Re: [PERFORM] execute cursor fetch
On Tue, 12 Oct 2004, Stef wrote: Pierre-Frédéric Caillaud mentioned : = http://www.postgresql.org/docs/7.4/static/jdbc-query.html#AEN24298 My question is : Is this only true for postgres versions = 7.4 ? I see the same section about Setting fetch size to turn cursors on and off is not in the postgres 7.3.7 docs. Does this mean 7.3 the JDBC driver for postgres 7.4 doesn't support this ? You need the 7.4 JDBC driver, but can run it against a 7.3 (or 7.2) database. Also note the 8.0 JDBC driver can only do this against a 7.4 or 8.0 database and not older versions. Kris Jurka ---(end of broadcast)--- TIP 3: if posting/reading through Usenet, please send an appropriate subscribe-nomail command to [EMAIL PROTECTED] so that your message can get through to the mailing list cleanly
Re: [PERFORM] execute cursor fetch
Hi, If anyone can help pls, I have a question abt the execution of cursor create/fetch/move , in particular about disk cost. When a cursor is created, is the whole table (with the required columns) got put into memory? otherwise how does it work? (in term of disk read and transfer?) after user issues command move/fetch, how does postgre speed up the query in compare to normal selection? Thanks a lot, regards, MT Ho __ Do you Yahoo!? Yahoo! Mail Address AutoComplete - You start. We finish. http://promotions.yahoo.com/new_mail ---(end of broadcast)--- TIP 4: Don't 'kill -9' the postmaster
Re: [PERFORM] execute cursor fetch
I just discovered this : http://www.postgresql.org/docs/7.4/static/jdbc-query.html#AEN24298 On Tue, 12 Oct 2004 04:43:43 -0700 (PDT), my ho [EMAIL PROTECTED] wrote: Hi, If anyone can help pls, I have a question abt the execution of cursor create/fetch/move , in particular about disk cost. When a cursor is created, is the whole table (with the required columns) got put into memory? otherwise how does it work? (in term of disk read and transfer?) after user issues command move/fetch, how does postgre speed up the query in compare to normal selection? Thanks a lot, regards, MT Ho __ Do you Yahoo!? Yahoo! Mail Address AutoComplete - You start. We finish. http://promotions.yahoo.com/new_mail ---(end of broadcast)--- TIP 4: Don't 'kill -9' the postmaster ---(end of broadcast)--- TIP 3: if posting/reading through Usenet, please send an appropriate subscribe-nomail command to [EMAIL PROTECTED] so that your message can get through to the mailing list cleanly
Re: [PERFORM] execute cursor fetch
Pierre-Frédéric Caillaud mentioned : = http://www.postgresql.org/docs/7.4/static/jdbc-query.html#AEN24298 My question is : Is this only true for postgres versions = 7.4 ? I see the same section about Setting fetch size to turn cursors on and off is not in the postgres 7.3.7 docs. Does this mean 7.3 the JDBC driver for postgres 7.4 doesn't support this ? Kind Regards Stefan ---(end of broadcast)--- TIP 7: don't forget to increase your free space map settings
Re: [PERFORM] execute cursor fetch
my ho [EMAIL PROTECTED] writes: If anyone can help pls, I have a question abt the execution of cursor create/fetch/move , in particular about disk cost. When a cursor is created, is the whole table (with the required columns) got put into memory? No. The plan is set up and then incrementally executed each time you say FETCH. how does postgre speed up the query in compare to normal selection? The only difference from a SELECT is that the planner will prefer fast-start plans, on the theory that you may not be intending to retrieve the whole result. For instance it might prefer an indexscan to a seqscan + sort, when it otherwise wouldn't. regards, tom lane ---(end of broadcast)--- TIP 9: the planner will ignore your desire to choose an index scan if your joining column's datatypes do not match
