Question of dostats
Frank Yunyao Qu asked whether dropping distributions with UPDATE STATISTICS LOW is needed before running dostats daily. Art Kagel said neither is needed; with auto stats enabled use --force to override, and he runs dostats without --force on weekdays and with --force at weekends. A TCP connection is preferred, since dostats may use two connections that shared memory cannot give.
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Hi, Art, We use Dostats to update stats daily. The basic steps of the cronjob are, Step 1) update statistics low drop distributions Step 2 ) dostats -d mydatabase Question, Is step 1 (drop distribution) needed before running dostats? Thanks Frank
No. It is not necessary to do an UODATE STAUSTUCS LOW... before running dostats. It handles that for you in different ways. Art ------------------------------ Art S. Kagel, President and Principal Consultant ASK Database Management Corp. www.askdbmgt.com ------------------------------
OH, and there is no reason to drop distributions either. If you disable auto stat mode then dostats will update all tables for all pertinent columns. If you have auto stats enabled, just add the --force option to dostats to override the auto mode. I usually set up my clients to leave auto stats enabled but run dostats without --force daily during the week and with --force over the weekend. That will minimize runtime during the week while generating fresh stats for highly active tables once or twice during the week when needed, but force fresh stats weekly for every table. Art ------------------------------ Art S. Kagel, President and Principal Consultant ASK Database Management Corp. www.askdbmgt.com ------------------------------
Thanks Art. Another question, Is TCP connection preferred to other type of connection (e.g, shm, ssl, ....) for running dostats ? Thanks Frank
Yes. Many dostats rune used two connections egging you cannot do over a shared memory connection. There is an option to use a shared memory connection but then you can only process one database per run. Art ------------------------------ Art S. Kagel, President and Principal Consultant ASK Database Management Corp. www.askdbmgt.com ------------------------------