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Oracle Internal

Oracle Commit

Oracle Commit

Oracle Commit Work Process

  • before commit
    • Oracle revocation the undo record in the buffer of the SGA, the undo record contains the old value update and delete table row.
    • Oracle redo log buffer in the SGA generated redo log record
    • Oracle Database modify the SGA buffer
  • during commit
    • The redo records on the transaction is marked as the committed transactions with the unque SCN.
    • redo log buffer is written to redo log files on disk
    • Oracle released the locks held, marking the transaction is completed

Oracle commit parameters

  • commit_wait initialization parameters
  • commit_wait={nowait|wait|force_wait}

    Oracle default commit mode is wait

    why to use the commit_wait: control redo log write mode

    When to use the commit_nowait

    • There are a large number of transaction redo, need to write redo log information
    • Tolerate partial loss of data
    • Wait for LGWR to write to the application can not stand

    force wait: oracle will use the default submission

  • commit_logging initialization parameters
  • commit_logging={immediat|batch}

    immediate: LGWR will redo information is written to the redo log file immediately

    batch: redo information will be buffer, that is not immediately written to redo redo log files

commit options

commit write wait;
commit write nowait
commit write batch;
commit write immediate;

wait, nowait control when descending redo information is written to the redo logs immediat, batch control in what way redo information is written to the redo logs

Notes: PL/SQL default mode batch nowait

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About daviewning

I am an Oracle DBA

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