[GRASS-dev] postgresql speed
mlennert at club.worldonline.be
Wed Mar 4 08:32:18 EST 2009
On 03/03/09 22:17, Wouter Boasson wrote:
> In reply to Vincent's remarks on database interfaces:
> I don't know how the db.* modules are implemented, but I can't imagine that
> they process the data themselves.
No, they use the underlying engine of the backend. But connection is
costly. This is why scripts which had a loop calling [v.]db.* statements
in each run of the loop should be rewritten to collect SQL statements in
a temp file and then call db.execute once at the end. See  for the
example of v.rast.stats.
See also some comments of Radim in  under "Attributes".
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