285 lines
8.8 KiB
SQL
285 lines
8.8 KiB
SQL
-- Generic extended statistics support
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-- We will be checking execution plans without/with statistics, so
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-- let's make sure we get simple non-parallel plans. Also set the
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-- work_mem low so that we can use small amounts of data.
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SET max_parallel_workers = 0;
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SET max_parallel_workers_per_gather = 0;
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SET work_mem = '128kB';
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-- Verify failures
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CREATE STATISTICS tst;
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CREATE STATISTICS tst ON a, b;
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CREATE STATISTICS tst FROM sometab;
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CREATE STATISTICS tst ON a, b FROM nonexistant;
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CREATE STATISTICS tst ON a, b FROM pg_class;
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CREATE STATISTICS tst ON relname, relname, relnatts FROM pg_class;
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CREATE STATISTICS tst ON relnatts + relpages FROM pg_class;
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CREATE STATISTICS tst ON (relpages, reltuples) FROM pg_class;
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CREATE STATISTICS tst (unrecognized) ON relname, relnatts FROM pg_class;
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-- Ensure stats are dropped sanely, and test IF NOT EXISTS while at it
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CREATE TABLE ab1 (a INTEGER, b INTEGER, c INTEGER);
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CREATE STATISTICS IF NOT EXISTS ab1_a_b_stats ON a, b FROM ab1;
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CREATE STATISTICS IF NOT EXISTS ab1_a_b_stats ON a, b FROM ab1;
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DROP STATISTICS ab1_a_b_stats;
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CREATE SCHEMA regress_schema_2;
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CREATE STATISTICS regress_schema_2.ab1_a_b_stats ON a, b FROM ab1;
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-- Let's also verify the pg_get_statisticsobjdef output looks sane.
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SELECT pg_get_statisticsobjdef(oid) FROM pg_statistic_ext WHERE stxname = 'ab1_a_b_stats';
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DROP STATISTICS regress_schema_2.ab1_a_b_stats;
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-- Ensure statistics are dropped when columns are
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CREATE STATISTICS ab1_b_c_stats ON b, c FROM ab1;
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CREATE STATISTICS ab1_a_b_c_stats ON a, b, c FROM ab1;
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CREATE STATISTICS ab1_b_a_stats ON b, a FROM ab1;
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ALTER TABLE ab1 DROP COLUMN a;
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\d ab1
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-- Ensure statistics are dropped when table is
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SELECT stxname FROM pg_statistic_ext WHERE stxname LIKE 'ab1%';
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DROP TABLE ab1;
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SELECT stxname FROM pg_statistic_ext WHERE stxname LIKE 'ab1%';
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-- Ensure things work sanely with SET STATISTICS 0
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CREATE TABLE ab1 (a INTEGER, b INTEGER);
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ALTER TABLE ab1 ALTER a SET STATISTICS 0;
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INSERT INTO ab1 SELECT a, a%23 FROM generate_series(1, 1000) a;
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CREATE STATISTICS ab1_a_b_stats ON a, b FROM ab1;
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ANALYZE ab1;
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ALTER TABLE ab1 ALTER a SET STATISTICS -1;
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-- partial analyze doesn't build stats either
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ANALYZE ab1 (a);
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ANALYZE ab1;
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DROP TABLE ab1;
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-- Verify supported object types for extended statistics
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CREATE schema tststats;
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CREATE TABLE tststats.t (a int, b int, c text);
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CREATE INDEX ti ON tststats.t (a, b);
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CREATE SEQUENCE tststats.s;
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CREATE VIEW tststats.v AS SELECT * FROM tststats.t;
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CREATE MATERIALIZED VIEW tststats.mv AS SELECT * FROM tststats.t;
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CREATE TYPE tststats.ty AS (a int, b int, c text);
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CREATE FOREIGN DATA WRAPPER extstats_dummy_fdw;
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CREATE SERVER extstats_dummy_srv FOREIGN DATA WRAPPER extstats_dummy_fdw;
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CREATE FOREIGN TABLE tststats.f (a int, b int, c text) SERVER extstats_dummy_srv;
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CREATE TABLE tststats.pt (a int, b int, c text) PARTITION BY RANGE (a, b);
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CREATE TABLE tststats.pt1 PARTITION OF tststats.pt FOR VALUES FROM (-10, -10) TO (10, 10);
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CREATE STATISTICS tststats.s1 ON a, b FROM tststats.t;
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CREATE STATISTICS tststats.s2 ON a, b FROM tststats.ti;
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CREATE STATISTICS tststats.s3 ON a, b FROM tststats.s;
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CREATE STATISTICS tststats.s4 ON a, b FROM tststats.v;
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CREATE STATISTICS tststats.s5 ON a, b FROM tststats.mv;
