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Welcome to Tibero GTS!

Intermittent Disconnection of DB Link

Document Type | Troubleshooting

Category | Administration

Applicable Product Versions | 5SP1FS06, 6FS01, 6FS02, 6FS03, 6FS04, 6FS05, 6FS06, 6FS07

Error Codes | 2131, 12130

Document Number | TADTS025

 

Issue

  • This explains the symptom where an existing DB Link disconnects intermittently.
  • There are cases where connection to the remote DB is possible via tbsql, but not via DB Link.
Note [Applicable Environment]
  • Tibero6 FS07 (Linux)
  • MSSQL 2016 (Windows)
-- Connection to MSSQL possible via tbsql
[tibero@localhost ~]$tbsql tibero/tibero@msgate
tbSQL 6
TmaxData Corporation Copyright (c) 2008-. All rights reserved.
Connected to SQL SERVER GATEWAY using msgate.

SQL> select * from test;
C1
ใ…กใ…กใ…กใ…กใ…กใ…กใ…กใ…ก
Alice


1 row selected.


-- Connection not possible via DB Link
[tibero@localhost ~]$tbsql tibero/tmax
tbSQL 6
TmaxData Corporation Copyright (c) 2008-. All rights reserved.
Connected to Tibero.


SQL> create database link mslink connnect to tibero identified by 'tibero' using 'msgate';
Database Link 'MSLINK' created.


SQL> select * from tibero_test@mslink;
TBR-12130 : Unable to connect to remote database(RemoteDB_name=MSLINK).
TBR-2131 : Generic I/O error.

 

Cause

  • The issue occurs because the connection time to the remote DB via DB Link exceeds the DBLINK_CONN_TIMEOUT value.
  • In Tibero, when connecting through a DB Link, if the connection is not established within the DBLINK_CONN_TIMEOUT period, it is treated as a timeout.
 
 

Solutions

Check the Gateway log to see if there are intervals exceeding the DBLINK_CONN_TIMEOUT value, then apply the parameter dynamically.
# jgw.log 
-- It takes about 1 minute until connection success is returned

09:07:17.559 146163 [SessThr-12] INFO  com.tmax.tibero.gateway.comm.SQLServerComm  - LOCAL Transaction mode starting...
09:08:13.665 202269 [SessThr-12] TRACE com.tmax.tibero.gateway.comm.SQLServerComm  - connection succeeded. [
# Dynamically apply DBLINK_CONN_TIMEOUT parameter
ex) alter system set DBLINK_CONN_TIMEOUT=100;

To apply the parameter after future DB restarts, it must be added to the tip file. 

  • Linux : $TB_HOME/config/$TB_SID.tip
  • Windows : %TB_HOME%/config/%TB_SID%.tip

Note

Until Tibero6 version, the default value of DBLINK_CONN_TIMEOUT was set to 10 seconds, but from Tibero7 onwards, the default value has been changed to 100 seconds. 

 

 

 

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