Eduardo Morras uttered:
At 19:32 01/06/2007, you wrote:
When you have a connection with multiple attached databases and the
connection acquires an exclusive lock, does it always lock all attached
databases or does it keep track of which databases require the lock? Does
using separate databases and attaching them improve concurrency (by
providing finer-grained locking)?
It locks all attached databases. No, it does not improve concurrency but
i can improve speed if database files are on more than one phisical
disk. The sqlite bottleneck is i/o access on most cases.
Tip for performance on Linux and ext3.
Mount your database filesystem with "data=journal" option to write data to
the journal before being written in place. This reduces latency
drastically, as the journal is contiguous and written at the full IO rate
of the device without seeks. An example of the effect it has on a test I
did can be found here:
http://www.osnews.com/permalink.php?news_id=16522&comment_id=184137
Christian
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