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Informix Error -454

-454 'loc_read()' failed.

The loc_read() function provided in the locator structure for a BYTE or TEXT value in this statement was called and returned a negative return code. When the value is located using user-supplied functions (loc_loctype contains LOCUSER), this function is part of the program and you have to diagnose its problems yourself. When the value is located in a file (loc_loctype contains LOCFILE or, in a 4GL program, the variable has been located in a file), this error indicates that the system-supplied loc_read() function was not able to read from the file.

Oninit® Troubleshooting Guidance

Reasons / Common Causes

-454 is the read-side counterpart of -452/-453 in the same loc_*()-function family: loc_read(), invoked as part of a BYTE/TEXT locator operation, returned a negative code.

  1. When using a user-supplied locator function, the failure is entirely application-defined — diagnosing it is the application developer's own responsibility.
  2. When using the system-supplied function accessing a file, the read from that file failed — potentially from a disk-level I/O error, the file being truncated/modified externally mid- operation, or similar OS-level conditions.
Solutions / Resolution
  1. For a user-supplied locator function, add diagnostic logging inside it to determine why loc_read() is returning a negative code.
  2. For a file-based locator, check for disk-level I/O errors around the time of the failure.
  3. Check whether the file was modified or truncated externally while the read operation was in progress.
Examples
Checking for external file modification during a read
-- Confirm the file backing a file-based locator wasn't being
-- written to, truncated, or removed by another process while
-- this read operation was in progress.
Diagnostic Checks
  1. Determine whether a user-supplied or system-supplied (file-based) loc_read() is in use.
  2. For a user-supplied function, add logging inside it to find the actual failure reason.
  3. For a file-based locator, check for disk I/O errors or external file modification.
Related Errors / Related Topics
  • -452 — "'loc_open()' failed." The open-side counterpart in the same locator-function- failure family.
  • -453 — "'loc_close()' failed." The close-side counterpart in the same family.

Same diagnostic split as -452/-453 — determine whether a user-supplied or system-supplied loc_read() is involved before troubleshooting further.