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df32ad4b79
This patch adds an optimization to the DecompressChunk node. If the query 'order by' and the compression 'order by' are compatible (query 'order by' is equal or a prefix of compression 'order by'), the compressed batches of the segments are decompressed in parallel and merged using a binary heep. This preserves the ordering and the sorting of the result can be prevented. Especially LIMIT queries benefit from this optimization because only the first tuples of some batches have to be decompressed. Previously, all segments were completely decompressed and sorted. Fixes: #4223 Co-authored-by: Sotiris Stamokostas <sotiris@timescale.com>
76 lines
3.0 KiB
SQL
76 lines
3.0 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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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_unoptimized.out', :'TEST_OUTPUT_DIR', :'TEST_BASE_NAME') as "TEST_RESULTS_UNOPTIMIZED",
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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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-- 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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-- 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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-- disable incremental sort here to make plans comparable to PG < 13
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SELECT CASE WHEN current_setting('server_version_num')::int/10000 >= 13 THEN set_config('enable_incremental_sort','off',false) ELSE 'off' END;
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-- In the following test cases, we test that certain indexes are used. By using the
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-- timescaledb.enable_decompression_sorted_merge optimization, we are pushing a sort node
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-- below the DecompressChunk node, which operates on the batches. This could lead to flaky
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-- tests because the input data is small and PostgreSQL switches from IndexScans to
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-- SequentialScans. Disable the optimization for the following tests to ensure we have
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-- stable query plans in all CI environments.
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SET timescaledb.enable_decompression_sorted_merge = 0;
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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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