15. Updating Data : How to Avoid Propagation
 
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How to Avoid Propagation
During batch operations Vector automatically propagates the changes buffered in memory to the disk-resident table. Because such propagation can be costly in terms of time and resources, it is best to avoid frequent propagation to large tables by using one of the following approaches:
• Consider disabling automatic propagation by setting [system] update_propagation = false.
• For large tables with frequent inserts, consider using RAW (see Raw Table Storage Format) storage format.
• For tables with a clustered index, keep the volume of data changed below what will easily fit in RAM.
Note:  The data changes buffered in memory are not compressed.
• If a clustered index must be used for query performance, stage batches of inserts and deletes in one or more separate tables and use the MODIFY...TO COMBINE Statement--Merge and Update Data to add them to the table.
• Enforce propagation at a convenient moment, as described in MODIFY...TO COMBINE Statement--Merge and Update Data.