Обсуждение: JDBC memory usage
Hello, I noticed that I keep running out of memory when trying to run a query that returns 100,000 rows or so. Searching the archives, it seems that the JDBC driver reads the entire ResultSet into memory at once rather than using cursors. This is definitely not the desired behavior for this particular query. Has this been fixed recently? I'm using PostgreSQL 7.3.4 with the corresponding JDBC driver. Thanks! -- Bill -- Bill Schneider Chief Architect Vecna Technologies 5004 Lehigh Rd., Suite B College Park, MD 20740 bschneider@vecna.com t: 301-864-7253 x1140 f: 301-699-3180
Quoting Bill Schneider <bschneider@vecna.com>: > Hello, > > I noticed that I keep running out of memory when trying to run a query > that returns 100,000 rows or so. > > Searching the archives, it seems that the JDBC driver reads the entire > ResultSet into memory at once rather than using cursors. This is > definitely not the desired behavior for this particular query. > > Has this been fixed recently? I'm using PostgreSQL 7.3.4 with the > corresponding JDBC driver. I ran into this problem. The driver developers informed me that this problem is fixed in 7.4, and that the new driver can be used with a 7.3 server. (This exchange should be in the pgsql-jdbc archives.) Jack Orenstein ---------------------------------------------------------------- This message was sent using IMP, the Internet Messaging Program.
Bill Schneider wrote: > Hello, > > I noticed that I keep running out of memory when trying to run a query > that returns 100,000 rows or so. > > Searching the archives, it seems that the JDBC driver reads the entire > ResultSet into memory at once rather than using cursors. This is > definitely not the desired behavior for this particular query. > > Has this been fixed recently? I'm using PostgreSQL 7.3.4 with the > corresponding JDBC driver. Do all of: - use current development drivers and a 7.4 server, or pre-build-302 drivers and a 7.2/7.3/7.4 server - call Connection.setAutoCommit(false) - create statements that produce resultsets of type TYPE_FORWARD_ONLY - call Statement.setFetchSize(<positive integer>) - use queries that consist of a single SELECT with no trailing ';' (only a requirement if using older drivers) Then the driver should use cursors to batch access to the resultset. -O