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List:       postgresql-general
Subject:    Re: [HACKERS] Minor correction in alter_table.sgml
From:       Tom Lane <tgl () sss ! pgh ! pa ! us>
Date:       2016-11-30 16:17:10
Message-ID: 19669.1480522630 () sss ! pgh ! pa ! us
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Stephen Frost <sfrost@snowman.net> writes:
> Seems like this would be a bit better:

> ------
> All the actions, when acting on a single table and not using the ALL IN
> TABLESPACE form, except RENAME and SET SCHEMA, can be combined into a
> list of multiple alterations to be applied.
> ------

> I note that we say 'in parallel', but given that we have actual parallel
> operations now, we should probably shy away from using that except in
> cases where we actually mean operations utilizing multiple parallel
> processes.

I follow your beef with use of the word "parallel", but your proposed
rewording loses the entire point of multiple actions per ALTER TABLE;
namely that they're accomplished without repeated scans of the table.

Also the above seems a bit clunky; doesn't ALL IN TABLESPACE fall outside
the restriction "acting on a single table"?

So maybe something like

	All the forms of ALTER TABLE that act on a single table,
	except RENAME and SET SCHEMA, can be combined into a
	list of multiple alterations to be applied together.

We would have to enlarge on what "together" means, but I think there may
already be text explaining that further down.

			regards, tom lane


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