Oracle10g 五種不同的block size

5種block size： 2k、4k、8k、16k、32k 。

Toms Kyte的書上講了：當且僅當建立資料庫時指定了一個非標準的塊大小（不是2的冪）時，才會有6種不同的塊大小 .

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A database can have as many as five data block sizes. The database always allocates and uses disk space in units of data blocks. The data block size is typically 8KB to 32KB and must be a multiple of the physical block size of the storage device.

Larger data block sizes are more common in data warehousing environments where the larger block size can yield shallower Btree indexes and thus better performance 。