On 14.11.2013 22:10, Simon Riggs wrote:
On 16 January 2013 00:40, Simon Riggs <si...@2ndquadrant.com> wrote:
SeqAm allows you to specify a plugin that alters the behaviour for
sequence allocation and resetting, aimed specifically at clustering
New command options on end of statement allow syntax
CREATE SEQUENCE foo_seq
Production version of this, ready for commit to PG 9.4
Includes test extension which allows sequences without gaps - "gapless".
Test using seq_test.psql after creating extension.
No dependencies on other patches.
It's pretty hard to review the this without seeing the "other"
implementation you're envisioning to use this API. But I'll try:
I wonder if the level of abstraction is right. The patch assumes that
the on-disk storage of all sequences is the same, so the access method
can't change that. But then it leaves the details of actually updating
the on-disk block, WAL-logging and all, as the responsibility of the
access method. Surely that's going to look identical in all the seqams,
if they all use the same on-disk format. That also means that the
sequence access methods can't be implemented as plugins, as plugins
can't do WAL-logging.
The comment in seqam.c says that there's a private column reserved for
access method-specific data, called am_data, but that seems to be the
only mention of am_data in the patch.
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