Re: [Proposal] Allow users to specify multiple tables in VACUUM commands

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: "Bossart, Nathan" <bossartn(at)amazon(dot)com>
Cc: Michael Paquier <michael(dot)paquier(at)gmail(dot)com>, "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org>, "Masahiko Sawada" <sawada(dot)mshk(at)gmail(dot)com>, "David G(dot) Johnston" <david(dot)g(dot)johnston(at)gmail(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>
Subject: Re: [Proposal] Allow users to specify multiple tables in VACUUM commands
Date: 2017-09-21 22:26:50
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"Bossart, Nathan" <bossartn(at)amazon(dot)com> writes:
> [ 0001-error_on_duplicate_columns_in_analyze_v6.patch ]

I've pushed (and back-patched) the 0001 patch, with some significant

* The list_concat_unique implementation is O(N^2), and seems a bit obscure
as well. Perhaps there will never be so many column list entries that
the speed is a big issue, but I'm not sure. I replaced the list with a
bitmap to avoid the risk.

* I did not see the point of having "ANALYZE t (x,x,x,nosuchcolumn)"
complain about nosuchcolumn rather than the duplicated x entries,
especially not if it meant you couldn't say which column was duplicated.
So I folded the test into the primary loop and made the error look
more like what you get for a nonexistent column.

* I didn't like the test case at all: it was repetitive and it actually
failed to exhibit the originally problematic behavior with unpatched
code, which is generally a minimum expectation for a regression test.
(I think that's because you used an empty table, for which ANALYZE will
not try to make any pg_statistic entries.) So I rewrote that, and made
it use an existing table rather than create a whole new one just for this.

I'll take a look at the updated 0002 tomorrow, but if anyone living in
a different timezone wants to review it meanwhile, feel free.

regards, tom lane

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