bitmap heap scan recheck for gin/fts with no lossy blocks

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