Hi, Yes, the EXPLAIN output is hard read. The formatting will be easier to read in the next version (the changes are committed to the trunk in case you want to try it). I also added documentation:
http://h2database.com/html/performance2.html#explain_plan > - What exactly does the scanCount stand for? As far as I understand, > it is not the size of the current result set. Is it the number of > index / table look-ups? It's the number of rows scanned in this table or index. > - All join conditions are replaced by "ON 1=1", the actual conditions > have been moved to the WHERE part. What does this tell me? Nothing. "ON 1=1" is used to make it a valid statement. > I don't assume H2 actually performs the cartesian product first for all joins. H2 uses indexes if possible. > I'm working on a performance problem where an additional restriction > in the WHERE part results in a 12 times slower execution which I just > cannot explain. I'll be glad to post the query if someone is > interested. Sure, please post the query plan. > I'm working with v1.2.139. The optimizer didn't change much since then, except that in version 1.3.x a few optimizations are enabled, but without knowing the query I can't tell you if they will help. See the change log for details: http://www.h2database.com/html/changelog.html Regards, Thomas -- You received this message because you are subscribed to the Google Groups "H2 Database" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/h2-database?hl=en.
