DBA survival BLOG

I found several queries running on a MySQL 5.0 database like this one:

SELECT PATH, NAME FROM JBP_OBJECT_NODE  WHERE PK IN (
SELECT NODE_KEY FROM JBP_OBJECT_NODE_SEC WHERE ROLE IN (
SELECT jr.jbp_name FROM jbp_users ju, jbp_role_membership jrm,
jbp_roles jr
WHERE jrm.jbp_uid = ju.jbp_uid
AND jr.jbp_rid = jrm.jbp_rid
AND ju.jbp_uname = 'LUDOVICO'
AND ju.jbp_enabled = 1));

This query is related to JBoss Portal and does a full scan on table JBP_OBJECT_NODE.

It has bad performances (>0.8 sec) with just a few records:

mysql> select count(*) from JBP_OBJECT_NODE;
+———-+
| count(*) |
+———-+
|    33461 |
+———-+

If I rewrite the query using an inner join (à la Oracle, please forgive me) instead of a subquery I get an index scan:

SELECT DISTINCT a.PATH, a.NAME /* , b.NODE_KEY */ FROM  JBP_OBJECT_NODE
a, JBP_OBJECT_NODE_SEC b
WHERE a.pk=b.NODE_KEY
AND b.ROLE IN (
SELECT jr.jbp_name FROM jbp_users ju, jbp_role_membership jrm,
jbp_roles jr
WHERE jrm.jbp_uid = ju.jbp_uid
AND jr.jbp_rid = jrm.jbp_rid
AND ju.jbp_uname = 'UTDEMO'
AND ju.jbp_enabled = 1);

With 30k records the execution time falls down from 0.8 secs to 0.01 secs…
That’s NOT all! I found this open bug:

https://jira.jboss.org/jira/browse/JBPORTAL-2040

With many users registered in, the JBoss Portal Admin console tooks over a minute to show a single page…

I don’t like portals…