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From Josh Elser <els...@apache.org>
Subject Re: PSQ processlist
Date Tue, 10 Sep 2019 17:18:22 GMT
As you might already know, JDBC is "stateful" in what it does. You have 
a Connection, which creates Statements, and the combination of those two 
track queries being run.

However, HTTP is a stateless protocol. As such, PQS has to cache things 
in memory in order to make this approach work.

To this point, there are Connection and Statement caches which, once 
they are not used, are evicted from the cache and closed[1]. I know that 
Phoenix is not capable of interrupting/free'ing all resources used by a 
Phoenix query (e.g. you cannot interrupt an HBase RPC once it's 
running), but it's likely that Phoenix would clean up the client-side 
state to the best of its ability when the Statement/Connection are closed.

Maybe someone knows the answer to that off the top of their head. 
Otherwise, hopefully this information is a starting point for you to 
look at the code and/or run some experiments.

[1] https://phoenix.apache.org/server.html "Configurations relating to 
the server connection cache."

On 9/10/19 11:28 AM, Aleksandr Saraseka wrote:
> Thank you Josh, this is very helpful.
> Another question - can we kill long running query in PQS somehow ?
> 
> On Mon, Sep 9, 2019 at 5:09 PM Josh Elser <elserj@apache.org 
> <mailto:elserj@apache.org>> wrote:
> 
>     Not unique to PQS, see:
> 
>     https://issues.apache.org/jira/browse/PHOENIX-2715
> 
>     On 9/9/19 9:02 AM, Aleksandr Saraseka wrote:
>      > Hello.
>      > Does Phoenix Query Server have any possibility to track running
>     queries
>      > ? Like user connects with thin client and run some long running
>     query,
>      > can I understand who and what is running ?
>      >
>      > --
>      >               Aleksandr Saraseka
>      > DBA
>      > 380997600401
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> 
> 
> -- 
> 		Aleksandr Saraseka
> DBA
> 380997600401
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