Datapump Estimate parameter

ESTIMATE

Default: BLOCKS

Purpose

Specifies the method that Export will use to estimate how much disk space each table in the export job will consume (in bytes). The estimate is printed in the log file and displayed on the client’s standard output device. The estimate is for table row data only; it does not include metadata.

Syntax and Description

ESTIMATE={BLOCKS | STATISTICS}

• BLOCKS – The estimate is calculated by multiplying the number of database blocks used by the source objects, times the appropriate block sizes.
• STATISTICS – The estimate is calculated using statistics for each table. For this method to be as accurate as possible, all tables should have been analyzed recently.

Restrictions

If the Data Pump export job involves compressed tables, the default size estimation given for the compressed table is inaccurate when ESTIMATE=BLOCKS is used. This is because the size estimate does not reflect that the data was stored in a compressed form. To get a more accurate size estimate for compressed tables, use ESTIMATE=STATISTICS.

Example : Estimate= Statistics

C:\Users\mazar>expdp testnet/testnet tables=mytest estimate=statistics directory=data_pump_dir dumpfile=estimate_Stat.dmp logfile=estimate.log

Export: Release 11.2.0.1.0 - Production on Tue Nov 9 09:53:33 2010

Copyright (c) 1982, 2009, Oracle and/or its affiliates.  All rights reserved.

Connected to: Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
Starting "TESTNET"."SYS_EXPORT_TABLE_01":  testnet/******** tables=mytest estimate=statistics directory=data_pump_dir dumpfile=estimate_Stat.dmp logfile=estima
te.log
Estimate in progress using STATISTICS method...
Processing object type TABLE_EXPORT/TABLE/TABLE_DATA
.  estimated "TESTNET"."MYTEST"                          6.582 KB
Total estimation using STATISTICS method: 6.582 KB
Processing object type TABLE_EXPORT/TABLE/TABLE
Processing object type TABLE_EXPORT/TABLE/STATISTICS/TABLE_STATISTICS
. . exported "TESTNET"."MYTEST"                          6.625 KB       1 rows
Master table "TESTNET"."SYS_EXPORT_TABLE_01" successfully loaded/unloaded
******************************************************************************
Dump file set for TESTNET.SYS_EXPORT_TABLE_01 is:
  C:\APP\ORACLE\MAZAR\ADMIN\AZARDB\DPDUMP\ESTIMATE_STAT.DMP
Job "TESTNET"."SYS_EXPORT_TABLE_01" successfully completed at 09:54:23

Estimate=blocks

C:\Users\mazar>expdp testnet/testnet tables=mytest estimate=blocks directory=data_pump_dir dumpfile=estimatestat.dmp logfile=estimatest.log

Export: Release 11.2.0.1.0 - Production on Tue Nov 9 09:55:26 2010

Copyright (c) 1982, 2009, Oracle and/or its affiliates.  All rights reserved.

Connected to: Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
Starting "TESTNET"."SYS_EXPORT_TABLE_01":  testnet/******** tables=mytest estimate=blocks directory=data_pump_dir dumpfile=estimatestat.dmp logfile=estimatest.
log
Estimate in progress using BLOCKS method...
Processing object type TABLE_EXPORT/TABLE/TABLE_DATA
.  estimated "TESTNET"."MYTEST"                             64 KB
Total estimation using BLOCKS method: 64 KB
Processing object type TABLE_EXPORT/TABLE/TABLE
Processing object type TABLE_EXPORT/TABLE/STATISTICS/TABLE_STATISTICS
. . exported "TESTNET"."MYTEST"                          6.625 KB       1 rows
Master table "TESTNET"."SYS_EXPORT_TABLE_01" successfully loaded/unloaded
******************************************************************************
Dump file set for TESTNET.SYS_EXPORT_TABLE_01 is:
  C:\APP\ORACLE\MAZAR\ADMIN\AZARDB\DPDUMP\ESTIMATESTAT.DMP
Job "TESTNET"."SYS_EXPORT_TABLE_01" successfully completed at 09:55:49
C:\Users\mazar>

ESTIMATE_ONLY

Default: n

Purpose

Instructs Export to estimate the space that a job would consume, without actually performing the export operation.

Syntax and Description

ESTIMATE_ONLY={y | n}

If ESTIMATE_ONLY=y, then Export estimates the space that would be consumed, but quits without actually performing the export operation.

Example :

C:\Users\mazar>set oracle_sid=azardb

C:\Users\mazar>expdp testnet/testnet estimate_only=y nologfile=y

Export: Release 11.2.0.1.0 - Production on Tue Nov 9 09:47:32 2010

Copyright (c) 1982, 2009, Oracle and/or its affiliates.  All rights reserved.

Connected to: Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
Starting "TESTNET"."SYS_EXPORT_SCHEMA_01":  testnet/******** estimate_only=y nologfile=y
Estimate in progress using BLOCKS method...
Processing object type SCHEMA_EXPORT/TABLE/TABLE_DATA
.  estimated "TESTNET"."A"                                   9 MB
.  estimated "TESTNET"."DEPT"                               64 KB
.  estimated "TESTNET"."MYTEST"                             64 KB
.  estimated "TESTNET"."TEST"                               64 KB
.  estimated "TESTNET"."EMP"                                 0 KB
.  estimated "TESTNET"."MYVAR"                               0 KB
Total estimation using BLOCKS method: 9.187 MB
Job "TESTNET"."SYS_EXPORT_SCHEMA_01" successfully completed at 09:50:00

Ref :

http://download.oracle.com/docs/cd/B19306_01/server.102/b14215/dp_export.htm