- The ESTIMATE_ONLY parameter cannot be used in conjunction with the QUERY parameter dumpfile.
- Estimate Parameter do not give the accurate size . It gives the approax. size of the dumpfile .
- 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.
- The estimate may also be inaccurate if the QUERY, SAMPLE, or REMAP_DATA parameter is used.