Re: How to pass around collation information

2010/5/28 alvherre <alvherre(at)commandprompt(dot)com>:
> Excerpts from Peter Eisentraut's message of vie may 28 12:27:52 -0400 2010:
>
>> Option 2, invent some new mechanism that accompanies a datum or a type
>> whereever it goes.  Kind of like typmod, but not really.  Then the
>> collation information would presumably be made available to functions
>> through the fmgr interface.  The binary representation of data values
>> stays the same.
>
> Is the collation a property of the datum, or one of the comparison?
> If the latter, should it be really be made a sidecar of a datum, or
> would it make more sense to attach it to the operation being performed?

>
> I wonder if instead of trying to pass it down multiple layers till
> bttextcmp and further down, it would make more sense to set a global
> variable somewhere in the high levels, and only have it checked in
> varstr_cmp.
>

Maybe collation is property of some operation: func call, sort, ... I
prefer to put collation info to FunctionCallInfo structure. Usually
you cannot change collation per row - collation is attached to
expression.

Regards

Pavel
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> Álvaro Herrera <alvherre(at)commandprompt(dot)com>
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