docs(notes): add 2025-03-24-db2-lock-monitor-en.md

Author: lzwjava

notes/2025-03-24-db2-lock-monitor-en.md

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+---
+title: Monitoring Lock Activity in Db2
+lang: en
+layout: post
+audio: false
+translated: false
+generated: true
+---
+
+I'll expand on how to monitor lock activity in Db2 using various tools and commands.
+
+### Using db2pd Command
+
+The `db2pd` command is a non-intrusive diagnostic tool that provides real-time information:
+
+```
+db2pd -locks detailed
+```
+
+This provides detailed lock information including:
+- Lock holder details (application handle, authorization ID)
+- Lock wait details
+- Lock object type (table, row, etc.)
+- Lock state (share, exclusive, etc.)
+- Lock duration
+
+For more specific lock information:
+```
+db2pd -transactions
+db2pd -applications
+db2pd -locks show detail
+```
+
+### Using Administrative Views and Table Functions
+
+#### SYSIBMADM.SNAPLOCK View
+```sql
+SELECT 
+    AGENT_ID, 
+    TABSCHEMA, 
+    TABNAME, 
+    LOCK_OBJECT_TYPE, 
+    LOCK_MODE, 
+    LOCK_STATUS, 
+    LOCK_ESCALATION 
+FROM SYSIBMADM.SNAPLOCK
+WHERE TABNAME = 'YOUR_TABLE_NAME'
+```
+
+#### MON_LOCKWAITS Table Function
+```sql
+SELECT 
+    APPLICATION_HANDLE, 
+    APPLICATION_NAME, 
+    LOCK_OBJECT_TYPE, 
+    LOCK_MODE, 
+    LOCK_WAIT_START_TIME, 
+    LOCK_WAIT_ELAPSED_TIME 
+FROM TABLE(MON_LOCKWAITS(-2)) AS LOCKWAITS
+```
+
+#### MON_GET_LOCKS Table Function
+```sql
+SELECT 
+    APPLICATION_HANDLE, 
+    LOCK_OBJECT_TYPE, 
+    LOCK_NAME, 
+    LOCK_MODE, 
+    LOCK_STATUS 
+FROM TABLE(MON_GET_LOCKS(NULL, -2)) AS T
+```
+
+### Using ADMIN_GET_TAB_INFO Table Function
+To see which applications are holding locks on specific tables:
+
+```sql
+SELECT 
+    TABSCHEMA, 
+    TABNAME, 
+    LOCK_COUNT, 
+    LOCK_WAIT_COUNT, 
+    LOCK_WAIT_TIME, 
+    LOCK_ESCAL_COUNT 
+FROM TABLE(ADMIN_GET_TAB_INFO('', '', -2)) AS T
+```
+
+### Identify Locking Applications
+
+```sql
+SELECT 
+    APPL_ID, 
+    AGENT_ID, 
+    APPL_NAME, 
+    AUTHID, 
+    LOCK_WAIT_TIME, 
+    LOCKS_WAITING 
+FROM TABLE(MON_GET_CONNECTION(NULL, -2)) AS CONN
+WHERE LOCKS_WAITING > 0
+```
+
+### Solving Lock Contention
+
+After identifying the lock issues:
+
+1. **Force applications if necessary**:
+   ```
+   db2 force application (application-handle)
+   ```
+
+2. **Adjust isolation levels** for problematic transactions:
+   ```sql
+   SET CURRENT ISOLATION = CS; -- Cursor Stability
+   ```
+
+3. **Modify application behavior**:
+   - Reduce transaction duration
+   - Use row-level locking instead of table-level
+   - Add WITH UR to read-only queries
+
+4. **Configure lock timeouts**:
+   ```sql
+   UPDATE DB CFG FOR database_name USING LOCKTIMEOUT 30
+   ```
+
+These monitoring techniques help identify lock contention issues in your Db2 database so you can resolve them effectively.