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Date: Thu, 6 Sep 2012 08:13:44 +1000
Subject: Re: Python Interview Questions
From: Chris Angelico <rosuav@gmail.com>
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Xref: csiph.com comp.lang.python:28543

On Thu, Sep 6, 2012 at 2:40 AM, Ian Kelly <ian.g.kelly@gmail.com> wrote:
> On Wed, Sep 5, 2012 at 9:34 AM, Chris Angelico <rosuav@gmail.com> wrote:
>> On Thu, Sep 6, 2012 at 1:22 AM, Ian Kelly <ian.g.kelly@gmail.com> wrote:
>>> The lack of an ORDER BY is the least of the problems with that SQL.
>>> He's also using LIMIT without OFFSET, so the only thing that the
>>> 'item' argument changes is how many rows are returned (all but one of
>>> which are ignored), not which one is actually fetched.
>>
>> No, he's using the two-arg form of LIMIT.
>
> My mistake.  I didn't even know there was a two-arg form of LIMIT.
> Must be a MySQL thing. :-)

Yeah, it's not something I've used, but when my current job started,
we were using MySQL and I used to eyeball the logs to see what queries
were performing most suboptimally. (There were some pretty egregious
ones. Most memorable was rewriting a TEXT field several times a second
with several KB of PHP serialized array with status/statistical
information. Structured information, yes. Stored as a clob.) My first
databasing experience was DB2, with the uber-verbose "FETCH FIRST n
ROW[S] ONLY", but now I'm happily on Postgres.

Everyone who wants to use LIMIT without ORDER BY should try their code
on Postgres. You'll quickly discover the problem.

ChrisA