diff options
Diffstat (limited to 'doc/src/sgml/bloom.sgml')
| -rw-r--r-- | doc/src/sgml/bloom.sgml | 16 |
1 files changed, 12 insertions, 4 deletions
diff --git a/doc/src/sgml/bloom.sgml b/doc/src/sgml/bloom.sgml index 0e734f3d6e6..6a8a60b8c70 100644 --- a/doc/src/sgml/bloom.sgml +++ b/doc/src/sgml/bloom.sgml @@ -121,9 +121,10 @@ SELECT 10000000 Seq Scan on tbloom (cost=0.00..213744.00 rows=250 width=24) (actual time=357.059..357.059 rows=0 loops=1) Filter: ((i2 = 898732) AND (i5 = 123451)) Rows Removed by Filter: 10000000 + Buffers: shared hit=63744 Planning Time: 0.346 ms Execution Time: 357.076 ms -(5 rows) +(6 rows) </programlisting> </para> @@ -144,9 +145,10 @@ CREATE INDEX Seq Scan on tbloom (cost=0.00..213744.00 rows=2 width=24) (actual time=351.016..351.017 rows=0 loops=1) Filter: ((i2 = 898732) AND (i5 = 123451)) Rows Removed by Filter: 10000000 + Buffers: shared hit=63744 Planning Time: 0.138 ms Execution Time: 351.035 ms -(5 rows) +(6 rows) </programlisting> </para> @@ -168,11 +170,13 @@ CREATE INDEX Recheck Cond: ((i2 = 898732) AND (i5 = 123451)) Rows Removed by Index Recheck: 2300 Heap Blocks: exact=2256 + Buffers: shared hit=21864 -> Bitmap Index Scan on bloomidx (cost=0.00..178436.00 rows=1 width=0) (actual time=20.005..20.005 rows=2300 loops=1) Index Cond: ((i2 = 898732) AND (i5 = 123451)) + Buffers: shared hit=19608 Planning Time: 0.099 ms Execution Time: 22.632 ms -(8 rows) +(10 rows) </programlisting> </para> @@ -199,14 +203,18 @@ CREATE INDEX -------------------------------------------------------------------&zwsp;-------------------------------------------------------- Bitmap Heap Scan on tbloom (cost=9.29..13.30 rows=1 width=24) (actual time=0.032..0.033 rows=0 loops=1) Recheck Cond: ((i5 = 123451) AND (i2 = 898732)) + Buffers: shared read=6 -> BitmapAnd (cost=9.29..9.29 rows=1 width=0) (actual time=0.047..0.047 rows=0 loops=1) + Buffers: shared hit=6 -> Bitmap Index Scan on btreeidx5 (cost=0.00..4.52 rows=11 width=0) (actual time=0.026..0.026 rows=7 loops=1) Index Cond: (i5 = 123451) + Buffers: shared hit=3 -> Bitmap Index Scan on btreeidx2 (cost=0.00..4.52 rows=11 width=0) (actual time=0.007..0.007 rows=8 loops=1) Index Cond: (i2 = 898732) + Buffers: shared hit=3 Planning Time: 0.264 ms Execution Time: 0.047 ms -(9 rows) +(13 rows) </programlisting> Although this query runs much faster than with either of the single indexes, we pay a penalty in index size. Each of the single-column |