What’s wrong with my ArcGIS – PostGIS setup?

ArcGIS and PostGIS: Taming the Beast (and Making it Play Nice)

So, you’re trying to hook up ArcGIS to PostGIS? Awesome! It’s a seriously powerful combo for wrangling geospatial data. But let’s be honest, getting them to play nice together can sometimes feel like herding cats. I’ve been there, trust me. This isn’t just about connecting databases; it’s about making your spatial data sing. Let’s dive into some common snags and how to fix them.

Connection Calamities: Why Can’t We Connect?

First off, the dreaded connection issues. This is usually the first wall you hit. What’s going on? Well, a big culprit is often those PostgreSQL client files. ArcGIS should have them, but sometimes they’re outdated or just plain missing. Think of it like needing the right adapter to plug your fancy new gadget into an old wall socket. Make sure you’ve got the latest client files that ArcGIS supports, especially after any database upgrades. It’s a simple step, but easily overlooked.

But wait, there’s more! Your database itself might be playing hard to get. By default, PostgreSQL is all like, “Nah, I only talk to computers on this machine.” To let ArcGIS in on the fun, you’ve got to tweak the pg_hba.conf file. This file is basically the bouncer at the database club, deciding who gets in and how. You need to tell it to allow connections from your ArcGIS machine. Messing with this file can feel a bit scary, but don’t worry, there are plenty of guides online to walk you through it. And of course, double-check those login credentials! You’d be surprised how often a simple typo is the culprit.

Oh, and one more thing: ArcGIS has been a 64-bit-only party since version 10.1. So, if you’re rocking a 32-bit database server, that’s a no-go. It’s like trying to fit a square peg in a round hole. Also, when creating an Enterprise Geodatabase, PostgreSQL wants everything to match – think matching outfits for extensions. The DLLs for your PostgreSQL release must be chilling in the ArcGIS support folder.

Data Type Drama: When Good Data Goes Bad

Alright, you’re connected! High five! But hold on, the drama might not be over. Sometimes ArcGIS throws a fit when it tries to actually use the data. Why? Because ArcGIS can be a bit… particular about how things are stored.

One classic problem is mixing geometry types in the same column. It’s cool if you have both “POLYGON” and “MULTIPOLYGON” hanging out together, but if you try to mix “POLYGON” and “POINT,” ArcGIS will slam the door in your face. Trust me, I’ve seen it happen. It’s like inviting oil and water to the same party.

Another gotcha: ArcGIS usually only wants one spatial column per table when you’re registering existing tables from PostGIS. And forget about user-defined types – ArcGIS isn’t a fan.

Also, if you’re trying to write data to an existing ArcGIS Portal or ArcGIS Online Feature Service layer, make sure your data matches the existing schema. If the schema doesn’t match, you’ll get errors.

Schema Shenanigans and Access Adventures

ArcGIS gets its list of tables from the public.geometry_columns view (or pg_catalog in newer PostGIS versions). Make sure your imported shapefiles are showing up here, and that the coord_dimension, srid, and type columns have the right info. Think of it as making sure your data has the right passport and visa to enter the ArcGIS country.

Also, the schema where your tables live needs to be accessible to the PostgreSQL account you’re using to connect from ArcGIS. If the schema name is different from your username, you might need to adjust the search_path variable. It’s like telling ArcGIS, “Hey, look in this neighborhood for the data!” And ArcGIS often uses a schema matching the connecting user’s name to store log tables. If that schema is missing, things can get weird.

Performance Panic: Why Is Everything So Slow?

Okay, everything’s connected, the data looks good, but… it’s slow. Painfully slow. What gives? Well, there are a few usual suspects.

One common culprit is data irregularity. However, there are straightforward ways to address funky data to get cleaner faster queries .

Indexes are your friends! Spatial indexes, in particular, can seriously speed up spatial joins and other operations. It’s like having an index in a book – it helps you find what you’re looking for much faster. Paul Ramsey from Crunchy Data suggests using explain analyze to see if your indexes are actually being used. If not, it’s time to do some indexing!

Also, older PostgreSQL versions can sometimes struggle with TOAST tables. These tables store large values that don’t fit into normal data pages. If you suspect this is the problem, try forcing the query planner to use the index. It’s a bit of a hack, but it can sometimes do the trick.

Geometry Gremlins: When Shapes Go Bad

ArcGIS has its own way of deciding if two points are the same. When it reads a geometry, it snaps the points to an underlying grid and removes any duplicates. Sometimes, this can make your geometries invalid! You might see an error like “The number of points is less than required for feature.” The fix? Use PostGIS to snap the vertices to an equivalent grid and remove the duplicates before you hand it over to ArcGIS.

Version Vagaries: Playing the Compatibility Game

Esri has a list of which PostgreSQL versions play nicely with each ArcGIS release. It’s crucial to check this list! Using unsupported versions is just asking for trouble. Esri supports the specified release and higher, so you only need to match the major version .

Alternatives: When ArcGIS Isn’t the Answer

Let’s be real: if you’re just trying to edit a PostGIS database, ArcGIS might not be the best tool for the job. Sometimes, QGIS, GeoServer, or other PostGIS-friendly software are a better fit. But hey, PostGIS can still open up your spatial database to other uses!

The Takeaway: Patience, Grasshopper

Getting ArcGIS and PostGIS to work together can be a journey. There will be bumps in the road, trust me. But by understanding these common issues and how to solve them, you’ll be well on your way to a powerful and efficient geospatial setup. Remember to check the documentation for your specific versions of ArcGIS and PostGIS, and don’t be afraid to ask for help! The geospatial community is full of friendly folks who are happy to share their knowledge. Now go forth and conquer your data!