什么是dynamic index？

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This showplan message indicates that a query using or clauses or an in (values list) clause uses multiple index scans(also called the "secial OR strategy" instead of using a dynamic index.

什么是dynamic index(动态索引)？

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The term dynamic index refers to a worktable of row IDs used to process some queries that use or clauses or an in(values list).

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When the OR strategy is used,Adaptive Server builds a list of all the row IDs that match the query,sorts the list  to remove duplicates,and uses the list  to retrieve the rows from the table.