Is hash join slower in 12.2 compared to 11.2.0.3 or am i hitting a bug?
From: kunwar singh <krishsingh.111_at_gmail.com>
Date: Sat, 25 Jan 2020 21:24:27 -0500
Message-ID: <CAJSrDUoZGSq2NxOdzW15e4EK+FHwoHh=khECepr-vGAvVVMtKw_at_mail.gmail.com>
Hi Listers,
select /*+ gather_plan_statistics monitor leading(a,b) use_hash(a,b) full(a) full(b) */ *from TMP_emp a, tmp_dba_objects b where a.empno=b.object_id
| Elapsed | Cpu | IO | Application | Other | Fetch | Buffer | Read | Read |
| Time(s) | Time(s) | Waits(s) | Waits(s) | Waits(s) | Calls | Gets | Reqs | Bytes |
| 7.83 | 5.18 | 2.46 | 0.01 | 0.18 | 4 | 8742 | 91 | 68MB |
| Id | Operation | Name | Rows | Cost | Time | Start | Execs | Rows | Read | Read | Mem | Activity | Activity Detail |
Date: Sat, 25 Jan 2020 21:24:27 -0500
Message-ID: <CAJSrDUoZGSq2NxOdzW15e4EK+FHwoHh=khECepr-vGAvVVMtKw_at_mail.gmail.com>
Hi Listers,
I am doing a testing of migrating app for a customer from 11.2.0.3 to 12.2 and find the queries doing hash join are taking upto 4x more time. Hash join step is the one taking the time , more cpu and more elapsed time. *Is this a known issue or any bug? I searched in MOS , no hits or maybe i am not using correct keywords to match. *
Note that i am doing testing on base releases of 11.2.0.3 & 12.2 for simplifying my testcase.
- *Testcase * create table tmp_dba_objects AS SELECT *from dba_objects where rownum <20001; insert into tmp_dba_objects select *from tmp_dba_objects; insert into tmp_dba_objects select *from tmp_dba_objects; insert into tmp_dba_objects select *from tmp_dba_objects; insert into tmp_dba_objects select *from tmp_dba_objects; insert into tmp_dba_objects select *from tmp_dba_objects;
create table TMP_EMP ( EMPNO NUMBER);
insert into TMP_EMP select min(object_id) from tmp_dba_objects;
commit;
alter system flush shared_pool;
alter system flush buffer_cache;
select /*+ gather_plan_statistics monitor leading(a,b) use_hash(a,b)
full(a) full(b) */ *from TMP_emp a, tmp_dba_objects b where
a.empno=b.object_id;
set lin 300 pages 9999
select *from table(dbms_xplan.display_cursor(NULL,NULL,'IOSTATS LAST'));
2.
*SQL monitor report outputs *SQL Monitoring Report -
*12.2.0.1*SQL Text
select /*+ gather_plan_statistics monitor leading(a,b) use_hash(a,b) full(a) full(b) */ *from TMP_emp a, tmp_dba_objects b where a.empno=b.object_id
Global Information
Status : DONE (ALL ROWS) Instance ID : 1 Session : KUNWAR (40:7639) SQL ID : 0257vnkax6zak SQL Execution ID : 16777216 Execution Started : 01/26/2020 02:52:50 First Refresh Time : 01/26/2020 02:52:50 Last Refresh Time : 01/26/2020 02:52:58 Duration : 8s <<<<<<< 8 seconds Module/Action : SQL*Plus/- Service : SYS$USERS Program : sqlplus_at_devserver1 (TNS V1-V3) Fetch Calls : 4
Global Stats
| Elapsed | Cpu | IO | Application | Other | Fetch | Buffer | Read | Read |
| Time(s) | Time(s) | Waits(s) | Waits(s) | Waits(s) | Calls | Gets | Reqs | Bytes |
| 7.83 | 5.18 | 2.46 | 0.01 | 0.18 | 4 | 8742 | 91 | 68MB |
SQL Plan Monitoring Details (Plan Hash Value=1398591261)
| Id | Operation | Name | Rows | Cost | Time | Start | Execs | Rows | Read | Read | Mem | Activity | Activity Detail |
| | | | (Estim) | | Active(s) | Active | | (Actual) | Reqs | Bytes | (Max) | (%) | (#samples) |
| 0 | SELECT STATEMENT | | | | 8
| +1 | 1 | 32 | | | . | |
|
| 1 | HASH JOIN | | 32 | 2482 | 8
| +1 | 1 | 32 | | | 708KB | |
| -- Just as a side note that ASH is not getting
populated, due to some other reason
| 2 | TABLE ACCESS FULL | TMP_EMP | 1 | 3 | 1
| +1 | 1 | 1 | 2 | 16384 | . | |
|
| 3 | TABLE ACCESS FULL | TMP_DBA_OBJECTS | 640K | 2477 | 8
| +1 | 1 | 640K | 80 | 68MB | . | |
|
