[postgis-devel] Concurrent Modification and Feature Locking

[Mark Cave-Ayland]

> -----Original Message-----
> From: postgis-devel-bounces at postgis.refractions.net [mailto:postgis-devel-
> bounces at postgis.refractions.net] On Behalf Of Cory Horner
> Sent: 17 July 2006 20:53
> To: strk at refractions.net
> Cc: postgis-devel at postgis.refractions.net
> Subject: [postgis-devel] Concurrent Modification and Feature Locking
> 
> Hi Sandro et al,
> 
> We're currently working on eliminating some bugs in the geotools postgis
> plugin, for use in uDig, etc.  One problem we've encountered has been
> concurrent modification of features.  In geotools we keep a transaction
> alive for some time, as the user tweaks features to their heart's
> content.  Unfortunately, when one user modifies a feature and keeps the
> transaction open, a second user attempting to edit the same feature will
> experience a lockup while they wait for the first user to either commit
> or revert.
> 
> What i'm wondering is if there is a way to ask PostGIS (postgres) if a
> feature is locked, or is lockable, so we may toss exceptions or
> otherwise deny modification of a feature when it is not possible?
> 
> Thanks,
> Cory.


Hi Cory,

We can try and help, although we need a more detailed test case to work out
exactly what the issues are. An ideal test case would be a sample .sql file
to load into a blank PostGIS database with some sample geometries, along
with a transcript of example commands typed into 2 simultaneous psql
sessions to replicate the lockup you are seeing.


Kind regards,

Mark.

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