From: | Leonardo Francalanci <m_lists(at)yahoo(dot)it> |
---|---|
To: | pgsql-hackers(at)postgresql(dot)org |
Subject: | Re: Fast insertion indexes: why no developments |
Date: | 2013-11-05 09:57:17 |
Message-ID: | 1383645437129-5776976.post@n5.nabble.com |
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Thread: | |
Lists: | pgsql-hackers |
Simon Riggs wrote
> Minmax indexes seem to surprise many people, so broad generalisations
> aren't likely to be useful.
>
> I think the best thing to do is to publish some SQL requests that
> demonstrate in detail what you are trying to achieve and test them
> against minmax indexes. That way we can discuss what does work and
> what doesn't work well enough yet.
While I do believe in testing (since "In theory there is no difference
between theory and practice. In practice there is"), I would like to know
the "properties" of the minmax index before trying it.
What is it supposed to be good at? What are the pros/cons? We can't ask all
the users to just "try" the index and see if it works for them.
As I said, my understanding is that is very efficient (both in insertion and
in searching) when data is somehow ordered in the table. But maybe I got it
wrong...
Anyway, the sql scenario is simple: a table with 4 bigint indexes; data in
the fields is a random bigint in the range 1-10000000. Insertion is 5-10K
rows/second. One search every 1-5 seconds, by one of the indexed fields
(only equality, no range). There's also an index on a timestamp field, but
that's not random so it doesn't give that many problems (it's actually the
one where I wanted to try the minmax).
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