Hi,
I have read that GIN indexes don't require a recheck cond for full text search as long as work_mem is big enough, otherwise you get lossy blocks, and the recheck cond.
In my case, I have no lossy blocks (from what I could tell), but I do have a recheck...
EXPLAIN (ANALYZE, BUFFERS) SELECT COUNT(1) FROM enterprises WHERE fts @@ 'activ'::tsquery
"Aggregate (cost=264555.07..264555.08 rows=1 width=0) (actual time=25813.920..25813.921 rows=1 loops=1)"
" Buffers: shared hit=1 read=178192"
" -> Bitmap Heap Scan on enterprises (cost=5004.86..263202.54 rows=541014 width=0) (actual time=170.546..25663.048 rows=528376 loops=1)"
" Recheck Cond: (fts @@ '''activ'''::tsquery)"
" Heap Blocks: exact=178096"
" Buffers: shared hit=1 read=178192"
" -> Bitmap Index Scan on enterprises_fts_idx (cost=0.00..4869.61 rows=541014 width=0) (actual time=120.214..120.214 rows=528376 loops=1)"
" Index Cond: (fts @@ '''activ'''::tsquery)"
" Buffers: shared hit=1 read=96"
"Planning time: 2.383 ms"
"Execution time: 25824.476 ms"
Any advice would be greatly appreciated. I'm running PostgreSQL 9.4.1.
Thank you,
Laurent Debacker
