| From: | Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Peter Eisentraut <peter_e(at)gmx(dot)net>, Magnus Hagander <magnus(at)hagander(dot)net>, Itagaki Takahiro <itagaki(dot)takahiro(at)gmail(dot)com>, Andy Colson <andy(at)squeakycode(dot)net>, Noah Misch <noah(at)leadboat(dot)com>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: texteq/byteaeq: avoid detoast [REVIEW] |
| Date: | 2011-01-18 08:03:01 |
| Message-ID: | 4D354935.7090702@enterprisedb.com |
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| Lists: | pgsql-hackers |
On 17.01.2011 22:33, Tom Lane wrote:
> Peter Eisentraut<peter_e(at)gmx(dot)net> writes:
>> On mån, 2011-01-17 at 07:35 +0100, Magnus Hagander wrote:
>>> In fact, aren't there cases where the *length test* also fails?
>
>> Currently, two text values are only equal of strcoll() considers them
>> equal and the bits are the same. So this patch is safe in that regard.
>
>> There is, however, some desire to loosen this.
>
> That isn't ever going to happen, unless you'd like to give up hash joins
> and hash aggregation on text values.
You could canonicalize the string first in the hash function. I'm not
sure if we have all the necessary information at hand there, but at
least with some encoding/locale-specific support functions it'd be possible.
--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com
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