Match a phrase ending in a prefix with full text search

Question

I\'m looking for a way to emulate something like SELECT * FROM table WHERE attr LIKE \'%text%\' using a tsvector in PostgreSQL.

I\'ve created a tsvector

Answer 1

Postgres 9.6 introduces phrase search capabilities for full text search. So this works now:

SELECT title
FROM  tbl
WHERE title_tsv @@ to_tsquery('zend <-> fram:*');

<-> being the FOLLOWED BY operator.

It finds 'foo Zend framework bar' or 'Zend frames', but not 'foo Zend has no framework bar'.

Quoting the release notes for Postgres 9.6:

A phrase-search query can be specified in tsquery input using the new operators <-> and <N>. The former means that the lexemes before and after it must appear adjacent to each other in that order. The latter means they must be exactly N lexemes apart.

For best performance support the query with a GIN index:

CREATE INDEX tbl_title_tsv_idx ON tbl USING GIN (title_tsv);

Or don't store title_tsv in the table at all (bloating it and complicating writes). You can use an expression index instead:

CREATE INDEX tbl_title_tsv_idx ON tbl USING GIN (to_tsvector('english', title));

You need to specify the text search configuration (often language-specific) to make the expression immutable. And adapt the query accordingly:

...
WHERE to_tsvector('english', title) @@ to_tsquery('english', 'zend <-> fram:*');