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https://github.com/timescale/timescaledb.git
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91a73c3e17
The statistics on segmentby and metadata columns are very important as they affect the decompressed data a thousand-fold. Statistics on the compressed columns are irrelevant, as the regular postgres planner cannot understand the compressed columns. This commit sets the statistics for compressed tables based on this, weighting the uncompressed columns greatly, and the compressed columns not-at-all.
170 lines
6.3 KiB
SQL
170 lines
6.3 KiB
SQL
-- This file and its contents are licensed under the Timescale License.
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-- Please see the included NOTICE for copyright information and
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-- LICENSE-TIMESCALE for a copy of the license.
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\ir include/rand_generator.sql
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\c :TEST_DBNAME :ROLE_SUPERUSER
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\ir include/compression_utils.sql
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\c :TEST_DBNAME :ROLE_DEFAULT_PERM_USER
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CREATE TABLE test1 ("Time" timestamptz, i integer, b bigint, t text);
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SELECT table_name from create_hypertable('test1', 'Time', chunk_time_interval=> INTERVAL '1 day');
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INSERT INTO test1 SELECT t, gen_rand_minstd(), gen_rand_minstd(), gen_rand_minstd()::text FROM generate_series('2018-03-02 1:00'::TIMESTAMPTZ, '2018-03-28 1:00', '1 hour') t;
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ALTER TABLE test1 set (timescaledb.compress, timescaledb.compress_segmentby = '', timescaledb.compress_orderby = '"Time" DESC');
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SELECT
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$$
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SELECT * FROM test1 ORDER BY "Time"
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$$ AS "QUERY" \gset
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SELECT 'test1' AS "HYPERTABLE_NAME" \gset
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\ir include/compression_test_hypertable.sql
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\set TYPE timestamptz
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\set ORDER_BY_COL_NAME Time
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\set SEGMENT_META_COL_MIN _ts_meta_min_1
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\set SEGMENT_META_COL_MAX _ts_meta_max_1
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\ir include/compression_test_hypertable_segment_meta.sql
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-- check stats
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SELECT DISTINCT attname, attstattarget
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FROM pg_attribute
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WHERE attrelid = '_timescaledb_internal._compressed_hypertable_2'::REGCLASS
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AND attnum > 0
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ORDER BY attname;
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SELECT DISTINCT attname, attstattarget
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FROM pg_attribute
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WHERE attrelid in (SELECT "Child" FROM test.show_subtables('_timescaledb_internal._compressed_hypertable_2'))
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AND attnum > 0
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ORDER BY attname;
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TRUNCATE test1;
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/* should be no data in table */
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SELECT * FROM test1;
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/* nor compressed table */
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SELECT * FROM _timescaledb_internal._compressed_hypertable_2;
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/* the compressed table should have not chunks */
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EXPLAIN (costs off) SELECT * FROM _timescaledb_internal._compressed_hypertable_2;
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--add test for altered hypertable
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CREATE TABLE test2 ("Time" timestamptz, i integer, b bigint, t text);
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SELECT table_name from create_hypertable('test2', 'Time', chunk_time_interval=> INTERVAL '1 day');
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--create some chunks with the old column numbers
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INSERT INTO test2 SELECT t, gen_rand_minstd(), gen_rand_minstd(), gen_rand_minstd()::text FROM generate_series('2018-03-02 1:00'::TIMESTAMPTZ, '2018-03-04 1:00', '1 hour') t;
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ALTER TABLE test2 DROP COLUMN b;
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--add default a value
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ALTER TABLE test2 ADD COLUMN c INT DEFAULT -15;
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--add default NULL
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ALTER TABLE test2 ADD COLUMN d INT;
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--write to both old chunks and new chunks with different column #s
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INSERT INTO test2 SELECT t, gen_rand_minstd(), gen_rand_minstd()::text, gen_rand_minstd(), gen_rand_minstd() FROM generate_series('2018-03-02 1:00'::TIMESTAMPTZ, '2018-03-06 1:00', '1 hour') t;
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ALTER TABLE test2 set (timescaledb.compress, timescaledb.compress_segmentby = '', timescaledb.compress_orderby = 'c, "Time" DESC');
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SELECT
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$$
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SELECT * FROM test2 ORDER BY c, "Time"
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$$ AS "QUERY" \gset
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SELECT 'test2' AS "HYPERTABLE_NAME" \gset
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\ir include/compression_test_hypertable.sql
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\set TYPE int
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\set ORDER_BY_COL_NAME c
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\set SEGMENT_META_COL_MIN _ts_meta_min_1
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\set SEGMENT_META_COL_MAX _ts_meta_max_1
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\ir include/compression_test_hypertable_segment_meta.sql
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\set TYPE timestamptz
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\set ORDER_BY_COL_NAME Time
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\set SEGMENT_META_COL_MIN _ts_meta_min_2
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\set SEGMENT_META_COL_MAX _ts_meta_max_2
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\ir include/compression_test_hypertable_segment_meta.sql
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--TEST4 create segments with > 1000 rows.
