = 'OBJECT_NAME';

COUNT(*)
----------
255

Elapsed: 00:00:00.01
SQL>
SQL> select
2 count(*)
3 from
4 user_tab_histograms
5 where
6 table_name = 'T'
7 and column_name = 'OBJECT_NAME';

COUNT(*)
----------
255

Elapsed: 00:00:00.01
SQL>
SQL> exec dbms_stats.set_global_prefs('PUBLISH', 'TRUE')

PL/SQL procedure successfully completed.

Elapsed: 00:00:00.01
SQL>

set echo on timing on

show parameter pga
show parameter processes

-- alter session set workarea_size_policy = manual sort_area_size = 40000000;

drop table t1 purge;

drop table t2 purge;

create table t1
as
select mod(rownum, 27) as user_id, rownum as object_id from dual connect by level <= 30000;

create table t2
as
select distinct user_id from t1;

exec dbms_stats.gather_table_stats(null, 't1', method_opt => 'for all columns size 1')

exec dbms_stats.gather_table_stats(null, 't2', method_opt => 'for all columns size 1')

column low_val new_value low_value
column high_val new_value high_value

select
max(user_id) + 1 as low_val
, max(user_id) + max(user_id) - min(user_id) + 1 as high_val
from
t2;

-- Invalidate any cursors using T1
comment on table t1 is '';

alter session set statistics_level = all;

-- alter session set tracefile_identifier = 'smm_trace_correct_cardinality';

-- alter session set "_smm_trace" = 65535;

select /*+ full(@inner t1)
full(@inner t2)
full(@inner t3)
leading(@inner t2 t3 t1)
use_nl(@inner t3)
use_hash(@inner t1)
no_swap_join_inputs(@inner t1)
use_hash_aggregation(@inner)
*/
max(cnt)
from
(
select /*+ qb_name(inner) */ count(*) as cnt, t1.object_id, t3.user_id
from t1, t2, t2 t3
where t1.user_id = t2.user_id
group by t1.object_id, t3.user_id
)
;

-- alter session set "_smm_trace" = 0;

set pagesize 0 linesize 200 trimspool on tab off

select * from table(dbms_xplan.display_cursor(null, null, 'ALLSTATS LAST'));

set pagesize 14

-- Fudge the statistics so that the join cardinality between t1 and t2 will be 0 (rounded up to 1)
declare
srec dbms_stats.statrec;
novals dbms_stats.numarray;
distcnt number;
avgclen number;
nullcnt number;
density number;
srec2 dbms_stats.statrec;
begin
dbms_stats.get_column_stats(null, 't1', 'user_id', distcnt => distcnt, avgclen => avgclen, nullcnt => nullcnt, density => density, srec => srec);
srec2.epc := 2;
novals := dbms_stats.numarray(
&low_value,
&high_value
);
srec2.bkvals := null;
dbms_stats.prepare_column_values(srec2,novals);
dbms_stats.set_column_stats(
ownname=>null,
tabname=>'t1',
colname=>'user_id',
distcnt=>distcnt,
nullcnt=>nullcnt,
srec=>srec2,
avgclen=>avgclen,
density=>density
);
end;
/

-- Invalidate any cursors using T1
comment on table t1 is '';

alter session set statistics_level = all;

-- alter session set tracefile_identifier = 'smm_trace_wrong_cardinality';

-- alter session set "_smm_trace" = 65535;

select /*+ full(@inner t1)
full(@inner t2)
full(@inner t3)
leading(@inner t2 t3 t1)
use_nl(@inner t3)
use_hash(@inner t1)
no_swap_join_inputs(@inner t1)
use_hash_aggregation(@inner)
*/
max(cnt)
from
(
select /*+ qb_name(inner) */ count(*) as cnt, t1.object_id, t3.user_id
from t1, t2, t2 t3
where t1.user_id = t2.user_id
group by t1.object_id, t3.user_id
)
;

-- alter session set "_smm_trace" = 0;

set pagesize 0 linesize 200 trimspool on tab off

select * from table(dbms_xplan.display_cursor(null, null, 'ALLSTATS LAST'));

Connected to:
Oracle Database 10g Enterprise Edition Release 10.2.0.5.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options

SQL>
SQL> show parameter pga

NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
pga_aggregate_target big integer 200M
SQL> show parameter processes

NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
aq_tm_processes integer 0
db_writer_processes integer 1
gcs_server_processes integer 0
job_queue_processes integer 10
log_archive_max_processes integer 2
processes integer 150
SQL>
SQL> -- alter session set workarea_size_policy = manual sort_area_size = 40000000;
SQL>
SQL> drop table t1 purge;
drop table t1 purge
*
ERROR at line 1:
ORA-00942: table or view does not exist

Elapsed: 00:00:00.01
SQL>
SQL> drop table t2 purge;
drop table t2 purge
*
ERROR at line 1:
ORA-00942: table or view does not exist

Elapsed: 00:00:00.00
SQL>
SQL> create table t1
2 as
3 select mod(rownum, 27) as user_id, rownum as object_id from dual connect by level <= 30000;

Table created.

Elapsed: 00:00:00.07
SQL>
SQL> create table t2
2 as
3 select distinct user_id from t1;

Table created.

Elapsed: 00:00:00.06
SQL>
SQL> exec dbms_stats.gather_table_stats(null, 't1', method_opt => 'for all columns size 1')

PL/SQL procedure successfully completed.

Elapsed: 00:00:00.09
SQL>
SQL> exec dbms_stats.gather_table_stats(null, 't2', method_opt => 'for all columns size 1')

PL/SQL procedure successfully completed.

Elapsed: 00:00:00.04
SQL>
SQL> column low_val new_value low_value
SQL> column high_val new_value high_value
SQL>
SQL> select
2 max(user_id) + 1 as low_val
3 , max(user_id) + max(user_id) - min(user_id) + 1 as high_val
4 from
5 t2;

LOW_VAL HIGH_VAL
---------- ----------
27 53

Elapsed: 00:00:00.00
SQL>
SQL> -- Invalidate any cursors using T1
SQL> comment on table t1 is '';

Comment created.

Elapsed: 00:00:00.04
SQL>
SQL> alter session set statistics_level = all;

Session altered.

Elapsed: 00:00:00.00
SQL>
SQL> -- alter session set tracefile_identifier = 'smm_trace_correct_cardinality';
SQL>
SQL> -- alter session set "_smm_trace" = 65535;
SQL>
SQL> select /*+ full(@inner t1)
2 full(@inner t2)
3 full(@inner t3)
4 leading(@inner t2 t3 t1)
5 use_nl(@inner t3)
6 use_hash(@inner t1)
7 no_swap_join_inputs(@inner t1)
8 use_hash_aggregation(@inner)
9 */
10 max(cnt)
11 from
12 (
13 select /*+ qb_name(inner) */ count(*) as cnt, t1.object_id, t3.user_id
14 from t1, t2, t2 t3
15 where t1.user_id = t2.user_id
16 group by t1.object_id, t3.user_id
17 )
18 ;

MAX(CNT)
----------
1

Elapsed: 00:00:00.71
SQL>
SQL> -- alter session set "_smm_trace" = 0;
SQL>
SQL> set pagesize 0 linesize 200 trimspool on tab off
SQL>
SQL> select * from table(dbms_xplan.display_cursor(null, null, 'ALLSTATS LAST'));
SQL_ID 2s1sdfhvhajv3, child number 0
-------------------------------------
select /*+ full(@inner t1) full(@inner t2) full(@inner t3) leading(@inner
t2 t3 t1) use_nl(@inner t3) use_hash(@inner t1) no_swap_join_inputs(@inner
t1) use_hash_aggregation(@inner) */ max(cnt) from ( select /*+ qb_name(inner) */ count(*)
as cnt, t1.object_id, t3.user_id from t1, t2, t2 t3 where t1.user_id = t2.user_id group by t1.object_id,
t3.user_id )

Plan hash value: 3134842094

--------------------------------------------------------------------------------------------------------------------
| Id | Operation | Name | Starts | E-Rows | A-Rows | A-Time | Buffers | OMem | 1Mem | Used-Mem |
--------------------------------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | | 1 |00:00:00.72 | 139 | | | |
| 1 | SORT AGGREGATE | | 1 | 1 | 1 |00:00:00.72 | 139 | | | |
| 2 | VIEW | | 1 | 570K| 810K|00:00:00.43 | 139 | | | |
| 3 | HASH GROUP BY | | 1 | 570K| 810K|00:00:00.43 | 139 | 35M| 5521K| 38M (0)|
|* 4 | HASH JOIN | | 1 | 807K| 810K|00:00:00.02 | 139 | 1348K| 1348K| 1093K (0)|
| 5 | NESTED LOOPS | | 1 | 729 | 729 |00:00:00.01 | 84 | | | |
| 6 | TABLE ACCESS FULL| T2 | 1 | 27 | 27 |00:00:00.01 | 3 | | | |
| 7 | TABLE ACCESS FULL| T2 | 27 | 27 | 729 |00:00:00.01 | 81 | | | |
| 8 | TABLE ACCESS FULL | T1 | 1 | 29907 | 30000 |00:00:00.01 | 55 | | | |
--------------------------------------------------------------------------------------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------

4 - access("T1"."USER_ID"="T2"."USER_ID")

29 rows selected.

Elapsed: 00:00:00.12
SQL>
SQL> set pagesize 14
SQL>
SQL> -- Fudge the statistics so that the join cardinality between t1 and t2 will be 0 (rounded up to 1)
SQL> declare
2 srec dbms_stats.statrec;
3 novals dbms_stats.numarray;
4 distcnt number;
5 avgclen number;
6 nullcnt number;
7 density number;
8 srec2 dbms_stats.statrec;
9 begin
10 dbms_stats.get_column_stats(null, 't1', 'user_id', distcnt => distcnt, avgclen => avgclen, nullcnt => nullcnt, density => density, srec => srec);
11 srec2.epc := 2;
12 novals := dbms_stats.numarray(
13 &low_value,
14 &high_value
15 );
16 srec2.bkvals := null;
17 dbms_stats.prepare_column_values(srec2,novals);
18 dbms_stats.set_column_stats(
19 ownname=>null,
20 tabname=>'t1',
21 colname=>'user_id',
22 distcnt=>distcnt,
23 nullcnt=>nullcnt,
24 srec=>srec2,
25 avgclen=>avgclen,
26 density=>density
27 );
28 end;
29 /
old 13: &low_value,
new 13: 27,
old 14: &high_value
new 14: 53

PL/SQL procedure successfully completed.

