I am currently running processing on two feature classes (points, number of points are 5000+ and 8000+ respectively) in ArcGIS 10.2 on personal geodatabase using iteration and selection by attributes/location.

The size of PGDB intially is only about 2MB however after the processing finishes it increases upto 400MB. My outputs of the processing are saved in a separate file GDB.

Can anyone explain to me why the size of original PGDB increases. Is this because the SQL queries are also saved in that PGDB.

How can I delete them? All i need is the original PGDB (with the orginal size) and the outputs stored in a separate GDB.


Not sure at to the why, but how to address the issue, try running the Compact tool on the mdb, that should trim some of the size.

  • The selections are stored internally to the database and that space is not reused, i.e. a new selection = more new space. All that unused space is dead rows in delta tables so a compact will get rid of it - that's what it's for. Consider using file geodatabase, it doesn't (seem to) have that problem. – Michael Stimson Jul 14 '15 at 0:34
  • File geodatabase also has a compaction option (a compression option as well, though they're very different), but Access is much more profligate with disk space. – Vince Jul 14 '15 at 1:40
  • Personal Geodatabases are more prone to bloating @Vince, and it's very noticeable as it's all one file. File geodatabases are broken up into many files so it's not as immediately apparent if it is bloating - also file geodatabases don't have a 2GB size limit so aren't as affected by bloating either. I can recall a 2MB pGDB with a topology editing in ArcGis 8.3 maxing out and needing compacting twice a day (approx 1.8GB) then reducing back to 2MB. I had to keep an eye on the size and exit out when it got too big or 'save edits' would fail and I'd loose the edits. – Michael Stimson Jul 14 '15 at 2:52
  • I've always played with real databases (ORA,MSS,PG,DB2,INF), so I never had to sweat 2Gb limits, though loading 12Tb of raster catalogs without BIGFILE tablespaces was another story. – Vince Jul 14 '15 at 3:03

You could try compacting your personal geodatabase:

as you delete and add records over time, the records within each file lose their order, and unused space develops as records are removed and new ones are added elsewhere in the file. This causes the file system to perform more record-seeking operations within each file, slowing the rate at which records are accessed.

To compact a geodatabase, right-click it in the Catalog tree and click Compact Database.

  • Like the quote, is there a link as to where it's from? – Michael Stimson Jul 14 '15 at 0:35
  • yeah, it's the link above ;) – Stephen Lead Jul 14 '15 at 0:41

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