Re: Sequence Access Method WIP

On 2014-11-24 13:16:24 +0200, Heikki Linnakangas wrote:
> To be clear: I don't think this API is very good for its stated purpose, for
> implementing global sequences for use in a cluster. For the reasons I've
> mentioned before.  I'd like to see two changes to this proposal:
> 
> 1. Make the AM implementation solely responsible for remembering the "last
> value". (if it's a global or remote sequence, the current value might not be
> stored in the local server at all)

I think that reason isn't particularly good. The practical applicability
for such a implementation doesn't seem to be particularly large.

> 2. Instead of the single amdata field, make it possible for the
> implementation to define any number of fields with any datatype in the
> tuple. That would make debugging, monitoring etc. easier.

My main problem with that approach is that it pretty much nails the door
shut for moving sequences into a catalog table instead of the current,
pretty insane, approach of a physical file per sequence. Currently, with
our without seqam, it'd not be all that hard to force it into a catalog,
taking care to to force each tuple onto a separate page...


Greetings,

Andres Freund

-- Andres Freund                       http://www.2ndQuadrant.com/PostgreSQL Development, 24x7 Support, Training &
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