Re: like/ilike improvements - Mailing list pgsql-hackers

From Andrew Dunstan
Subject Re: like/ilike improvements
Date
Msg-id 46531AAD.9030209@dunslane.net
Whole thread Raw
In response to Re: like/ilike improvements  (Tom Lane <tgl@sss.pgh.pa.us>)
Responses Re: like/ilike improvements  (Andrew Dunstan <andrew@dunslane.net>)
List pgsql-hackers

Tom Lane wrote:
> Andrew Dunstan <andrew@dunslane.net> writes:
>   
>> ... It turns out (according to the analysis) that the 
>> only time we actually need to use NextChar is when we are matching an 
>> "_" in a like/ilike pattern.
>>     
>
> I thought we'd determined that advancing bytewise for "%" was also risky,
> in two cases:
>
> 1. Multibyte character set that is not UTF8 (more specifically, does not
> have a guarantee that first bytes and not-first bytes are distinct)
>   

I will review - I thought we had ruled that out.

Which non-UTF8 multi-byte charset would be best to test with?

> 2. "_" immediately follows the "%".
>
>             
>   

The patch in fact calls NextChar in this case.

cheers

andrew


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