Re: [HACKERS] maintenance_work_mem memory constraint?
--On Montag, November 26, 2007 21:41:33 +0100 I wrote: --On Montag, November 26, 2007 13:02:14 -0500 Tom Lane [EMAIL PROTECTED] wrote: Bernd Helmle [EMAIL PROTECTED] writes: ... But isn't it worth to special case the code in grow_memtuples() (and maybe other places where sort is likely to use more RAM), so that we can remove this constraint on 64-Bit systems with many RAM built in? Or am I missing something very important?. AFAICS this patch can increase the number of sortable tuples by at most 2X (less one). That doesn't seem worth getting very worked up about ... regards, tom lane That's true. Well, i haven't meant the diff as a discussable patch at all. It's just what i've done to understand why we have this limit for tuplesort. afaics, the main constraint here is MaxAllocSize, and i just wonder if that doesn't introduce unnecessary limits on systems which can use many RAM for index creation and wether we can be more generous here. So one idea could be to allow larger allocation requests during sorting on systems where we know that this is likely to work. And, to complete my concerns, if i can afford to give maintenance_work_mem 10GB and the system just uses 2GB this is somewhere near a bug. -- Thanks Bernd ---(end of broadcast)--- TIP 2: Don't 'kill -9' the postmaster
Re: [HACKERS] maintenance_work_mem memory constraint?
Bernd Helmle [EMAIL PROTECTED] writes: ... But isn't it worth to special case the code in grow_memtuples() (and maybe other places where sort is likely to use more RAM), so that we can remove this constraint on 64-Bit systems with many RAM built in? Or am I missing something very important?. AFAICS this patch can increase the number of sortable tuples by at most 2X (less one). That doesn't seem worth getting very worked up about ... regards, tom lane ---(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
Re: [HACKERS] maintenance_work_mem memory constraint?
--On Montag, November 26, 2007 13:02:14 -0500 Tom Lane [EMAIL PROTECTED] wrote: Bernd Helmle [EMAIL PROTECTED] writes: ... But isn't it worth to special case the code in grow_memtuples() (and maybe other places where sort is likely to use more RAM), so that we can remove this constraint on 64-Bit systems with many RAM built in? Or am I missing something very important?. AFAICS this patch can increase the number of sortable tuples by at most 2X (less one). That doesn't seem worth getting very worked up about ... regards, tom lane That's true. Well, i haven't meant the diff as a discussable patch at all. It's just what i've done to understand why we have this limit for tuplesort. afaics, the main constraint here is MaxAllocSize, and i just wonder if that doesn't introduce unnecessary limits on systems which can use many RAM for index creation and wether we can be more generous here. So one idea could be to allow larger allocation requests during sorting on systems where we know that this is likely to work. -- Thanks Bernd ---(end of broadcast)--- TIP 5: don't forget to increase your free space map settings
