I had a question today while considering the way to [potentially improve performance and stability of my ETL’s.  Basically, does Netezza need to be groomed when truncating a table as part of a destructive load strategy?  The answer is no, a Netezza table does not need to be groomed after a truncate operation—see IBM Tip quoted below.

Tip: When you delete all the contents of a table, consider using the TRUNCATE command rather than the DELETE command, which eliminates the need to run the GROOM TABLE command.”

Once the data is loaded, following the truncate, running Generate Statistics on the table is strongly recommended.

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Related References

Generate Statistics

PUREDATA SYSTEM FOR ANALYTICS, PUREDATA SYSTEM FOR ANALYTICS 7.2.1, IBM NETEZZA DATABASE USER DOCUMENTATION, NETEZZA SQL COMMAND REFERENCE, GENERATE STATISTICS

• https://www.ibm.com/support/knowledgecenter/en/SSULQD_7.2.1/com.ibm.nz.dbu.doc/r_dbuser_generate_statistics.html

Groom Table

PUREDATA SYSTEM FOR ANALYTICS, PUREDATA SYSTEM FOR ANALYTICS 7.2.1, IBM NETEZZA DATABASE USER DOCUMENTATION, NETEZZA SQL COMMAND REFERENCE, Groom table

• https://www.ibm.com/support/knowledgecenter/en/SSULQD_7.2.1/com.ibm.nz.dbu.doc/r_dbuser_groom_table.html

Truncate

PureData System for Analytics, PureData System for Analytics 7.2.1, IBM Netezza database user documentation, Netezza SQL command reference, truncate

• https://www.ibm.com/support/knowledgecenter/en/SSULQD_7.2.1/com.ibm.nz.dbu.doc/r_dbuser_truncate.html