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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Thread: | |
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)
From | Date | Subject | |
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Next Message | Joseph S | 2007-07-31 22:31:07 | Re: BUG #3500: Horrible performance when wrong type is set in prepared statement |
Previous Message | Tom Lane | 2007-07-31 19:55:31 | Re: BUG #3494: may be Query Error: subplan does not executed |