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Explain About Light Scans In Informix ? |
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Answer» A LIGHT SCAN may occur when INFORMIX internal OPTIMIZER decides that the BEST execution plan will be a sequential scan (bad query selectivity, lack of indexes…). In this case, if the optimizer further decides that the data set resulting from the query will not fit in the buffer pool, it will bypass it. The result is a light scan. A light scan may occur when Informix internal optimizer decides that the best execution plan will be a sequential scan (bad query selectivity, lack of indexes…). In this case, if the optimizer further decides that the data set resulting from the query will not fit in the buffer pool, it will bypass it. The result is a light scan. |
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