How to speed up Import
Here are are some suggestions.
1. Check the database alert log. If you see messages like Checkpoint Incomplete, or if log files are switching frequently, then you need to increase the size and number of redo log files.
2. Set or increase the size of the BUFFER parameter on your import. This will increase the size of the buffer that Oracle uses to do the bulk inserts.
3. If possible, create a large UNDO tablespace, and switch to that large UNDO tablespace by using the alter system undo_tablespace=Large_Undo before the import. Then, run the IMP with the COMMIT=N option. After the import completes, switch back to the old UNDO tablespace and then drop the large one if it is no longer necessary. If you do not have the enough space for a larger redo then try increasing the COMMIT parameter setting on the IMP command.
4. Increase the SORT_AREA_SIZE parameter. Increasing this parameter will provide more space for sorting operations when creating indexes.
5. Increase the LOG_CHECKPOINT_INTERVAL. This will help to reduce the number of checkpoints.
Here are are some suggestions from Chris Marquez
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Faster IMPORTS
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Set IMP parameter COMMIT = Y.
Set IMP parameter RECORDLENGTH >= EXP RECORDLENGTH value.
Set IMP parameter BUFFER = MB (Set in the MB range not KB range)
Set IMP parameter STATISTICS = NONE (9i, n/a 8i)
Set IMP parameter RECALCULATE_STATISTICS = N. (8i, n/a 9i)
Set IMP parameter ANALYZE = N. (8i, n/a 9i)
Set IMP parameter INDEXES = N (Import them later…separately)
Set init.ora parameter LOG_ARCHIVE_START = FALSE *&* alter database
noarchivelog;
Set init.ora parameter _disable_logging = TRUE (Warning, this could be
dangerous and unrecoverable in failure. Backup immediately after import
- * Redo records (to disk) will NOT be generated (redo WAS generated in
the log buffer.) [Even with _disable_logging you still “switch” logs
when they get “full”])
Set init.ora parameter _wait_for_sync = FALSE (Warning, this could be
dangerous and unrecoverable in failure. Backup immediately after import
- _wait_for_sync: Wait_for_sync is an oracle generic parameter which,
when set to false, will allow the system to complete commits without
waiting for the redo-log buffer flushes to complete.)
Make redo logs enormous; 500MB, 1GB, etc.
Use Locally Managed Tablespaces on target database.
Thursday, September 27, 2007
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