How to calibrate the IO read speed for the query optimizer?

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If I remember correctly SQL Anywhere provides a method to calibrate the real local IO speed, so that the optimizer is not using anymore the 40x speed assumption for sequential reads compared to random reads of the database files.

Does anyone know more details?

e.g. is the calibration time dependent on the database size?

asked 13 Dec '10, 15:33

Martin's gravatar image

Martin
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accept rate: 14%

edited 14 Dec '10, 08:17

One Answer:
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I guess you are refering to the ALTER DATABASE CALIBRATE statements:

-- Syntax 2 - Performing calibration
ALTER DATABASE {
 CALIBRATE [ SERVER ]
 | CALIBRATE DBSPACE dbspace-name
 | CALIBRATE DBSPACE TEMPORARY
 | CALIBRATE GROUP READ
 | CALIBRATE PARALLEL READ
 | RESTORE DEFAULT CALIBRATION

No, I don't know more details...

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answered 13 Dec '10, 16:12

Volker%20Barth's gravatar image

Volker Barth
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accept rate: 34%

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question asked: 13 Dec '10, 15:33

question was seen: 2,148 times

last updated: 14 Dec '10, 08:17

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