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Wait# 45 nam='db file scattered read'

Discussion in 'Server Administration and Options' started by aayan_110, Jan 16, 2011.

  1. aayan_110

    aayan_110 Active Member

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    Hi Guyz

    One of my setup screen in my Oracle Financials Application was running very slow while querying, updatin ,& saving.
    When i checked the trace file it showing me msg

    Wait# 45 nam='db file scattered read'

    how to solve this , can you answer me in detail, your help would be appreciated.

  2. prashant

    prashant Forum Advisor

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    New Delhi, India

    db file scattered read event usually occurs for full table scan, since table scan is 'scattered' as opposed to index scan (sequential).

    Full table scan can happen in a lot of cases:-

    1) No index on where clause columns
    2) Stale statistics
    3) Proper statistics for a very small table (FTS is preffered)
    4) init.ora parameters like 'db_file_multiblock_read_count', 'optimizer_index_caching' etc.

    I would advise you to take a tkprof of the trace file to get a more clear picture.

    You can use following command for the same:-

    tkprof <trace_file_name>.trc output_file.prf sys=no waits=yes sort=fchela,exeela,prsela explain=schema_name/password@tns.db_domain

    This will tell us whether db scattered read is the problem which needs to be addressed. If yes what is the query, its explain plan etc.

    aayan_110 likes this.