The column is there for a long time – even 9i documentation have it. I’ve never thought about it until today when I caought something extraordinary on 126.96.36.199 instance.
Starting with 10g oracle introduced SQL_ID for simplicity; it is used in combination with CHILD_NUMBER to locate a particular row in the V$SQL. The documentation is clear (bold is mine):
V$SQL lists statistics on shared SQL areas without the GROUP BY clause and contains one row for each child of the original SQL text entered
Here is a recent thread from OTN forums. The question raised is WTF? whether a hint in the examples section of DBMS_PARALLEL_EXECUTE documentation have to be used or not and why it is there. What do you think about it? Have a look in the documentation and mark your choice in a poll: PS. In [...]
Some time ago there was a thread on the SQL.ru forum where user has asked the never-ending question “why CBO is doing this?”. The problem was a simple count(*) of parent-child tables join with no FK constraint was executed in very strange way: via NESTED LOOPS using child as a driving table. Here is a [...]