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Commit 16fa9b2b30
introduced a faster way to build GiST indexes, by
sorting all the data. This commit adds the sortsupport functions needed
to make use of that feature for btree_gist.
Author: Andrey Borodin
Discussion: https://www.postgresql.org/message-id/2F3F7265-0D22-44DB-AD71-8554C743D943@yandex-team.ru
99 lines
2.0 KiB
Plaintext
99 lines
2.0 KiB
Plaintext
-- float4 check
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CREATE TABLE float4tmp (a float4);
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\copy float4tmp from 'data/float4.data'
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SET enable_seqscan=on;
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SELECT count(*) FROM float4tmp WHERE a < -179.0;
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count
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-------
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244
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(1 row)
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SELECT count(*) FROM float4tmp WHERE a <= -179.0;
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count
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-------
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245
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(1 row)
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SELECT count(*) FROM float4tmp WHERE a = -179.0;
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count
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-------
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1
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(1 row)
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SELECT count(*) FROM float4tmp WHERE a >= -179.0;
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count
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-------
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303
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(1 row)
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SELECT count(*) FROM float4tmp WHERE a > -179.0;
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count
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-------
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302
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(1 row)
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SELECT a, a <-> '-179.0' FROM float4tmp ORDER BY a <-> '-179.0' LIMIT 3;
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a | ?column?
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------------+-----------
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-179 | 0
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-189.02386 | 10.023865
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-158.17741 | 20.822586
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(3 rows)
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SET client_min_messages = DEBUG1;
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CREATE INDEX float4idx ON float4tmp USING gist ( a );
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DEBUG: building index "float4idx" on table "float4tmp" serially
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DEBUG: using sorted GiST build
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CREATE INDEX float4idx_b ON float4tmp USING gist ( a ) WITH (buffering=on);
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DEBUG: building index "float4idx_b" on table "float4tmp" serially
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DROP INDEX float4idx_b;
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RESET client_min_messages;
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SET enable_seqscan=off;
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SELECT count(*) FROM float4tmp WHERE a < -179.0::float4;
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count
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-------
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244
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(1 row)
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SELECT count(*) FROM float4tmp WHERE a <= -179.0::float4;
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count
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-------
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245
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(1 row)
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SELECT count(*) FROM float4tmp WHERE a = -179.0::float4;
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count
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-------
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1
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(1 row)
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SELECT count(*) FROM float4tmp WHERE a >= -179.0::float4;
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count
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-------
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303
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(1 row)
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SELECT count(*) FROM float4tmp WHERE a > -179.0::float4;
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count
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-------
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302
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(1 row)
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EXPLAIN (COSTS OFF)
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SELECT a, a <-> '-179.0' FROM float4tmp ORDER BY a <-> '-179.0' LIMIT 3;
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QUERY PLAN
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----------------------------------------------------
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Limit
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-> Index Only Scan using float4idx on float4tmp
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Order By: (a <-> '-179'::real)
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(3 rows)
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SELECT a, a <-> '-179.0' FROM float4tmp ORDER BY a <-> '-179.0' LIMIT 3;
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a | ?column?
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------------+-----------
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-179 | 0
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-189.02386 | 10.023865
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-158.17741 | 20.822586
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(3 rows)
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