Shulou(Shulou.com)06/01 Report--

This event occurs during the process of loading the same data block into memory, and multiple sessions select the same data block at the same time causing buffer lock contention. In oracle 9i, it is equivalent to "buffer busy waits", and in Oracle 10.1 and later, this event is broken down into "read by other session" wait events.

Select c.PARAMETER1,c.PARAMETER2,c.PARAMETER3 from v$event_name c where c.name='read by other session'

PARAMETER1 PARAMETER2 PARAMETER3

File# block# class#

Parameters:

P1 = file# Absolute File# (AFN)

P2 = block#

P3 = class# Block class

The file# absolute file number (AFN) contains the file number of the data file waiting for the block needed for the session.

Block# waits for the block number of the above file to be accessed by the session.

Block classes that class# is waiting for:

Class 1 stands for "block" and can be a table or index

Category 4 of class means "Duan Tou"

Class > = 15 means "undo block"

Find blocker:

SELECT SID mySID, blocking_session

P1 "FILE#", p2 "BLOCK#", p3 "class#", row_wait_obj# OBJECT_ID

FROM v$session

WHERE event = 'read by other session'

AND STATE='WAITING'

Find the object:

SELECT relative_fno, owner, segment_name, segment_type

FROM dba_extents

WHERE file_id = & FILE

AND & BLOCK BETWEEN block_id AND block_id + blocks-1

Reduce the wait event:

1. Optimize sql to reduce block read in

two。 Increase the size of sga

Mos:WAITEVENT: "read by other session" Reference Note (document ID 732891.1)

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