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3ccae48f44
This works by extracting trigrams from the given regular expression, in generally the same spirit as the previously-existing support for LIKE searches, though of course the details are far more complicated. Currently, only GIN indexes are supported. We might be able to make it work with GiST indexes later. The implementation includes adding API functions to backend/regex/ to provide a view of the search NFA created from a regular expression. These functions are meant to be generic enough to be supportable in a standalone version of the regex library, should that ever happen. Alexander Korotkov, reviewed by Heikki Linnakangas and Tom Lane
93 lines
3.7 KiB
SQL
93 lines
3.7 KiB
SQL
CREATE EXTENSION pg_trgm;
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select show_trgm('');
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select show_trgm('(*&^$@%@');
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select show_trgm('a b c');
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select show_trgm(' a b c ');
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select show_trgm('aA bB cC');
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select show_trgm(' aA bB cC ');
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select show_trgm('a b C0*%^');
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select similarity('wow','WOWa ');
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select similarity('wow',' WOW ');
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select similarity('---', '####---');
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CREATE TABLE test_trgm(t text);
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\copy test_trgm from 'data/trgm.data'
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select t,similarity(t,'qwertyu0988') as sml from test_trgm where t % 'qwertyu0988' order by sml desc, t;
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select t,similarity(t,'gwertyu0988') as sml from test_trgm where t % 'gwertyu0988' order by sml desc, t;
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select t,similarity(t,'gwertyu1988') as sml from test_trgm where t % 'gwertyu1988' order by sml desc, t;
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select t <-> 'q0987wertyu0988', t from test_trgm order by t <-> 'q0987wertyu0988' limit 2;
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create index trgm_idx on test_trgm using gist (t gist_trgm_ops);
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set enable_seqscan=off;
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select t,similarity(t,'qwertyu0988') as sml from test_trgm where t % 'qwertyu0988' order by sml desc, t;
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select t,similarity(t,'gwertyu0988') as sml from test_trgm where t % 'gwertyu0988' order by sml desc, t;
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select t,similarity(t,'gwertyu1988') as sml from test_trgm where t % 'gwertyu1988' order by sml desc, t;
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explain (costs off)
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select t <-> 'q0987wertyu0988', t from test_trgm order by t <-> 'q0987wertyu0988' limit 2;
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select t <-> 'q0987wertyu0988', t from test_trgm order by t <-> 'q0987wertyu0988' limit 2;
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drop index trgm_idx;
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create index trgm_idx on test_trgm using gin (t gin_trgm_ops);
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set enable_seqscan=off;
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select t,similarity(t,'qwertyu0988') as sml from test_trgm where t % 'qwertyu0988' order by sml desc, t;
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select t,similarity(t,'gwertyu0988') as sml from test_trgm where t % 'gwertyu0988' order by sml desc, t;
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select t,similarity(t,'gwertyu1988') as sml from test_trgm where t % 'gwertyu1988' order by sml desc, t;
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create table test2(t text);
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insert into test2 values ('abcdef');
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insert into test2 values ('quark');
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insert into test2 values (' z foo bar');
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create index test2_idx_gin on test2 using gin (t gin_trgm_ops);
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set enable_seqscan=off;
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explain (costs off)
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select * from test2 where t like '%BCD%';
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explain (costs off)
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select * from test2 where t ilike '%BCD%';
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select * from test2 where t like '%BCD%';
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select * from test2 where t like '%bcd%';
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select * from test2 where t like E'%\\bcd%';
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select * from test2 where t ilike '%BCD%';
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select * from test2 where t ilike 'qua%';
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select * from test2 where t like '%z foo bar%';
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select * from test2 where t like ' z foo%';
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explain (costs off)
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select * from test2 where t ~ '[abc]{3}';
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explain (costs off)
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select * from test2 where t ~* 'DEF';
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select * from test2 where t ~ '[abc]{3}';
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select * from test2 where t ~ 'a[bc]+d';
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select * from test2 where t ~ '(abc)*$';
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select * from test2 where t ~* 'DEF';
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select * from test2 where t ~ 'dEf';
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select * from test2 where t ~* '^q';
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select * from test2 where t ~* '[abc]{3}[def]{3}';
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select * from test2 where t ~* 'ab[a-z]{3}';
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select * from test2 where t ~* '(^| )qua';
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select * from test2 where t ~ 'q.*rk$';
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select * from test2 where t ~ 'q';
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select * from test2 where t ~ '[a-z]{3}';
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select * from test2 where t ~* '(a{10}|b{10}|c{10}){10}';
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select * from test2 where t ~ 'z foo bar';
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select * from test2 where t ~ ' z foo bar';
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select * from test2 where t ~ ' z foo bar';
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select * from test2 where t ~ ' z foo';
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drop index test2_idx_gin;
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create index test2_idx_gist on test2 using gist (t gist_trgm_ops);
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set enable_seqscan=off;
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explain (costs off)
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select * from test2 where t like '%BCD%';
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explain (costs off)
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select * from test2 where t ilike '%BCD%';
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select * from test2 where t like '%BCD%';
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select * from test2 where t like '%bcd%';
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select * from test2 where t like E'%\\bcd%';
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select * from test2 where t ilike '%BCD%';
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select * from test2 where t ilike 'qua%';
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