Oracle大表碎片分析整理
expdp导出表耗时6分钟，预估大小69.7GB，导出大小6.8GB，大概有61GB的碎片
利用show_space查看表的相关信息如下：
Total Blocks............................9136640
Total Bytes.............................74847354880
Unused Blocks...........................0
Unused Bytes............................0
Last Used Ext FileId....................8
Last Used Ext BlockId...................1712256
Last Used Block.........................8192
The segment is analyzed.
0% -- 25% free space blocks.............6
0% -- 25% free space bytes..............49152
25% -- 50% free space blocks............9
25% -- 50% free space bytes.............73728
50% -- 75% free space blocks............19
50% -- 75% free space bytes.............155648
75% -- 100% free space blocks...........8006297
75% -- 100% free space bytes............65587585024 --->> ≈ 61GB
Unused Blocks...........................0
Unused Bytes............................0
Total Blocks............................1121012
Total bytes.............................9183330304
-----------------------------------------------清理碎片之前磁盘队列很高
对表做了truncate之后再次查看，以及过了8小时之后查看的结果对比如下：
truncate后的数据：
PL/SQL 过程已成功完成。
Total Blocks............................8192 ---->总分配的数据块数量
Total Bytes.............................67108864 ---->总分配的数据块大小 8192*8*1024
Unused Blocks...........................8158 ---->未使用的数据块数量
Unused Bytes............................66830336 ---->未使用的数据块大小 8158*8*1024
Last Used Ext FileId....................4
Last Used Ext BlockId...................875520
Last Used Block.........................34
The segment is analyzed.
0% -- 25% free space blocks.............0
0% -- 25% free space bytes..............0
25% -- 50% free space blocks............0
25% -- 50% free space bytes.............0
50% -- 75% free space blocks............0
50% -- 75% free space bytes.............0
75% -- 100% free space blocks...........0
75% -- 100% free space bytes............0
Unused Blocks...........................0
Unused Bytes............................0
Total Blocks............................0
Total bytes.............................0
-----------------------------------------------
8小时后再次查看
PL/SQL 过程已成功完成。
Total Blocks............................8192
Total Bytes.............................67108864
Unused Blocks...........................7936
Unused Bytes............................65011712
Last Used Ext FileId....................4
Last Used Ext BlockId...................875520
Last Used Block.........................256
The segment is analyzed.
0% -- 25% free space blocks.............2
0% -- 25% free space bytes..............16384
25% -- 50% free space blocks............2
25% -- 50% free space bytes.............16384
50% -- 75% free space blocks............3
50% -- 75% free space bytes.............24576
75% -- 100% free space blocks...........69
75% -- 100% free space bytes............565248
Unused Blocks...........................142
Unused Bytes............................1163264
Total Blocks............................4
Total bytes.............................32768
-----------------------------------------------
PL/SQL 过程已成功完成。对表做一次统计信息收集后再查看一次
execute dbms_stats.gather_table_stats(ownname => 'test',tabname => 'tabname' ,estimate_percent => null ,method_opt => 'for all indexed columns' ,cascade => true);
Total Blocks............................8192
Total Bytes.............................67108864
Unused Blocks...........................7936
Unused Bytes............................65011712
Last Used Ext FileId....................4
Last Used Ext BlockId...................875520
Last Used Block.........................256
The segment is analyzed.
0% -- 25% free space blocks.............1
0% -- 25% free space bytes..............8192
25% -- 50% free space blocks............3
25% -- 50% free space bytes.............24576
50% -- 75% free space blocks............1
50% -- 75% free space bytes.............8192
75% -- 100% free space blocks...........69
75% -- 100% free space bytes............565248
Unused Blocks...........................142
Unused Bytes............................1163264
Total Blocks............................6
Total bytes.............................49152
-----------------------------------------------
PL/SQL 过程已成功完成。清理之后磁盘队列基本为0