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Do not use index if no limit or limit + offset > expected tuples unless enable_seqscan = off

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This commit is contained in:
Andrew Kane
2024-01-20 17:16:42 -08:00
parent a1a38156d7
commit 8b06719ae9
4 changed files with 154 additions and 0 deletions
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64
test/t/019_ivfflat_limit.pl Normal file
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use strict;
use warnings;
use PostgresNode;
use TestLib;
use Test::More;
# Initialize node
my $node = get_new_node('node');
$node->init;
$node->start;
# Create table and index
$node->safe_psql("postgres", "CREATE EXTENSION vector;");
$node->safe_psql("postgres", "CREATE TABLE tst (v vector(3));");
$node->safe_psql("postgres",
"INSERT INTO tst SELECT ARRAY[random(), random(), random()] FROM generate_series(1, 1000) i;"
);
$node->safe_psql("postgres", "CREATE INDEX ON tst USING ivfflat (v vector_l2_ops) WITH (lists = 10);");
# Test limit
my $explain = $node->safe_psql("postgres", qq(
EXPLAIN ANALYZE SELECT * FROM tst ORDER BY v <-> '[1,2,3]' LIMIT 100;
));
like($explain, qr/Index Scan/);
# Test limit with probes
$explain = $node->safe_psql("postgres", qq(
SET ivfflat.probes = 2;
EXPLAIN ANALYZE SELECT * FROM tst ORDER BY v <-> '[1,2,3]' LIMIT 200;
));
like($explain, qr/Index Scan/);
# Test limit + offset
$explain = $node->safe_psql("postgres", qq(
EXPLAIN ANALYZE SELECT * FROM tst ORDER BY v <-> '[1,2,3]' LIMIT 90 OFFSET 10;
));
like($explain, qr/Index Scan/);
# Test limit > expected tuples
$explain = $node->safe_psql("postgres", qq(
EXPLAIN ANALYZE SELECT * FROM tst ORDER BY v <-> '[1,2,3]' LIMIT 101;
));
like($explain, qr/Seq Scan/);
# Test limit > expected tuples with probes
$explain = $node->safe_psql("postgres", qq(
SET ivfflat.probes = 2;
EXPLAIN ANALYZE SELECT * FROM tst ORDER BY v <-> '[1,2,3]' LIMIT 201;
));
like($explain, qr/Seq Scan/);
# Test limit + offset > expected tuples
$explain = $node->safe_psql("postgres", qq(
EXPLAIN ANALYZE SELECT * FROM tst ORDER BY v <-> '[1,2,3]' LIMIT 91 OFFSET 10;
));
like($explain, qr/Seq Scan/);
# Test no limit
$explain = $node->safe_psql("postgres", qq(
EXPLAIN ANALYZE SELECT * FROM tst ORDER BY v <-> '[1,2,3]';
));
like($explain, qr/Seq Scan/);
done_testing();

62
test/t/020_hnsw_limit.pl Normal file
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use strict;
use warnings;
use PostgresNode;
use TestLib;
use Test::More;
# Initialize node
my $node = get_new_node('node');
$node->init;
$node->start;
# Create table and index
$node->safe_psql("postgres", "CREATE EXTENSION vector;");
$node->safe_psql("postgres", "CREATE TABLE tst (v vector(3));");
$node->safe_psql("postgres",
"INSERT INTO tst SELECT ARRAY[random(), random(), random()] FROM generate_series(1, 1000) i;"
);
$node->safe_psql("postgres", "CREATE INDEX ON tst USING hnsw (v vector_l2_ops);");
# Test limit
my $explain = $node->safe_psql("postgres", qq(
EXPLAIN ANALYZE SELECT * FROM tst ORDER BY v <-> '[1,2,3]' LIMIT 40;
));
like($explain, qr/Index Scan/);
# Test limit with CTE
$explain = $node->safe_psql("postgres", qq(
EXPLAIN ANALYZE WITH cte AS (SELECT * FROM tst ORDER BY v <-> '[1,2,3]' LIMIT 40) SELECT * FROM cte;
));
like($explain, qr/Index Scan/);
# Test limit + offset
$explain = $node->safe_psql("postgres", qq(
EXPLAIN ANALYZE SELECT * FROM tst ORDER BY v <-> '[1,2,3]' LIMIT 30 OFFSET 10;
));
like($explain, qr/Index Scan/);
# Test limit > ef_search
$explain = $node->safe_psql("postgres", qq(
EXPLAIN ANALYZE SELECT * FROM tst ORDER BY v <-> '[1,2,3]' LIMIT 41;
));
like($explain, qr/Seq Scan/);
# Test limit > ef_search with CTE
$explain = $node->safe_psql("postgres", qq(
EXPLAIN ANALYZE WITH cte AS (SELECT * FROM tst ORDER BY v <-> '[1,2,3]' LIMIT 41) SELECT * FROM cte;
));
like($explain, qr/Seq Scan/);
# Test limit + offset > ef_search
$explain = $node->safe_psql("postgres", qq(
EXPLAIN ANALYZE SELECT * FROM tst ORDER BY v <-> '[1,2,3]' LIMIT 31 OFFSET 10;
));
like($explain, qr/Seq Scan/);
# Test no limit
$explain = $node->safe_psql("postgres", qq(
EXPLAIN ANALYZE SELECT * FROM tst ORDER BY v <-> '[1,2,3]';
));
like($explain, qr/Seq Scan/);
done_testing();