"Simon Riggs" <[EMAIL PROTECTED]> writes: > On Wed, 2007-12-05 at 08:24 +0000, Gregory Stark wrote: >> "Tom Lane" <[EMAIL PROTECTED]> writes: >> >> > Simon Riggs <[EMAIL PROTECTED]> writes: >> >> I'm thinking that there isn't any way currently of working out how big a >> >> compressed toast object is? >> > >> > pg_column_size() ? >> >> I was going to send the same thing but I think he's looking for the >> compressed >> size of *external* data. >> >> In fact there isn't really any convenient way to find out something is stored >> external. pg_column_size reports the toast raw size of externally stored >> data. >> >> There does seem to be a need for a more general pg_column_info which returns >> a >> tuple (external bool, rawsize integer, storedsize integer). > > That sounds more like what I was after. > > So let me check my understanding: For TOASTed data pg_column_size() > tells you how many bytes the column value occupies when decompressed.
Wait, no, it's supposed to be the actual size on disk. *checks* yeah, it's the extsize which is the size of the datum in the toast table. So you could find the compression ratio by calling length() and pg_column_size() at least for text data. I still think a single function returning those columns would be a nice thing to have to make the api complete. -- Gregory Stark EnterpriseDB http://www.enterprisedb.com Get trained by Bruce Momjian - ask me about EnterpriseDB's PostgreSQL training! ---------------------------(end of broadcast)--------------------------- TIP 6: explain analyze is your friend
