Virtual Graph Connection and Logging

Support
1

Problem ... I am connecting to a flaky Postgres DB. Sometimes the connection is dropped.

I can run the same query in Studio or programmatically where sometimes I get results and sometimes I don't. According to stardog.log and the API return codes, all the queries are successful. But, really, they aren't.

Shouldn't Stardog catch this?

Andrea

2

In addition, I can access the Postgres DB using psql and get a query response.

So, somewhere along the way, Stardog is returning a successful query with no results.

Andrea

3

Lastly, if I close Stardog and Studio and restart everything .... then the virtual graphs seem to work.

But only for a few times before Studio white screens or the results turn back into successful queries with no results.

Andrea

4

I don't understand how a query can return successfully (no error in the log) but also fail as you describe. Sometimes connections go stale while sitting in our connection pool, but that type of failure leads to errors in the log, so I'm not confident that's what's happening here.

Could you add this entry to your server/dbms/log4j2.xml file and restart and share the results, indicating which queries were successful and which failed?

                <Logger name="com.complexible.stardog.virtual" level="DEBUG" additivity="false">
                        <AppenderRef ref="stardogAppender"/>
                </Logger>

Thank you,
-Paul

5

Will do!

BTW, this also happened to a colleague of mine. Exact same behavior using PyCharm -> pystardog -> same Postgres DB. Always indicates successful query.

6

I haven't forgotten to do this, but have been pretty consumed working other problems. It is still on my todo list for this week.

Andrea

7

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