View Issue Details
| ID | Project | Category | View Status | Date Submitted | Last Update |
|---|---|---|---|---|---|
| 0000314 | Pgpool-II | Bug | public | 2017-06-06 20:29 | 2017-06-07 14:22 |
| Reporter | nagata | Assigned To | t-ishii | ||
| Priority | normal | Severity | major | Reproducibility | have not tried |
| Status | resolved | Resolution | open | ||
| Product Version | 3.5.8 | ||||
| Target Version | 3.5.9 | ||||
| Summary | 0000314: kind mismatch error with extended protocol when close for portal is issued | ||||
| Description | With streaming-replication mode and extended protocol, kind mismatch error occurs if Close (portal) messages is sent before Bind. FATAL: failed to read kind from backend DETAIL: kind mismatch among backends. Possible last query was: "SELECT * FROM test_tbl" kind details are: 0[E: prepared statement "S_1" does not exist] 1[2]] For details, see Steps To Reproduce. Such Close messages before query execution can be issued by JDBC. For details, see comments about processDeadParsedQueries and processDeadPortals. https://github.com/pgjdbc/pgjdbc/blob/master/pgjdbc/src/main/java/org/postgresql/core/v3/QueryExecutorImpl.java [Analysis] When Close is issued from frontend, Pgpool-II send this message to both the primary and the standby by rewriting query_context->where_to_send[]. Due to this, Bind message following is also sent to both backends, but Parse was sent only one backend, so the error occurs. LOG: DB node id: 1 backend pid: 32586 statement: Parse: SELECT * FROM test_tbl LOG: DB node id: 1 backend pid: 32586 statement: B message LOG: DB node id: 1 backend pid: 32586 statement: Execute: SELECT * FROM test_tbl LOG: DB node id: 1 backend pid: 32586 statement: C message LOG: DB node id: 0 backend pid: 32585 statement: C message LOG: DB node id: 1 backend pid: 32586 statement: B message LOG: DB node id: 0 backend pid: 32585 statement: B message LOG: DB node id: 1 backend pid: 32586 statement: Execute: SELECT * FROM test_tbl LOG: DB node id: 0 backend pid: 32585 statement: Execute: SELECT * FROM test_tbl WARNING: packet kind of backend 0 ['E'] does not match with master/majority nodes packet kind ['2'] FATAL: failed to read kind from backend DETAIL: kind mismatch among backends. Possible last query was: "SELECT * FROM test_tbl" kind details are : 0[E: prepared statement "S_1" does not exist] 1[2] HINT: check data consistency among db nodes [Patch] The attached is a simple patch to fix it. In this fix, Close message is sent to only the load blance node when this is Close for portals. Instead when this is Close for statements, this is sent to both nodes as same as before. | ||||
| Steps To Reproduce | Use pgproto -------------------------------------------- 'Q' "DROP TABLE IF EXISTS test_tbl" 'Q' "CREATE TABLE test_tbl(i INT)" 'Q' "INSERT INTO test_tbl VALUES(1)" 'Y' 'Y' 'Y' 'P' "S_1" "SELECT * FROM test_tbl" 0 'B' "C_1" "S_1" 0 0 0 'E' "C_1" 0 'S' 'Y' 'C' 'P' "C_1" 'B' "C_2" "S_1" 0 0 0 'E' "C_2" 0 'S' 'Y' 'X' -------------------------------------------- | ||||
| Tags | No tags attached. | ||||
|
|
|
|
|
Yes, the bind message complains that the prepared statement S_1 is missing on node 0. However I think the proposed fix is not quite correct. Suppose parse_before_bind() was executed before and client wants to explicitly close the portal to reuse the same named portal, your patch leaves the portal on the primary node and will cause the error "the portal is already used". Proper fix would be: if Pgpool-II rewrite the where_to_send map data, it should be restored later on. I will work on in the direction. BTW, 'Q' "DROP TABLE IF EXISTS test_tbl" 'Q' "CREATE TABLE test_tbl(i INT)" 'Q' "INSERT INTO test_tbl VALUES(1)" 'Y' 'Y' 'Y' are not quite correct from the frontend/backend protocol's view. Client should send next query upon receiving read query for message. The should be: 'Q' "DROP TABLE IF EXISTS test_tbl" 'Y' 'Q' "CREATE TABLE test_tbl(i INT)" 'Y' 'Q' "INSERT INTO test_tbl VALUES(1)" 'Y' |
|
|
Fix committed. |
| Date Modified | Username | Field | Change |
|---|---|---|---|
| 2017-06-06 20:29 | nagata | New Issue | |
| 2017-06-06 20:29 | nagata | File Added: fix_kind_mismatch.patch | |
| 2017-06-06 21:12 | nagata | Steps to Reproduce Updated | |
| 2017-06-06 21:17 | nagata | Description Updated | |
| 2017-06-07 11:30 | t-ishii | Assigned To | => t-ishii |
| 2017-06-07 11:30 | t-ishii | Status | new => assigned |
| 2017-06-07 11:46 | t-ishii | Note Added: 0001533 | |
| 2017-06-07 11:54 | t-ishii | Target Version | => 3.5.9 |
| 2017-06-07 14:21 | t-ishii | Note Added: 0001534 | |
| 2017-06-07 14:22 | t-ishii | Status | assigned => resolved |
