| 摘要 |
A block map is associated with a multi-dimensionally clustered (MDC) base table in a database to maintain a "free" or "in use" status for each of the contiguous blocks in the table. Additionally, information may be stored in the block map to indicate whether, after loading data, a given block in the base table requires constraint checking operation or whether, based on changes to the block, a materialized query table dependent upon the table requires a refresh operation. Each time data is loaded into the table, the associated block map is updated. When delayed constraint check or refresh operations are to be performed, the block map is consulted to learn which blocks require the operations. After one of the constraint check or refresh operations is performed, the associated block map is again updated. The block map enables a method to efficiently identify data blocks in a base table, changes to which trigger incremental constraint checking operations and incremental maintenance operations of dependent materialized query tables.
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