Elapsed: 00:00:00.03
SQL>
SQL> -- Invalidate any cursors using T1
SQL> comment on table t1 is '';

Comment created.

Elapsed: 00:00:00.03
SQL>
SQL> alter session set statistics_level = all;

Session altered.

Elapsed: 00:00:00.01
SQL>
SQL> -- alter session set tracefile_identifier = 'smm_trace_wrong_cardinality';
SQL>
SQL> -- alter session set "_smm_trace" = 65535;
SQL>
SQL> select /*+ full(@inner t1)
2 full(@inner t2)
3 full(@inner t3)
4 leading(@inner t2 t3 t1)
5 use_nl(@inner t3)
6 use_hash(@inner t1)
7 no_swap_join_inputs(@inner t1)
8 use_hash_aggregation(@inner)
9 */
10 max(cnt)
11 from
12 (
13 select /*+ qb_name(inner) */ count(*) as cnt, t1.object_id, t3.user_id
14 from t1, t2, t2 t3
15 where t1.user_id = t2.user_id
16 group by t1.object_id, t3.user_id
17 )
18 ;

MAX(CNT)
----------
1

Elapsed: 00:00:01.37
SQL>
SQL> -- alter session set "_smm_trace" = 0;
SQL>
SQL> set pagesize 0 linesize 200 trimspool on tab off
SQL>
SQL> select * from table(dbms_xplan.display_cursor(null, null, 'ALLSTATS LAST'));
SQL_ID 2s1sdfhvhajv3, child number 0
-------------------------------------
select /*+ full(@inner t1) full(@inner t2) full(@inner t3) leading(@inner t2 t3 t1)
use_nl(@inner t3) use_hash(@inner t1) no_swap_join_inputs(@inner t1) use_hash_aggregation(@inner)
*/ max(cnt) from ( select /*+ qb_name(inner) */ count(*) as cnt, t1.object_id, t3.user_id from t1, t2, t2 t3 where t1.user_id =
t2.user_id group by t1.object_id, t3.user_id )

Plan hash value: 3134842094

------------------------------------------------------------------------------------------------------------------------------------------------
| Id | Operation | Name | Starts | E-Rows | A-Rows | A-Time | Buffers | Reads | Writes | OMem | 1Mem | Used-Mem | Used-Tmp|
------------------------------------------------------------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | | 1 |00:00:01.37 | 139 | 2715 | 2715 | | | | |
| 1 | SORT AGGREGATE | | 1 | 1 | 1 |00:00:01.37 | 139 | 2715 | 2715 | | | | |
| 2 | VIEW | | 1 | 1 | 810K|00:00:00.62 | 139 | 2715 | 2715 | | | | |
| 3 | HASH GROUP BY | | 1 | 1 | 810K|00:00:00.62 | 139 | 2715 | 2715 | 35M| 5521K| 7010K (1)| 23552 |
|* 4 | HASH JOIN | | 1 | 1 | 810K|00:00:00.01 | 139 | 0 | 0 | 1348K| 1348K| 1167K (0)| |
| 5 | NESTED LOOPS | | 1 | 729 | 729 |00:00:00.01 | 84 | 0 | 0 | | | | |
| 6 | TABLE ACCESS FULL| T2 | 1 | 27 | 27 |00:00:00.01 | 3 | 0 | 0 | | | | |
| 7 | TABLE ACCESS FULL| T2 | 27 | 27 | 729 |00:00:00.01 | 81 | 0 | 0 | | | | |
| 8 | TABLE ACCESS FULL | T1 | 1 | 29907 | 30000 |00:00:00.01 | 55 | 0 | 0 | | | | |
------------------------------------------------------------------------------------------------------------------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------

4 - access("T1"."USER_ID"="T2"."USER_ID")

28 rows selected.

Elapsed: 00:00:00.03
SQL>

Connected to:
Oracle Database 10g Enterprise Edition Release 10.2.0.5.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options

SQL>
SQL> show parameter pga

NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
pga_aggregate_target big integer 200M
SQL> show parameter processes

NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
aq_tm_processes integer 0
db_writer_processes integer 1
gcs_server_processes integer 0
job_queue_processes integer 10
log_archive_max_processes integer 2
processes integer 150
SQL>
SQL> drop table t1 purge;

Table dropped.

Elapsed: 00:00:00.04
SQL>
SQL> drop table t2 purge;

Table dropped.

Elapsed: 00:00:00.04
SQL>
SQL> create table t1
2 as
3 select mod(rownum, 15) as user_id, rownum as object_id from dual connect by level <= 30000;

Table created.

Elapsed: 00:00:00.06
SQL>
SQL> create table t2
2 as
3 select distinct user_id from t1;

Table created.

Elapsed: 00:00:00.03
SQL>
SQL> exec dbms_stats.gather_table_stats(null, 't1', method_opt => 'for all columns size 1')

PL/SQL procedure successfully completed.

Elapsed: 00:00:00.09
SQL>
SQL> exec dbms_stats.gather_table_stats(null, 't2', method_opt => 'for all columns size 1')

PL/SQL procedure successfully completed.

Elapsed: 00:00:00.04
SQL>
SQL> column low_val new_value low_value
SQL> column high_val new_value high_value
SQL>
SQL> select
2 max(user_id) + 1 as low_val
3 , max(user_id) + max(user_id) - min(user_id) + 1 as high_val
4 from
5 t2;

LOW_VAL HIGH_VAL
---------- ----------
15 29

Elapsed: 00:00:00.00
SQL>
SQL> -- Invalidate any cursors using T1
SQL> comment on table t1 is '';

Comment created.

Elapsed: 00:00:00.00
SQL>
SQL> alter session set statistics_level = all;

Session altered.

Elapsed: 00:00:00.00
SQL>
SQL> -- alter session set tracefile_identifier = 'smm_trace_correct_cardinality';
SQL>
SQL> -- alter session set "_smm_trace" = 65535;
SQL>
SQL> select /*+ full(@inner t1)
2 full(@inner t2)
3 full(@inner t3)
4 leading(@inner t2 t3 t1)
5 use_nl(@inner t3)
6 use_hash(@inner t1)
7 no_swap_join_inputs(@inner t1)
8 no_use_hash_aggregation(@inner)
9 */
10 max(cnt)
11 from
12 (
13 select /*+ qb_name(inner) */ count(*) as cnt, t1.object_id, t3.user_id
14 from t1, t2, t2 t3
15 where t1.user_id = t2.user_id
16 group by t1.object_id, t3.user_id
17 )
18 ;

MAX(CNT)
----------
1

Elapsed: 00:00:00.54
SQL>
SQL> -- alter session set "_smm_trace" = 0;
SQL>
SQL> set pagesize 0 linesize 200 trimspool on tab off
SQL>
SQL> select * from table(dbms_xplan.display_cursor(null, null, 'ALLSTATS LAST'));
SQL_ID 94tqnspjuzk8x, child number 0
-------------------------------------
select /*+ full(@inner t1) full(@inner t2) full(@inner t3) leading(@inner
t2 t3 t1) use_nl(@inner t3) use_hash(@inner t1) no_swap_join_inputs(@inner
t1) no_use_hash_aggregation(@inner) */ max(cnt) from ( select /*+ qb_name(inner) */
count(*) as cnt, t1.object_id, t3.user_id from t1, t2, t2 t3 where t1.user_id = t2.user_id group by
t1.object_id, t3.user_id )

Plan hash value: 2068941295

--------------------------------------------------------------------------------------------------------------------
| Id | Operation | Name | Starts | E-Rows | A-Rows | A-Time | Buffers | OMem | 1Mem | Used-Mem |
--------------------------------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | | 1 |00:00:00.53 | 103 | | | |
| 1 | SORT AGGREGATE | | 1 | 1 | 1 |00:00:00.53 | 103 | | | |
| 2 | VIEW | | 1 | 315K| 450K|00:00:00.37 | 103 | | | |
| 3 | SORT GROUP BY | | 1 | 315K| 450K|00:00:00.37 | 103 | 28M| 1913K| 25M (0)|
|* 4 | HASH JOIN | | 1 | 446K| 450K|00:00:00.01 | 103 | 1348K| 1348K| 1097K (0)|
| 5 | NESTED LOOPS | | 1 | 225 | 225 |00:00:00.01 | 48 | | | |
| 6 | TABLE ACCESS FULL| T2 | 1 | 15 | 15 |00:00:00.01 | 3 | | | |
| 7 | TABLE ACCESS FULL| T2 | 15 | 15 | 225 |00:00:00.01 | 45 | | | |
| 8 | TABLE ACCESS FULL | T1 | 1 | 29787 | 30000 |00:00:00.01 | 55 | | | |
--------------------------------------------------------------------------------------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------

4 - access("T1"."USER_ID"="T2"."USER_ID")

29 rows selected.

Elapsed: 00:00:00.03
SQL>
SQL> set pagesize 14
SQL>
SQL> -- Fudge the statistics so that the join cardinality between t1 and t2 will be 0 (rounded up to 1)
SQL> declare
2 srec dbms_stats.statrec;
3 novals dbms_stats.numarray;
4 distcnt number;
5 avgclen number;
6 nullcnt number;
7 density number;
8 srec2 dbms_stats.statrec;
9 begin
10 dbms_stats.get_column_stats(null, 't1', 'user_id', distcnt => distcnt, avgclen => avgclen, nullcnt => nullcnt, density => density, srec => srec);
11 srec2.epc := 2;
12 novals := dbms_stats.numarray(
13 &low_value,
14 &high_value
15 );
16 srec2.bkvals := null;
17 dbms_stats.prepare_column_values(srec2,novals);
18 dbms_stats.set_column_stats(
19 ownname=>null,
20 tabname=>'t1',
21 colname=>'user_id',
22 distcnt=>distcnt,
23 nullcnt=>nullcnt,
24 srec=>srec2,
25 avgclen=>avgclen,
26 density=>density
27 );
28 end;
29 /
old 13: &low_value,
new 13: 15,
old 14: &high_value
new 14: 29

PL/SQL procedure successfully completed.

Elapsed: 00:00:00.01
SQL>
SQL> -- Invalidate any cursors using T1
SQL> comment on table t1 is '';

Comment created.

Elapsed: 00:00:00.00
SQL>
SQL> alter session set statistics_level = all;

Session altered.

