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https://github.com/timescale/timescaledb.git
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ce73f25a87
This patch optimizes how first()/last() initialize the compare function. Previously the compare function would be looked up for every transition function call but since polymorphic types are resolved at parse time for a specific aggregate instance the compare function will not change during its lifetime. Additionally this patch also fixes a memory leak when using first()/last() on pointer types. These changes lead to a roughly 2x speed improvement for first()/ last() and make the memory usage near-constant. Fixes #3935
121 lines
4.6 KiB
PL/PgSQL
121 lines
4.6 KiB
PL/PgSQL
-- This file and its contents are licensed under the Apache License 2.0.
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-- Please see the included NOTICE for copyright information and
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-- LICENSE-APACHE for a copy of the license.
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-- canary for results diff
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-- this should be only output of results diff
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SELECT setting, current_setting(setting) AS value from (VALUES ('timescaledb.enable_optimizations')) v(setting);
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:PREFIX SELECT time, gp, temp FROM btest ORDER BY time;
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:PREFIX SELECT last(temp, time) FROM btest;
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:PREFIX SELECT first(temp, time) FROM btest;
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:PREFIX SELECT last(temp, time_alt) FROM btest;
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:PREFIX SELECT first(temp, time_alt) FROM btest;
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:PREFIX SELECT gp, last(temp, time) FROM btest GROUP BY gp ORDER BY gp;
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:PREFIX SELECT gp, first(temp, time) FROM btest GROUP BY gp ORDER BY gp;
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--check whole row
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:PREFIX SELECT gp, first(btest, time) FROM btest GROUP BY gp ORDER BY gp;
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--check toasted col
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:PREFIX SELECT gp, left(last(strid, time), 10) FROM btest GROUP BY gp ORDER BY gp;
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:PREFIX SELECT gp, last(temp, strid) FROM btest GROUP BY gp ORDER BY gp;
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:PREFIX SELECT gp, last(strid, temp) FROM btest GROUP BY gp ORDER BY gp;
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BEGIN;
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--check null value as last element
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INSERT INTO btest VALUES('2018-01-20T09:00:43', '2017-01-20T09:00:55', 2, NULL);
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:PREFIX SELECT last(temp, time) FROM btest;
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--check non-null element "overrides" NULL because it comes after.
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INSERT INTO btest VALUES('2019-01-20T09:00:43', '2018-01-20T09:00:55', 2, 30.5);
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:PREFIX SELECT last(temp, time) FROM btest;
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--check null cmp element is skipped
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INSERT INTO btest VALUES('2018-01-20T09:00:43', NULL, 2, 32.3);
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:PREFIX SELECT last(temp, time_alt) FROM btest;
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-- fist returns NULL value
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:PREFIX SELECT first(temp, time_alt) FROM btest;
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-- test first return non NULL value
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INSERT INTO btest VALUES('2016-01-20T09:00:00', '2016-01-20T09:00:00', 2, 36.5);
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:PREFIX SELECT first(temp, time_alt) FROM btest;
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--check non null cmp element insert after null cmp
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INSERT INTO btest VALUES('2020-01-20T09:00:43', '2020-01-20T09:00:43', 2, 35.3);
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:PREFIX SELECT last(temp, time_alt) FROM btest;
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:PREFIX SELECT first(temp, time_alt) FROM btest;
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--cmp nulls should be ignored and not present in groups
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:PREFIX SELECT gp, last(temp, time_alt) FROM btest GROUP BY gp ORDER BY gp;
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--Previously, some bugs were found with NULLS and numeric types, so test that
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INSERT INTO btest_numeric VALUES ('2019-01-20T09:00:43', NULL);
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:PREFIX SELECT last(quantity, time) FROM btest_numeric;
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--check non-null element "overrides" NULL because it comes after.
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INSERT INTO btest_numeric VALUES('2020-01-20T09:00:43', 30.5);
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:PREFIX SELECT last(quantity, time) FROM btest_numeric;
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-- do index scan for last
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:PREFIX SELECT last(temp, time) FROM btest;
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-- do index scan for first
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:PREFIX SELECT first(temp, time) FROM btest;
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-- can't do index scan when ordering on non-index column
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:PREFIX SELECT first(temp, time_alt) FROM btest;
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-- do index scan for subquery
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:PREFIX SELECT * FROM (SELECT last(temp, time) FROM btest) last;
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-- can't do index scan when using group by
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:PREFIX SELECT last(temp, time) FROM btest GROUP BY gp ORDER BY gp;
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-- do index scan when agg function is used in CTE subquery
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:PREFIX WITH last_temp AS (SELECT last(temp, time) FROM btest) SELECT * from last_temp;
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-- do index scan when using both FIRST and LAST aggregate functions
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:PREFIX SELECT first(temp, time), last(temp, time) FROM btest;
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-- verify results when using both FIRST and LAST
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:PREFIX SELECT first(temp, time), last(temp, time) FROM btest;
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-- do index scan when using WHERE
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:PREFIX SELECT last(temp, time) FROM btest WHERE time <= '2017-01-20T09:00:02';
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-- can't do index scan for MAX and LAST combined (MinMax optimization fails when having different aggregate functions)
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:PREFIX SELECT max(time), last(temp, time) FROM btest;
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-- can't do index scan when using FIRST/LAST in ORDER BY
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:PREFIX SELECT last(temp, time) FROM btest ORDER BY last(temp, time);
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-- do index scan
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:PREFIX SELECT last(temp, time) FROM btest WHERE temp < 30;
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-- SELECT first(temp, time) FROM btest WHERE time >= '2017-01-20 09:00:47';
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-- do index scan
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:PREFIX SELECT first(temp, time) FROM btest WHERE time >= '2017-01-20 09:00:47';
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-- can't do index scan when using WINDOW function
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:PREFIX SELECT gp, last(temp, time) OVER (PARTITION BY gp) AS last FROM btest;
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-- test constants
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:PREFIX SELECT first(100, 100) FROM btest;
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-- create an index so we can test optimization
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CREATE INDEX btest_time_alt_idx ON btest(time_alt);
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:PREFIX SELECT last(temp, time_alt) FROM btest;
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--test nested FIRST/LAST - should optimize
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:PREFIX SELECT abs(last(temp, time)) FROM btest;
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-- test nested FIRST/LAST in ORDER BY - no optimization possible
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:PREFIX SELECT abs(last(temp, time)) FROM btest ORDER BY abs(last(temp,time));
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ROLLBACK;
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