Support Concurrent Update
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Support Concurrent Update
Presented by: MATAAC, Gladys G.
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Concurrent Update
• occurs when multiple users make updates to the same database at the same time.
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The Concurrent Update Problem
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Batch Processing
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Batch Processing
• processing technique in which a single update program reads the batch of records in this file one at a time and erforms the appropriate updates to the database.
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Two-Phase Locking
• Locking- denies ither users access to data while the DBMS processes one user's update to the database
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Two-Phase Locking
• Two-Phase Locking- approach of handling locks where the DBMS hold locks until it completes all the updates in the transaction.– Growing Phase- fist phase in which the
DBMS locks more rows and releases none of the locks.
– Shrinking Phase- second phase in which the DBMS releases all the locks and acquires no new locks.