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From Vladimir Ozerov <voze...@gridgain.com>
Subject Re: Additional SQL metrics
Date Thu, 02 Mar 2017 08:36:19 GMT
Denis,

Query execution is complex process involving different stages which are not
very easy to match with each other. Especially provided that any node can
leave topology at any time. Another problem is that engine evolves and
metrics like "did a query do broadcast or unicast" may easily become
useless at some point, because for example there will be neither unicast,
nor broadast, but something different. On the other hand I completely agree
that performance monitoring is essential part of any mature DBMS.

I would start with metrics which are both very basic and easy to implement
at the same time. For example we can add fingerprint (hash) to every query
which will be used to join "map" and "reduce" parts with each other and add
the following basic metrics:
1) Execution count for particular query
2) Number of map nodes - min, max, avg
3) Map step duration (if applicable) - min, max, avg
4) Reduce step duration (if applicable) - min, max, avg

Once done users will be able to get statistics for particular queries.

Vladimir.


On Tue, Feb 28, 2017 at 3:12 AM, Denis Magda <dmagda@apache.org> wrote:

> BTW,
>
> What if we expose per-query metrics below as a part of EXPLAIN ANALYZE?
> Sergi, is this feasible?
>
> —
> Denis
>
> > On Feb 27, 2017, at 2:35 PM, Denis Magda <dmagda@apache.org> wrote:
> >
> > Igniters,
> >
> > Let’s shed more light on SQL query execution internals introducing a set
> of useful metrics (https://issues.apache.org/jira/browse/IGNITE-4757).
> >
> > Per-query metrics. Total history size is defined by *CacheConfiguration.
> getQueryDetailMetricsSize*:
> > * if a query was executed in the collocated or non-collocated mode.
> Three results are valid: collocated, non-collocated, simple query (no
> joins).
> > * non-collocated query: size of the data exchanged between the nodes to
> complete a join.
> > * non-collocated query: did a query do broadcast or unicast to get data
> needed to complete a join.
> > * non-collocated and collocated query: a part of the time spent joining
> the data.
> >
> > CacheMetrics:
> > * an average number of executed SQL queries (collocated, non-collocated,
> simple query (no joins)).
> >
> > Please don’t hesitate do share suggest another metrics or improve
> proposed ones.
> >
> > —
> > Denis
>
>

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