> From: pgsql-performance-owner@xxxxxxxxxxxxxx > [mailto:pgsql-performance-owner@xxxxxxxxxxxxxx] On Behalf Of > Dan Harris > > After some digging, I've found that the planner is choosing > to apply a necessary seq scan to the table. Unfortunately, > it's scanning the whole table, when it seems that it could > have joined it to a smaller table first and reduce the > amount of rows it would have to scan dramatically ( 70 > million to about 5,000 ). > Joining will reduce the amount of rows to scan for the filter, but performing the join is non-trivial. If postgres is going to join two tables together without applying any filter first then it will have to do a seqscan of one of the tables, and if it chooses the table with 5000 rows, then it will have to do 5000 index scans on a table with 70 million records. I don't know which way would be faster. I wonder if you could find a way to use an index to do the text filter. Maybe tsearch2? I haven't used anything like that myself, maybe someone else has more input.
