39 lines
1.4 KiB
Plaintext
39 lines
1.4 KiB
Plaintext
-- Test bitmap AND and OR
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-- Generate enough data that we can test the lossy bitmaps.
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-- There's 55 tuples per page in the table. 53 is just
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-- below 55, so that an index scan with qual a = constant
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-- will return at least one hit per page. 59 is just above
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-- 55, so that an index scan with qual b = constant will return
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-- hits on most but not all pages. 53 and 59 are prime, so that
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-- there's a maximum number of a,b combinations in the table.
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-- That allows us to test all the different combinations of
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-- lossy and non-lossy pages with the minimum amount of data
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CREATE TABLE bmscantest (a int, b int, t text);
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INSERT INTO bmscantest
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SELECT (r%53), (r%59), 'foooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo'
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FROM generate_series(1,70000) r;
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CREATE INDEX i_bmtest_a ON bmscantest(a);
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CREATE INDEX i_bmtest_b ON bmscantest(b);
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-- We want to use bitmapscans. With default settings, the planner currently
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-- chooses a bitmap scan for the queries below anyway, but let's make sure.
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set enable_indexscan=false;
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set enable_seqscan=false;
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-- Lower work_mem to trigger use of lossy bitmaps
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set work_mem = 64;
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-- Test bitmap-and.
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SELECT count(*) FROM bmscantest WHERE a = 1 AND b = 1;
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count
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-------
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23
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(1 row)
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-- Test bitmap-or.
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SELECT count(*) FROM bmscantest WHERE a = 1 OR b = 1;
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count
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-------
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2485
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(1 row)
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-- clean up
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DROP TABLE bmscantest;
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