EC
1989
MySQLERRORNotableQueryHIGH confidence

Unknown HANDLER statement

Production Risk

Low — statement is rejected; no data is modified.

What this means

A HANDLER ... READ or HANDLER ... CLOSE was issued for a handler name that was not opened with HANDLER ... OPEN, or the handler was already closed.

Why it happens
  1. 1HANDLER READ issued before HANDLER OPEN.
  2. 2Handler name misspelled in HANDLER READ or HANDLER CLOSE.
  3. 3Handler was implicitly closed (e.g. by DDL on the table) before the read.
How to reproduce
trigger — this will error
trigger — this will error
HANDLER nonexistent_handler READ FIRST;

expected output

ERROR 1989 (42000): Unknown HANDLER 'nonexistent_handler'.

Fix

Open the handler before reading

Open the handler before reading
HANDLER my_table OPEN AS h1;
HANDLER h1 READ FIRST;
HANDLER h1 CLOSE;

Why this works

A HANDLER must be explicitly opened and its alias used consistently.

What not to do

✕

Sources
Official documentation ↗

MySQL 8.0 — 1989 ER_UNKNOWN_STMT_HANDLER

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