pg_subtrans

Hello,

I am attempting to get information on the pg_subtrans directory. I
found this morning that one had a large number of files queued in it.
It filled the disk partition on which pgdata resides. After moving,
linking and restarting as a temporary solution, the engine properly
worked off these files. So, I'm trying now to get to the root cause of
why it filled in the first place -- however I'm not sure when postgres
engine uses this directory. I've searched the documentation and mailing
list archive, but can't find much. Can anyone give me a link or some
more information?

Thank you in advance for your time!

Kevin

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