I think my question may be not good to ask here. But I don't have any idea where I can ask this question. Can I get some place to ask this? or Can I get protocol specification?
I am making proxy authentication of Impala. And I got some trouble about packet protocol side. So I need to know why happened.
This is explain of detail.
When Impala gave return datas to client it gave some weird 4 bytes randomly. For example When ODBC client was getting datas about string column, Impala gave weird 4 bytes before string length. This packet includes string list.
0x00 0x00 0x00 0x02 0x30 0x30 0x02 0x00 0x00 0x02 <--- what is it? 0x00 0x00 0x00 0x02 0x30 0x30
Currently I've found kind of that 4 bytes a lot. And I am trying to find some rule what happen but it's impossible to know that.
I found reason why it had extra 4 bytes. Because ODBC was using packet size of 4 bytes so that Impala server always separated packet what it wanted to send even if it was one result set.
For example, JDBC dosen't have packet size of front of packet. So if JDBC connected server, Impala would send result packet at once. But if ODBC connected server, Impala would separated result set packet maxium 0x20000.