Not recovering from interrupted database connection while query is executing

[itssimon]

If the connection to the ClickHouse database is interrupted while a query is executing, asynch is unable to recover from it. Any subsequent queries fail with the following exception:

ProgrammingError: some records have not been fetched. fetch the remaining records before executing the next query

It looks like this is because the is_query_executing attribute on the Connection remains True if the end of stream packet was missed.

I'm not even sure how to work around this. I've had to restart my application to recover from this, which is far from ideal.

[itssimon]

This may also be related to https://github.com/long2ice/asynch/issues/71

[tiejunhu]

still got this issue with latest master version

[boolka]

Got this error too. And think i get the point. When we was release the connection to the pool we need to call reset_state. Then connection will be passed to new consumer clean

[boolka]

@tiejunhu you can use my hint right now.

...
try:
    await cursor.execute(...)
except (SocketTimeoutError, NetworkError, gaierror):
    await conn.close()

You must close connection mannually on some network errors

[tiejunhu]

@tiejunhu you can use my hint right now.

...
try:
    await cursor.execute(...)
except (SocketTimeoutError, NetworkError, gaierror):
    await conn.close()

You must close connection mannually on some network errors

Thank you. I used a similar solution: close the connection before returning it to the pool, then retry the request.

[stankudrow]

@tiejunhu , @itssimon , @boolka , hi. The Pool API changed, could you see if the reconnection is broken and the issue is back?