Elapsed: 00:00:00.00
SQL>
SQL> -- alter session set tracefile_identifier = 'smm_trace_wrong_cardinality';
SQL>
SQL> -- alter session set "_smm_trace" = 65535;
SQL>
SQL> select /*+ full(@inner t1)
2 full(@inner t2)
3 full(@inner t3)
4 leading(@inner t2 t3 t1)
5 use_nl(@inner t3)
6 use_hash(@inner t1)
7 no_swap_join_inputs(@inner t1)
8 no_use_hash_aggregation(@inner)
9 */
10 max(cnt)
11 from
12 (
13 select /*+ qb_name(inner) */ count(*) as cnt, t1.object_id, t3.user_id
14 from t1, t2, t2 t3
15 where t1.user_id = t2.user_id
16 group by t1.object_id, t3.user_id
17 )
18 ;

MAX(CNT)
----------
1

Elapsed: 00:00:00.56
SQL>
SQL> -- alter session set "_smm_trace" = 0;
SQL>
SQL> set pagesize 0 linesize 200 trimspool on tab off
SQL>
SQL> select * from table(dbms_xplan.display_cursor(null, null, 'ALLSTATS LAST'));
SQL_ID 94tqnspjuzk8x, child number 0
-------------------------------------
select /*+ full(@inner t1) full(@inner t2) full(@inner t3) leading(@inner
t2 t3 t1) use_nl(@inner t3) use_hash(@inner t1) no_swap_join_inputs(@inner
t1) no_use_hash_aggregation(@inner) */ max(cnt) from ( select /*+ qb_name(inner) */
count(*) as cnt, t1.object_id, t3.user_id from t1, t2, t2 t3 where t1.user_id = t2.user_id group by
t1.object_id, t3.user_id )

Plan hash value: 2068941295

--------------------------------------------------------------------------------------------------------------------
| Id | Operation | Name | Starts | E-Rows | A-Rows | A-Time | Buffers | OMem | 1Mem | Used-Mem |
--------------------------------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | | 1 |00:00:00.55 | 103 | | | |
| 1 | SORT AGGREGATE | | 1 | 1 | 1 |00:00:00.55 | 103 | | | |
| 2 | VIEW | | 1 | 1 | 450K|00:00:00.38 | 103 | | | |
| 3 | SORT GROUP BY | | 1 | 1 | 450K|00:00:00.38 | 103 | 28M| 1913K| 25M (0)|
|* 4 | HASH JOIN | | 1 | 1 | 450K|00:00:00.01 | 103 | 1348K| 1348K| 1053K (0)|
| 5 | NESTED LOOPS | | 1 | 225 | 225 |00:00:00.01 | 48 | | | |
| 6 | TABLE ACCESS FULL| T2 | 1 | 15 | 15 |00:00:00.01 | 3 | | | |
| 7 | TABLE ACCESS FULL| T2 | 15 | 15 | 225 |00:00:00.01 | 45 | | | |
| 8 | TABLE ACCESS FULL | T1 | 1 | 29787 | 30000 |00:00:00.01 | 55 | | | |
--------------------------------------------------------------------------------------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------

4 - access("T1"."USER_ID"="T2"."USER_ID")

29 rows selected.

Elapsed: 00:00:00.03
SQL>

Connected to:
Oracle Database 10g Enterprise Edition Release 10.2.0.5.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options

SQL>
SQL> alter session set statistics_level = all;

Session altered.

Elapsed: 00:00:00.00
SQL>
SQL> alter session set tracefile_identifier = 'smm_trace_wrong_cardinality_repeated_execution';

Session altered.

Elapsed: 00:00:00.00
SQL>
SQL> alter session set "_smm_trace" = 65535;

Session altered.

Elapsed: 00:00:00.00
SQL>
SQL> select /*+ full(@inner t1)
2 full(@inner t2)
3 full(@inner t3)
4 leading(@inner t2 t3 t1)
5 use_nl(@inner t3)
6 use_hash(@inner t1)
7 no_swap_join_inputs(@inner t1)
8 use_hash_aggregation(@inner)
9 */
10 max(cnt)
11 from
12 (
13 select /*+ qb_name(inner) */ count(*) as cnt, t1.object_id, t3.user_id
14 from t1, t2, t2 t3
15 where t1.user_id = t2.user_id
16 group by t1.object_id, t3.user_id
17 )
18 ;

MAX(CNT)
----------
1

Elapsed: 00:00:00.76
SQL>
SQL> alter session set "_smm_trace" = 0;

Session altered.

Elapsed: 00:00:00.00
SQL>
SQL> set pagesize 0 linesize 200 trimspool on tab off
SQL>
SQL> select * from table(dbms_xplan.display_cursor(null, null, 'ALLSTATS LAST'));
SQL_ID 2s1sdfhvhajv3, child number 0
-------------------------------------
select /*+ full(@inner t1) full(@inner t2) full(@inner t3) leading(@inner t2 t3 t1)
use_nl(@inner t3) use_hash(@inner t1) no_swap_join_inputs(@inner t1)
use_hash_aggregation(@inner) */ max(cnt) from ( select /*+ qb_name(inner) */ count(*) as cnt, t1.object_id,
t3.user_id from t1, t2, t2 t3 where t1.user_id = t2.user_id group by t1.object_id, t3.user_id )

Plan hash value: 3134842094

------------------------------------------------------------------------------------------------------------------------------
| Id | Operation | Name | Starts | E-Rows | A-Rows | A-Time | Buffers | OMem | 1Mem | Used-Mem | Used-Tmp|
------------------------------------------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | | 1 |00:00:00.75 | 139 | | | | |
| 1 | SORT AGGREGATE | | 1 | 1 | 1 |00:00:00.75 | 139 | | | | |
| 2 | VIEW | | 1 | 1 | 810K|00:00:00.44 | 139 | | | | |
| 3 | HASH GROUP BY | | 1 | 1 | 810K|00:00:00.44 | 139 | 35M| 5521K| 38M (0)| |
|* 4 | HASH JOIN | | 1 | 1 | 810K|00:00:00.01 | 139 | 1348K| 1348K| 1412K (0)| |
| 5 | NESTED LOOPS | | 1 | 729 | 729 |00:00:00.01 | 84 | | | | |
| 6 | TABLE ACCESS FULL| T2 | 1 | 27 | 27 |00:00:00.01 | 3 | | | | |
| 7 | TABLE ACCESS FULL| T2 | 27 | 27 | 729 |00:00:00.01 | 81 | | | | |
| 8 | TABLE ACCESS FULL | T1 | 1 | 29836 | 30000 |00:00:00.01 | 55 | | | | |
------------------------------------------------------------------------------------------------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------

4 - access("T1"."USER_ID"="T2"."USER_ID")

28 rows selected.

Elapsed: 00:00:00.03
SQL>

SQL> comment on table t1 is '';

Comment created.

Elapsed: 00:00:00.01
SQL> set echo on timing on
SQL>
SQL> alter session set statistics_level = all;

Session altered.

Elapsed: 00:00:00.00
SQL>
SQL> alter session set tracefile_identifier = 'smm_trace_wrong_cardinality_repeated_exec_invalid';

Session altered.

Elapsed: 00:00:00.01
SQL>
SQL> alter session set "_smm_trace" = 65535;

Session altered.

Elapsed: 00:00:00.00
SQL>
SQL> select /*+ full(@inner t1)
2 full(@inner t2)
3 full(@inner t3)
4 leading(@inner t2 t3 t1)
5 use_nl(@inner t3)
6 use_hash(@inner t1)
7 no_swap_join_inputs(@inner t1)
8 use_hash_aggregation(@inner)
9 */
10 max(cnt)
11 from
12 (
13 select /*+ qb_name(inner) */ count(*) as cnt, t1.object_id, t3.user_id
14 from t1, t2, t2 t3
15 where t1.user_id = t2.user_id
16 group by t1.object_id, t3.user_id
17 )
18 ;
1

Elapsed: 00:00:01.29
SQL>
SQL> alter session set "_smm_trace" = 0;

Session altered.

Elapsed: 00:00:00.00
SQL>
SQL> set pagesize 0 linesize 200 trimspool on tab off
SQL>
SQL> select * from table(dbms_xplan.display_cursor(null, null, 'ALLSTATS LAST'));
SQL_ID 2s1sdfhvhajv3, child number 0
-------------------------------------
select /*+ full(@inner t1) full(@inner t2) full(@inner t3) leading(@inner t2 t3 t1)
use_nl(@inner t3) use_hash(@inner t1) no_swap_join_inputs(@inner t1) use_hash_aggregation(@inner)
*/ max(cnt) from ( select /*+ qb_name(inner) */ count(*) as cnt, t1.object_id, t3.user_id from t1, t2, t2 t3 where t1.user_id =
t2.user_id group by t1.object_id, t3.user_id )

Plan hash value: 3134842094

------------------------------------------------------------------------------------------------------------------------------------------------
| Id | Operation | Name | Starts | E-Rows | A-Rows | A-Time | Buffers | Reads | Writes | OMem | 1Mem | Used-Mem | Used-Tmp|
------------------------------------------------------------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | | 1 |00:00:01.28 | 139 | 2715 | 2715 | | | | |
| 1 | SORT AGGREGATE | | 1 | 1 | 1 |00:00:01.28 | 139 | 2715 | 2715 | | | | |
| 2 | VIEW | | 1 | 1 | 810K|00:00:00.61 | 139 | 2715 | 2715 | | | | |
| 3 | HASH GROUP BY | | 1 | 1 | 810K|00:00:00.61 | 139 | 2715 | 2715 | 35M| 5521K| 7067K (1)| 23552 |
|* 4 | HASH JOIN | | 1 | 1 | 810K|00:00:00.01 | 139 | 0 | 0 | 1348K| 1348K| 1129K (0)| |
| 5 | NESTED LOOPS | | 1 | 729 | 729 |00:00:00.01 | 84 | 0 | 0 | | | | |
| 6 | TABLE ACCESS FULL| T2 | 1 | 27 | 27 |00:00:00.01 | 3 | 0 | 0 | | | | |
| 7 | TABLE ACCESS FULL| T2 | 27 | 27 | 729 |00:00:00.01 | 81 | 0 | 0 | | | | |
| 8 | TABLE ACCESS FULL | T1 | 1 | 29836 | 30000 |00:00:00.01 | 55 | 0 | 0 | | | | |
------------------------------------------------------------------------------------------------------------------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------

4 - access("T1"."USER_ID"="T2"."USER_ID")

28 rows selected.

