{"record":{"id":"c8a790556a10b558","repo":"risingwavelabs/risingwave","slug":"alter-table-set-backfill-parallelism-is-not-suppor","errorCode":null,"errorMessage":"ALTER TABLE SET BACKFILL PARALLELISM is not supported for iceberg table: {}.{}","messagePattern":"ALTER TABLE SET BACKFILL PARALLELISM is not supported for iceberg table: (.+?)\\.(.+?)","errorType":"error_code","errorClass":null,"httpStatus":null,"severity":"error","filePath":"src/frontend/src/handler/mod.rs","lineNumber":1781,"sourceCode":"                table_name\n            );\n        }\n        AlterTableOperation::RenameTable { .. } => {\n            bail!(\n                \"ALTER TABLE RENAME is not supported for iceberg table: {}.{}\",\n                schema_name,\n                table_name\n            );\n        }\n        AlterTableOperation::SetParallelism { .. } => {\n            bail!(\n                \"ALTER TABLE SET PARALLELISM is not supported for iceberg table: {}.{}\",\n                schema_name,\n                table_name\n            );\n        }\n        AlterTableOperation::SetBackfillParallelism { .. } => {\n            bail!(\n                \"ALTER TABLE SET BACKFILL PARALLELISM is not supported for iceberg table: {}.{}\",\n                schema_name,\n                table_name\n            );\n        }\n        AlterTableOperation::RefreshSchema => {\n            bail!(\n                \"ALTER TABLE REFRESH SCHEMA is not supported for iceberg table: {}.{}\",\n                schema_name,\n                table_name\n            );\n        }\n        AlterTableOperation::AlterRateLimit(rate_limit)\n            if rate_limit.rate_limit_type == AlterRateLimitType::Source =>\n        {\n            bail!(\n                \"ALTER TABLE SET SOURCE RATE LIMIT is not supported for iceberg table: {}.{}\",\n                schema_name,","sourceCodeStart":1763,"sourceCodeEnd":1799,"githubUrl":"https://github.com/risingwavelabs/risingwave/blob/6469eb736d691e8e9b8a419a57edd6429ca77417/src/frontend/src/handler/mod.rs#L1763-L1799","documentation":"Changing backfill parallelism (`ALTER TABLE ... SET BACKFILL PARALLELISM`) is rejected for Iceberg-backed tables. This tuning knob is not available for the streaming jobs associated with Iceberg sinks.","triggerScenarios":"Executing `ALTER TABLE <iceberg_table> SET BACKFILL PARALLELISM ...` on a table backed by an Iceberg sink.","commonSituations":"Speeding up or throttling an ongoing backfill; operational runbooks that adjust backfill parallelism across all tables.","solutions":["Recreate the table and Iceberg sink specifying backfill parallelism in the creation DDL.","Accept default backfill parallelism for the Iceberg table.","Exclude Iceberg tables from backfill-parallelism automation."],"exampleFix":"// before\nALTER TABLE iceberg_t SET BACKFILL PARALLELISM = 4;\n// after\n-- recreate table/sink with backfill_parallelism set at creation","handlingStrategy":"validation","validationCode":"-- Skip SET BACKFILL PARALLELISM for iceberg-backed tables\nSELECT relation_kind FROM rw_catalog.rw_relations WHERE name = 't';\n-- only issue for non-iceberg tables","typeGuard":"fn is_backfill_parallelism_change(op: &AlterTableOperation) -> bool {\n    matches!(op, AlterTableOperation::SetBackfillParallelism {..})\n}","tryCatchPattern":"match client.alter_table_set_backfill_parallelism(table, p).await {\n    Err(e) if e.message().contains(\"SET BACKFILL PARALLELISM is not supported\") => {\n        // accept defaults or recreate with backfill_parallelism at creation\n    }\n    other => other?,\n}","preventionTips":["Configure backfill parallelism in the creation DDL for Iceberg tables.","Exclude Iceberg tables from backfill-tuning runbooks.","Verify relation type before parallelism ALTERs."],"tags":["sql","iceberg","parallelism","backfill","unsupported-operation"],"backgroundTag":"operation-not-supported","analyzedSha":"6469eb736d691e8e9b8a419a57edd6429ca77417","analyzedAt":"2026-09-11T21:06:21.487Z","contentChangedAt":"2026-09-11T21:06:21.487Z","schemaVersion":2},"datasetVersion":"2026-09-14T16:17:12.679Z"}