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CREATE TABLE test4 (
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timec TIMESTAMPTZ NOT NULL,
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location TEXT NOT NULL,
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location2 char(10) NOT NULL,
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temperature DOUBLE PRECISION NULL,
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humidity DOUBLE PRECISION NULL
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);
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--we want all the data to go into 1 chunk. so use 1 year chunk interval
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select create_hypertable( 'test4', 'timec', chunk_time_interval=> '1 year'::interval);
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alter table test4 set (timescaledb.compress, timescaledb.compress_segmentby = 'location', timescaledb.compress_orderby = 'timec');
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insert into test4
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select generate_series('2018-01-01 00:00'::timestamp, '2018-01-31 00:00'::timestamp, '1 day'), 'NYC', 'klick', 55, 75;
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insert into test4
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select generate_series('2018-02-01 00:00'::timestamp, '2018-02-14 00:00'::timestamp, '1 min'), 'POR', 'klick', 55, 75;
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select table_name, num_chunks
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from timescaledb_information.hypertable
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where table_name like 'test4';
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select location, count(*)
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from test4
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group by location;
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SELECT $$ SELECT * FROM test4 ORDER BY timec $$ AS "QUERY" \gset
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SELECT 'test4' AS "HYPERTABLE_NAME" \gset
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\ir include/compression_test_hypertable.sql
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\set TYPE TIMESTAMPTZ
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\set ORDER_BY_COL_NAME timec
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\set SEGMENT_META_COL_MIN _ts_meta_min_1
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\set SEGMENT_META_COL_MAX _ts_meta_max_1
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\ir include/compression_test_hypertable_segment_meta.sql
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-- check stats with segmentby
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SELECT DISTINCT attname, attstattarget
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FROM pg_attribute
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WHERE attrelid = '_timescaledb_internal._compressed_hypertable_6'::REGCLASS
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AND attnum > 0
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ORDER BY attname;
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SELECT DISTINCT attname, attstattarget
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FROM pg_attribute
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WHERE attrelid in (SELECT "Child" FROM test.show_subtables('_timescaledb_internal._compressed_hypertable_6'))
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AND attnum > 0
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ORDER BY attname;
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--add hypertable with order by a non by-val type with NULLs
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CREATE TABLE test5 (
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time TIMESTAMPTZ NOT NULL,
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device_id TEXT NULL,
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temperature DOUBLE PRECISION NULL
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);
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--we want all the data to go into 1 chunk. so use 1 year chunk interval
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select create_hypertable( 'test5', 'time', chunk_time_interval=> '1 day'::interval);
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alter table test5 set (timescaledb.compress, timescaledb.compress_orderby = 'device_id, time');
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insert into test5
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select generate_series('2018-01-01 00:00'::timestamp, '2018-01-10 00:00'::timestamp, '2 hour'), 'device_1', gen_rand_minstd();
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insert into test5
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select generate_series('2018-01-01 00:00'::timestamp, '2018-01-10 00:00'::timestamp, '2 hour'), 'device_2', gen_rand_minstd();
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insert into test5
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select generate_series('2018-01-01 00:00'::timestamp, '2018-01-10 00:00'::timestamp, '2 hour'), NULL, gen_rand_minstd();
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SELECT $$ SELECT * FROM test5 ORDER BY device_id, time $$ AS "QUERY" \gset
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SELECT 'test5' AS "HYPERTABLE_NAME" \gset
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\ir include/compression_test_hypertable.sql
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\set TYPE TEXT
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\set ORDER_BY_COL_NAME device_id
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\set SEGMENT_META_COL_MIN _ts_meta_min_1
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\set SEGMENT_META_COL_MAX _ts_meta_max_1
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\ir include/compression_test_hypertable_segment_meta.sql
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TRUNCATE test5;
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SELECT * FROM test5;
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