[CALCITE-6139] Avatica-Go sends the same offset for the FetchRequest

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: avatica-go-5.2.0
• Fix Version/s: avatica-go-5.3.0
• Component/s: avatica-go
• Assignee: Egor Ryashin
• Reporter: Egor Ryashin
• Created: 28/Nov/23 11:17
• Updated: 11/Dec/23 07:50
• Resolved: 29/Nov/23 08:02

Description

This exception happens when Apache Druid Avatica protobuf endpoint is used: "Druid can only fetch forward. Requested offset”.
I tried to debug that and saw that any simple query fails if it triggers fetching of multiple frames. I speculate that when the first ExucuteRequest is sent

msg := &message.ExecuteRequest{
StatementHandle:    s.handle,
ParameterValues:    s.parametersToTypedValues(args),
FirstFrameMaxSize:  s.conn.config.frameMaxSize,
HasParameterValues: true,
}

and the result set is created after

rsets = append(rsets, &resultSet{
columns: columns,
done:    frame.Done,
offset:  frame.Offset,
data:    data,
})

then for the next frame FetchRequest is sent but it uses the same 0 offset (the data for that offset was returned with the ExecuteRequest)

res, err := r.conn.httpClient.post(context.Background(), &message.FetchRequest{

ConnectionId: r.conn.connectionId,
StatementId:  r.statementID,
Offset:       resultSet.offset,
FrameMaxSize: r.conn.config.frameMaxSize,
})

So, in short, I think Avatica-Go sends 2 requests with the same offset that makes Druid to fail.

Issue Links

• links to: PR