On Wed, Jul 6, 2011 at 6:17 AM, John R Pierce pierce@hogranch.com wrote:
On 07/05/11 9:04 PM, Charles Polisher wrote:
The PostgreSQL wiki seems to say that database tables are allocated in 1GB extents. In workloads with which I am familiar, with an RDBMS the extents don't bounce around all that much, i.e. the vast majority of writes do not result in a change to the underlying database's storage allocation. Once in a while a new extent is allocated. http://www.postgresql.org/docs/current/static/storage-file-layout.html I suppose there could be exceptions, but I haven't run across one personally.
you misread that.
When a table or index exceeds 1 GB, it is divided into gigabyte-sized/segments/. The first segment's file name is the same as the filenode; subsequent segments are named filenode.1, filenode.2, etc. This arrangement avoids problems on platforms that have file size limitations. ...
Each file is no larger than 1GB (by default), but its written and expanded as needed, not in any fixed size increment.
The "WAL" files you refer to are apparently database transaction logs. According to the wiki, these too are allocated in extents (WAL segments) of 16MB each.
The wal logs are 16M files, also written sequentially as needed, and nearly continuously on a insert/update intensive database. they are not reused, rather, old wal files are deleted (unless you're archiving), and new ones are created continuously.
-- john r pierce N 37, W 122 santa cruz ca mid-left coast
Hi Everyone,
I just tried to install EXT4 onto a CentOS 5 machine but it failed. Does anyone know in which repository it is?
root@usaxen01:[~]$ cat /etc/redhat-release CentOS release 5 (Final)
root@usaxen01:[~]$ uname -a Linux usaxen01 2.6.18-8.1.15.el5xen #1 SMP Mon Oct 22 09:01:12 EDT 2007 x86_64 x86_64 x86_64 GNU/Linux
root@usaxen01:[~]$ yum -y install e4fsprogs Loading "installonlyn" plugin Setting up Install Process Setting up repositories Reading repository metadata in from local files Excluding Packages in global exclude list Finished Parsing package install arguments Nothing to do