It seems that PG uses the PGDATA directory even for operations that affect databases on different tablespaces. For example, when an index is created on a table that is in tablespace TS, the index ends up in TS (as it should), but first a temporary file (with size comparable to the final index) is written below PGDATA, and is truncated only at the end of the operation. As a more drastic example: I created a DB on a tablespace TS, and copied a 25 MB file into one of its tables. I ended up having 60 MB of extra data in $PGDATA/pg_xlog that doesn't go away even after dropping the database. The docs (19.6 Tablespaces) says "The tablespace associated with a database is used to store the system catalogs of that database, as well as any temporary files created by server processes using that database." so I must be missing something. Andras
