[OSM-dev] Limitation on downloading ways via /map API Call

SteveC steve at asklater.com
Sun Jul 9 21:12:43 BST 2006

* @ 09/07/06 05:12:50 PM crschmidt at crschmidt.net wrote:
> This seems to me to be ignoring the fact that we have a get_multi
> function which does exactly what this SQL does, for a single way: given

No, it's not ignoring it. It's making a balanced decision about calling
the way function hundreds of times or trying to grab all that data at
once. Up until today, as you know, it wasn't apparent that the
group_concat functions would have a limit.

> persistent database connections, there should be no significant slowdown
> on getting data in multiple queries instead of one query.
> However, the current code doesn't use persistent database connections,
> which would explain why the code was done the way it was. 

No, it wouldnt.

If the db connections were persistant, it still makes sense to pull the
data out in one go.

> This doesn't seem to me to be very hard to fix: all the SQL currently
> uses the call_sql function, which uses get_connection, which currently is:

Actually, you would want a pool of db connections not just one.

have fun,

SteveC steve at asklater.com http://www.asklater.com/steve/

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