[JDEV] xdb_sql suggestions
jabber at raditha.com
Fri Sep 5 12:08:13 CDT 2003
You could be right about the index being forgotten :-) and you are right
about making an index with a smaller width than the full column. But i
haven't seen such a drastic drop in performance as you seem to have
encountered without indices.
One other point that i noted is that most of the key fields are not
numeric this also leads to a big drop in performance both for inserts
Matthias Wimmer wrote:
>Raditha Dissanayake schrieb am 2003-09-05 19:20:00:
>>I guess Bentoit and Co might have left the tables without indices
>>because there's a large number of inserts being done on these tables.
>>That's because mod_roster passes the entire roster to XDB when a change
>>occurs. xdb_sql deletes the whole lot and inserts them anew.
>>I did a patch for this sometime back but never got around to
>>contributing it. With that patch the roster entries just get updated
>>instead of delete/insert. Let me try to dig it up and send it in.
>I don't know if it is faster without an index on small databases, but on
>amessage the difference is enormous. Without the index it was not really
>usable. It the insert operation would get that expensive with the
>indexes, I don't think it would exist on the rosterusers table. It think
>the index has just been forgotten.
>And on the rosterusers table the index could get smaller and wouldn't
>decrease performance if it is limited to maybe the first 32 characters
>of username and jid.
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