Craig de Stigter <craig.destigter@xxxxxxxxxxxxxxx> writes: > We are using the PostgreSQL pg_stats view to estimate file sizes for some > geodata exports. However, the following query gives us totally different > results on different servers: > select avg_width from pg_stats where tablename='some_geodata' and attname = > 'GEOMETRY'; I'm afraid that query is pretty much completely useless for what you want to do. What it should be giving you is the average width of the field values on-disk, which is to say after compression and toasting. It would probably be all right for narrow columns but it's likely to be a huge underestimate of the external textual size for wide field values. Having said that, though, these numbers make no sense to me: > PostgreSQL 8.3.7 on i486-pc-linux-gnu, compiled by GCC gcc-4.3.real (Ubuntu > 4.3.2-1ubuntu11) 4.3.2 >> 81803 > PostgreSQL 8.2.9 on i486-pc-linux-gnu, compiled by GCC cc (GCC) 4.1.2 > (Ubuntu 4.1.2-0ubuntu4) >> 20450 It should be impossible to get a value larger than the block size, or even more than about a quarter of the block size because that's where TOAST will start doing its thing. Are you running modified source code? regards, tom lane -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