Elapsed: 00:00:00.03
SQL>

Connected to:
Oracle Database 10g Enterprise Edition Release 10.2.0.5.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options

SQL>
SQL> show parameter pga

NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
pga_aggregate_target big integer 200M
SQL> show parameter processes

NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
aq_tm_processes integer 0
db_writer_processes integer 1
gcs_server_processes integer 0
job_queue_processes integer 10
log_archive_max_processes integer 2
processes integer 150
SQL>
SQL> -- alter session set workarea_size_policy = manual sort_area_size = 40000000;
SQL>
SQL> drop table t1 purge;

Table dropped.

Elapsed: 00:00:00.01
SQL>
SQL> drop table t2 purge;

Table dropped.

Elapsed: 00:00:00.04
SQL>
SQL> create table t1
2 as
3 select mod(rownum, 27) as user_id, rownum as object_id from dual connect by level <= 30000;

Table created.

Elapsed: 00:00:00.06
SQL>
SQL> alter table t1 parallel 2;

Table altered.

Elapsed: 00:00:00.03
SQL>
SQL> create table t2
2 as
3 select distinct user_id from t1;

Table created.

Elapsed: 00:00:00.03
SQL>
SQL> exec dbms_stats.gather_table_stats(null, 't1', method_opt => 'for all columns size 1')

PL/SQL procedure successfully completed.

Elapsed: 00:00:00.04
SQL>
SQL> exec dbms_stats.gather_table_stats(null, 't2', method_opt => 'for all columns size 1')

PL/SQL procedure successfully completed.

Elapsed: 00:00:00.04
SQL>
SQL> column low_val new_value low_value
SQL> column high_val new_value high_value
SQL>
SQL> select
2 max(user_id) + 1 as low_val
3 , max(user_id) + max(user_id) - min(user_id) + 1 as high_val
4 from
5 t2;

LOW_VAL HIGH_VAL
---------- ----------
27 53

Elapsed: 00:00:00.00
SQL>
SQL> -- Invalidate any cursors using T1
SQL> comment on table t1 is '';

Comment created.

Elapsed: 00:00:00.00
SQL>
SQL> alter session set statistics_level = all;

Session altered.

Elapsed: 00:00:00.00
SQL>
SQL> alter session set tracefile_identifier = 'smm_trace_correct_cardinality';

Session altered.

Elapsed: 00:00:00.01
SQL>
SQL> alter session set "_smm_trace" = 65535;

Session altered.

Elapsed: 00:00:00.00
SQL>
SQL> select /*+ full(@inner t1)
2 full(@inner t2)
3 full(@inner t3)
4 leading(@inner t2 t3 t1)
5 use_nl(@inner t3)
6 use_hash(@inner t1)
7 no_swap_join_inputs(@inner t1)
8 use_hash_aggregation(@inner)
9 */
10 max(cnt)
11 from
12 (
13 select /*+ qb_name(inner) */ count(*) as cnt, t1.object_id, t3.user_id
14 from t1, t2, t2 t3
15 where t1.user_id = t2.user_id
16 group by t1.object_id, t3.user_id
17 )
18 ;

MAX(CNT)
----------
1

Elapsed: 00:00:00.42
SQL>
SQL> alter session set "_smm_trace" = 0;

Session altered.

Elapsed: 00:00:00.00
SQL>
SQL> set pagesize 0 linesize 200 trimspool on tab off
SQL>
SQL> select * from table(dbms_xplan.display_cursor(null, null, 'ALLSTATS'));
SQL_ID 2s1sdfhvhajv3, child number 0
-------------------------------------
select /*+ full(@inner t1) full(@inner t2) full(@inner t3) leading(@inner t2 t3 t1)
use_nl(@inner t3) use_hash(@inner t1) no_swap_join_inputs(@inner t1)
use_hash_aggregation(@inner) */ max(cnt) from ( select /*+ qb_name(inner) */ count(*) as cnt, t1.object_id,
t3.user_id from t1, t2, t2 t3 where t1.user_id = t2.user_id group by t1.object_id, t3.user_id )

Plan hash value: 464898991

--------------------------------------------------------------------------------------------------------------------------------
| Id | Operation | Name | Starts | E-Rows | A-Rows | A-Time | Buffers | OMem | 1Mem | O/1/M |
--------------------------------------------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | | 1 |00:00:00.43 | 87 | | | |
| 1 | SORT AGGREGATE | | 1 | 1 | 1 |00:00:00.43 | 87 | | | |
| 2 | PX COORDINATOR | | 1 | | 2 |00:00:00.43 | 87 | | | |
| 3 | PX SEND QC (RANDOM) | :TQ10002 | 0 | 1 | 0 |00:00:00.01 | 0 | | | |
| 4 | SORT AGGREGATE | | 2 | 1 | 2 |00:00:00.81 | 0 | | | |
| 5 | VIEW | | 2 | 575K| 810K|00:00:00.48 | 0 | | | |
| 6 | HASH GROUP BY | | 2 | 575K| 810K|00:00:00.48 | 0 | 35M| 5521K| 2/0/0|
| 7 | PX RECEIVE | | 2 | 814K| 810K|00:00:00.01 | 0 | | | |
| 8 | PX SEND HASH | :TQ10001 | 0 | 814K| 0 |00:00:00.01 | 0 | | | |
|* 9 | HASH JOIN | | 2 | 814K| 810K|00:00:00.01 | 89 | 1348K| 1348K| 2/0/0|
| 10 | BUFFER SORT | | 2 | | 1458 |00:00:00.01 | 0 | 29696 | 29696 | 2/0/0|
| 11 | PX RECEIVE | | 2 | 729 | 1458 |00:00:00.01 | 0 | | | |
| 12 | PX SEND BROADCAST | :TQ10000 | 0 | 729 | 0 |00:00:00.01 | 0 | | | |
| 13 | NESTED LOOPS | | 1 | 729 | 729 |00:00:00.01 | 84 | | | |
| 14 | TABLE ACCESS FULL| T2 | 1 | 27 | 27 |00:00:00.01 | 3 | | | |
| 15 | TABLE ACCESS FULL| T2 | 27 | 27 | 729 |00:00:00.01 | 81 | | | |
| 16 | PX BLOCK ITERATOR | | 2 | 30164 | 30000 |00:00:00.01 | 89 | | | |
|* 17 | TABLE ACCESS FULL | T1 | 18 | 30164 | 30000 |00:00:00.01 | 89 | | | |
--------------------------------------------------------------------------------------------------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------

9 - access("T1"."USER_ID"="T2"."USER_ID")
17 - access(:Z>=:Z AND :Z<=:Z)

38 rows selected.

Elapsed: 00:00:00.03
SQL>
SQL> set pagesize 14
SQL>
SQL> -- Fudge the statistics so that the join cardinality between t1 and t2 will be 0 (rounded up to 1)
SQL> declare
2 srec dbms_stats.statrec;
3 novals dbms_stats.numarray;
4 distcnt number;
5 avgclen number;
6 nullcnt number;
7 density number;
8 srec2 dbms_stats.statrec;
9 begin
10 dbms_stats.get_column_stats(null, 't1', 'user_id', distcnt => distcnt, avgclen => avgclen, nullcnt => nullcnt, density => density, srec => srec);
11 srec2.epc := 2;
12 novals := dbms_stats.numarray(
13 &low_value,
14 &high_value
15 );
16 srec2.bkvals := null;
17 dbms_stats.prepare_column_values(srec2,novals);
18 dbms_stats.set_column_stats(
19 ownname=>null,
20 tabname=>'t1',
21 colname=>'user_id',
22 distcnt=>distcnt,
23 nullcnt=>nullcnt,
24 srec=>srec2,
25 avgclen=>avgclen,
26 density=>density
27 );
28 end;
29 /
old 13: &low_value,
new 13: 27,
old 14: &high_value
new 14: 53

PL/SQL procedure successfully completed.

Elapsed: 00:00:00.00
SQL>
SQL> -- Invalidate any cursors using T1
SQL> comment on table t1 is '';

Comment created.

Elapsed: 00:00:00.00
SQL>
SQL> alter session set statistics_level = all;

Session altered.

Elapsed: 00:00:00.00
SQL>
SQL> alter session set tracefile_identifier = 'smm_trace_wrong_cardinality';

Session altered.

Elapsed: 00:00:00.00
SQL>
SQL> alter session set "_smm_trace" = 65535;

Session altered.

Elapsed: 00:00:00.00
SQL>
SQL> select /*+ full(@inner t1)
2 full(@inner t2)
3 full(@inner t3)
4 leading(@inner t2 t3 t1)
5 use_nl(@inner t3)
6 use_hash(@inner t1)
7 no_swap_join_inputs(@inner t1)
8 use_hash_aggregation(@inner)
9 */
10 max(cnt)
11 from
12 (
13 select /*+ qb_name(inner) */ count(*) as cnt, t1.object_id, t3.user_id
14 from t1, t2, t2 t3
15 where t1.user_id = t2.user_id
16 group by t1.object_id, t3.user_id
17 )
18 ;

MAX(CNT)
----------
1

Elapsed: 00:00:01.17
SQL>
SQL> alter session set "_smm_trace" = 0;

Session altered.

