{"record":{"id":"8614892142593fd3","repo":"apache/iceberg","slug":"cannot-add-column-s-since-setting-default-values-861489","errorCode":null,"errorMessage":"Cannot add column %s since setting default values in Spark is currently unsupported","messagePattern":"Cannot add column (.+?) since setting default values in Spark is currently unsupported","errorType":"exception","errorClass":"UnsupportedOperationException","httpStatus":null,"severity":"error","filePath":"spark/v4.1/spark/src/main/java/org/apache/iceberg/spark/Spark3Util.java","lineNumber":252,"sourceCode":"      TableChange.After after = (TableChange.After) update.position();\n      String referenceField = peerName(update.fieldNames(), after.column());\n      pendingUpdate.moveAfter(DOT.join(update.fieldNames()), referenceField);\n\n    } else if (update.position() instanceof TableChange.First) {\n      pendingUpdate.moveFirst(DOT.join(update.fieldNames()));\n\n    } else {\n      throw new IllegalArgumentException(\"Unknown position for reorder: \" + update.position());\n    }\n  }\n\n  private static void apply(UpdateSchema pendingUpdate, TableChange.AddColumn add) {\n    Preconditions.checkArgument(\n        add.isNullable(),\n        \"Incompatible change: cannot add required column: %s\",\n        leafName(add.fieldNames()));\n    if (add.defaultValue() != null) {\n      throw new UnsupportedOperationException(\n          String.format(\n              \"Cannot add column %s since setting default values in Spark is currently unsupported\",\n              leafName(add.fieldNames())));\n    }\n\n    Type type = SparkSchemaUtil.convert(add.dataType());\n    pendingUpdate.addColumn(\n        parentName(add.fieldNames()), leafName(add.fieldNames()), type, add.comment());\n\n    if (add.position() instanceof TableChange.After) {\n      TableChange.After after = (TableChange.After) add.position();\n      String referenceField = peerName(add.fieldNames(), after.column());\n      pendingUpdate.moveAfter(DOT.join(add.fieldNames()), referenceField);\n\n    } else if (add.position() instanceof TableChange.First) {\n      pendingUpdate.moveFirst(DOT.join(add.fieldNames()));\n\n    } else {","sourceCodeStart":234,"sourceCodeEnd":270,"githubUrl":"https://github.com/apache/iceberg/blob/86d9c8fc543e7c56c9f624eb725f76c9baff9570/spark/v4.1/spark/src/main/java/org/apache/iceberg/spark/Spark3Util.java#L234-L270","documentation":"Thrown when an AddColumn TableChange carries a non-null default value. Iceberg's Spark integration in this version cannot express column DEFAULT values through Spark DDL, so adding a column with a default is rejected rather than silently ignored.","triggerScenarios":"ALTER TABLE ... ADD COLUMN c INT DEFAULT 5, or building a TableChange.addColumn(...) with a defaultValue via the catalog API on Spark.","commonSituations":"Porting DDL from engines/database systems that support column defaults (Postgres, Delta with defaults); programmatic catalog code that populates defaultValue.","solutions":["Remove the DEFAULT clause from the ADD COLUMN statement","Add the column without a default, then backfill existing data with an UPDATE if a value is needed","Upgrade Iceberg — newer versions may support default values via schema defaults"],"exampleFix":"// before\nALTER TABLE t ADD COLUMN c INT DEFAULT 5;\n// after\nALTER TABLE t ADD COLUMN c INT;\nUPDATE t SET c = 5 WHERE c IS NULL;","handlingStrategy":"validation","validationCode":"if (change instanceof TableChange.AddColumn && ((TableChange.AddColumn) change).defaultValue() != null) {\n  throw new IllegalArgumentException(\"Column default values are not supported via Spark\");\n}","typeGuard":null,"tryCatchPattern":"try {\n  catalogAlterTable(ident, changes);\n} catch (UnsupportedOperationException e) {\n  if (e.getMessage().contains(\"default values in Spark is currently unsupported\")) {\n    // retry without default, then backfill\n  }\n}","preventionTips":["Strip DEFAULT clauses when translating DDL from other engines","Add columns nullable, then backfill with UPDATE","Check Iceberg release notes for default-value support before relying on it"],"tags":["spark","schema","default-values"],"backgroundTag":"unsupported-operation","analyzedSha":"86d9c8fc543e7c56c9f624eb725f76c9baff9570","analyzedAt":"2026-09-12T00:46:39.097Z","contentChangedAt":"2026-09-12T00:46:39.097Z","schemaVersion":2},"datasetVersion":"2026-09-23T08:17:48.524Z"}