On 15.04.2011 13:32, Radosław Smogura wrote:
If I may, I want to share some concept to use mmap in PG. It's far, far
away from perfect, but it's keeps WAL before data. As well I crated
table, with index, inserted few values, and I done vacuum full on this
table. Db inits welcome from orginal sources.
Performance of read (if backend is loaded) is really good, query time
goes down from 450ms to about 410ms. Update may be slower - but work is
in progress (I will start with write, as I went to point when simple
updates may be performed). Even that I didn't covered all aspects off
updating, it's simple to do it, just to call PreopareBufferToUpdate
before modifing buffer, ofc some ideas of increasing this are still in
my head.
Any comments, suggestions welcome.
The patch is quite hard to read because of random whitespace changes and
other stylistic issues, but I have a couple of high-level questions on
the design:
* Does each process have its own mmappings, or are the mmapping done to
shared buffers?
* How do you handle locking? Do you still need to allocate a shared
buffer for each mmapped page?
--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com
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