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(9) Storage Structure and Relationships

 
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  •  
  • Extent Allocation and Deallocation
    SQL> alter table xxx allocation extent (size 1m datafile 'xxx');
    SQL> alter table xxx deallocation unused;
  • Database Block
    (1) set at tablespace creation
          SQL> create tablespace kong2 datafile 'xxx' blocksize 8k; (必须指定db_8k_cache_size)
    (2)DB_BLOCK_SIZE is the default block size
  • initrans   maxtrans 

    pctfree: 导致row migration(系统开销)

    pctused:通知可以再使用

  • Configuring Automatic Segment-Space Management
    SQL> create tablespace xxx ... SEGMENT SPACE MANAGEMENT AUTO;
  • Manual Segment Space Management (pctfree,pctused,freelist)

     

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