On Tue, 2007-11-13 at 08:36 -0800, SHARMILA JOTHIRAJAH wrote: > Hi > I have a table with 29384048 records in oracle and postgresql. The > table has 47 columns (16 numeric and 27 varchar and the rest > timestamp). The tablesize in postgresql is twice as much than the > tablesize in oracle (for the same number of rows and columns). There > are no updates or deletes in this table. It is a test table that is > used only for querying. The tables are vacuumed regularly > > Even a simple seqscan query takes twice as much time in postgres than > in oracle. > Does postgresql generally occupy more space than oracle tables? > Thanks > Sharmila PostgreSQL generally does occupy slightly more space. However, your case is extreme due to the number of columns in the table. In PostgreSQL 8.2 and before, it would store a full 4 byte length header for every variable-width field (which is any text type). 8.3 (currently in beta) will substantially reduce this overhead, usually just storing one byte of overhead for every variable-width field (saving 3 bytes), and also reducing the per-row overhead by either 4 or 8 bytes (depending on platform). My quick calculations show that you could save up to (47*3 + 8)*29384048 = 4378223152. So you might save up to 4GB with 8.3! It would be fairly easy for you to check for yourself exactly how much by downloading the beta. Regards, Jeff Davis ---------------------------(end of broadcast)--------------------------- TIP 5: don't forget to increase your free space map settings
