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Database Administrator's Guide

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When a key search occurs on partitioned indexes that are not ordered as the partition key, all of the partition members must be opened, which can take a significant amount of time if the number of partitions is large. One operation where unnecessary time was spent was resizing (allocate new + copy + free old) the users file control block. Previously, this grew in increments of 32 (MAXMEMB + 1) files. With partition files used through SQL, thousands of files may be opened by a single query. A change was made which increased the rate at which this array grows by doubling in size up to 2 thousand files. This change reduced the total query time by 4% in a case with 1000 files. This will affect memory usage, as it will now increase in increments of up to 500 KB (for large numbers of files already opened) versus 8KB with the old approach. This option reverts to the old approach.