Informix Error -347

Reasons / Common Causes

-347 fires when an explicit LOCK TABLE (or the implicit exclusive lock required by structural statements like ALTER TABLE, RENAME, or CREATE INDEX) can't be obtained.

1. Lock conflicts — another session already holds a lock on the table incompatible with exclusive access.
2. The server's lock table is full — a system-wide configuration limit (LOCKS in the onconfig file) has been reached, and no new locks can be granted regardless of the specific table.
3. Low-level operating-system lock mechanism issues — a rarer, infrastructure-level failure below the database server itself.

Solutions / Resolution

1. Check the accompanying ISAM error code first, per the official guidance, for the specific underlying reason.
2. Check for other sessions holding locks on the table:

   SELECT l.tabname, l.owner, s.username FROM sysmaster:syslocks l, sysmaster:syssessions s
   WHERE l.owner = s.sid AND l.tabname = 'orders';
   

3. Check the server's current lock usage against its configured LOCKS limit:

   onstat -
   

   (the basic status summary, which includes a Locks row showing used vs. configured). If the lock table is full, either wait for other activity to release locks or consider increasing the LOCKS configuration parameter (a DBA/configuration change, not a query fix).
4. Schedule structural DDL during a lower-traffic window if lock contention is the recurring cause, since exclusive access competes directly with normal application activity.

Examples

Checking for lock contention before a DDL operation

SELECT l.tabname, l.owner, s.username FROM sysmaster:syslocks l, sysmaster:syssessions s
WHERE l.owner = s.sid AND l.tabname = 'orders';
-- if populated, wait for those sessions to complete or coordinate
-- with them before retrying the DDL

Checking overall lock table utilization

onstat -
-- look at the Locks row for used-vs.-configured numbers

Diagnostic Checks

1. Read the accompanying ISAM error code for the specific underlying reason.
2. Check sysmaster:syslocks for conflicting locks on the target table.
3. Check onstat - for overall lock table utilization against the configured LOCKS limit.

Related Errors / Related Topics

• -314 — "Table table-name currently in use." A closely related concurrent-access failure — both concern obtaining exclusive-enough access to a table for a structural operation.
• -346 — "Could not update a row in the table." Another storage-engine-level failure that can share lock contention as a root cause.

Check both table-specific lock contention and overall lock-table capacity — a full lock table (a server-wide condition) can produce this same error even without any conflict on this specific table.