Hi :) powered by the great talk for newbie hackers by Neil Conway & Gavin Sherry [1] at the anniversary summit I sneaked into the Code Sprint and started working a bit on a Todo from Neil's Code Sprint Page:
"Add a psql option to have it submit SELECT queries via a cursor, to avoid excessive memory consumption when manipulating large result sets" Gavin gave me a sketch of a patch that added a new command line option to psql that would have it use cursors for selects. One of the problems with this was that a user would expect psql to work as usual (including all format and output option stuff) and to do this properly most of the psql output code would need to be refactored. Thinking about it, we had the idea to just introduce a new \ operator that would output the results of a select (using cursors) in an indipendent code path. Who's selecting gigabytes of stuff into a HTML table anyway? So, I've introduced a new \u command that from a user perspective is identical to \g (it executes the query buffer), just that it uses cursors and honours only the field separator. For example you could just do select a, c, g from big \u bigout.dat The patch is here [2], is working, but needs some performance improvment and double checking. Which I won't do before getting some feedback that what I'm doing does make any sense at all ;) Bye, Chris [1] http://neilconway.org/talks/hacking/ [2] http://www.1006.org/tmp/psql_cursor-3.patch ---------------------------(end of broadcast)--------------------------- TIP 9: In versions below 8.0, the planner will ignore your desire to choose an index scan if your joining column's datatypes do not match
