{"record":{"id":"0481272ec0a2d39e","repo":"apache/iceberg","slug":"unsupported-table-change-modifywatermark-048127","errorCode":null,"errorMessage":"Unsupported table change: ModifyWatermark.","messagePattern":"Unsupported table change: ModifyWatermark\\.","errorType":"exception","errorClass":"UnsupportedOperationException","httpStatus":null,"severity":"error","filePath":"flink/v2.3/flink/src/main/java/org/apache/iceberg/flink/util/FlinkAlterTableUtil.java","lineNumber":137,"sourceCode":"   *\n   * @param pendingUpdate an uncommitted UpdateSchema operation to configure\n   * @param schemaChanges a list of Flink table changes\n   */\n  public static void applySchemaChanges(\n      UpdateSchema pendingUpdate, List<TableChange> schemaChanges) {\n    for (TableChange change : schemaChanges) {\n      if (change instanceof TableChange.AddColumn) {\n        applyAddColumn(pendingUpdate, (TableChange.AddColumn) change);\n      } else if (change instanceof TableChange.ModifyColumn) {\n        TableChange.ModifyColumn modifyColumn = (TableChange.ModifyColumn) change;\n        applyModifyColumn(pendingUpdate, modifyColumn);\n      } else if (change instanceof TableChange.DropColumn) {\n        TableChange.DropColumn dropColumn = (TableChange.DropColumn) change;\n        pendingUpdate.deleteColumn(dropColumn.getColumnName());\n      } else if (change instanceof TableChange.AddWatermark) {\n        throw new UnsupportedOperationException(\"Unsupported table change: AddWatermark.\");\n      } else if (change instanceof TableChange.ModifyWatermark) {\n        throw new UnsupportedOperationException(\"Unsupported table change: ModifyWatermark.\");\n      } else if (change instanceof TableChange.DropWatermark) {\n        throw new UnsupportedOperationException(\"Unsupported table change: DropWatermark.\");\n      } else if (change instanceof TableChange.AddUniqueConstraint) {\n        TableChange.AddUniqueConstraint addPk = (TableChange.AddUniqueConstraint) change;\n        applyUniqueConstraint(pendingUpdate, addPk.getConstraint());\n      } else if (change instanceof TableChange.ModifyUniqueConstraint) {\n        TableChange.ModifyUniqueConstraint modifyPk = (TableChange.ModifyUniqueConstraint) change;\n        applyUniqueConstraint(pendingUpdate, modifyPk.getNewConstraint());\n      } else if (change instanceof TableChange.DropConstraint) {\n        throw new UnsupportedOperationException(\"Unsupported table change: DropConstraint.\");\n      } else {\n        throw new UnsupportedOperationException(\"Cannot apply unknown table change: \" + change);\n      }\n    }\n  }\n\n  private static void applyAddColumn(UpdateSchema pendingUpdate, TableChange.AddColumn addColumn) {\n    Column flinkColumn = addColumn.getColumn();","sourceCodeStart":119,"sourceCodeEnd":155,"githubUrl":"https://github.com/apache/iceberg/blob/86d9c8fc543e7c56c9f624eb725f76c9baff9570/flink/v2.3/flink/src/main/java/org/apache/iceberg/flink/util/FlinkAlterTableUtil.java#L119-L155","documentation":"applySchemaChanges rejects watermark modifications: any TableChange.ModifyWatermark reaching the Iceberg catalog alter path throws UnsupportedOperationException because Iceberg (via this Flink bridge) cannot store watermark table properties.","triggerScenarios":"Executing 'ALTER TABLE ... MODIFY WATERMARK' (or ALTER ... REPLACE/WATERMARK adjustments) through the Iceberg Flink catalog.","commonSituations":"Migrating native Flink table DDL workflows to Iceberg tables and reusing watermark DDL statements unchanged.","solutions":["Remove the MODIFY WATERMARK statement; redefine the watermark in the consuming Flink job/source DDL instead.","Drop and recreate the view/source definition with the desired watermark semantics outside Iceberg metadata.","Check Iceberg release notes for watermark table-feature support before retrying."],"exampleFix":null,"handlingStrategy":"validation","validationCode":"boolean hasWatermarkChange = changes.stream().anyMatch(c -> c instanceof TableChange.ModifyWatermark || c instanceof TableChange.AddWatermark || c instanceof TableChange.DropWatermark);\nif (hasWatermarkChange) throw new IllegalArgumentException('Watermark changes unsupported by Iceberg Flink catalog');","typeGuard":null,"tryCatchPattern":"try { catalog.alterTable(tableIdent, changes); } catch (UnsupportedOperationException e) { /* fall back to pipeline-level watermark config */ }","preventionTips":["Manage watermarks at the job/source level rather than table metadata","Strip watermark clauses from DDL migration scripts targeting Iceberg","Check Iceberg release notes for watermark feature support"],"tags":["flink","sql","schema-change","unsupported"],"backgroundTag":"operation-not-supported","analyzedSha":"86d9c8fc543e7c56c9f624eb725f76c9baff9570","analyzedAt":"2026-09-12T00:46:39.097Z","contentChangedAt":"2026-09-12T00:46:39.097Z","schemaVersion":2},"datasetVersion":"2026-09-14T16:17:12.679Z"}