Informix Error -348

Reasons / Common Causes

-348 is the read-side counterpart of -346: an unexpected error occurs while fetching a row, rather than while updating one. As with -346, the official guidance points to the accompanying ISAM error code as the real diagnostic path, with hardware errors and lock conflicts called out as the two most common underlying causes.

1. A locking conflict — another session holds a lock incompatible with the read being attempted (relevant for certain isolation levels/lock modes).
2. Hardware-level errors — disk I/O failures affecting the dbspace/chunk holding the table's data.
3. A more specific underlying condition identified only by the accompanying ISAM error code.

Solutions / Resolution

1. Check the accompanying ISAM error code first, per the official guidance, for the specific underlying reason.
2. Check for lock contention on the table being read, particularly if using a locking isolation level (SET ISOLATION TO REPEATABLE READ/CURSOR STABILITY and similar) where reads themselves can conflict with other sessions' locks:

   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 for hardware/disk-level errors in the online log and OS logs around the same timestamp.

Examples

Checking for lock contention affecting a read

SELECT l.tabname, l.owner, s.username FROM sysmaster:syslocks l, sysmaster:syssessions s
WHERE l.owner = s.sid AND l.tabname = 'orders';
-- relevant especially under isolation levels where reads can
-- conflict with other sessions' locks

Diagnostic Checks

1. Read the accompanying ISAM error code for the specific underlying reason.
2. Check sysmaster:syslocks for lock contention on the table.
3. Check the online log / OS logs for hardware or I/O errors at the same timestamp.

Related Errors / Related Topics

• -346 — "Could not update a row in the table." The write-side counterpart of this same class of unexpected storage-engine-level failure.
• -347 — "Could not open table for exclusive access." Another table-access failure, at the level of obtaining exclusive access for DDL rather than reading row data.

Check the ISAM error code first — the same underlying causes (locking and hardware) apply here as for the update-side error -346.