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EXPDP预估导出空间estimate，estimate_only

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ESTIMATE

默认：blocks

指定计算每张表使用磁盘空间的方法

ESTIMATE=[BLOCKS | STATISTICS]

1.BLOCKS – 通过块数和块大小计算?

2.STATISTICS -每张表的统计信息计算

限制

1.如果压缩了表，那么使用ESTIMATE=BLOCKS计算的值时不准确的，这个时候就应该使用ESTIMATE=STATISTICS.?

2.在QUERY，REMAP_DATA参数使用的情况下也不准确

?[oracle@lzl ~]$ expdp scott/tiger TABLES=emp ESTIMATE=STATISTICS DIRECTORY=lzl_dir DUMPFILE=estimate_stat.dmp

Export: Release 11.2.0.3.0 – Production on Wed Jul 12 23:29:44 2017

Copyright (c) 1982, 2011, Oracle and/or its affiliates.  All rights reserved.

Connected to: Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 – 64bit Production

With the Partitioning, OLAP, Data Mining and Real Application Testing options

Starting “SCOTT”.”SYS_EXPORT_TABLE_01″:  scott/******** TABLES=emp ESTIMATE=STATISTICS DIRECTOR