Elapsed: 00:00:00.00
SQL>
SQL> set pagesize 0 linesize 200 trimspool on tab off
SQL>
SQL> select * from table(dbms_xplan.display_cursor(null, null, 'ALLSTATS'));
SQL_ID 2s1sdfhvhajv3, child number 0
-------------------------------------
select /*+ full(@inner t1) full(@inner t2) full(@inner t3) leading(@inner t2 t3 t1) use_nl(@inner t3)
use_hash(@inner t1) no_swap_join_inputs(@inner t1) use_hash_aggregation(@inner) */ max(cnt) from ( select /*+
qb_name(inner) */ count(*) as cnt, t1.object_id, t3.user_id from t1, t2, t2 t3 where t1.user_id = t2.user_id group by t1.object_id, t3.user_id )

Plan hash value: 464898991

------------------------------------------------------------------------------------------------------------------------------------------------------------
| Id | Operation | Name | Starts | E-Rows | A-Rows | A-Time | Buffers | Reads | Writes | OMem | 1Mem | O/1/M | Max-Tmp |
------------------------------------------------------------------------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | | 1 |00:00:01.16 | 87 | 0 | 0 | | | | |
| 1 | SORT AGGREGATE | | 1 | 1 | 1 |00:00:01.16 | 87 | 0 | 0 | | | | |
| 2 | PX COORDINATOR | | 1 | | 2 |00:00:01.16 | 87 | 0 | 0 | | | | |
| 3 | PX SEND QC (RANDOM) | :TQ10002 | 0 | 1 | 0 |00:00:00.01 | 0 | 0 | 0 | | | | |
| 4 | SORT AGGREGATE | | 2 | 1 | 2 |00:00:02.25 | 0 | 2460 | 2460 | | | | |
| 5 | VIEW | | 2 | 1 | 810K|00:00:01.53 | 0 | 2460 | 2460 | | | | |
| 6 | HASH GROUP BY | | 2 | 1 | 810K|00:00:01.53 | 0 | 2460 | 2460 | 35M| 5521K| | 11264 |
| 7 | PX RECEIVE | | 2 | 1 | 810K|00:00:00.01 | 0 | 0 | 0 | | | | |
| 8 | PX SEND HASH | :TQ10001 | 0 | 1 | 0 |00:00:00.01 | 0 | 0 | 0 | | | | |
|* 9 | HASH JOIN | | 2 | 1 | 810K|00:00:00.01 | 89 | 0 | 0 | 1348K| 1348K| 2/0/0| |
| 10 | BUFFER SORT | | 2 | | 1458 |00:00:00.01 | 0 | 0 | 0 | 29696 | 29696 | 2/0/0| |
| 11 | PX RECEIVE | | 2 | 729 | 1458 |00:00:00.01 | 0 | 0 | 0 | | | | |
| 12 | PX SEND BROADCAST | :TQ10000 | 0 | 729 | 0 |00:00:00.01 | 0 | 0 | 0 | | | | |
| 13 | NESTED LOOPS | | 1 | 729 | 729 |00:00:00.01 | 84 | 0 | 0 | | | | |
| 14 | TABLE ACCESS FULL| T2 | 1 | 27 | 27 |00:00:00.01 | 3 | 0 | 0 | | | | |
| 15 | TABLE ACCESS FULL| T2 | 27 | 27 | 729 |00:00:00.01 | 81 | 0 | 0 | | | | |
| 16 | PX BLOCK ITERATOR | | 2 | 30164 | 30000 |00:00:00.01 | 89 | 0 | 0 | | | | |
|* 17 | TABLE ACCESS FULL | T1 | 18 | 30164 | 30000 |00:00:00.01 | 89 | 0 | 0 | | | | |
------------------------------------------------------------------------------------------------------------------------------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------

9 - access("T1"."USER_ID"="T2"."USER_ID")
17 - access(:Z>=:Z AND :Z<=:Z)

37 rows selected.

Elapsed: 00:00:00.04
SQL>

set echo on timing on

show parameter pga
show parameter processes

-- alter session set workarea_size_policy = manual sort_area_size = 40000000;

drop table t1 purge;

drop table t2 purge;

create table t1
as
select mod(rownum, 27) as user_id, rownum as object_id from dual connect by level <= 30000;

create table t2
as
select distinct user_id from t1;

exec dbms_stats.gather_table_stats(null, 't1', method_opt => 'for all columns size 1')

exec dbms_stats.gather_table_stats(null, 't2', method_opt => 'for all columns size 1')

column low_val new_value low_value
column high_val new_value high_value

select
max(user_id) + 1 as low_val
, max(user_id) + max(user_id) - min(user_id) + 1 as high_val
from
t2;

-- Invalidate any cursors using T1
comment on table t1 is '';

alter session set statistics_level = all;

alter session set tracefile_identifier = 'smm_trace_correct_cardinality';

alter session set "_smm_trace" = 65535;

select /*+ full(@inner t1)
full(@inner t2)
full(@inner t3)
leading(@inner t2 t3 t1)
use_nl(@inner t3)
use_nl(@inner t1)
use_hash_aggregation(@inner)
*/
max(user_id)
from
(
select /*+ qb_name(inner) no_merge */ distinct t1.object_id, t3.user_id
from t1, t2, t2 t3
where t1.user_id = t2.user_id
)
;

alter session set "_smm_trace" = 0;

set pagesize 0 linesize 200 trimspool on tab off

select * from table(dbms_xplan.display_cursor(null, null, 'ALLSTATS LAST'));

set pagesize 14

-- Fudge the statistics so that the join cardinality between t1 and t2 will be 0 (rounded up to 1)
declare
srec dbms_stats.statrec;
novals dbms_stats.numarray;
distcnt number;
avgclen number;
nullcnt number;
density number;
srec2 dbms_stats.statrec;
begin
dbms_stats.get_column_stats(null, 't1', 'user_id', distcnt => distcnt, avgclen => avgclen, nullcnt => nullcnt, density => density, srec => srec);
srec2.epc := 2;
novals := dbms_stats.numarray(
&low_value,
&high_value
);
srec2.bkvals := null;
dbms_stats.prepare_column_values(srec2,novals);
dbms_stats.set_column_stats(
ownname=>null,
tabname=>'t1',
colname=>'user_id',
distcnt=>distcnt,
nullcnt=>nullcnt,
srec=>srec2,
avgclen=>avgclen,
density=>density
);
end;
/

-- Invalidate any cursors using T1
comment on table t1 is '';

alter session set statistics_level = all;

alter session set tracefile_identifier = 'smm_trace_wrong_cardinality';

alter session set "_smm_trace" = 65535;

select /*+ full(@inner t1)
full(@inner t2)
full(@inner t3)
leading(@inner t2 t3 t1)
use_nl(@inner t3)
use_nl(@inner t1)
use_hash_aggregation(@inner)
*/
max(user_id)
from
(
select /*+ qb_name(inner) no_merge */ distinct t1.object_id, t3.user_id
from t1, t2, t2 t3
where t1.user_id = t2.user_id
)
;

alter session set "_smm_trace" = 0;

set pagesize 0 linesize 200 trimspool on tab off

select * from table(dbms_xplan.display_cursor(null, null, 'ALLSTATS LAST'));

Connected to:
Oracle Database 11g Enterprise Edition Release 11.1.0.7.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options

SQL>
SQL> show parameter pga

NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
pga_aggregate_target big integer 0
SQL> show parameter processes

NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
aq_tm_processes integer 0
db_writer_processes integer 1
gcs_server_processes integer 0
global_txn_processes integer 1
job_queue_processes integer 1000
log_archive_max_processes integer 4
processes integer 150
SQL>
SQL> -- alter session set workarea_size_policy = manual sort_area_size = 40000000;
SQL>
SQL> drop table t1 purge;

Table dropped.

Elapsed: 00:00:00.01
SQL>
SQL> drop table t2 purge;

Table dropped.

Elapsed: 00:00:00.00
SQL>
SQL> create table t1
2 as
3 select mod(rownum, 27) as user_id, rownum as object_id from dual connect by level <= 30000;

Table created.

Elapsed: 00:00:00.04
SQL>
SQL> create table t2
2 as
3 select distinct user_id from t1;

Table created.

Elapsed: 00:00:00.04
SQL>
SQL> exec dbms_stats.gather_table_stats(null, 't1', method_opt => 'for all columns size 1')

PL/SQL procedure successfully completed.

Elapsed: 00:00:00.06
SQL>
SQL> exec dbms_stats.gather_table_stats(null, 't2', method_opt => 'for all columns size 1')

PL/SQL procedure successfully completed.

Elapsed: 00:00:00.01
SQL>
SQL> column low_val new_value low_value
SQL> column high_val new_value high_value
SQL>
SQL> select
2 max(user_id) + 1 as low_val
3 , max(user_id) + max(user_id) - min(user_id) + 1 as high_val
4 from
5 t2;

LOW_VAL HIGH_VAL
---------- ----------
27 53

Elapsed: 00:00:00.00
SQL>
SQL> -- Invalidate any cursors using T1
SQL> comment on table t1 is '';

Comment created.

Elapsed: 00:00:00.00
SQL>
SQL> alter session set statistics_level = all;

Session altered.

Elapsed: 00:00:00.00
SQL>
SQL> alter session set tracefile_identifier = 'smm_trace_correct_cardinality';

Session altered.

Elapsed: 00:00:00.00
SQL>
SQL> alter session set "_smm_trace" = 65535;

Session altered.

Elapsed: 00:00:00.00
SQL>
SQL> select /*+ full(@inner t1)
2 full(@inner t2)
3 full(@inner t3)
4 leading(@inner t2 t3 t1)
5 use_nl(@inner t3)
6 use_nl(@inner t1)
7 use_hash_aggregation(@inner)
8 */
9 max(user_id)
10 from
11 (
12 select /*+ qb_name(inner) no_merge */ distinct t1.object_id, t3.user_id
13 from t1, t2, t2 t3
14 where t1.user_id = t2.user_id
15 )
16 ;

MAX(USER_ID)
------------
26

Elapsed: 00:00:01.79
SQL>
SQL> alter session set "_smm_trace" = 0;

Session altered.

Elapsed: 00:00:00.00
SQL>
SQL> set pagesize 0 linesize 200 trimspool on tab off
SQL>
SQL> select * from table(dbms_xplan.display_cursor(null, null, 'ALLSTATS LAST'));
SQL_ID 7cnqz02uwcs1a, child number 0
-------------------------------------
select /*+ full(@inner t1) full(@inner t2)
full(@inner t3) leading(@inner t2 t3 t1)
use_nl(@inner t3) use_nl(@inner t1)
use_hash_aggregation(@inner) */ max(user_id) from ( select /*+
qb_name(inner) no_merge */ distinct t1.object_id, t3.user_id from t1,
t2, t2 t3 where t1.user_id = t2.user_id )

Plan hash value: 1541846686

------------------------------------------------------------------------------------------------------------------------------------------------
| Id | Operation | Name | Starts | E-Rows | A-Rows | A-Time | Buffers | Reads | Writes | OMem | 1Mem | Used-Mem | Used-Tmp|
------------------------------------------------------------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | | 1 |00:00:01.78 | 40179 | 1470 | 1470 | | | | |
| 1 | SORT AGGREGATE | | 1 | 1 | 1 |00:00:01.78 | 40179 | 1470 | 1470 | | | | |
| 2 | VIEW | | 1 | 572K| 810K|00:00:00.97 | 40179 | 1470 | 1470 | | | | |
| 3 | HASH UNIQUE | | 1 | 572K| 810K|00:00:00.97 | 40179 | 1470 | 1470 | 25M| 3296K| 6029K (1)| 13312 |
| 4 | NESTED LOOPS | | 1 | 810K| 810K|00:00:00.01 | 40179 | 0 | 0 | | | | |
| 5 | NESTED LOOPS | | 1 | 729 | 729 |00:00:00.01 | 84 | 0 | 0 | | | | |
| 6 | TABLE ACCESS FULL| T2 | 1 | 27 | 27 |00:00:00.01 | 3 | 0 | 0 | | | | |
| 7 | TABLE ACCESS FULL| T2 | 27 | 27 | 729 |00:00:00.01 | 81 | 0 | 0 | | | | |
|* 8 | TABLE ACCESS FULL | T1 | 729 | 1111 | 810K|00:00:00.03 | 40095 | 0 | 0 | | | | |
------------------------------------------------------------------------------------------------------------------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------

8 - filter("T1"."USER_ID"="T2"."USER_ID")

30 rows selected.

