| From: | Joseph S <jks(at)selectacast(dot)net> | 
|---|---|
| To: | pgsql-bugs(at)postgresql(dot)org | 
| Subject: | EXPLAIN ANALYZE for bitmapAnd and bitmapOr scans always reports rows = 0 | 
| Date: | 2007-07-31 22:26:46 | 
| Message-ID: | f8ocv1$ba$1@news.hub.org | 
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| Lists: | pgsql-bugs | 
 From this snipped you can see that the Bitmap Heap scan returns 123 
rows, but the BitmapAnd under it returns 0.  I would find it useful to 
determine how many rows were thrown out by the recheck.
                      ->  Bitmap Heap Scan on d  (cost=4959.18..16848.23 
rows=754 width=10) (actual time=344.126..1534.198 rows=123 loops=1)
                            Recheck Cond: ((s = $0) AND (sdate >= 
'2007-06-30'::date) AND (sdate <= '2007-07-30'::date))
                            Filter: (snipped filter conditions here)
                            ->  BitmapAnd  (cost=4959.18..4959.18 
rows=3218 width=0) (actual time=337.002..337.002 rows=0 loops=1)
                                  ->  Bitmap Index Scan on d_idx1 
(cost=0.00..1035.58 rows=54796 width=0) (actual time=96.478..96.478 
rows=30338 loops=1)
                                        Index Cond: (s = $0)
                                  ->  Bitmap Index Scan on d_idx2 
(cost=0.00..3922.98 rows=183437 width=0) (actual time=235.680..235.680 
rows=181322 loops=1)
                                        Index Cond: ((sdate >= 
'2007-06-30'::date) AND (sdate <= '2007-07-30'::date))
This was on:
PostgreSQL 8.2.4 on x86_64-unknown-linux-gnu, compiled by GCC gcc (GCC) 
3.4.6 20060404 (Red Hat 3.4.6-3)
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