Just curious if anyone else is seeing this behaviour..
SQL> set long 500000 SQL> @pt "select * from v$sql where sql_id = '1km492z723vpu'" SQL_TEXT : alter table scott.emp SQL_FULLTEXT : alter table scott.emp SQL_ID : 1km492z723vpu ...
Suffice to say, there’s a lot more to that SQL statement, but its lost in v$sql. Once complete, it does appear in full in v$sqlstats, but its a pain when you cant see the whole statement..
I posted a fair amount of stuff on how Oracle is generating IOs, and especially large IOs, meaning more than one Oracle block, so > 8KB. This is typically what is happening when the Oracle database is executing a row source which does a full segment scan. Let’s start off with a quiz: what you think Oracle is the maximum IO size the Oracle engine is capable of requesting of the Operating System (so the IO size as can be seen at the SCI (system call interface) layer? If you made up your answer, remember it, and read on!
The real intention of this blogpost is to describe what is going on in the Oracle database kernel, but also what is being done in the Linux kernel. Being a performance specialised Oracle DBA means you have to understand what the operating system does. I often see that it’s of the utmost importance to understand how an IO ends up as a request at the NAS or SAN head, so you understand what a storage admin is talking about.
One of the presentations I went to at the DOAG conference earlier on this month was called “PL/SQL Tuning, finding the perf. bottleneck with hierarchical profiler” by Radu Parvu from Finland. If you do a lot of PL/SQL programming and haven’t noticed the dbms_hprof package yet make sure you take a good look at it.
A peripheral question that came up at the end of the session asked about problems with line numbers in pl/sql procedures; why, when you get a run-time error, does the reported line number sometimes look wrong, and how do you find the right line. I can answer (or give at least one reason for) the first part, but not the second part; Julian Dontcheff had an answer for the second bit, but unfortunately I failed to take a note of it.
In Oracle database version 126.96.36.199, Oracle introduced the Oracle In-Memory Database option. It is possible…
There was a question on OTN a few days ago asking the following question:
Here’s a query that ran okay on 11g, but crashed with Oracle error “ORA-01843: not a valid month” after upgrade to 12c; why ?
The generically correct answer, of course, is that the OP had been lucky (or unlucky, depending on your point of view) on 11g – and I’ll explain that answer in another blog posting.
That isn’t the point of this posting, though. This posting is a test of observation and deduction. One of the respondants in the thread had conveniently supplied a little bit of SQL that I copied and fiddled about with to demonstrate a point regarding CPU costing, but as I did so I thought I’d show you the following and ask a simple question.’
Those of you that have been around Oracle for some time may already be aware of the various OTN tours. These tours bring well known speakers to some of the smaller (relatively speaking) regions that often don’t get to see some of the big name speakers, simply because of audience size. Over the past couple of years, I’ve been involved in the OTN APAC tour, and recently returned from the New Zealand leg of the tour for this year. I presented two workshops – one on Database Lifecycle Management and one on DBaaS – as well as standing in for a sick presenter and covering Snap Clone in Enterprise Manager 12c. For me, the best value for the conference was (as it so often is) the time spent interacting both with customers and other speakers / exhibitors. It was great to catch up with so many people I haven’t seen for a long time, both from within Oracle and outside of it.
One of the reasons I like user group conferences is meeting new people in my “area” – these people at the conference not only like technology and probably some of the same technology I do but, as they are at a conference, are probably inclined to learn stuff, meet people and maybe share ideas. I’m not actually very good face-to-face socially with people I do not know, so I like to tilt things in my favour if I can!
But sometimes you have odd experiences.
I keep having this conversation over and over, in retail stores, restaurants and other establishments- women coming up to me and asking, “Can you tell me about that watch you have on?”
It made me realize that it could be really intimidating to:
1. Ask questions of the sales staff in most stores.
I know others may want to know how to do this and I had challenges until Gagan Chawla, a teammate from Oracle, was kind enough to point out how to still get to this hidden, little gold nugget, so I’m posting it here for others!