[SQL] Partitioned tables not using index for min and max 8.2.7?
Hi I am running the following query again a partitioned table in 8.2.7. It does index scans which is unexpected as there are indexes for the log_date column. min(log_date) from data.table "Aggregate (cost=739932.02..739932.02 rows=1 width=8)" " -> Append (cost=0.00..685106.21 rows=21930321 width=8)" "-> Seq Scan on table (cost=0.00..33827.10 rows=1215710 width=8)" "-> Seq Scan on table_yy2009mm03 table (cost=0.00..88056.39 rows=438839 width=8)" "-> Seq Scan on table_yy2009mm04 table (cost=0.00..204606.67 rows=7344967 width=8)" "-> Seq Scan on table_yy2009mm05 table (cost=0.00..159210.91 rows=5735091 width=8)" "-> Seq Scan on table_yy2009mm06 table (cost=0.00..199393.74 rows=7195574 width=8)" "-> Seq Scan on table_yy2009mm07 table (cost=0.00..11.40 rows=140 width=8)" though if i run it only agains the one table it is significantly faster and uses the index select min(log_date) from only data.table "Result (cost=0.06..0.07 rows=1 width=0)" " InitPlan" "-> Limit (cost=0.00..0.06 rows=1 width=8)" " -> Index Scan using idx_table_log_date_only on table (cost=0.00..68272.93 rows=1215710 width=8)" "Filter: (log_date IS NOT NULL)" Am I doing something wrong or is this expected. I tried the old method of SELECT col FROM table ORDER BY col DESC LIMIT 1 But it does not work either. -- Tim Haak Email: [email protected] Tel: +27 12 658 9019 begin:vcard fn:Timothy Haak n:Haak;Timothy email;internet:[email protected] tel;work:+27 12 658 9019 tel;cell:+27 83 778 7100 x-mozilla-html:TRUE version:2.1 end:vcard -- Sent via pgsql-sql mailing list ([email protected]) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-sql
Re: [SQL] Partitioned tables not using index for min and max 8.2.7?
Cool thanks then not something I'm doing wrong :). Is this going to be changed or is changed in a latter version of postgres. (Do I need to do and upgrade or write a work around :) ) Tom Lane wrote: Tim Haak writes: I am running the following query again a partitioned table in 8.2.7. It does index scans which is unexpected as there are indexes for the log_date column. The index min/max optimization only works on single tables at the moment. Sorry. regards, tom lane -- Tim Haak Email: [email protected] Tel: +27 12 658 9019 begin:vcard fn:Timothy Haak n:Haak;Timothy email;internet:[email protected] tel;work:+27 12 658 9019 tel;cell:+27 83 778 7100 x-mozilla-html:TRUE version:2.1 end:vcard -- Sent via pgsql-sql mailing list ([email protected]) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-sql
