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https://github.com/timescale/timescaledb.git
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7b3929e30d
This optimization will replace the MergeAppendPath for queries on hypertables ordered by the time partitioning column and with a LIMIT clause with an ordered AppendPath. This optimization will remove the need for last point queries to access every chunk of a hypertable. This commit also adds struct TimescaleDBPrivate which is stored in RelOptInfo->fdw_private to store TimescaleDB-specific plan state between different planner hook invocations in the plan. We needed to add TimescaleDBPrivate to store a flag indicating whether or not to use ordered append between different parts of the planner.
133 lines
3.7 KiB
SQL
133 lines
3.7 KiB
SQL
-- 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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-- print chunks ordered by time to ensure ordering we want
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SELECT
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ht.table_name AS hypertable,
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c.table_name AS chunk,
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ds.range_start
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FROM
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_timescaledb_catalog.chunk c
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INNER JOIN _timescaledb_catalog.chunk_constraint cc ON c.id = cc.chunk_id
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INNER JOIN _timescaledb_catalog.dimension_slice ds ON ds.id=cc.dimension_slice_id
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INNER JOIN _timescaledb_catalog.dimension d ON ds.dimension_id = d.id
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INNER JOIN _timescaledb_catalog.hypertable ht ON d.hypertable_id = ht.id
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ORDER BY ht.table_name, range_start;
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-- test ASC for ordered chunks
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:PREFIX SELECT
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time, device_id, value
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FROM ordered_append
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ORDER BY time ASC LIMIT 1;
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-- test DESC for ordered chunks
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:PREFIX SELECT
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time, device_id, value
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FROM ordered_append
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ORDER BY time DESC LIMIT 1;
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-- test ASC for reverse ordered chunks
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:PREFIX SELECT
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time, device_id, value
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FROM ordered_append_reverse
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ORDER BY time ASC LIMIT 1;
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-- test DESC for reverse ordered chunks
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:PREFIX SELECT
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time, device_id, value
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FROM ordered_append_reverse
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ORDER BY time DESC LIMIT 1;
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-- test query with ORDER BY column not in targetlist
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:PREFIX SELECT
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device_id, value
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FROM ordered_append
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ORDER BY time ASC LIMIT 1;
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-- ORDER BY may include other columns after time column
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:PREFIX SELECT
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time, device_id, value
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FROM ordered_append
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ORDER BY time DESC, device_id LIMIT 1;
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-- queries with ORDER BY non-time column shouldn't use ordered append
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:PREFIX SELECT
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time, device_id, value
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FROM ordered_append
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ORDER BY device_id LIMIT 1;
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-- time column must be primary sort order
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:PREFIX SELECT
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time, device_id, value
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FROM ordered_append
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ORDER BY device_id, time LIMIT 1;
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-- queries without LIMIT shouldnt use ordered append
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:PREFIX SELECT
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time, device_id, value
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FROM ordered_append
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ORDER BY time ASC;
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-- queries without ORDER BY shouldnt use ordered append (still uses append though)
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:PREFIX SELECT
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time, device_id, value
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FROM ordered_append
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LIMIT 1;
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-- test interaction with constraint exclusion
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:PREFIX SELECT
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time, device_id, value
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FROM ordered_append
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WHERE time > '2000-01-07'
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ORDER BY time ASC LIMIT 1;
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:PREFIX SELECT
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time, device_id, value
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FROM ordered_append
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WHERE time > '2000-01-07'
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ORDER BY time DESC LIMIT 1;
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-- min/max queries
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:PREFIX SELECT max(time) FROM ordered_append;
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:PREFIX SELECT min(time) FROM ordered_append;
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-- test first/last (doesn't use ordered append yet)
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:PREFIX SELECT first(time, time) FROM ordered_append;
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:PREFIX SELECT last(time, time) FROM ordered_append;
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-- test query with time_bucket
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:PREFIX SELECT
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time_bucket('1d',time), device_id, value
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FROM ordered_append
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ORDER BY time ASC LIMIT 1;
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-- test query with order by time_bucket (should not use ordered append)
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:PREFIX SELECT
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time_bucket('1d',time), device_id, value
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FROM ordered_append
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ORDER BY 1 LIMIT 1;
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-- test query with order by time_bucket (should not use ordered append)
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:PREFIX SELECT
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time_bucket('1d',time), device_id, value
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FROM ordered_append
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ORDER BY time_bucket('1d',time) LIMIT 1;
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-- test query with now() should result in ordered append with constraint aware append
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:PREFIX SELECT * FROM ordered_append WHERE time < now() + '1 month'
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ORDER BY time DESC limit 1;
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-- test CTE
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:PREFIX WITH i AS (SELECT * FROM ordered_append WHERE time < now() ORDER BY time DESC limit 100)
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SELECT * FROM i;
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-- test LATERAL with ordered append in the outer query
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:PREFIX SELECT * FROM ordered_append, LATERAL(SELECT * FROM (VALUES (1),(2)) v) l ORDER BY time DESC limit 2;
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-- test LATERAL with ordered append in the lateral query
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:PREFIX SELECT * FROM (VALUES (1),(2)) v, LATERAL(SELECT * FROM ordered_append ORDER BY time DESC limit 2) l;
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