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CREATE STATISTICS tststats.s6 ON a, b FROM tststats.ty;
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CREATE STATISTICS tststats.s7 ON a, b FROM tststats.f;
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CREATE STATISTICS tststats.s8 ON a, b FROM tststats.pt;
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CREATE STATISTICS tststats.s9 ON a, b FROM tststats.pt1;
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DO $$
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DECLARE
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relname text := reltoastrelid::regclass FROM pg_class WHERE oid = 'tststats.t'::regclass;
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BEGIN
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EXECUTE 'CREATE STATISTICS tststats.s10 ON a, b FROM ' || relname;
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EXCEPTION WHEN wrong_object_type THEN
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RAISE NOTICE 'stats on toast table not created';
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END;
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$$;
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\set VERBOSITY terse \\ -- suppress cascade details
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DROP SCHEMA tststats CASCADE;
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DROP FOREIGN DATA WRAPPER extstats_dummy_fdw CASCADE;
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\set VERBOSITY default
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-- n-distinct tests
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CREATE TABLE ndistinct (
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filler1 TEXT,
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filler2 NUMERIC,
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a INT,
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b INT,
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filler3 DATE,
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c INT,
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d INT
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);
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-- over-estimates when using only per-column statistics
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INSERT INTO ndistinct (a, b, c, filler1)
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SELECT i/100, i/100, i/100, cash_words((i/100)::money)
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FROM generate_series(1,30000) s(i);
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ANALYZE ndistinct;
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-- Group Aggregate, due to over-estimate of the number of groups
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EXPLAIN (COSTS off)
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SELECT COUNT(*) FROM ndistinct GROUP BY a, b;
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EXPLAIN (COSTS off)
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SELECT COUNT(*) FROM ndistinct GROUP BY b, c;
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EXPLAIN (COSTS off)
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SELECT COUNT(*) FROM ndistinct GROUP BY a, b, c;
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EXPLAIN (COSTS off)
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SELECT COUNT(*) FROM ndistinct GROUP BY a, b, c, d;
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EXPLAIN (COSTS off)
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SELECT COUNT(*) FROM ndistinct GROUP BY b, c, d;
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-- correct command
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CREATE STATISTICS s10 ON a, b, c FROM ndistinct;
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ANALYZE ndistinct;
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SELECT stxkind, stxndistinct
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FROM pg_statistic_ext WHERE stxrelid = 'ndistinct'::regclass;
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-- Hash Aggregate, thanks to estimates improved by the statistic
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EXPLAIN (COSTS off)
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SELECT COUNT(*) FROM ndistinct GROUP BY a, b;
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EXPLAIN (COSTS off)
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SELECT COUNT(*) FROM ndistinct GROUP BY b, c;
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EXPLAIN (COSTS off)
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SELECT COUNT(*) FROM ndistinct GROUP BY a, b, c;
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-- last two plans keep using Group Aggregate, because 'd' is not covered
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-- by the statistic and while it's NULL-only we assume 200 values for it
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EXPLAIN (COSTS off)
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SELECT COUNT(*) FROM ndistinct GROUP BY a, b, c, d;
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EXPLAIN (COSTS off)
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SELECT COUNT(*) FROM ndistinct GROUP BY b, c, d;
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TRUNCATE TABLE ndistinct;
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-- under-estimates when using only per-column statistics
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INSERT INTO ndistinct (a, b, c, filler1)
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SELECT mod(i,50), mod(i,51), mod(i,32),
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cash_words(mod(i,33)::int::money)
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FROM generate_series(1,10000) s(i);
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ANALYZE ndistinct;
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SELECT stxkind, stxndistinct
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FROM pg_statistic_ext WHERE stxrelid = 'ndistinct'::regclass;
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-- plans using Group Aggregate, thanks to using correct esimates
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EXPLAIN (COSTS off)
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SELECT COUNT(*) FROM ndistinct GROUP BY a, b;
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EXPLAIN (COSTS off)
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SELECT COUNT(*) FROM ndistinct GROUP BY a, b, c;
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EXPLAIN (COSTS off)
