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http://hi.baidu.com/oracle_10g/blog/item/7b0b0e4fe7bb7335afc3abdb.html不是很详细,比如报名,培训安排,课程内容,考式内容等等都没提到; 是讲9i的ocm,10g不知收费与老试内容是否有变化可以抽点时间到hk考一下.[@more@]m

When you create or resize tempfiles, they are not always guaranteed allocationof disk space for the file size specified. On certain file systems (for example,UNIX) disk blocks are allocated not at file creation or resizing, but before theblocks are accessed.Caution: This enables fast tempfile creation and resizing;however, the disk could run of space later when the tempfiles areaccessed.在创建或resize后，接下来做一个大的排序操作，让空间得到分配，这样真正到了用的时候就不会花时间在allocate上了. 并

Delete, update两类语句可以增加block中的free space释放的空间在下面的条件下可以被随后的insert使用1) insert与释放空间的delete/update在同一个事务中,insert在后2) insert与delete/update在不同事务中, 只有当delete/update所在事务提交后，insert才能使用释放的空间block中释放的空间可能不连续, oracle在下面两个条件满足时会愈合块中碎片1) update/insert语句尝试使用这个块在存储 a new row piece，而这个块包含有足够的free space(算上连续空间与碎片空间)2) 因为不连续,这个new row piece无法insert进来这种做的原因是为了性能考

Free space can be managed automatically or manually.Free space can be managed automatically inside database segments. The in-segment free/used space is tracked using bitmaps, as opposed to free lists. Automatic segment-space management offers the following benefits:.Ease of useBetter space utilization, especially for the objects with highly varying row sizesBetter run-time adjustment to variations in concurrent accessBetter multi-instance behavior in terms of performance/space utilizationYou spe

Although you can allocate additional extents, the blocks themselves are allocated separately. If you allocate an extent to a specific instance, the blocks are immediately allocated to the free list. However, if the extent is not allocated to a specific instance, then the blocks themselves are allocated only when the high water mark moves. The high water mark is the boundary between used and unused space in a segment.分配extent时,blocks不是马上分配,分成两种情况:1, 如果extent分配到具体的instance(r