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Date: Wed, 8 Jan 2025 17:17:13 +0100
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Subject: Re: Virtual generated columns
To: jian he <jian.universality@gmail.com>
Cc: pgsql-hackers <pgsql-hackers@postgresql.org>,
 Dean Rasheed <dean.a.rasheed@gmail.com>
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From: Peter Eisentraut <peter@eisentraut.org>
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On 04.12.24 05:55, jian he wrote:
> On Fri, Nov 29, 2024 at 6:13 PM Peter Eisentraut <peter@eisentraut.org> wrote:
>>
>> - Added support for virtual columns in trigger column lists.  (For that,
>> I renamed ExecInitStoredGenerated() to ExecInitGenerated(), which
>> handles the computation of ri_extraUpdatedCols.)
>>
> 
> why not duplicate some code from ExecInitStoredGenerated to
> ExecGetExtraUpdatedCols?

This answers itself: I'd rather not duplicate code.  I don't see that as 
an improvement.

> * now the expression is that something initiated for the virtual
> generated column. which may not be necessary for virtual columns.
> let's make ResultRelInfo->ri_GeneratedExprsI,
> ResultRelInfo->ri_GeneratedExprsU be NULL for virtual columns.
> 
> currently it may look like this:
> (gdb) p resultRelInfo->ri_GeneratedExprsU
> $20 = (ExprState **) 0x34f9638
> (gdb) p resultRelInfo->ri_GeneratedExprsU[0]
> $21 = (ExprState *) 0x0
> (gdb) p resultRelInfo->ri_GeneratedExprsU[1]
> $22 = (ExprState *) 0x0
> (gdb) p resultRelInfo->ri_GeneratedExprsU[2]
> $23 = (ExprState *) 0x40

I have fixed that in v11.

> * ExecInitStoredGenerated main used in ExecComputeStoredGenerated.
> * we also need to slightly change ExecInitGenerated's comments.

also fixed

> * in InitResultRelInfo, do we need explicit set ri_Generated_valid to false?

Doesn't seem necessary.  The struct is initialized to zero at the beginning.