How Do You Associate a Query With its Invoking Procedure?

Previous Topic Next Topic
 
classic Classic list List threaded Threaded
7 messages Options
Reply | Threaded
Open this post in threaded view
|

How Do You Associate a Query With its Invoking Procedure?

Fd Habash

In API function may invoke 10 queries. Ideally, I would like to know what queries are invoked by it and how long each took.

 

I’m using pg_stat_statement. I can see the API function statement, but how do I deterministically identify all queries invoked by it?

 

 

----------------
Thank you

 

Reply | Threaded
Open this post in threaded view
|

Re: How Do You Associate a Query With its Invoking Procedure?

Fd Habash
Any ideas, please? 

On Thu, Sep 13, 2018, 3:49 PM Fd Habash <[hidden email]> wrote:

In API function may invoke 10 queries. Ideally, I would like to know what queries are invoked by it and how long each took.

 

I’m using pg_stat_statement. I can see the API function statement, but how do I deterministically identify all queries invoked by it?

 

 

----------------
Thank you

 

Reply | Threaded
Open this post in threaded view
|

Re: How Do You Associate a Query With its Invoking Procedure?

David G Johnston
In reply to this post by Fd Habash
On Thu, Sep 13, 2018 at 12:49 PM, Fd Habash <[hidden email]> wrote:

In API function may invoke 10 queries. Ideally, I would like to know what queries are invoked by it and how long each took.

 

I’m using pg_stat_statement. I can see the API function statement, but how do I deterministically identify all queries invoked by it?


pg_stat_statement is a global tracker that throws away execution context, in this case the process id, needed to track the level of detail you desire.  I think the best you can do is log all statements and durations to the log file and parse that.

For the "what queries are invoked by it" you can just read the source code...

As there is no canned solution to provide the answer you seek the final solution you come up with will be influenced by your access patterns, specific needs, and (in)ability to write C code (though maybe there is an extension out there you could leverage...).

David J.

Reply | Threaded
Open this post in threaded view
|

Re: How Do You Associate a Query With its Invoking Procedure?

Rick Otten-2
On Fri, Sep 14, 2018 at 12:34 PM David G. Johnston <[hidden email]> wrote:
On Thu, Sep 13, 2018 at 12:49 PM, Fd Habash <[hidden email]> wrote:

In API function may invoke 10 queries. Ideally, I would like to know what queries are invoked by it and how long each took.

 

I’m using pg_stat_statement. I can see the API function statement, but how do I deterministically identify all queries invoked by it?


pg_stat_statement is a global tracker that throws away execution context, in this case the process id, needed to track the level of detail you desire.  I think the best you can do is log all statements and durations to the log file and parse that.


If you have big queries you almost certainly will want to bump your "track_activity_query_size" value bigger to be able to capture the whole query.

You are going to have to find the queries in the api source code.  If they are not distinct enough to easily figure out which was which you can do things to make them distinct.  One of the easiest things is to add a "literal" column to the query:

select
  'query_1',
   first_name,
...

Then when you look in the query statements in the database you can see that literal column and tell which query it was that invoked it.

You can also make them unique by renaming columns:

select
  first_name as 'query1_first_name'
...

Depending on your ORM or whether your api calls queries directly, you could add comments to the query as well:
select
  -- this one is query 1
  first_name,
...

Unfortunately there is no out of the box "github hook" that can automatically connect a query from your postgresql logs to the lines of code in your api.

Reply | Threaded
Open this post in threaded view
|

Re: How Do You Associate a Query With its Invoking Procedure?

Roman Konoval
In reply to this post by Fd Habash
If you can change the application then one option is to set application_name so that it contains API function name. This should happen before the first call in API function hits the database. After the API function finishes it should reset application_name.

Then you can enable logging of all queries and set the format to include application_name parameter. This way every query is logged and each log entry has an application name.

Several things to keep in mind:
1. logging everything may affect performance
2. application_name is 64 chars by default

Regards,
Roman Konoval


On Sep 13, 2018, at 21:49, Fd Habash <[hidden email]> wrote:

In API function may invoke 10 queries. Ideally, I would like to know what queries are invoked by it and how long each took. 
 
I’m using pg_stat_statement. I can see the API function statement, but how do I deterministically identify all queries invoked by it?
 
 
----------------
Thank you

Reply | Threaded
Open this post in threaded view
|

Re: How Do You Associate a Query With its Invoking Procedure?

Patrick Molgaard
In reply to this post by Fd Habash
You might find application-level tracing a more practical answer - e.g. check out Datadog APM for a (commercial) plug and play approach or Jaeger for a self-hostable option.

Patrick
On Fri, Sep 14, 2018 at 4:38 PM Fred Habash <[hidden email]> wrote:
Any ideas, please? 

On Thu, Sep 13, 2018, 3:49 PM Fd Habash <[hidden email]> wrote:

In API function may invoke 10 queries. Ideally, I would like to know what queries are invoked by it and how long each took.

 

I’m using pg_stat_statement. I can see the API function statement, but how do I deterministically identify all queries invoked by it?

 

 

----------------
Thank you

 

Reply | Threaded
Open this post in threaded view
|

Re: How Do You Associate a Query With its Invoking Procedure?

Fd Habash
All great ideas.

I was thinking something similar to some other RDBMS engines where SQL is automatically tied to the invoking PROGRAM_ID  with zero setup on the client side. I thought there could be something similar in PG somewhere in the catalog. 

As always, great support. This level of support helps a lot in our migration to Postgres. 

————-
Thank you. 

On Sep 15, 2018, at 5:24 AM, Patrick Molgaard <[hidden email]> wrote:

You might find application-level tracing a more practical answer - e.g. check out Datadog APM for a (commercial) plug and play approach or Jaeger for a self-hostable option.

Patrick
On Fri, Sep 14, 2018 at 4:38 PM Fred Habash <[hidden email]> wrote:
Any ideas, please? 

On Thu, Sep 13, 2018, 3:49 PM Fd Habash <[hidden email]> wrote:

In API function may invoke 10 queries. Ideally, I would like to know what queries are invoked by it and how long each took.

 

I’m using pg_stat_statement. I can see the API function statement, but how do I deterministically identify all queries invoked by it?

 

 

----------------
Thank you