Re: [ADMIN] Cannot connect to the database (PG 7.3)

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: "Nigel J(dot) Andrews" <nandrews(at)investsystems(dot)co(dot)uk>
Cc: Michiel Lange <michiel(at)minas(dot)demon(dot)nl>, pgsql-hackers(at)postgresql(dot)org, Peter Eisentraut <peter_e(at)gmx(dot)net>
Subject: Re: [ADMIN] Cannot connect to the database (PG 7.3)
Date: 2003-01-29 04:40:58
Message-ID: 19363.1043815258@sss.pgh.pa.us
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>> After some looking, it appears the culprit is
>> assign_session_authorization() in commands/variable.c, which is assuming
>> that a numeric-looking parameter string should be taken as a numeric
>> user sysid, rather than an actual user name.
>>
>> The reason this was done was to avoid the need to do catalog lookups
>> when restoring a prior setting during error recovery. That's still a
>> valid concern, so right offhand I don't see an easy fix. Any ideas?

I've got an idea ... it's a bit grotty, but certainly not as ugly as
prohibiting all-numeric user names.

The problem for assign_session_authorization is to store a numeric sysid
in a form that can't be mistaken for a user name. There is no string
that can't be generated by a quoted identifier (except for strings with
embedded nulls, which won't really help us here). However, there *is*
the NAMEDATALEN limit. What if we generate strings consisting of, say,
NAMEDATALEN+1 'x's and then the numeric sysid?

This might seem a tad wasteful of storage, but at most a couple of such
strings need be stored at one time, so it's really insignificant (the
code space to implement any more-complex solution would probably be
more).

If anyone has a cleaner solution, let's hear it; otherwise I'll put this
in.

regards, tom lane

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