I'm a big fan of this idea. There was a brief discussion on the topic over
on PHOENIX-2715.

My first concern is that the collected information is huge -- easily far
larger than the user data for a busy cluster. For instance, a couple 10's
of GB stored user data, guideposts set to default 100mb, enable salting on
a table with an "innocent" value of 10 or 20 and the collection of RPCs can
easily grow into the hundreds for simple queries. Even if you catalog just
the "logical" RPC's - HBase Client API calls that Phoenix plans rather than
the underlying HBase Client RPCs - this will be quite large. The guidepost
themselves for such a table would be on the order of 30mb.

My next concern is about the sensitive query parameters being stored. It's
entirely reasonable to expect a table to store sensitive information that
should not be exposed to operations.

Thus, my suggestions:
* minimize the unbounded nature of this table by truncating all columns to
some max length -- perhaps 5k or 10k.
* enable a default TTL on the schema. 7 days seems like a good starting
point.
* consider controlling which columns are populated via some operational
mechanism. Use Logger level as an example, with INFO the default setting.
Which data is stored at this level? Then at DEBUG, then TRACE. Maybe
timestamp, SQL, and explain are at INFO. DEBUG adds bound parameters and
scan metrics. TRACE adds RPCs and timing, snapshot metadata.

Thanks,
Nick

On Mon, Feb 26, 2018 at 1:57 PM, Josh Elser <els...@apache.org> wrote:

> Hiya,
>
> I wanted to share this little design doc with you about some feature work
> we've been thinking about. The following is a Google doc in which anyone
> should be allowed to comment. Feel free to comment there, or here on the
> thread.
>
> https://s.apache.org/phoenix-query-log
>
> The high-level goal is to create a construct in which Phoenix clients will
> automatically serialize information about the queries they run to a table
> for retrospective analysis. Ideally, this information would be stored in a
> Phoenix table. We want this data to help answer questions like:
>
> * What queries are running against my system
> * What specific queries started between 535AM and 620AM two days ago
> * What queries are user "bob" running
> * Are my user's queries effectively using the indexes in the system
>
> Anti-goals for include:
>
> * Cluster impact (computation/memory) usage of a query
> * Query performance may be slowed to ensure all data is serialized
> * A third-party service dedicated to ensuring query info is serialized (in
> the event of client failure)
>
> Take a look at the document and let us know what you think please. I'm
> happy to try to explain this in greater detail.
>
> - Josh (on behalf of myself, Ankit, Rajeshbabu, and Sergey)
>

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