The header contains the data block address, table dictionary, row directory, and transaction slots that are used when transactions make changes to rows in the block headers grow from the top down. Data Space: oRow data is inserted into the block from the bottom up. Free Space: oThe free space in a block is in the middle of the block. Thus both the header and the row data space can grow when necessary. The free space in a block is contiguous initially. However deletion and updates may fragment the free space in the block. The free space in the block is coalesced by the database server when necessary. ANSWER 10:
For a data segment represents the minimum percentage of used space that the database server tries to maintain for each data block of the table. A block is put back on the free list when its used space falls below PCTUS ED. The free list of a segment is a list of blocks that are candidate for accommodating future inserts. A segment, by default, is created with one free list. Segment can be created with a higher number of free lists by setting the FREELISTS parameter of storage clause. And by default for PCTFREE is 40% Both PCTFREE and PCTUS ED are calculated as percentages of available data space that is the block space that remains after deducting the header space from total block size.
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- Spring '18
- Disk partitioning, cluster key