nzvacuumcat in Netezza
nzvacuumcat in Netezza is:
– Netezza background process which strats at Netezza boot time.All background processes are started by startupsvr background process
– During, Netezza boot time it invokes VACUUM command to groom system tables for faster table scans by removing deleted records and shrinking the system tables.
– When Netezza is running, it checks for database system table growth above 120 KB (checks every 60 secs) and invokes system table vacuum if it grows above 128 KB.
– VACUUM command takes exclusive locks on all system catalog tables before vacuuming the system tables.
– nzvacuumcat will shrink the database size only when Vacuum command runs succesfully.
– If it is not able to aquire locks, system will write ‘Could not acquire lock for lazy vacuum’ message in pg.log and will try again after some time.