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Home -> Community -> Mailing Lists -> Oracle-L -> RE: HELP! Index Debate!
Ron,
It has been my understanding that in order for the conpound index to
be used the query had to match the order the index was created. Multiple
indexes would not do a whole lot of good for you just make the optmizer
work harder to figure things out. It would add a confusion factor other
wise how would there be a relationship between each column in the index.
An Index on column col1 and a second index on col2 would have a
different tree that an index on col1,col2.
With the additional index (compound or not) on the PROD_ID the
execution time will decrease as it will use the index scan for the join
condition in the where clause T6."PROD_ID"=T4."PROD_ID"(+) . Before
there was no index and the full table scan resulted.
Looking at the where clause and in this case the developer might be
correct as the where clause referres to the T6 table = to multiple other
tables different columns.
Ron
>>> rlsmith_at_kmg.com 07/31/03 04:34PM >>>
Please help resolve this dispute.
We have a query that runs over 5 hours. Sections of the query are
listed below.
The table QOH_DAY_FACT table had only on index and that was on the
TIME_ID column. I propose adding an index with PROD_ID, WHS_ID,
LOT_ID,
WHS_LOC, TIME_ID and QUALITY_ID. My test shows the runtime was
reduced
to about 1.5 hours.
The developer said all the columns in the index except PROD_ID were being ignored. He says there should be six separate indexes, one for each column before Oracle will use them.
Also, does the order of the columns in the index have to match the
order
of the columns in the WHERE CLAUS or is it more important to match the
WHERE CLAUS to the data content (least number of rows first)?
I will be running more tests, but I would like some input on this if anyone has an opinion.
Thanks!
Ron
select T1."COUNTRY_NAME" "c1"
, T2."PRODTN_PROC_NAME" "c2"
, T2."PLANT_NAME" "c3"
, T1."WHS_NAME" "c4"
, T1."WHS_CMPLX_NAME" "c5"
, T3."WHS_LOC_NAME" "c6"
, T4."GRADE_DESC" "c7"
, T4."PACK_DESC" "c8"
, T5."FULL_DT" "c9"
, T6."QOH_MT" "c10".......
....from "DWMART"."DISTRIB_FCLTY_DIM" T1
, "DWMART"."MFG_FCLTY_DIM" T2
, "DWMART"."DISTRIB_LOC_DIM" T3
, "DWMART"."TIME_DIM" T5
, "DWMART"."QUALITY_DIM" T7
, "DWMART"."QOH_DAY_FACT" T6
, "DWMART"."PROD_DIM" T4
where T6."PROD_ID"=T4."PROD_ID"(+) and T6."WHS_ID"=T1."WHS_ID" and T6."LOT_ID"=T2."LOT_ID" and T6."WHS_LOC_ID"=T3."WHS_LOC_ID"
-- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Smith, Ron L. INET: rlsmith_at_kmg.com Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing). -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Ron Rogers INET: RROGERS_at_galottery.org Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).Received on Thu Jul 31 2003 - 15:54:24 CDT
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