Child Cursor and Plan
- From: Sreejith S Nair <Sreejith.Sreekantan@xxxxxxxxxx>
- To: oracle-l@xxxxxxxxxxxxx
- Date: Thu, 2 Feb 2012 19:06:32 +0530
Hi Friends,
Oracle 11.2.0.2 on Solaris 10.
From my understanding a child cursor is generated when a sql statement
will have multiple execution plans. Here is what I see in one of our
database
SYS> select sql_id,child_number,hash_value,PLAN_HASH_VALUE,CHILD_ADDRESS
from v$sql where sql_id='c8gnrhxma4tas';
SQL_ID CHILD_NUMBER HASH_VALUE PLAN_HASH_VALUE CHILD_ADDRESS
------------- ------------ ---------- --------------- ----------------
c8gnrhxma4tas 0 1721918808 4024720576 00000004481E01A8
c8gnrhxma4tas 1 1721918808 4024720576 0000000456DEF070
c8gnrhxma4tas 2 1721918808 4024720576 0000000448F3C210
c8gnrhxma4tas 3 1721918808 4024720576 000000047CA5BD30
c8gnrhxma4tas 4 1721918808 4024720576 0000000448476B88
c8gnrhxma4tas 5 1721918808 4024720576 000000047C217998
c8gnrhxma4tas 6 1721918808 4024720576 00000004483B0B78
c8gnrhxma4tas 7 1721918808 4024720576 000000047C3F9668
Here I see that CHILD_NUMBER and different CHILD_ADDRESS are generated for
same PLAN_HASH_VALUE. Can someone please give some light on what exactly
is a child cursor ?
This is what I got from Google. Could not find a proper definition in
documentation.May be I missed ?
The parent cursor contains the SQL statement text only, but no execution
plan.
Execution plans are found in child cursors. Child cursors are also called
versions.
With Regards,
Sreejith
--
Sreejith S Nair
Associate Systems Architect | AOS DBA Team
IBS Software Services Private Ltd.
2nd Floor, IBS Campus, Technopark Campus, Trivandrum - 695 581, Kerala,
India
((Direct) +91 471 661 4707 ) +91 808 648 5523
*sreejith.sreekantan@xxxxxxxxxx
8 www.ibsplc.com
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