Re: Event 'db file seq. read' stuck for hours on the same file#/block# ?

DA Morgan wrote:

> Haximus wrote:
>
>> Just a thought... latch contention? 'db file seq. read' is for control
>> file and datafile header access
>
> Is your advice based on ignorance or intended to do harm?
>
> Source:
>

http://download-west.oracle.com/docs/cd/B14117_01/server.101/b10752/instance_tune.htm#15959
>
> db file sequential read
> This event signifies that the user process is reading a buffer into the
> SGA buffer cache and is waiting for a physical I/O call to return. A
> sequential read is a single-block read.

Perhaps you should look at the 8.1.7 docs which state "This event is also used for rebuilding the controlfile, dumping datafile headers, and getting the database file headers." Now, obviously this isn't the case as the poster has already identified that the read appears stuck on an index block.

Anywho... this is beside the point I wanted to make, which is something is obviously blocking the read from completing... like for example another session accessing to the same block, in which case could result in a 'buffer busy wait' hang, that sort of thing, or latch contention.... get the idea?

Just a tip: quoting from manuals doesn't help anyone when obviously you do not seem to understand the underlying processes involved. Received on Tue Mar 01 2005 - 13:58:39 CST