bricklen <bricklen@xxxxxxxxx> writes: > On Tue, Nov 9, 2010 at 3:29 PM, Tom Lane <tgl@xxxxxxxxxxxxx> wrote: >> The query doesn't seem to match the plan. Â Where is that OR (c.id = >> 38441828354::bigint) condition coming from? > Ah sorry, I was testing it with and without that part. Here is the > corrected query, with that as part of the join condition: > explain analyze > select c.id, c.transactionid, c.clickgenerated, c.confirmed, > c.rejected, cr.rejectedreason > from conversion c > inner join conversionrejected cr on cr.idconversion = c.id or c.id = 38441828354 > where date = '2010-11-06' > and idaction = 12906 > and idaffiliate = 198338 > order by transactionid; Hm. Well, the trouble with that query is that if there is any conversion row with c.id = 38441828354, it will join to *every* row of conversionrejected. The planner not unreasonably assumes there will be at least one such row, so it comes up with a join size estimate that's >= size of conversionrejected; and it also tends to favor a seqscan since it thinks it's going to have to visit every row of conversionrejected anyway. If you have reason to think the c.id = 38441828354 test is usually dead code, you might see if you can get rid of it, or at least rearrange the query as a UNION of two independent joins. regards, tom lane -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
