What causes ""Parent relevant column can't be updated " + tableName + "->" + joinKey" in MyCATApache/Mycat-Server?

Exclude the joinKey from the SET clause; re-parent via DELETE from the old parent's child set + INSERT under the new parent

MyCATApache/Mycat-Server · error · SQLNonTransientException

"Parent relevant column can't be updated " + tableName +…

Error message

"Parent relevant column can't be updated " + tableName + "->" + joinKey

What it means

When a table has a parent (child table of an ER-join relationship), the joinKey column linking it to the parent must stay consistent for Mycat's ER routing. confirmShardColumnNotUpdated rejects any UPDATE whose SET clause modifies the joinKey with SQLNonTransientException, because it would break child-row co-location with the parent.

Solutions

Exclude the joinKey from the SET clause; re-parent via DELETE from the old parent's child set + INSERT under the new parent
Update only non-join-key columns in the statement
Restructure ER relations if re-parenting is a frequent business operation

Example fix

-- before
UPDATE order_detail SET order_id = 999 WHERE detail_id = 55;
-- after
INSERT INTO order_detail (detail_id, order_id, ...) VALUES (55, 999, ...);
DELETE FROM order_detail WHERE detail_id = 55; -- remove from old parent's shard

Defensive patterns

Strategy: validation

Validate before calling

if (isChildTable(table) && updateSetColumns.contains(childConfig.getJoinKey())) {
    throw new IllegalArgumentException("joinKey " + childConfig.getJoinKey() + " is not updatable");
}

Try / catch

try { executeUpdate(sql); } catch (SQLNonTransientException e) { if (e.getMessage().startsWith("Parent relevant column can't be updated")) { doDeleteInsertInstead(); } else throw e; }

Prevention

Exclude joinKey columns from entity update statements
Re-parent child rows via delete+insert
Configure join keys on immutable identifier columns
Filter ORM update payloads to mutable business fields only

When it happens

Trigger: An UPDATE on a child table (configured with <childTable parent="..." joinKey="...">) whose SET clause assigns to the joinKey column (e.g. `UPDATE order_detail SET order_id=999 WHERE ...`).

Common situations: Re-parenting child rows to a different parent row; data-fix scripts rewriting foreign-key columns on ER-sharded child tables; ORMs syncing the whole entity including the FK.

Understand the failure class

Background: UnsupportedOperationException and "is not supported" errors: when a library deliberately refuses a call — this error's family across 30 libraries.

Related errors

AI-assisted analysis of MyCATApache/Mycat-Server@65f8d8beb7 (2026-09-11). Data as JSON: /api/errors/b113d75d9fd32762. Report an issue: GitHub.

Appendix: source

Thrown at src/main/java/io/mycat/route/parser/druid/impl/DruidUpdateParser.java:241

                if (column.contains(StringUtil.TABLE_COLUMN_SEPARATOR)) {
                    column = column.substring(column.indexOf(".") + 1).trim().toUpperCase();
                }
                if (partitionColumn != null && partitionColumn.equals(column)) {
                    boolean canUpdate;
                    canUpdate = ((update.getWhere() != null) && shardColCanBeUpdated(update.getWhere(),
                            partitionColumn, item.getValue(), false));

                    if (!canUpdate) {
                        String msg = "Sharding column can't be updated " + tableName + "->" + partitionColumn;
                        LOGGER.warn(msg);
                        throw new SQLNonTransientException(msg);
                    }
                }
                if (hasParent) {
                    if (column.equals(joinKey)) {
                        String msg = "Parent relevant column can't be updated " + tableName + "->" + joinKey;
                        LOGGER.warn(msg);
                        throw new SQLNonTransientException(msg);
                    }
                    rrs.setCacheAble(true);
                }
            }
        }
    }
}

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