LGWR group commits(原)
LGWR group comments the transactions when there are more than one transactions commited while the previous commition processed.[@more@]In times of high activity, LGWR can write to the redo log file using group commits. For example, assume that a user commits a transaction. LGWR must write the transaction's redo entries to disk, and as this happens, other users issue COMMIT statements. However, LGWR cannot write to the redo log file to commit these transactions until it has completed its previous