![]() ![]() I don't think the citext type changes this, though it does make things more convenient. AFAIK there is no way to index a case-insensitive pattern match ( ILIKE or ~~*) on a case-sensitive text/varchar in PostgreSQL at this time. LIKE, ILIKE, and RLIKE all perform similar operations however, RLIKE uses POSIX EXE (Extended Regular Expression) syntax instead of the SQL pattern syntax. ![]() ILIKE will use index, but only in some case. Nor will it use an index on lower(column_name) text_pattern_ops. If you build an index like: CREATE INDEX idxindexname ON yourtable (LOWER (columnname) ASC NULLS LAST) Lower will use index. One significant difference between LIKE / RLIKE and the full-text search predicates is that the former act on exact fields while the latter also work on analyzed fields. You can use these SQL commands via phpMyAdmin on our Cloudways Alternative hosting plans. LIKE is case sensitive, ILIKE is case insensitive. Will column_name ilike 'value' use lower(column_name) index? LIKE The LIKE command is used in a WHERE clause to search for a specified pattern in a column. The predicates LIKE and ILIKE are used to search for strings that match a given pattern, so you can search or for a single word (or string) in a long text field. Sometimes it's smarter to just choose the slower but easier option and spend yourtime/effort elsewhere. LIKE, ILIKE, and RLIKE all perform similar operations however, RLIKE uses POSIX EXE (Extended Regular Expression) syntax instead of the SQL pattern syntax used by LIKE and ILIKE. Unlike the LIKE function, string matching is case-insensitive. People use those things all over the place in their application and therefore it makes sense to approach the topic from a performance point of view. ILIKE Allows matching of strings based on comparison with a pattern. The other question is whether the difference is worth caring about, and that depends on your data and workload. LIKE and ILIKE are two fundamental SQL features. AFAIK a text_pattern_ops index (useful for LIKE) won't do you any good for ILIKE. That's because Pg can do a bitmap index scan with the expression index, but for the ilike it'll have to do a seqscan. I would expect a significant difference between an expression index on lower(col) with lower(col) = lower('constant') vs use of col ilike 'constant', with the expression index on lower(col) the faster. Measure it and see, using explain analyze on test data.
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