Re: Re: Idea: recycle WAL segments, don't delete/recreate 'em
Re: Re: Idea: recycle WAL segments, don't delete/recreate 'em
От:
Bruce Momjian <pgman@candle.pha.pa.us>
Дата:
Checking application/pgp-signature: FAILURE -- Start of PGP signed section. > Hi - > > pgman wrote: > > : Most Unix filesystems will not allocate disk blocks until you write in > : them. [...] > > Yes, I understand that, but how is it a problem for postgresql? Uh, I thought we did that so we were not allocating file system blocks during WAL writes. Performance is bad when we do that. -- Bruce Momjian | http://candle.pha.pa.us pgman@candle.pha.pa.us | (610) 853-3000 + If your life is a hard drive, | 830 Blythe Avenue + Christ can be your backup. | Drexel Hill, Pennsylvania 19026
Re: Re: Idea: recycle WAL segments, don't delete/recreate 'emm
От:
Jan Wieck <JanWieck@Yahoo.com>
Дата:
Bruce Momjian wrote: > > Checking application/pgp-signature: FAILURE > -- Start of PGP signed section. > > Hi - > > > > pgman wrote: > > > > : Most Unix filesystems will not allocate disk blocks until you write in > > : them. [...] > > > > Yes, I understand that, but how is it a problem for postgresql? > > Uh, I thought we did that so we were not allocating file system blocks > during WAL writes. Performance is bad when we do that. Performance isn't the question. The problem is when you get a "disk full" just in the middle of the need to write important WAL information. While preallocation of a new WAL file, it's OK and controlled, but there are more delicate portions of the code. Jan -- #======================================================================# # It's easier to get forgiveness for being wrong than for being right. # # Let's break this rule - forgive me. # #================================================== JanWieck@Yahoo.com # _________________________________________________________ Do You Yahoo!? Get your free @yahoo.com address at http://mail.yahoo.com
