Re: LIKE indexing proposal

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От Zeugswetter Andreas SB SD
Тема Re: LIKE indexing proposal
Дата
Msg-id 46C15C39FEB2C44BA555E356FBCD6FA4961FA7@m0114.s-mxs.net
обсуждение исходный текст
Ответ на LIKE indexing proposal  (Peter Eisentraut <peter_e@gmx.net>)
Ответы Re: LIKE indexing proposal  (Tom Lane <tgl@sss.pgh.pa.us>)
Список pgsql-hackers
> Peter Eisentraut <peter_e@gmx.net> writes:
> > I would like to re-table my proposal from many moons ago to allow
> > pattern-matching operations to use indexes under any locale.

Wouldn't existing b-trees be sufficient, if they could be 'scanned' starting
with the operator >= ? Thus a LIKE 'ABC%' could be done by stepping an (ascending)
index fom x >= 'ABC' up to the first key that does not have 'ABC' as first
characters ?

Seems this would be of more general use, than an extra index for LIKE, no ?
Some upper bound would still be needed for a selectivity estimate, but for
estimation purposes it would not really need to be watertight.

Andreas



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