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https://github.com/timescale/timescaledb.git
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35ea80ffdf
This implements an optimization to allow now() expression to be used during plan time chunk exclusions. Since now() is stable it would not normally be considered for plan time chunk exclusion. To enable this behaviour we convert `column > now()` expressions into `column > const AND column > now()`. Assuming that time always moves forward this is safe even for prepared statements. This optimization works for SELECT, UPDATE and DELETE. On hypertables with many chunks this can lead to a considerable speedup for certain queries. The following expressions are supported: - column > now() - column >= now() - column > now() - Interval - column > now() + Interval - column >= now() - Interval - column >= now() + Interval Interval must not have a day or month component as those depend on timezone settings. Some microbenchmark to show the improvements, I did best of five for all of the queries. -- hypertable with 1k chunks -- with optimization select * from metrics1k where time > now() - '5m'::interval; Time: 3.090 ms -- without optimization select * from metrics1k where time > now() - '5m'::interval; Time: 145.640 ms -- hypertable with 5k chunks -- with optimization select * from metrics5k where time > now() - '5m'::interval; Time: 4.317 ms -- without optimization select * from metrics5k where time > now() - '5m'::interval; Time: 775.259 ms -- hypertable with 10k chunks -- with optimization select * from metrics10k where time > now() - '5m'::interval; Time: 4.853 ms -- without optimization select * from metrics10k where time > now() - '5m'::interval; Time: 1766.319 ms (00:01.766) -- hypertable with 20k chunks -- with optimization select * from metrics20k where time > now() - '5m'::interval; Time: 6.141 ms -- without optimization select * from metrics20k where time > now() - '5m'::interval; Time: 3321.968 ms (00:03.322) Speedup with 1k chunks: 47x Speedup with 5k chunks: 179x Speedup with 10k chunks: 363x Speedup with 20k chunks: 540x
62 lines
1.9 KiB
MySQL
62 lines
1.9 KiB
MySQL
-- 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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SET timescaledb.enable_now_constify TO FALSE;
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SELECT
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format('include/%s.sql', :'TEST_BASE_NAME') as "TEST_QUERY_NAME",
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format('%s/shared/results/%s_results_uncompressed.out', :'TEST_OUTPUT_DIR', :'TEST_BASE_NAME') as "TEST_RESULTS_UNCOMPRESSED",
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format('%s/shared/results/%s_results_compressed.out', :'TEST_OUTPUT_DIR', :'TEST_BASE_NAME') as "TEST_RESULTS_COMPRESSED"
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\gset
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SELECT format('\! diff -u --label "Uncompressed results" --label "Compressed results" %s %s', :'TEST_RESULTS_UNCOMPRESSED', :'TEST_RESULTS_COMPRESSED') as "DIFF_CMD"
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\gset
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-- get EXPLAIN output for all variations
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\set PREFIX 'EXPLAIN (analyze, costs off, timing off, summary off)'
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\set PREFIX_VERBOSE 'EXPLAIN (analyze, costs off, timing off, summary off, verbose)'
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set work_mem to '64MB';
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set max_parallel_workers_per_gather to 0;
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\set TEST_TABLE 'metrics'
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\ir :TEST_QUERY_NAME
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\set TEST_TABLE 'metrics_space'
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\ir :TEST_QUERY_NAME
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\set TEST_TABLE 'metrics_compressed'
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\ir :TEST_QUERY_NAME
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\set TEST_TABLE 'metrics_space_compressed'
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\ir :TEST_QUERY_NAME
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-- get results for all the queries
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-- run queries on uncompressed hypertable and store result
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\set PREFIX ''
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\set PREFIX_VERBOSE ''
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\set ECHO none
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SET client_min_messages TO error;
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-- run queries on compressed hypertable and store result
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\set TEST_TABLE 'metrics'
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\o :TEST_RESULTS_UNCOMPRESSED
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\ir :TEST_QUERY_NAME
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\set TEST_TABLE 'metrics_compressed'
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\o :TEST_RESULTS_COMPRESSED
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\ir :TEST_QUERY_NAME
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\o
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-- diff compressed and uncompressed results
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:DIFF_CMD
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-- do the same for space partitioned hypertable
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\set TEST_TABLE 'metrics_space'
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\o :TEST_RESULTS_UNCOMPRESSED
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\ir :TEST_QUERY_NAME
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\set TEST_TABLE 'metrics_space_compressed'
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\o :TEST_RESULTS_COMPRESSED
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\ir :TEST_QUERY_NAME
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\o
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-- diff compressed and uncompressed results
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:DIFF_CMD
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