Thanks everyone for your wonderful suggestions. And thanks for leaving the "hey stupid" off your reply header :-)
Rachel - Thanks for the bitmapped idea. These tables don't change often, so that may be a good alternative. Iain - Thanks so much for the detailed suggestions. Rick - Good sanity check, yes, I analyzed the tables. Jared - RET has 281 values, pretty evenly distributed Cary - Query returns 185 rows. Bill - Thanks for the suggestions and insights. Stephane - Good notice that only am values are used. Guess that is why Oracle accessed the data blocks anyway with my new indexes. Duh. Good ideas. Jeff - Thanks for the "Mickey Mouse" tag. I may need that in the future. Previously this data was on an old mainframe and the business itself was restricted by the inflexibility. My gut reaction was that they overcompensated. Thanks everyone for the wonderful ideas. I was just given a hot project, so it may be a day or two before I get a chance to explore all of them, but I'll let you know. Dennis Williams DBA Lifetouch, Inc. [EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]> -----Original Message----- Sent: Tuesday, September 10, 2002 2:19 PM To: Multiple recipients of list ORACLE-L I am trying to tune a SQL query on Oracle 8.1.6. I have tried several optimizations, but so far have made no improvements. I would appreciate any suggestions. SELECT am.lid, am.name FROM am, so, sa WHERE so.lid = am.lid AND so.key_ = sa.so_key AND am.active = 1 AND so.code = 11 AND sa.ret = 'SB' ORDER BY am.name Tables: am - 250,000 rows, 220,000 rows have active = 1, the others are 0. so - 1.3 million rows, lid has 250,000 distinct values, key_ is unique, code has 12 values, evenly distributed. sa - 1.3 million rows, ret has 281 values, fairly evenly distributed. so_key is pretty unique. Now, you'll probably say there is essentially a 1-1 relationship between so and sa. You are right, but the developer insists this flexibility is essential. The query executes in 16 seconds and returns 185 rows. This is felt to be too slow for an online lookup screen. explain plan results: SELECT STATEMENT Cost = 2955 SORT ORDER BY HASH JOIN HASH JOIN TABLE ACCESS FULL SA TABLE ACCESS FULL SO TABLE ACCESS FULL AM Here is what I've tried so far: Using hints to force Oracle to use indexes. Query Plan ---------------------------------------------------------------------------- ---- SELECT STATEMENT Cost = 62031 SORT AGGREGATE NESTED LOOPS HASH JOIN TABLE ACCESS BY INDEX ROWID SA INDEX FULL SCAN SO_KEY3 TABLE ACCESS BY INDEX ROWID SO INDEX RANGE SCAN PRG_CODE3 TABLE ACCESS BY INDEX ROWID AM INDEX UNIQUE SCAN LID6 Timing result 25 minutes Next I tried creating new indexes that combine both the accessing column as well as the retrieved column, thinking that Oracle could get the result from the index block and not need to retrieve the data block. create index test1 on am (lid, active); create index test2 on sa (so_key, code); SELECT STATEMENT Cost = 2951 SORT AGGREGATE HASH JOIN HASH JOIN INDEX FULL SCAN TEST2 TABLE ACCESS FULL SO TABLE ACCESS BY INDEX ROWID AM INDEX RANGE SCAN TEST1 Hinting so Oracle will use the new indexes, for one table Oracle uses the index only and for the other table, Oracle hits both the index and table itself. Response time is slightly longer than the original query. At this point I'm fresh out of ideas, so any ideas would be appreciated. Thanks. Dennis Williams DBA Lifetouch, Inc. [EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]> -- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: DENNIS WILLIAMS INET: [EMAIL PROTECTED] Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051 San Diego, California -- Public Internet access / Mailing Lists -------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: [EMAIL PROTECTED] (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.com -- Author: DENNIS WILLIAMS INET: [EMAIL PROTECTED] Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051 San Diego, California -- Public Internet access / Mailing Lists -------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: [EMAIL PROTECTED] (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).