Value too large for column "CAMUNDA_PROD"."ACT_HI_VARINST"."TEXT_"

Camunda 7 Topics
2

@rlehnert You’re encountering the “Value too large for column” error because Camunda 7.9.0 tries to store a variable’s value (typically a String or serialized object) in the ACT_HI_VARINST.TEXT_ column, which is limited to 2000 characters (bytes) in Oracle due to NVARCHAR2(2000).

:mag: Root Cause:

In Camunda 7.9.0:

  • If a variable value is short (<= 2000 characters), it is stored in the TEXT_ column.
  • If it exceeds the size, it should be stored in the BYTEARRAY_ column via the ACT_GE_BYTEARRAY table.
  • However, Camunda only does this if the variable is declared as a serializable Java object or a byte array, not for long strings.

Recommended Solutions

Option 1: Upgrade Camunda Version

Camunda 7.15+ has much better handling of long string variables. It automatically stores long strings in the ACT_GE_BYTEARRAY table.

  • Advantage: No DB schema changes required.

  • How:

    • Upgrade to at least Camunda 7.15 (7.19 is better).
    • Re-test process definitions that store large string variables.
    • Optionally, enable the StringValueSerializer fallback mechanism (available in newer versions).

Option 2: Store Large Variables as Serialized Objects

If you cannot upgrade, you can explicitly store long values in a way Camunda uses the BYTEARRAY_ mechanism:

runtimeService.setVariable(processInstanceId,
    "longStringVar",
    Variables.serializedObjectValue(largeString)
        .serializationDataFormat(SerializationDataFormats.JAVA)
        .create());
  • Pros: Bypasses the TEXT_ column entirely.
  • Cons: Stored as a serialized object, not plain text.

Option 3: Manual Workaround Using CLOB (Not Recommended)

You can alter the table to change the column TEXT_ from NVARCHAR2(2000) to CLOB, but Camunda does not officially support this, and it may break assumptions in:

  • Query performance
  • Compatibility with Camunda APIs
  • Variable deserialization

If you still want to go ahead:

ALTER TABLE CAMUNDA_PROD.ACT_HI_VARINST MODIFY TEXT_ CLOB;

:warning: Side Effects:

  • CLOB access requires different handling in Java JDBC (stream-based).
  • It may break Camunda internal SQL queries that expect TEXT_ to be NVARCHAR2.
  • Indexes on this column (if any) will be invalidated.

Best Practice (Short-Term Fix)

If upgrade isn’t possible yet:

  • Avoid setting long strings as process variables directly.

  • Instead:

    • Store large data in external storage (e.g., DB or S3).
    • Pass a reference (ID or URL) as a short string variable.