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Explain About Light Scans In Informix? |
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Answer» Light SCANS occur under the following conditions: The optimizer CHOOSES a SEQUENTIAL scan of the table. The number of pages in the table is greater than the number of buffers in the buffer pool. The isolation LEVEL OBTAINS no lock or a shared lock on the table: Dirty Read (including non logging databases) isolation level Repeatable Read isolation level if the table has a shared or exclusive lock Committed Read isolation if the table has a shared lock Light scans occur under the following conditions: The optimizer chooses a sequential scan of the table. The number of pages in the table is greater than the number of buffers in the buffer pool. The isolation level obtains no lock or a shared lock on the table: Dirty Read (including non logging databases) isolation level Repeatable Read isolation level if the table has a shared or exclusive lock Committed Read isolation if the table has a shared lock |
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