Hi, > a "where ... in" clause with 500 values (like "where x in [v0, v1, v2, .... v499]"), which ran with average time 120 seconds.
120 seconds for 500 entries sounds like a problem with the data or the query. Do you have an index on that column? See also http://h2database.com/html/performance.html#explain_plan Regards, Thomas On Sun, Oct 6, 2013 at 6:29 AM, Brian Craft <[email protected]> wrote: > Reading over the archive on the subject of threads has left me mostly > still confused about how h2 handles concurrency, so I've been doing some > tests, instead. > > I started with largish queries that all have a "where ... in" clause with > 500 values (like "where x in [v0, v1, v2, .... v499]"), which ran with > average time 120 seconds. > > I then re-ran the same queries as sets of 500 queries (each with a single > value, like "where x in [v0]"), splitting the queries across different > threads. These sets of 500 queries ran much faster, average 30 seconds. It > also made much more use of the disk: io stats where much higher, which is > consistent with the queries running concurrently. > > The docs seem to indicate that a query in one thread blocks queries in > other threads, so I'm not sure how to interpret these numbers. Maybe I > misunderstood the docs, and queries do run concurrently? I'm not using > MULTI_THREADED. > > -- > You received this message because you are subscribed to the Google Groups > "H2 Database" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > Visit this group at http://groups.google.com/group/h2-database. > For more options, visit https://groups.google.com/groups/opt_out. > -- You received this message because you are subscribed to the Google Groups "H2 Database" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/h2-database. For more options, visit https://groups.google.com/groups/opt_out.
