Default: There is no default
Purpose
Allows you to specify a percentage of the data rows to be sampled and unloaded from the source database.
Syntax and Description
SAMPLE=[[schema_name.]table_name:]sample_percent
This parameter allows you to export subsets of data by specifying the percentage of data to be sampled and exported. The sample_percent indicates the probability that a row will be selected as part of the sample. It does not mean that the database will retrieve exactly that amount of rows from the table. The value you supply for sample_percent can be anywhere from .000001 up to, but not including, 100.
The sample_percent can be applied to specific tables. In the following example, 50% of the HR.EMPLOYEES table will be exported:
SAMPLE="HR"."EMPLOYEES":50
If you specify a schema, then you must also specify a table. However, you can specify a table without specifying a schema; the current user will be assumed. If no table is specified, then the sample_percent value applies to the entire export job.
You can use this parameter with the Data Pump Import PCTSPACE transform, so that the size of storage allocations matches the sampled data subset. (See the Import "TRANSFORM" parameter.)
Restrictions
The SAMPLE parameter is not valid for network exports.
Example
In the following example, the value 70 for SAMPLE is applied to the entire export job because no table name is specified.
> expdp hr DIRECTORY=dpump_dir1 DUMPFILE=sample.dmp SAMPLE=70