Elapsed: 00:00:00.03
SQL>
SQL> set pagesize 14
SQL>
SQL> -- Fudge the statistics so that the join cardinality between t1 and t2 will be 0 (rounded up to 1)
SQL> declare
2 srec dbms_stats.statrec;
3 novals dbms_stats.numarray;
4 distcnt number;
5 avgclen number;
6 nullcnt number;
7 density number;
8 srec2 dbms_stats.statrec;
9 begin
10 dbms_stats.get_column_stats(null, 't1', 'user_id', distcnt => distcnt, avgclen => avgclen, nullcnt => nullcnt, density => density, srec => srec);
11 srec2.epc := 2;
12 novals := dbms_stats.numarray(
13 &low_value,
14 &high_value
15 );
16 srec2.bkvals := null;
17 dbms_stats.prepare_column_values(srec2,novals);
18 dbms_stats.set_column_stats(
19 ownname=>null,
20 tabname=>'t1',
21 colname=>'user_id',
22 distcnt=>distcnt,
23 nullcnt=>nullcnt,
24 srec=>srec2,
25 avgclen=>avgclen,
26 density=>density
27 );
28 end;
29 /
old 13: &low_value,
new 13: 27,
old 14: &high_value
new 14: 53

PL/SQL procedure successfully completed.

Elapsed: 00:00:00.03
SQL>
SQL> -- Invalidate any cursors using T1
SQL> comment on table t1 is '';

Comment created.

Elapsed: 00:00:00.00
SQL>
SQL> alter session set statistics_level = all;

Session altered.

Elapsed: 00:00:00.00
SQL>
SQL> alter session set tracefile_identifier = 'smm_trace_wrong_cardinality';

Session altered.

Elapsed: 00:00:00.01
SQL>
SQL> alter session set "_smm_trace" = 65535;

Session altered.

Elapsed: 00:00:00.00
SQL>
SQL> select /*+ full(@inner t1)
2 full(@inner t2)
3 full(@inner t3)
4 leading(@inner t2 t3 t1)
5 use_nl(@inner t3)
6 use_nl(@inner t1)
7 use_hash_aggregation(@inner)
8 */
9 max(user_id)
10 from
11 (
12 select /*+ qb_name(inner) no_merge */ distinct t1.object_id, t3.user_id
13 from t1, t2, t2 t3
14 where t1.user_id = t2.user_id
15 )
16 ;

MAX(USER_ID)
------------
26

Elapsed: 00:00:01.26
SQL>
SQL> alter session set "_smm_trace" = 0;

Session altered.

Elapsed: 00:00:00.00
SQL>
SQL> set pagesize 0 linesize 200 trimspool on tab off
SQL>
SQL> select * from table(dbms_xplan.display_cursor(null, null, 'ALLSTATS LAST'));
SQL_ID 7cnqz02uwcs1a, child number 0
-------------------------------------
select /*+ full(@inner t1) full(@inner t2)
full(@inner t3) leading(@inner t2 t3 t1)
use_nl(@inner t3) use_nl(@inner t1)
use_hash_aggregation(@inner) */ max(user_id) from ( select /*+
qb_name(inner) no_merge */ distinct t1.object_id, t3.user_id from t1,
t2, t2 t3 where t1.user_id = t2.user_id )

Plan hash value: 1541846686

------------------------------------------------------------------------------------------------------------------------------------------------
| Id | Operation | Name | Starts | E-Rows | A-Rows | A-Time | Buffers | Reads | Writes | OMem | 1Mem | Used-Mem | Used-Tmp|
------------------------------------------------------------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | | 1 |00:00:01.26 | 40179 | 1470 | 1470 | | | | |
| 1 | SORT AGGREGATE | | 1 | 1 | 1 |00:00:01.26 | 40179 | 1470 | 1470 | | | | |
| 2 | VIEW | | 1 | 1 | 810K|00:00:00.98 | 40179 | 1470 | 1470 | | | | |
| 3 | HASH UNIQUE | | 1 | 1 | 810K|00:00:00.98 | 40179 | 1470 | 1470 | 25M| 3296K| 6093K (1)| 13312 |
| 4 | NESTED LOOPS | | 1 | 1 | 810K|00:00:00.01 | 40179 | 0 | 0 | | | | |
| 5 | NESTED LOOPS | | 1 | 729 | 729 |00:00:00.01 | 84 | 0 | 0 | | | | |
| 6 | TABLE ACCESS FULL| T2 | 1 | 27 | 27 |00:00:00.01 | 3 | 0 | 0 | | | | |
| 7 | TABLE ACCESS FULL| T2 | 27 | 27 | 729 |00:00:00.01 | 81 | 0 | 0 | | | | |
|* 8 | TABLE ACCESS FULL | T1 | 729 | 1 | 810K|00:00:00.01 | 40095 | 0 | 0 | | | | |
------------------------------------------------------------------------------------------------------------------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------

8 - filter("T1"."USER_ID"="T2"."USER_ID")

30 rows selected.

Elapsed: 00:00:00.03
SQL>

Connected to:
Oracle Database 11g Enterprise Edition Release 11.1.0.7.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options

SQL>
SQL> show parameter pga

NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
pga_aggregate_target big integer 0
SQL> show parameter processes

NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
aq_tm_processes integer 0
db_writer_processes integer 1
gcs_server_processes integer 0
global_txn_processes integer 1
job_queue_processes integer 1000
log_archive_max_processes integer 4
processes integer 150
SQL>
SQL> drop table t1 purge;

Table dropped.

Elapsed: 00:00:00.15
SQL>
SQL> drop table t2 purge;

Table dropped.

Elapsed: 00:00:00.07
SQL>
SQL> create table t1
2 as
3 select mod(rownum, 15) as user_id, rownum as object_id from dual connect by level <= 30000;

Table created.

Elapsed: 00:00:00.06
SQL>
SQL> create table t2
2 as
3 select distinct user_id from t1;

Table created.

Elapsed: 00:00:00.04
SQL>
SQL> exec dbms_stats.gather_table_stats(null, 't1', method_opt => 'for all columns size 1')

PL/SQL procedure successfully completed.

Elapsed: 00:00:00.04
SQL>
SQL> exec dbms_stats.gather_table_stats(null, 't2', method_opt => 'for all columns size 1')

PL/SQL procedure successfully completed.

Elapsed: 00:00:00.03
SQL>
SQL> column low_val new_value low_value
SQL> column high_val new_value high_value
SQL>
SQL> select
2 max(user_id) + 1 as low_val
3 , max(user_id) + max(user_id) - min(user_id) + 1 as high_val
4 from
5 t2;

LOW_VAL HIGH_VAL
---------- ----------
15 29

Elapsed: 00:00:00.00
SQL>
SQL> -- Invalidate any cursors using T1
SQL> comment on table t1 is '';

Comment created.

Elapsed: 00:00:00.00
SQL>
SQL> alter session set statistics_level = all;

Session altered.

Elapsed: 00:00:00.00
SQL>
SQL> alter session set tracefile_identifier = 'smm_trace_correct_cardinality';

Session altered.

Elapsed: 00:00:00.00
SQL>
SQL> alter session set "_smm_trace" = 65535;

Session altered.

Elapsed: 00:00:00.00
SQL>
SQL> select /*+ full(@inner t1)
2 full(@inner t2)
3 full(@inner t3)
4 leading(@inner t2 t3 t1)
5 use_nl(@inner t3)
6 use_nl(@inner t1)
7 no_swap_join_inputs(@inner t1)
8 no_use_hash_aggregation(@inner)
9 */
10 max(user_id)
11 from
12 (
13 select /*+ qb_name(inner) no_merge */ distinct t1.object_id, t3.user_id
14 from t1, t2, t2 t3
15 where t1.user_id = t2.user_id
16 )
17 ;

MAX(USER_ID)
------------
14

Elapsed: 00:00:00.73
SQL>
SQL> alter session set "_smm_trace" = 0;

Session altered.

Elapsed: 00:00:00.01
SQL>
SQL> set pagesize 0 linesize 200 trimspool on tab off
SQL>
SQL> select * from table(dbms_xplan.display_cursor(null, null, 'ALLSTATS LAST'));
SQL_ID ckb2sbz3y2z14, child number 0
-------------------------------------
select /*+ full(@inner t1) full(@inner t2)
full(@inner t3) leading(@inner t2 t3 t1)
use_nl(@inner t3) use_nl(@inner t1)
no_swap_join_inputs(@inner t1)
no_use_hash_aggregation(@inner) */ max(user_id) from ( select
/*+ qb_name(inner) no_merge */ distinct t1.object_id, t3.user_id from
t1, t2, t2 t3 where t1.user_id = t2.user_id )

Plan hash value: 3828303002

--------------------------------------------------------------------------------------------------------------------
| Id | Operation | Name | Starts | E-Rows | A-Rows | A-Time | Buffers | OMem | 1Mem | Used-Mem |
--------------------------------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | | 1 |00:00:00.71 | 12423 | | | |
| 1 | SORT AGGREGATE | | 1 | 1 | 1 |00:00:00.71 | 12423 | | | |
| 2 | VIEW | | 1 | 318K| 450K|00:00:00.62 | 12423 | | | |
| 3 | SORT UNIQUE | | 1 | 318K| 450K|00:00:00.62 | 12423 | 22M| 1744K| 20M (0)|
| 4 | NESTED LOOPS | | 1 | 450K| 450K|00:00:00.01 | 12423 | | | |
| 5 | NESTED LOOPS | | 1 | 225 | 225 |00:00:00.01 | 48 | | | |
| 6 | TABLE ACCESS FULL| T2 | 1 | 15 | 15 |00:00:00.01 | 3 | | | |
| 7 | TABLE ACCESS FULL| T2 | 15 | 15 | 225 |00:00:00.01 | 45 | | | |
|* 8 | TABLE ACCESS FULL | T1 | 225 | 2000 | 450K|00:00:00.01 | 12375 | | | |
--------------------------------------------------------------------------------------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------

8 - filter("T1"."USER_ID"="T2"."USER_ID")

31 rows selected.

