Query duration metrics

[Andrey Kornev <an...@hotmail.com>]

Hi,

It appears as if the query duration metric is a bit misleading.

GridQueryProcessor.executeQuery() doesn't actually "run" the query. It simply delegates query execution to a closure passed in as a parameter. The closure may or may not actually execute the query. In some (all?) cases, the closure simply creates and returns an Iterable (how does IgniteH2Indexing.runQueryTwoStep, for example). Actual query execution happens at some point later when user instantiates an Iterator from the Iterable. What's in fact recorded (by GridQueryProcessor on line 2477) as the "query duration" is just the query parsing stage as well as some query's AST manipulation logic that tries to convert the regular regular query to a map/reduce style query. So, it's basically a "prepare statement duration" that is currently reported as "query duration".

Am I missing something?

Thanks
Andrey

Re: Query duration metrics

[Vladimir Ozerov <vo...@gridgain.com>]

Hi Andrey,

You are right, current implementation of metrics is questionable. Please
feel free to file a ticket if you have ideas on how to improve it.

On Sun, Nov 5, 2017 at 11:17 PM, Andrey Kornev <an...@hotmail.com>
wrote:

> Hi,
>
> It appears as if the query duration metric is a bit misleading.
>
> GridQueryProcessor.executeQuery() doesn't actually "run" the query. It
> simply delegates query execution to a closure passed in as a parameter. The
> closure may or may not actually execute the query. In some (all?) cases,
> the closure simply creates and returns an Iterable (how does
> IgniteH2Indexing.runQueryTwoStep, for example). Actual query execution
> happens at some point later when user instantiates an Iterator from the
> Iterable. What's in fact recorded (by GridQueryProcessor on line 2477) as
> the "query duration" is just the query parsing stage as well as some
> query's AST manipulation logic that tries to convert the regular regular
> query to a map/reduce style query. So, it's basically a "prepare statement
> duration" that is currently reported as "query duration".
>
> Am I missing something?
>
> Thanks
> Andrey
>

Re: Misleading query duration metrics

[Valentin Kulichenko <va...@gmail.com>]

Andrey,

I think you're right. This logic was once refactored so that actual
execution happens only when cursor iteration starts, and I guess metrics
were not fixed accordingly. Can you file a ticket?

-Val

On Wed, Nov 8, 2017 at 9:27 AM, Andrey Kornev <an...@hotmail.com>
wrote:

> (Changed the subject to maybe make people actually read the posting.)
>
> Anyway, if somebody (who knows that code) could take a quick look to see
> if the duration is indeed computed correctly (or not), that would be
> greatly appreciated!
>
> Thanks
> Andrey
>
> ________________________________________
> From: Andrey Kornev <an...@hotmail.com>
> Sent: Sunday, November 5, 2017 12:17 PM
> To: dev@ignite.apache.org
> Subject: Query duration metrics
>
> Hi,
>
> It appears as if the query duration metric is a bit misleading.
>
> GridQueryProcessor.executeQuery() doesn't actually "run" the query. It
> simply delegates query execution to a closure passed in as a parameter. The
> closure may or may not actually execute the query. In some (all?) cases,
> the closure simply creates and returns an Iterable (how does
> IgniteH2Indexing.runQueryTwoStep, for example). Actual query execution
> happens at some point later when user instantiates an Iterator from the
> Iterable. What's in fact recorded (by GridQueryProcessor on line 2477) as
> the "query duration" is just the query parsing stage as well as some
> query's AST manipulation logic that tries to convert the regular regular
> query to a map/reduce style query. So, it's basically a "prepare statement
> duration" that is currently reported as "query duration".
>
> Am I missing something?
>
> Thanks
> Andrey
>

Misleading query duration metrics

[Andrey Kornev <an...@hotmail.com>]

(Changed the subject to maybe make people actually read the posting.)

Anyway, if somebody (who knows that code) could take a quick look to see if the duration is indeed computed correctly (or not), that would be greatly appreciated!

Thanks
Andrey

________________________________________
From: Andrey Kornev <an...@hotmail.com>
Sent: Sunday, November 5, 2017 12:17 PM
To: dev@ignite.apache.org
Subject: Query duration metrics

Hi,

It appears as if the query duration metric is a bit misleading.

GridQueryProcessor.executeQuery() doesn't actually "run" the query. It simply delegates query execution to a closure passed in as a parameter. The closure may or may not actually execute the query. In some (all?) cases, the closure simply creates and returns an Iterable (how does IgniteH2Indexing.runQueryTwoStep, for example). Actual query execution happens at some point later when user instantiates an Iterator from the Iterable. What's in fact recorded (by GridQueryProcessor on line 2477) as the "query duration" is just the query parsing stage as well as some query's AST manipulation logic that tries to convert the regular regular query to a map/reduce style query. So, it's basically a "prepare statement duration" that is currently reported as "query duration".

Am I missing something?

Thanks
Andrey