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PostgresqlDBA interview questions and answers

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Questions :I have three  tables which contains around 20millions of records. I am planning to update these three tables for all records. Could you suggest me best approaches to meet this, please?
Ans:
1.I think disable index before update ? And autovacuum off,arhvive off if possible.
2.Increase the check point time out
Increase shared buffer or wall beffer if archive enable.
3.Check any parallel option is there.

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