Elapsed: 00:00:00.06
SQL>
SQL> set pagesize 14
SQL>
SQL> -- Fudge the statistics so that the join cardinality between t1 and t2 will be 0 (rounded up to 1)
SQL> declare
2 srec dbms_stats.statrec;
3 novals dbms_stats.numarray;
4 distcnt number;
5 avgclen number;
6 nullcnt number;
7 density number;
8 srec2 dbms_stats.statrec;
9 begin
10 dbms_stats.get_column_stats(null, 't1', 'user_id', distcnt => distcnt, avgclen => avgclen, nullcnt => nullcnt, density => density, srec => srec);
11 srec2.epc := 2;
12 novals := dbms_stats.numarray(
13 &low_value,
14 &high_value
15 );
16 srec2.bkvals := null;
17 dbms_stats.prepare_column_values(srec2,novals);
18 dbms_stats.set_column_stats(
19 ownname=>null,
20 tabname=>'t1',
21 colname=>'user_id',
22 distcnt=>distcnt,
23 nullcnt=>nullcnt,
24 srec=>srec2,
25 avgclen=>avgclen,
26 density=>density
27 );
28 end;
29 /
old 13: &low_value,
new 13: 15,
old 14: &high_value
new 14: 29

PL/SQL procedure successfully completed.

Elapsed: 00:00:00.06
SQL>
SQL> -- Invalidate any cursors using T1
SQL> comment on table t1 is '';

Comment created.

Elapsed: 00:00:00.01
SQL>
SQL> alter session set statistics_level = all;

Session altered.

Elapsed: 00:00:00.00
SQL>
SQL> alter session set tracefile_identifier = 'smm_trace_wrong_cardinality';

Session altered.

Elapsed: 00:00:00.01
SQL>
SQL> alter session set "_smm_trace" = 65535;

Session altered.

Elapsed: 00:00:00.00
SQL>
SQL> select /*+ full(@inner t1)
2 full(@inner t2)
3 full(@inner t3)
4 leading(@inner t2 t3 t1)
5 use_nl(@inner t3)
6 use_nl(@inner t1)
7 no_swap_join_inputs(@inner t1)
8 no_use_hash_aggregation(@inner)
9 */
10 max(user_id)
11 from
12 (
13 select /*+ qb_name(inner) no_merge */ distinct t1.object_id, t3.user_id
14 from t1, t2, t2 t3
15 where t1.user_id = t2.user_id
16 )
17 ;

MAX(USER_ID)
------------
14

Elapsed: 00:00:00.74
SQL>
SQL> alter session set "_smm_trace" = 0;

Session altered.

Elapsed: 00:00:00.00
SQL>
SQL> set pagesize 0 linesize 200 trimspool on tab off
SQL>
SQL> select * from table(dbms_xplan.display_cursor(null, null, 'ALLSTATS LAST'));
SQL_ID ckb2sbz3y2z14, child number 0
-------------------------------------
select /*+ full(@inner t1) full(@inner t2)
full(@inner t3) leading(@inner t2 t3 t1)
use_nl(@inner t3) use_nl(@inner t1)
no_swap_join_inputs(@inner t1)
no_use_hash_aggregation(@inner) */ max(user_id) from ( select
/*+ qb_name(inner) no_merge */ distinct t1.object_id, t3.user_id from
t1, t2, t2 t3 where t1.user_id = t2.user_id )

Plan hash value: 3828303002

--------------------------------------------------------------------------------------------------------------------
| Id | Operation | Name | Starts | E-Rows | A-Rows | A-Time | Buffers | OMem | 1Mem | Used-Mem |
--------------------------------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | | 1 |00:00:00.73 | 12423 | | | |
| 1 | SORT AGGREGATE | | 1 | 1 | 1 |00:00:00.73 | 12423 | | | |
| 2 | VIEW | | 1 | 1 | 450K|00:00:00.61 | 12423 | | | |
| 3 | SORT UNIQUE | | 1 | 1 | 450K|00:00:00.61 | 12423 | 22M| 1744K| 20M (0)|
| 4 | NESTED LOOPS | | 1 | 1 | 450K|00:00:00.01 | 12423 | | | |
| 5 | NESTED LOOPS | | 1 | 225 | 225 |00:00:00.01 | 48 | | | |
| 6 | TABLE ACCESS FULL| T2 | 1 | 15 | 15 |00:00:00.01 | 3 | | | |
| 7 | TABLE ACCESS FULL| T2 | 15 | 15 | 225 |00:00:00.01 | 45 | | | |
|* 8 | TABLE ACCESS FULL | T1 | 225 | 1 | 450K|00:00:00.01 | 12375 | | | |
--------------------------------------------------------------------------------------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------

8 - filter("T1"."USER_ID"="T2"."USER_ID")

31 rows selected.

Elapsed: 00:00:00.01
SQL>
SQL> set doc off
SQL> doc
SQL>

set echo on timing on

spool hcc_function_based_indexes_testcase.log

drop table t_hcc_fbi purge;

-- Create table with HCC enabled
create table t_hcc_fbi compress for query low as select * from dba_objects where 1 = 2;

truncate table t_hcc_fbi;

-- Direct path inserts support HCC by default
insert /*+ append */ into t_hcc_fbi select * from dba_objects;

commit;

-- This is supposed to return DBMS_COMPRESSION.COMP_FOR_QUERY_LOW = 8
select distinct dbms_compression.get_compression_type(USER, 'T_HCC_FBI', rowid) from t_hcc_fbi;

-- So it is supported to have an FBI on HCC data
create index t_hcc_fbi_idx on t_hcc_fbi (lower(object_type));

truncate table t_hcc_fbi;

-- Let's make the FBI unusable, so it doesn't have to be maintained by the load
alter index t_hcc_fbi_idx unusable;

insert /*+ append */ into t_hcc_fbi select * from dba_objects;

commit;

-- But this will return DBMS_COMPRESSION.COMP_NOCOMPRESS = 1
select distinct dbms_compression.get_compression_type(USER, 'T_HCC_FBI', rowid) from t_hcc_fbi;

-- So the mere existence of a FBI, no matter if usable or unusable will prevent HCC with direct-path inserts / parallel DML
-- It is however fully supported to have them on HCC data, but you need to drop / re-create them in order to load the data
-- via direct-path inserts / parallel DML with HCC enabled

spool off

SQL>
SQL> drop table t_hcc_fbi purge;

Table dropped.

Elapsed: 00:00:00.13
SQL>
SQL> -- Create table with HCC enabled
SQL> create table t_hcc_fbi compress for query low as select * from dba_objects where 1 = 2;

Table created.

Elapsed: 00:00:00.09
SQL>
SQL> truncate table t_hcc_fbi;

Table truncated.

Elapsed: 00:00:00.01
SQL>
SQL> -- Direct path inserts support HCC by default
SQL> insert /*+ append */ into t_hcc_fbi select * from dba_objects;

72545 rows created.

Elapsed: 00:00:01.24
SQL>
SQL> commit;

Commit complete.

Elapsed: 00:00:00.00
SQL>
SQL> -- This is supposed to return DBMS_COMPRESSION.COMP_FOR_QUERY_LOW = 8
SQL> select distinct dbms_compression.get_compression_type(USER, 'T_HCC_FBI', rowid) from t_hcc_fbi;

DBMS_COMPRESSION.GET_COMPRESSION_TYPE(USER,'T_HCC_FBI',ROWID)
-------------------------------------------------------------
8

Elapsed: 00:00:09.51
SQL>
SQL> -- So it is supported to have an FBI on HCC data
SQL> create index t_hcc_fbi_idx on t_hcc_fbi (lower(object_type));

Index created.

Elapsed: 00:00:00.23
SQL>
SQL> truncate table t_hcc_fbi;

Table truncated.

Elapsed: 00:00:00.03
SQL>
SQL> -- Let's make the FBI unusable, so it doesn't have to be maintained by the load
SQL> alter index t_hcc_fbi_idx unusable;

Index altered.

Elapsed: 00:00:00.02
SQL>
SQL> insert /*+ append */ into t_hcc_fbi select * from dba_objects;

72546 rows created.

Elapsed: 00:00:01.01
SQL>
SQL> commit;

Commit complete.

Elapsed: 00:00:00.01
SQL>
SQL> -- But this will return DBMS_COMPRESSION.COMP_NOCOMPRESS = 1
SQL> select distinct dbms_compression.get_compression_type(USER, 'T_HCC_FBI', rowid) from t_hcc_fbi;

DBMS_COMPRESSION.GET_COMPRESSION_TYPE(USER,'T_HCC_FBI',ROWID)
-------------------------------------------------------------
1

Elapsed: 00:00:08.93
SQL>

set echo on timing on

set linesize 160 trimspool on tab off pagesize 0

spool deferred_segment_creation_parallel_dml_testcase.log

drop table t_source purge;

drop table t_deferred_parallel_dml purge;

-- Create a simple table as source for the insert
create table t_source parallel nologging
as
select * from dba_objects;

exec dbms_stats.gather_table_stats(null, 't_source')

-- No AUTO DOP for this session to prevent any side-effects of this feature
alter session set parallel_degree_policy = manual;

-- Note that even a CTAS operation can be segment-less
-- if the query doesn't return any rows
create table t_deferred_parallel_dml
segment creation deferred
as
select * from t_source where 1 = 2;

-- No segment although CTAS has been used
select count(*) from user_segments where segment_name = 'T_DEFERRED_PARALLEL_DML';

alter session enable parallel dml;

explain plan for
insert /*+ append parallel(t) */ into t_deferred_parallel_dml t select * from t_source;

-- This plan does not show parallel DML
select * from table(dbms_xplan.display);

drop table t_deferred_parallel_dml purge;

create table t_deferred_parallel_dml
segment creation immediate
as
select * from t_source where 1 = 2;

-- One segment
select count(*) from user_segments where segment_name = 'T_DEFERRED_PARALLEL_DML';

explain plan for
insert /*+ append parallel(t) */ into t_deferred_parallel_dml t select * from t_source;

-- This plan does show parallel DML
select * from table(dbms_xplan.display);

spool off

SQL>
SQL> drop table t_source purge;

Table dropped.

Elapsed: 00:00:00.04
SQL>
SQL> drop table t_deferred_parallel_dml purge;

Table dropped.

Elapsed: 00:00:00.01
SQL>
SQL> -- Create a simple table as source for the insert
SQL> create table t_source parallel nologging
2 as
3 select * from dba_objects;

Table created.

