| From: | "Zeugswetter Andreas SB SD" <ZeugswetterA(at)spardat(dot)at> |
|---|---|
| To: | "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us>, "Peter Eisentraut" <peter_e(at)gmx(dot)net> |
| Cc: | "PostgreSQL Development" <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: LIKE indexing proposal |
| Date: | 2003-05-13 09:29:01 |
| Message-ID: | 46C15C39FEB2C44BA555E356FBCD6FA4961FA7@m0114.s-mxs.net |
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| Lists: | pgsql-hackers |
> Peter Eisentraut <peter_e(at)gmx(dot)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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