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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
52 lines
1.7 KiB
MySQL
52 lines
1.7 KiB
MySQL
-- 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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\set TEST_BASE_NAME append
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SELECT format('include/%s_load.sql', :'TEST_BASE_NAME') as "TEST_LOAD_NAME",
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format('include/%s_query.sql', :'TEST_BASE_NAME') as "TEST_QUERY_NAME",
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format('%s/results/%s_results_optimized.out', :'TEST_OUTPUT_DIR', :'TEST_BASE_NAME') as "TEST_RESULTS_OPTIMIZED",
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format('%s/results/%s_results_unoptimized.out', :'TEST_OUTPUT_DIR', :'TEST_BASE_NAME') as "TEST_RESULTS_UNOPTIMIZED"
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\gset
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SELECT format('\! diff -u --label "Unoptimized results" --label "Optimized results" %s %s', :'TEST_RESULTS_UNOPTIMIZED', :'TEST_RESULTS_OPTIMIZED') as "DIFF_CMD"
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\gset
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SET timescaledb.enable_now_constify TO false;
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-- disable memoize node to make EXPLAIN output comparable between PG14 and previous versions
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SELECT CASE WHEN current_setting('server_version_num')::int/10000 >= 14 THEN set_config('enable_memoize','off',false) ELSE 'off' END AS enable_memoize;
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\set PREFIX 'EXPLAIN (analyze, costs off, timing off, summary off)'
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\ir :TEST_LOAD_NAME
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\ir :TEST_QUERY_NAME
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--generate the results into two different files
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\set ECHO errors
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SET client_min_messages TO error;
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\set PREFIX ''
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-- get results with optimizations disabled
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\o :TEST_RESULTS_UNOPTIMIZED
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SET timescaledb.enable_optimizations TO false;
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\ir :TEST_QUERY_NAME
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\o
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-- get query results with all optimizations
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\o :TEST_RESULTS_OPTIMIZED
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SET timescaledb.enable_optimizations TO true;
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\ir :TEST_QUERY_NAME
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\o
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:DIFF_CMD
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-- get query results with constraint aware append
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\o :TEST_RESULTS_OPTIMIZED
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SET timescaledb.enable_chunk_append TO false;
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\ir :TEST_QUERY_NAME
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\o
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:DIFF_CMD
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