Re: Unneccessary cmax in heap tuple ? - Mailing list pgsql-hackers

From Hiroshi Inoue
Subject Re: Unneccessary cmax in heap tuple ?
Date
Msg-id 39F6AC91.3F78BDAA@tpf.co.jp
Whole thread Raw
In response to Doesn't anyone around here run the regression tests on patches?  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-hackers

devik@cdi.cz wrote:

> Hello,
> Why is there cmax in tuple ? cxxx is used to determine
> if tuple was inserted/deleted by current command or
> past command. Because one command can't both insert
> and delete the same tuple, only something like "cupd"
> might be needed and flag which tells you whether cupd
> is time of insert or delete. This saves 4byte from
> header ..
>

If a tuple was inserted and updated in current transaction,
how could we judge if the tuple was valid for a given
ScanCommandId  ?
However there could be other improvements.

Regards.
Hiroshi Inoue



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