| From: | Ildar Musin <i(dot)musin(at)postgrespro(dot)ru> |
|---|---|
| To: | Alexander Korotkov <a(dot)korotkov(at)postgrespro(dot)ru> |
| Cc: | Peter Eisentraut <peter(dot)eisentraut(at)2ndquadrant(dot)com>, Bruce Momjian <bruce(at)momjian(dot)us>, Craig Ringer <craig(at)2ndquadrant(dot)com>, Ashutosh Bapat <ashutosh(dot)bapat(at)enterprisedb(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Heikki Linnakangas <hlinnaka(at)iki(dot)fi>, Tianzhou Chen <tianzhouchen(at)gmail(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Challenges preventing us moving to 64 bit transaction id (XID)? |
| Date: | 2017-09-05 09:55:32 |
| Message-ID: | a7374d4a-e463-3c86-4f56-c08d5d5d6aa9@postgrespro.ru |
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| Lists: | pgsql-hackers |
Hi Alexander,
On 22.06.2017 18:36, Alexander Korotkov wrote:
> On Wed, Jun 7, 2017 at 11:33 AM, Alexander Korotkov
> <a(dot)korotkov(at)postgrespro(dot)ru <mailto:a(dot)korotkov(at)postgrespro(dot)ru>> wrote:
> 0002-heap-page-special-1.patch
> Putting xid and multixact bases into PageHeaderData would take extra 16
> bytes on index pages too. That would be waste of space for indexes.
> This is why I decided to put bases into special area of heap pages.
> This patch adds special area for heap pages contaning prune xid and
> magic number. Magic number is different for regular heap page and
> sequence page.
We've discussed it earlier but it worth mentioning here too. You have
pd_prune_xid of type TransactionId which is treated elsewhere as
ShortTransactionId (see HeapPageGetPruneXid() and HeapPageSetPruneXid())
and hence introduces redundant 4 bytes. Could you please fix it?
--
Ildar Musin
i(dot)musin(at)postgrespro(dot)ru
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