What is the status of DB_PROPERTY CurrRead and CurrWrite?

This question is prompted by the new server properties introduced in Version 17...

CurrRead The current number of file reads that were issued by the database server, but that have not completed yet.

CurrWrite The current number of file writes that were issued by the database server, but that have not completed yet.

The addition of those properties implies that the database properties of the same name may in fact be reliable; is that true?

The question is important because historically the CurrIO database property has been so wildly inaccurate as to be completely useless.

Tue, Nov 8, 2011 at 10:00 AM... You are correct. Dan had already identified this as an issue with his Fuji testing: Yes, I recently found out that the CurrIO stat is completely bogus; it sits in a layer of the code that has many callpaths and not all are properly accounted for.

So... can we now trust the database properties CurrRead and CurrWrite in SQL Anywhere 17?

How about Version 16, and earlier releases?

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asked 21 Nov '15, 16:23

Breck Carter
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edited 21 Nov '15, 16:24

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There was a change to address the inaccuracies of these I/O counters. This fix made it into the 17 release but not to branches before that.

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answered 23 Nov '15, 13:54

Nick Elson S...
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accept rate: 32%

Hooray!

Now I can un-comment the code in Foxhound, at least for V17 target databases, to display CurrIO etcetera... incomplete I/O can be a bad sign for performance.

(25 Nov '15, 15:26) Breck Carter

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question asked: 21 Nov '15, 16:23

question was seen: 1,128 times

last updated: 25 Nov '15, 15:26

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What is the status of DB_PROPERTY CurrRead and CurrWrite?

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