Alvaro Herrera wrote:
Heikki Linnakangas wrote:
Teodor Sigaev wrote:


GIN speeds up '%foo%' too - which is impossible for btree. But I don't like a hack around LIKE support in BTree. This support uses outflank ways missing regular one.
You could satisfy '%foo%' using a regular and a reverse B-tree index, and a bitmap AND. Which is interestingly similar to the way you proposed to use a TIDBitmap within GIN.

Huh, can you?  I can see doing "col LIKE 'foo%' OR reverse(col) LIKE
reverse('%foo')" with two btree indexes, but not a true %foo% ...

That should be AND, not OR..

Hmm. It is the same as far as I can see. Am I missing something?

You couldn't support more complex patterns directly, like 'foo%bar%foo', but you could still split that into 'foo%' AND '%bar%' AND '%foo', and recheck the matches against the original pattern

--
  Heikki Linnakangas
  EnterpriseDB   http://www.enterprisedb.com

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