--- SQL Monitoring Report -*11.2.0.3* SQL Text ------------------------------ select /*+ gather_plan_statistics monitor leading(a,b) use_hash(a,b) full(a) full(b) */ *from TMP_emp a, tmp_dba_objects b where a.empno=b.object_id Global Information ------------------------------ Status : DONE (ALL ROWS) Instance ID : 1 Session : KUNWAR (147:18275) SQL ID : 0257vnkax6zak SQL Execution ID : 16777216 Execution Started : 01/26/2020 03:12:22 First Refresh Time : 01/26/2020 03:12:22 Last Refresh Time : 01/26/2020 03:12:24 Duration : 2s <<<<<<< 2 seconds Module/Action : SQL*Plus/- Service : SYS$USERS Program : sqlplus_at_devserver2.us.oracle.com (TNS V1-V3) Fetch Calls : 4 Global Stats ================================================================ | Elapsed | Cpu | IO | Fetch | Buffer | Read | Read | | Time(s) | Time(s) | Waits(s) | Calls | Gets | Reqs | Bytes | ================================================================ | 1.96 | 0.53 | 1.43 | 4 | 8844 | 83 | 69MB | ================================================================ SQL Plan Monitoring Details (Plan Hash Value=1398591261)Received on Sun Jan 26 2020 - 03:24:27 CET
=================================================================================================================================================================
| Id | Operation | Name | Rows | Cost | Time | Start | Execs | Rows | Read | Read | Mem | Activity | Activity Detail | | | | | (Estim) | | Active(s) | Active | | (Actual) | Reqs | Bytes | (Max) | (%) | (# samples) |
=================================================================================================================================================================
| 0 | SELECT STATEMENT | | | | 3 | +0 | 1 | 32 | | | | | | | 1 | HASH JOIN | | 32 | 2494 | 3 | +0 | 1 | 32 | | | 734K | | | | 2 | TABLE ACCESS FULL | TMP_EMP | 1 | 3 | 1 | +0 | 1 | 1 | 2 | 49152 | | | | | 3 | TABLE ACCESS FULL | TMP_DBA_OBJECTS | 640K | 2487 | 3 | +0 | 1 | 640K | 81 | 69MB | | 50.00 | direct path read (1) |
=================================================================================================================================================================
Not sure what diagnostic to dig deeper, strace/perf? i am not much familiar with these. oradebug oradebug short_stack in 12.2 shows lots of rows like below : ksedsts()+346<-ksdxfstk()+71<-ksdxcb()+912<-sspuser()+217<-__sighandler()<-clock_gettime()+331<-clock_gettime()+54<-00000000392A8918<-6D70726B00796669 ksedsts()+346<-ksdxfstk()+71<-ksdxcb()+912<-sspuser()+217<-__sighandler()<-clock_gettime()+331<-clock_gettime()+54<-kpusattr()+58060<-6B6D70726B007966 ksedsts()+346<-ksdxfstk()+71<-ksdxcb()+912<-sspuser()+217<-__sighandler()<-clock_gettime()+331<-clock_gettime()+54<-kzftfpc()+108<-6B6D70726B007966 ksedsts()+346<-ksdxfstk()+71<-ksdxcb()+912<-sspuser()+217<-__sighandler()<-clock_gettime()+331<-clock_gettime()+54<-dmsglLRPersist()+1480<-6B6D70726B007966 ksedsts()+346<-ksdxfstk()+71<-ksdxcb()+912<-sspuser()+217<-__sighandler()<-clock_gettime()+331<-clock_gettime()+54<-0000000016646A58<-6B6D70726B007966 ksedsts()+346<-ksdxfstk()+71<-ksdxcb()+912<-sspuser()+217<-__sighandler()<-clock_gettime()+331<-clock_gettime()+54<-000000001CD11420<-6B6D70726B007966 ksedsts()+346<-ksdxfstk()+71<-ksdxcb()+912<-sspuser()+217<-__sighandler()<-clock_gettime()+331<-clock_gettime()+54<-000000002305FE48<-6B6D70726B007966 ksedsts()+346<-ksdxfstk()+71<-ksdxcb()+912<-sspuser()+217<-__sighandler()<-clock_gettime()+331<-clock_gettime()+54<-000000002928CA8A<-6B6D70726B007966 ksedsts()+346<-ksdxfstk()+71<-ksdxcb()+912<-sspuser()+217<-__sighandler()<-clock_gettime()+331<-clock_gettime()+54<-000000002F6031FE<-6B6D70726B007966 ksedsts()+346<-ksdxfstk()+71<-ksdxcb()+912<-sspuser()+217<-__sighandler()<-clock_gettime()+331<-clock_gettime()+54<-00000000359BB229<-6B6D70726B007966 