Hi!
Try:
set engine_condition_pushdown = on;
explain select ip from ipaddr
where pool='INTERNET' and stype='S' and ls_id=3 and allocated is null
limit 1;
to see if you can push the predicates to improve performance.
BR
-- Martin
Mindaugas wrote:
Hello,
For the Radius server we're using MySQL cluster and the following
query looks too slow:
select ip from ipaddr
where pool='INTERNET' and stype='S' and ls_id=3 and allocated is null
limit 1;
Table ipaddr is small (~6MB, 38000 records). Fields in WHERE clause
have few values and no indexes:
- pool: 2 distinct values;
- stype: 6 distinct values;
- ls_id: 5 distinct values;
- allocated is null for ~30000 of records.
Table type is NDB. If I change it to MEMORY everything starts to fly.
Of course there are a lot of updates to ipaddr table too. For every
select there are 3 updates. But updates are of type "update something
where ip=ipaddr" and ipaddr is unique key.
What can cause slowdown in NDB case? Table is small and is in memory
(5.0 cluster). Maybe I can rewrite it in some better form for such case?
MySQL setting are basically default. I did not find something in
documentation about improving performance of NDB engine tables.
Maybe increase read_buffer_size which is currently the default 128k?
Server has 4GB of memory and runs x86_64 version of CentOS4 Linux.
Thanks,
Mindaugas
--
Martin Sköld, Ph.D
Software Engineer
MySQL AB, www.mysql.com
Office: +46 (0)730 31 26 21
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