Re: [HACKERS] [hackers]development suggestion needed
От | Don Baccus |
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Тема | Re: [HACKERS] [hackers]development suggestion needed |
Дата | |
Msg-id | 3.0.1.32.20000113174339.01078360@mail.pacifier.com обсуждение исходный текст |
Ответ на | Re: [HACKERS] [hackers]development suggestion needed (Tom Lane <tgl@sss.pgh.pa.us>) |
Ответы |
Re: [HACKERS] [hackers]development suggestion needed
Re: [HACKERS] [hackers]development suggestion needed |
Список | pgsql-hackers |
At 08:23 PM 1/13/00 -0500, Tom Lane wrote: >As far as the actual implementation goes, the low level access methods >go through a "storage manager" switch that was intended to allow for >the addition of a new storage manager, such as a raw-device manager. >So you could get a good deal of stuff working by implementing code that >parallels md.c/fd.c. The main problem at this point is that there is a >fair amount of utility code that goes out and does its own manipulation >of the database file structure. You'd need to clean that up by pushing >it all down below the storage manager switch (inventing new storage >manager calls as needed). This would need to be done to implement some sort of tablespace-style facility, too, right? I'm off Xun's thread in asking but I've been wondering. DBs like Oracle allow you to place tables and indices whereever you like in the filesystem. This is normally done to distribute things across different spindles, and in large, busy databases makes a significant difference. I've done some experimenting moving index files to a different spindle (using "ln" to fool postgres, of course) and insertions go measurably faster. Spindles are so cheap nowadays :) I know there's been discussion of letting folks specify where the WAL will be placed when it's implemented, for safety's sake - it will also improve performance. >You don't get to do either of the latter two unless you write a >raw-device storage manager Not within a single filesystem, but scattering things across spindles could be done without a raw-device storage manager :) (not what he's talking about, but heck, thought I'd raise it) - Don Baccus, Portland OR <dhogaza@pacifier.com> Nature photos, on-line guides, Pacific Northwest Rare Bird Alert Serviceand other goodies at http://donb.photo.net.
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