ksedsts()+346<-ksdxfstk()+71<-ksdxcb()+912<-sspuser()+217<-__sighandler()<-clock_gettime()+331<-clock_gettime()+54<-00000000003FAF84<-736B6D70726B0079 ksedsts()+346<-ksdxfstk()+71<-ksdxcb()+912<-sspuser()+217<-__sighandler()<-clock_gettime()+331<-clock_gettime()+54<-kfclUnlinkBh()+1586<-736B6D70726B0079 ksedsts()+346<-ksdxfstk()+71<-ksdxcb()+912<-sspuser()+217<-__sighandler()<-clock_gettime()+331<-clock_gettime()+54<-kdstf111010100001000km()+14<-736B6D70726B0079 ksedsts()+346<-ksdxfstk()+71<-ksdxcb()+912<-sspuser()+217<-__sighandler()<-clock_gettime()+331<-clock_gettime()+54<-0000000012BCB837<-736B6D70726B0079 ksedsts()+346<-ksdxfstk()+71<-ksdxcb()+912<-sspuser()+217<-__sighandler()<-clock_gettime()+331<-clock_gettime()+54<-0000000018D8C1B8<-736B6D70726B0079 ksedsts()+346<-ksdxfstk()+71<-ksdxcb()+912<-sspuser()+217<-__sighandler()<-clock_gettime()+331<-clock_gettime()+54<-000000001EFA8E9F<-736B6D70726B0079 ksedsts()+346<-ksdxfstk()+71<-ksdxcb()+912<-sspuser()+217<-__sighandler()<-clock_gettime()+331<-clock_gettime()+54<-00000000252DCF2E<-736B6D70726B0079 ksedsts()+346<-ksdxfstk()+71<-ksdxcb()+912<-sspuser()+217<-__sighandler()<-clock_gettime()+331<-clock_gettime()+54<-000000002B574A8C<-736B6D70726B0079 ksedsts()+346<-ksdxfstk()+71<-ksdxcb()+912<-sspuser()+217<-__sighandler()<-clock_gettime()+331<-clock_gettime()+54<-00000000317E01AF<-736B6D70726B0079 ksedsts()+346<-ksdxfstk()+71<-ksdxcb()+912<-sspuser()+217<-__sighandler()<-clock_gettime()+331<-clock_gettime()+54<-0000000037C374DF<-736B6D70726B0079 ksedsts()+346<-ksdxfstk()+71<-ksdxcb()+912<-sspuser()+217<-__sighandler()<-clock_gettime()+331<-clock_gettime()+54<-kdiss_fetch()+4710<-76736B6D70726B00 ksedsts()+346<-ksdxfstk()+71<-ksdxcb()+912<-sspuser()+217<-__sighandler()<-clock_gettime()+331<-clock_gettime()+54<-qmxxtiAdjMKXTIArgs()+384<-76736B6D70726B00 ksedsts()+346<-ksdxfstk()+71<-ksdxcb()+912<-sspuser()+217<-__sighandler()<-clock_gettime()+331<-clock_gettime()+54<-qesgvslice_0_MIN_MO_DA_F()+6004<-76736B6D70726B00 ksedsts()+346<-ksdxfstk()+71<-ksdxcb()+912<-sspuser()+217<-__sighandler()<-clock_gettime()+331<-clock_gettime()+54<-0000000014D30516<-76736B6D70726B00 ksedsts()+346<-ksdxfstk()+71<-ksdxcb()+912<-sspuser()+217<-__sighandler()<-clock_gettime()+331<-clock_gettime()+54<-000000001B002C0A<-76736B6D70726B00 ksedsts()+346<-ksdxfstk()+71<-ksdxcb()+912<-sspuser()+217<-__sighandler()<-clock_gettime()+331<-clock_gettime()+54<-000000002125D372<-76736B6D70726B00 ksedsts()+346<-ksdxfstk()+71<-ksdxcb()+912<-sspuser()+217<-__sighandler()<-clock_gettime()+331<-clock_gettime()+54<-00000000276006C7<-76736B6D70726B00 ksedsts()+346<-ksdxfstk()+71<-ksdxcb()+912<-sspuser()+217<-__sighandler()<-clock_gettime()+331<-clock_gettime()+54<-000000002D93D64B<-76736B6D70726B00 ksedsts()+346<-ksdxfstk()+71<-ksdxcb()+912<-sspuser()+217<-__sighandler()<-clock_gettime()+331<-clock_gettime()+54<-0000000033C3E57D<-76736B6D70726B00 ksedsts()+346<-ksdxfstk()+71<-ksdxcb()+912<-sspuser()+217<-__sighandler()<-clock_gettime()+331<-clock_gettime()+54<-0000000039EC64C6<-76736B6D70726B00 ksedsts()+346<-ksdxfstk()+71<-ksdxcb()+912<-sspuser()+217<-__sighandler()<-clock_gettime()+331<-clock_gettime()+54<-xsspfc_Comp504()+575<-5F76736B6D70726B I dont see these in 11.2 While researching i am saw some twitter conversation of Frank Pachot and thought this link could help , but i am not familar with tmux/gdb , so still reading :) : https://github.com/FranckPachot/demo/blob/master/TVD-JoinMethods.sql Maybe i will have to go to one of conferences like POUG for such advanced techniques :D -- Cheers, Kunwar -- http://www.freelists.org/webpage/oracle-l