[postgis-users] ArcGIS and PostGIS feedback

[Duarte Carreira (gmail)]

Hi Olivier.

We are an esri shop and have been slowly adopting postgis as our rdbms.

We use arcsde direct connections (no arcsde middleware service, just sde's
schema with tables, functions, triggrers, etc.). The other way, using native
connections from arcmap is just too slow (from the File menu).

Also, we obviously want to use postgis native geometry type. But what we
found out was that arcmap is 400% slower in some of our use cases. We
narrowed it down to the sql emitted by arcmap. ArcMap was taking 38s to draw
a spatial table (full zoom), while qgis took 15s. When using esri's
st_geometry type arcmap would drop to 8s. Please note this is a single use
case, others were also consistently slower but not nearly as much.

We opened a support ticket and the first answer was "it's just the way
postgis works". Which led me to send the sql that I logged when arcmap draw
the table and when qgis did it. The difference was in the sql sentence used
by each. One query took 38s another took 15s, for the same data. Eventually
I was told an enhancement request was opened, but it is not public and not
searchable.

At this point, we have some scripts that copy data from esri's st_geometry
to postgis geometry type, keeping in fact 2 copies of the data: one for esri
clients another for open source tools. This is not mandatory, just a choice
given our scenario. I think others could have chosen just the postgis
geometry type and live with arcmap performing badly with some tables.

Another final note: it was not easy for us to copy from esri's st_geometry
to postgis geometry using only sql. Since we can only use postgis 1.4 with
esri, the wkt produced by esri's st_astext is not compatible with postgis
geometryfromtext at 1.4 when there are z or m coords. Neither are binary
forms compatible. We ended up using esri's tools and arcsde configuration
keywords to make the conversion happen (which is a bit ironic I think). It
seems postgis 2.0 would accept esri's st_astext output but i haven't tried
it yet.

So there you go. Just my 2 cents... all that being said, I enjoy working
with arcmap+postgis. The thing that is more confusing to me is handling the
server memory usage from arcmap sessions - they can go from 100mb to 1gb.

Regards,
Duarte



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