[Pgpool-general] Error in pgpool

[Tatsuo Ishii]

> All
> 
> We are facing problem with pgpool where the java application fails in
> certain situation I/o problem.
> 
> When we see these problem we see in the db logs error statement like:
> 
> "ERROR:  prepared statement "S_3" does not exist".
> "LOG:  unexpected EOF on client connection"
> 
> We get the following log output in the pgpool log files:
> 
> 2009-03-17 12:24:56 DEBUG: pid 27834: detect_error: kind: C
> 2009-03-17 12:24:56 DEBUG: pid 27834: do_command: kind: C
> 2009-03-17 12:24:56 DEBUG: pid 27834: do_command: kind: Z
> 2009-03-17 12:24:56 DEBUG: pid 27834: pool_read_message_length: slot:
> 0 length: 5
> 2009-03-17 12:24:56 DEBUG: pid 27834: pool_read_message_length: slot:
> 1 length: 5
> 2009-03-17 12:24:56 DEBUG: pid 27834: ReadyForQuery: message length: 5
> 2009-03-17 12:24:56 DEBUG: pid 27834: ReadyForQuery: transaction state: I
> 2009-03-17 12:24:56 DEBUG: pid 27834: statement2: DEALLOCATE "S_3"
> 2009-03-17 12:24:56 DEBUG: pid 27834: SimpleQuery: set
> master_slave_dml query: DEALLOCATE "S_3"
> 2009-03-17 12:24:56 DEBUG: pid 27834: do_command: Query: BEGIN
> 2009-03-17 12:24:56 DEBUG: pid 27834: detect_error: kind: C
> 2009-03-17 12:24:56 DEBUG: pid 27834: do_command: kind: C
> 2009-03-17 12:24:56 DEBUG: pid 27834: do_command: kind: Z
> 2009-03-17 12:24:56 DEBUG: pid 27834: do_command: transaction state: T
> 2009-03-17 12:24:56 DEBUG: pid 27834: do_command: Query: BEGIN
> 2009-03-17 12:24:56 DEBUG: pid 27834: detect_error: kind: C
> 2009-03-17 12:24:56 DEBUG: pid 27834: do_command: kind: C
> 2009-03-17 12:24:56 DEBUG: pid 27834: do_command: kind: Z
> 2009-03-17 12:24:56 DEBUG: pid 27834: do_command: transaction state: T
> 2009-03-17 12:24:56 DEBUG: pid 27834: waiting for backend 0 completing the query
> 2009-03-17 12:24:56 DEBUG: pid 27834: detect_error: kind: C
> 2009-03-17 12:24:56 DEBUG: pid 27834: detect_error: kind: C
> 2009-03-17 12:24:56 DEBUG: pid 27834: detect_error: kind: C
> 2009-03-17 12:24:56 DEBUG: pid 27834: waiting for backend 1 completing the query
> 2009-03-17 12:24:56 DEBUG: pid 27834: read_kind_from_backend: read
> kind from 0 th backend C NUM_BACKENDS: 2
> 2009-03-17 12:24:56 DEBUG: pid 27834: read_kind_from_backend: read
> kind from 1 th backend E NUM_BACKENDS: 2
> 2009-03-17 12:24:56 ERROR: pid 27834: read_kind_from_backend: 1 th
> kind E does not match with master or majority connection k
> ind C
> 2009-03-17 12:24:56 ERROR: pid 27834: kind mismatch among backends.
> Possible last query was: "DEALLOCATE "S_3"" kind details
> are: 0[C] 1[E]
> 2009-03-17 12:24:58 DEBUG: pid 27834: I am 27834 accept fd 5
> 2009-03-17 12:24:58 DEBUG: pid 27834: Protocol Major: 3 Minor: 0
> database: rpt_production user: chakra
> 2009-03-17 12:24:58 DEBUG: pid 27834: new_connection: connecting 0 backend
> 2009-03-17 12:24:58 DEBUG: pid 27834: new_connection: connecting 1 backend
> 2009-03-17 12:24:58 DEBUG: pid 27834: pool_read_message_length: slot:
> 0 length: 8
> 2009-03-17 12:24:58 DEBUG: pid 27834: pool_read_message_length: slot:
> 1 length: 8
> 2009-03-17 12:24:58 DEBUG: pid 27834: pool_read_message_length2:
> master slot: 0 length: 28
> 2009-03-17 12:24:58 DEBUG: pid 27834: pool_read_message_length2:
> master slot: 1 length: 28
> 2009-03-17 12:24:58 DEBUG: pid 27834: 0 th backend: name:
> client_encoding value: UNICODE
> 2009-03-17 12:24:58 DEBUG: pid 27834: 1 th backend: name:
> client_encoding value: UNICODE
> 
> Why does pgpool try to DEALLOCATE a prepare statement on both the
> database servers, when pgpool is set in Matser/slave mode. Can any
> body high light how this issue can be solved. Will really appreciate
> your inputs in this.

Even if you are in master/slave mode, you need to send prepare to both
nodes for BEGIN statement. That's the reason why DEALLOCATE has been
sent to both nodes.

BTW, can you send us PostgreSQL log with statement logging enabled? It
will help to investigate why you are seeing error regarding S_3.
--
Tatsuo Ishii
SRA OSS, Inc. Japan