SPOOL estimation (Explain) and SPOOL value (QRYLOG)

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SPOOL estimation (Explain) and SPOOL value (QRYLOG)

Hi spool watchers,

As an exercise i picked up a user request that runned in 53 minutes with an actual spool of 1,5 TO (query monitor V14.10) and tried to optimize.

After explaining the query and adding recommended statistics on tables i was able to get an explain with spool estimations reduced to 200 GO at most (among 4 spools).

At last i runned the request and got the answerset in 1 minute and 20 seconds, with a spool of 25 GO (Qrylog).

How to match that unique value in the log and the estimated values in explain ?

Thanks for "explaining",

Pierre

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