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SELECT COUNT(*) FROM ndistinct GROUP BY a, b, c, d;
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EXPLAIN (COSTS off)
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SELECT COUNT(*) FROM ndistinct GROUP BY b, c, d;
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EXPLAIN (COSTS off)
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SELECT COUNT(*) FROM ndistinct GROUP BY a, d;
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DROP STATISTICS s10;
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SELECT stxkind, stxndistinct
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FROM pg_statistic_ext WHERE stxrelid = 'ndistinct'::regclass;
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-- dropping the statistics switches the plans to Hash Aggregate,
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-- due to under-estimates
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EXPLAIN (COSTS off)
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SELECT COUNT(*) FROM ndistinct GROUP BY a, b;
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EXPLAIN (COSTS off)
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SELECT COUNT(*) FROM ndistinct GROUP BY a, b, c;
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EXPLAIN (COSTS off)
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SELECT COUNT(*) FROM ndistinct GROUP BY a, b, c, d;
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EXPLAIN (COSTS off)
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SELECT COUNT(*) FROM ndistinct GROUP BY b, c, d;
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EXPLAIN (COSTS off)
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SELECT COUNT(*) FROM ndistinct GROUP BY a, d;
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-- functional dependencies tests
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CREATE TABLE functional_dependencies (
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filler1 TEXT,
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filler2 NUMERIC,
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a INT,
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b TEXT,
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filler3 DATE,
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c INT,
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d TEXT
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);
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SET random_page_cost = 1.2;
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CREATE INDEX fdeps_ab_idx ON functional_dependencies (a, b);
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CREATE INDEX fdeps_abc_idx ON functional_dependencies (a, b, c);
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-- random data (no functional dependencies)
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INSERT INTO functional_dependencies (a, b, c, filler1)
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SELECT mod(i, 23), mod(i, 29), mod(i, 31), i FROM generate_series(1,5000) s(i);
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ANALYZE functional_dependencies;
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EXPLAIN (COSTS OFF)
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SELECT * FROM functional_dependencies WHERE a = 1 AND b = '1';
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EXPLAIN (COSTS OFF)
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SELECT * FROM functional_dependencies WHERE a = 1 AND b = '1' AND c = 1;
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-- create statistics
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CREATE STATISTICS func_deps_stat (dependencies) ON a, b, c FROM functional_dependencies;
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ANALYZE functional_dependencies;
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EXPLAIN (COSTS OFF)
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SELECT * FROM functional_dependencies WHERE a = 1 AND b = '1';
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EXPLAIN (COSTS OFF)
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SELECT * FROM functional_dependencies WHERE a = 1 AND b = '1' AND c = 1;
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-- a => b, a => c, b => c
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TRUNCATE functional_dependencies;
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DROP STATISTICS func_deps_stat;
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INSERT INTO functional_dependencies (a, b, c, filler1)
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SELECT mod(i,100), mod(i,50), mod(i,25), i FROM generate_series(1,5000) s(i);
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ANALYZE functional_dependencies;
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EXPLAIN (COSTS OFF)
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SELECT * FROM functional_dependencies WHERE a = 1 AND b = '1';
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EXPLAIN (COSTS OFF)
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SELECT * FROM functional_dependencies WHERE a = 1 AND b = '1' AND c = 1;
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-- create statistics
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CREATE STATISTICS func_deps_stat (dependencies) ON a, b, c FROM functional_dependencies;
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ANALYZE functional_dependencies;
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EXPLAIN (COSTS OFF)
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SELECT * FROM functional_dependencies WHERE a = 1 AND b = '1';
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EXPLAIN (COSTS OFF)
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SELECT * FROM functional_dependencies WHERE a = 1 AND b = '1' AND c = 1;
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-- check change of column type doesn't break it
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ALTER TABLE functional_dependencies ALTER COLUMN c TYPE numeric;
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EXPLAIN (COSTS OFF)
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SELECT * FROM functional_dependencies WHERE a = 1 AND b = '1' AND c = 1;
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ANALYZE functional_dependencies;
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EXPLAIN (COSTS OFF)
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SELECT * FROM functional_dependencies WHERE a = 1 AND b = '1' AND c = 1;
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RESET random_page_cost;
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