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Re: [Spacewalk-list] Postgres spacewalk



On Mon, 21 Nov 2011, Parsons, Aron wrote:

I did some digging into this query because it is one that is very obviously
slow when working with real systems.

It seems that the left join to rhnchecksum is the culprit of this slow query.  Here's the effect on execution time by changing it to an inner join:
LEFT JOIN: 2973.886 ms
INNER JOIN: 1.444 ms

Based on what this query is used for and the columns we're selecting, this
seems safe to me; the inner join is just going to exclude rows that don't
exist in both, but that should never happen under normal operation.  I have
not tested this on Oracle, but have verified that client operations are
still operating normally.  The real world effect is that this takes a ~50s
'rhncfg-client diff' on the client down to ~3s.  I tested by updating the
query in /usr/share/rhn/server/handlers/config/rhn_config_management.py.

Is that true of symlinks?

jh


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