Re: Variable-length FunctionCallInfoData

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От
Andres Freund
Тема
Re: Variable-length FunctionCallInfoData
Дата
Msg-id
20190127071315.n5z6efwd5ybyrol6@alap3.anarazel.de
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Дерево обсуждения
Variable-length FunctionCallInfoData Andres Freund <andres@anarazel.de>
Re: Variable-length FunctionCallInfoData Peter Eisentraut <peter.eisentraut@2ndquadrant.com>
Re: Variable-length FunctionCallInfoData Andres Freund <andres@anarazel.de>
RE: Variable-length FunctionCallInfoData serge@rielau.com
Re: Variable-length FunctionCallInfoData Andres Freund <andres@anarazel.de>
Re: Variable-length FunctionCallInfoData Serge Rielau <serge@rielau.com>
Re: Variable-length FunctionCallInfoData Andres Freund <andres@anarazel.de>
Re: Variable-length FunctionCallInfoData Andres Freund <andres@anarazel.de>
Re: Variable-length FunctionCallInfoData Andrew Gierth <andrew@tao11.riddles.org.uk>
Re: Variable-length FunctionCallInfoData Tom Lane <tgl@sss.pgh.pa.us>
Re: Variable-length FunctionCallInfoData Andres Freund <andres@anarazel.de>
Re: Variable-length FunctionCallInfoData Andres Freund <andres@anarazel.de>
Re: Variable-length FunctionCallInfoData Andres Freund <andres@anarazel.de>
Re: Variable-length FunctionCallInfoData Tom Lane <tgl@sss.pgh.pa.us>
Re: Variable-length FunctionCallInfoData Andrew Dunstan <andrew.dunstan@2ndquadrant.com>
Re: Variable-length FunctionCallInfoData Andrew Dunstan <andrew.dunstan@2ndquadrant.com>
Re: Variable-length FunctionCallInfoData Greg Stark <stark@mit.edu>
Re: Variable-length FunctionCallInfoData Andres Freund <andres@anarazel.de>
Hi,

On 2019-01-27 08:03:17 +0100, Greg Stark wrote:
> I assume you already considered and rejected having a fixed size null
> bitmap followed by a variable size array of datums. That seems like it
> would be denser and work better with cpu cache.

It'd be more expensive to access individually (offset calculation +
masks, ~5 insn, not fully pipelineable), it'd not guarantee that the
null bit and datum are on the same cacheline, you could not pass the
null-bit to various functions accepting a bool*, you could not pass the
new equivalent NullableDatums to other functions (like both the past and
current solution allow).

Greetings,

Andres Freund

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