On 2013-08-12 06:12, Pierre wrote:
Thanks Thomasbut the profiler doesn't showed something interesting.
Anyway, the issue is related to H2, it doesn't supports massive
inserts. When the table size > 3 millions rows, it begins to be very
slow. Adding LOG=0;UNDO_LOG=0;NOLOCK/WHATEVER optmisation just delay
the ineluctable slow insertions, it optimize a lot but only if < 3
millions rows.
I know that because I created a bench and just looks at the numbers :
Two things are at work here:
(1) MySQL and HSQLDB cheat a little by not performing fsync() as often
as they should, so they are trading off increased risk of losing data
against better speed
(2) When you create an FK constraint, we create an index on the column
to speed up the foreign key checking, which it looks like MySQL and
HSQLDB do not do. This costs us in the insert benchmark because we have
to update an extra on-disk datastructure.
When I take those two factors out, the numbers start looking roughly
comparable.
One thing you might want to do when trying to run large volumes of data
through H2 is to bump up our cache size using something like:
";CACHE_SIZE=65536" in the URL.
Our default cache setting is a little conservative for larger deployments.
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