Elapsed: 00:00:03.32
SQL>
SQL> exec dbms_stats.gather_table_stats(null, 't_source')

PL/SQL procedure successfully completed.

Elapsed: 00:00:00.64
SQL>
SQL> -- No AUTO DOP for this session to prevent any side-effects of this feature
SQL> alter session set parallel_degree_policy = manual;

Session altered.

Elapsed: 00:00:00.00
SQL>
SQL> -- Note that even a CTAS operation can be segment-less
SQL> -- if the query doesn't return any rows
SQL> create table t_deferred_parallel_dml
2 segment creation deferred
3 as
4 select * from t_source where 1 = 2;

Table created.

Elapsed: 00:00:00.01
SQL>
SQL> -- No segment although CTAS has been used
SQL> select count(*) from user_segments where segment_name = 'T_DEFERRED_PARALLEL_DML';
0

Elapsed: 00:00:00.00
SQL>
SQL> alter session enable parallel dml;

Session altered.

Elapsed: 00:00:00.00
SQL>
SQL> explain plan for
2 insert /*+ append parallel(t) */ into t_deferred_parallel_dml t select * from t_source;

Explained.

Elapsed: 00:00:00.01
SQL>
SQL> -- This plan does not show parallel DML
SQL> select * from table(dbms_xplan.display);
Plan hash value: 1453990251

------------------------------------------------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | TQ |IN-OUT| PQ Distrib |
------------------------------------------------------------------------------------------------------------------------------
| 0 | INSERT STATEMENT | | 73251 | 6938K| 117 (1)| 00:00:02 | | | |
| 1 | LOAD AS SELECT | T_DEFERRED_PARALLEL_DML | | | | | | | |
| 2 | PX COORDINATOR | | | | | | | | |
| 3 | PX SEND QC (RANDOM)| :TQ10000 | 73251 | 6938K| 117 (1)| 00:00:02 | Q1,00 | P->S | QC (RAND) |
| 4 | PX BLOCK ITERATOR | | 73251 | 6938K| 117 (1)| 00:00:02 | Q1,00 | PCWC | |
| 5 | TABLE ACCESS FULL| T_SOURCE | 73251 | 6938K| 117 (1)| 00:00:02 | Q1,00 | PCWP | |
------------------------------------------------------------------------------------------------------------------------------

12 rows selected.

Elapsed: 00:00:00.06
SQL>
SQL> drop table t_deferred_parallel_dml purge;

Table dropped.

Elapsed: 00:00:00.03
SQL>
SQL> create table t_deferred_parallel_dml
2 segment creation immediate
3 as
4 select * from t_source where 1 = 2;

Table created.

Elapsed: 00:00:00.01
SQL>
SQL> -- One segment
SQL> select count(*) from user_segments where segment_name = 'T_DEFERRED_PARALLEL_DML';
1

Elapsed: 00:00:00.01
SQL>
SQL> explain plan for
2 insert /*+ append parallel(t) */ into t_deferred_parallel_dml t select * from t_source;

Explained.

Elapsed: 00:00:00.01
SQL>
SQL> -- This plan does show parallel DML
SQL> select * from table(dbms_xplan.display);
Plan hash value: 4111574378

------------------------------------------------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | TQ |IN-OUT| PQ Distrib |
------------------------------------------------------------------------------------------------------------------------------
| 0 | INSERT STATEMENT | | 73251 | 6938K| 117 (1)| 00:00:02 | | | |
| 1 | PX COORDINATOR | | | | | | | | |
| 2 | PX SEND QC (RANDOM) | :TQ10000 | 73251 | 6938K| 117 (1)| 00:00:02 | Q1,00 | P->S | QC (RAND) |
| 3 | LOAD AS SELECT | T_DEFERRED_PARALLEL_DML | | | | | Q1,00 | PCWP | |
| 4 | PX BLOCK ITERATOR | | 73251 | 6938K| 117 (1)| 00:00:02 | Q1,00 | PCWC | |
| 5 | TABLE ACCESS FULL| T_SOURCE | 73251 | 6938K| 117 (1)| 00:00:02 | Q1,00 | PCWP | |
------------------------------------------------------------------------------------------------------------------------------

12 rows selected.

Elapsed: 00:00:00.06
SQL>
SQL> spool off

-- Get the column list including hidden columns, but ignoring virtual columns added by function-based indexes
-- TODO: What about virtual columns (11g or later)?
select
decode(t.hidden_column,
'YES', 'SYS$' || internal_column_id || '$UNUSED',
t.column_name
) ||
' ' ||
lower(data_type) ||
decode(substr(data_type, 1, 9),
'TIMESTAMP', null,
'INTERVAL ', null,
decode(t.data_type,
'NUMBER', decode(t.data_precision || t.data_scale,
null, null,
'(' ||
decode(t.data_precision,
null, '*',
t.data_precision
) ||
decode(t.data_scale,
null, null,
',' || t.data_scale
) ||
')'
),
'FLOAT', '(' || t.data_precision || ')',
'LONG', null,
'LONG RAW', null,
'BLOB', null,
'CLOB', null,
'NCLOB', null,
'BFILE', null,
'CFILE', null,
'BINARY_FLOAT', null,
'BINARY_DOUBLE', null,
'MLSLABEL', null,
'ROWID', null,
'UROWID', null,
'DATE', null,
'(' ||
nvl(
nvl(
decode(t.char_length,
0, to_number(null),
t.char_length
),
t.char_col_decl_length
),
t.data_length
) ||
decode(t.character_set_name,
'CHAR_CS', decode(t.char_used,
'C', ' char',
'B', ' byte'
)
) ||
')'
)
) ||
' ' ||
decode(nullable,
'N', 'not null',
null
) ||
',' as column_def
from
all_tab_cols t
where
t.owner =
and t.table_name =
and t.segment_column_id is not null
order by
t.internal_column_id;

/**
* Drop a (sub-)partition residing in an offline tablespace
* @param p_object The original object to clean up
* @param p_temp_exc_table_name The name of the working table
* @param p_clean_tablespace_name The tablespace where to create the cleanup partition
* @param p_partition_name The name of the (sub-)partition to drop
* @param p_segment_type The type of the segment (TABLE[ ][SUB][PARTITION])
* @param p_last_partition_indicator For subpartitions indicate that this is
* the last subpartition - this will drop the whole partition
**/
procedure drop_partition(
p_object in r_oracle_object
, p_temp_exc_table_name in out oracle_object
, p_clean_tablespace_name in oracle_object
, p_partition_name in oracle_object
, p_segment_type in oracle_object
, p_last_partition_indicator in varchar2
)
as
s_sql large_sql;
s_partition_type varchar2(255);
s_exchange_table oracle_object;
e_partition_in_offline_ts exception;
pragma exception_init(e_partition_in_offline_ts, -14117);
-- We do this in an autonomous transaction to keep it separate
-- from any outside transactions like the "queue" transaction
-- used by the parallel clean up threads
pragma autonomous_transaction;
begin
-- Determine if this is a partition or subpartition
s_partition_type := substr(p_segment_type, 7, 255);

-- Step 1: Add a clean partition to the temporary cleanup table
s_sql := 'alter table ' || p_temp_exc_table_name || ' add partition p_cleanup values (42) tablespace ' || p_clean_tablespace_name;

execute(p_object.owner, s_sql);

-- Get the name of the unpartitioned table copy
s_exchange_table := get_exchange_table(p_object);

-- Step 2: Exchange the defect (sub-)partition with the unpartitioned copy table EXCLUDING indexes
s_sql := '
alter table ' || p_object.segment_name || '
exchange ' || s_partition_type || ' ' || p_partition_name || '
with table ' || s_exchange_table || '
excluding indexes without validation';

execute(p_object.owner, s_sql);

-- Step 3: Exchange the unpartitioned copy table with the partitioned copy table partition again EXCLUDING indexes
s_sql := '
alter table ' || p_temp_exc_table_name || '
exchange partition p_cleanup
with table ' || s_exchange_table || '
excluding indexes without validation';

execute(p_object.owner, s_sql);

-- Step 4: Drop the defect partition now residing in partitioned "waste-bin"table partition
-- Since we don't have any indexes this is possible now
s_sql := 'alter table ' || p_temp_exc_table_name || ' drop partition p_cleanup';

begin
execute(p_object.owner, s_sql);
exception
-- Any tables with LOBs will cause an exception since they will implicitly have a LOB INDEX added
-- Therefore the DROP PARTITION will fail with ORA-14117
-- The simplest solution is to drop and recreate the entire working table - note the serious side effects
-- of the underlying ORA-01110 error in 11.1.0.7. See below comments about the potential impact
-- of the health check monitoring
-- A smoother way of handling this to avoid these potential side-effects is to check if the
-- table has any indexes defined on it and then do not attempt to drop the partition but
-- immediately drop the entire table
when e_partition_in_offline_ts then
drop_temporary_exc_table(p_object, p_temp_exc_table_name);
p_temp_exc_table_name := create_temporary_exc_table(p_object, p_clean_tablespace_name, p_segment_type);
end;

-- Step 5: Drop the partition / subpartition which completes the cleanup
-- TODO: Are really all subpartitions of a partition affected?
-- If not, this logic needs to be revised
if (s_partition_type = 'SUBPARTITION' and p_last_partition_indicator = 'Y') then
s_sql := 'alter table ' || p_object.segment_name || ' drop partition ' || get_parent_partition(p_object, p_partition_name);

execute(p_object.owner, s_sql);
elsif s_partition_type = 'PARTITION' then
s_sql := 'alter table ' || p_object.segment_name || ' drop partition ' || p_partition_name;

execute(p_object.owner, s_sql);
end if;
end drop_partition;

========= Dump for error ORA 1110 (no incident) ========
----- DDE Action: 'DB_STRUCTURE_INTEGRITY_CHECK' (Async) -----

DDE rules only execution for: ORA 1110
----- START Event Driven Actions Dump ----
---- END Event Driven Actions Dump ----
----- START DDE Actions Dump -----
Executing SYNC actions
----- START DDE Action: 'DB_STRUCTURE_INTEGRITY_CHECK' (Async) -----
DDE Action 'DB_STRUCTURE_INTEGRITY_CHECK' was flood controlled
----- END DDE Action: 'DB_STRUCTURE_INTEGRITY_CHECK' (FLOOD CONTROLLED, 17 csec) -----
Executing ASYNC actions
----- END DDE Actions Dump (total 0 csec) -----