Skip to main content

oracle with clause and materialize hint

oracle guru Burleson's note  helped me to improve performance on a query cross database link
http://www.dba-oracle.com/t_with_clause.htm

we have a database link from oracle to MS SQL server using oracle DRDA, the following query take long to complete, I cannot wait for it to complete and have to kill the query.

SELECT count(*) FROM "ContractItem"@QSENCT002 A, "contractheader_cr"@QSENCT002 B
WHERE A. "ContractHeaderID" = B. "contractheaderid"
AND "ContractItemDayID" BETWEEN 37345 AND 37346
and not exists
(SELECT REVENUESTREAMEXPORTID FROM radiostage.REVENUESTREAMEXPORT_XREF WHERE DIVESTED = 'Y' and A."RevenueStreamExportID" =REVENUESTREAMEXPORTID )
/

After re-write the query using with clause and materialize hint, the query complete in 1 second.
However, if I give bigger range of date in the query, the performance is not improved much, so it's depends on case by case.

with ctview as
(select /*+ materialize */ * FROM "ContractItem"@QSENCT002 A, "contractheader_cr"@QSENCT002 B
WHERE A. "ContractHeaderID" = B. "contractheaderid"
AND "ContractItemDayID" BETWEEN 37345 AND 37346)
select count(*) from ctview
where ctview."RevenueStreamExportID" NOT IN (SELECT REVENUESTREAMEXPORTID FROM radiostage.REVENUESTREAMEXPORT_XREF WHERE DIVESTED = 'Y')

/

  COUNT(*)
----------
         0

Elapsed: 00:00:00.88

Execution Plan
----------------------------------------------------------
Plan hash value: 1488614543

--------------------------------------------------------------------------------------------------------------------------
| Id  | Operation                  | Name                        | Rows  | Bytes | Cost (%CPU)| Time  | Inst   |IN-OUT|
--------------------------------------------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT           |                             |     1 |    18 |   406   (1)| 00:00:05 |        |      |
|   1 |  TEMP TABLE TRANSFORMATION |                             |       |       |            |       |   |      |
|   2 |   LOAD AS SELECT           | SYS_TEMP_0FD9D6603_13638A70 |       |       |            |       |   |      |
|   3 |    REMOTE                  |                             |     5 |  1300 |   200   (0)| 00:00:03 | QSENC~ | R->S |
|   4 |   SORT AGGREGATE           |                             |     1 |    18 |            |       |   |      |
|*  5 |    HASH JOIN ANTI NA       |                             |     1 |    18 |     6  (17)| 00:00:01 |        |      |
|   6 |     VIEW                   |                             |     5 |    65 |     2   (0)| 00:00:01 |        |      |
|   7 |      TABLE ACCESS FULL     | SYS_TEMP_0FD9D6603_13638A70 |     5 |  1365 |     2   (0)| 00:00:01 |        |      |
|*  8 |     TABLE ACCESS FULL      | REVENUESTREAMEXPORT_XREF    |     4 |    20 |     3   (0)| 00:00:01 |        |      |
--------------------------------------------------------------------------------------------------------------------------

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

   5 - access("CTVIEW"."RevenueStreamExportID"="REVENUESTREAMEXPORTID")
   8 - filter("DIVESTED"='Y')

Remote SQL Information (identified by operation id):
----------------------------------------------------

   3 - SELECT A1."ContractItemID",A1."ContractHeaderID",A1."RevenueStreamExportID",A1."ContractItemDayID",A1."DayP
       artHalfHourID",A1."TransactionDayID",A1."ContractItemStatusID",A1."ContractItemTypeID",A1."SaleTypeID",A1."Industr
       yProductID",A1."TransactionCodeID",A1."AnnouncementTypeID",A1."NumberOfItems",A1."TotalCostGross",A1."TotalCostNet
       ",A1."TotalValueGross",A1."TotalValueNet",A1."IsBroadcast",A1."SpotLengthID",A1."CustomerID",A2."contractheaderid"
        FROM "ContractItem" A1,"contractheader_cr" A2 WHERE A1."ContractHeaderID"=A2."contractheaderid" AND
       A1."ContractItemDayID">=37345 AND A1."ContractItemDayID"<=37346 (accessing 'QSENCT002' )



Statistics
----------------------------------------------------------
        205  recursive calls
          7  db block gets
        217  consistent gets
          9  physical reads
       1392  redo size
        209  bytes sent via SQL*Net to client
        252  bytes received via SQL*Net from client
          2  SQL*Net roundtrips to/from client
          5  sorts (memory)
          0  sorts (disk)
          1  rows processed


11:26:12 RMS8DEV>

Comments

Popular posts from this blog

Opatch apply/lsinventory error: oneoff is corrupted or does not exist

I am applying the quarterly patch for 19c RDBMS, I tried using napply but failed, but somehow it corrupted the inventory though nothing applied. further apply and lsinventory command ran into error like this: $ ./OPatch/opatch lsinventory Oracle Interim Patch Installer version 12.2.0.1.21 Copyright (c) 2020, Oracle Corporation.  All rights reserved. Oracle Home       : /u02/app/oracle/19.0.0 Central Inventory : /u01/app/oraInventory    from           : /u02/app/oracle/19.0.0/oraInst.loc OPatch version    : 12.2.0.1.21 OUI version       : 12.2.0.7.0 Log file location : /u02/app/oracle/19.0.0/cfgtoollogs/opatch/opatch2020-09-08_13-35-59PM_1.log Lsinventory Output file location : /u02/app/oracle/19.0.0/cfgtoollogs/opatch/lsinv/lsinventory2020-09-08_13-35-59PM.txt -------------------------------------------------------------------------------- Inventory load failed... OPatch cannot load inventory ...

oracle dba_hist_sysmetric_summary

found this blog is helpful to get CPU and IO statistics on oracle database. http://shob-dbadmin.blogspot.ca/2012/12/how-to-find-total-io-of-database.html courtesy to  Shomil Bansal , below are hist writing, not mine. How to find total IO of the database instance Total IO of database instance is sum of the physical reads, physical writes and redo writes. There are several views to find these values. v$sysmetric  - Reports metric values for only the most current time sample 60 secs. v$sysmetric_summary  - Reports metric values for time sample of 1 hour. v$sysmetric_history  - Reports metric values every 60 sec from the time instance is up. Better way to analyse IO using this view to take deltas between two time periods. dba_hist_sysmetric_history  - All the above views are refreshed when the instance is restarted. This view, part of AWR, stores the historical stats. I have used this view for my report. Query: ====== set lines 350...

Oracle ASM DISK IO performance

Oracle OEM show a chart of disk performance, as shown in the chart below. when the OEM target database is 10gr2, the number of average disk response time (ms) is 0.01 ms, which unreasonable low. when the target database is 11gr2, the number is about 10ms, which I think is reasonable. it's time to find out where the discrepency comes from. The backend query is this one: set linesize 200 col name format a9 col path format a19 --col MB_per_sec format select t3.name,t2.name,t2.path,t2.reads,t2.read_time,round(t2.read_time/t2.reads*1000,3) rd_rspd_ms,t2.writes,round(t2.write_time/t2.writes*1000,3) wr_rspd_ms, round((t2.read_time+t2.write_time)/(t2.reads+t2.writes)*1000,3) dsk_rspd_ms,round((t2.bytes_read+t2.bytes_written)/1024/1024/(t2.read_time+t2.write_time))  MB_per_sec from V$asm_disk t2, v$asm_diskgroup t3 where t3.group_number=t2.group_number order by 1,2 / NAME      NAME      PATH               ...