{"record":{"id":"6f87dc3227df3af2","repo":"risingwavelabs/risingwave","slug":"alter-table-set-parallelism-is-not-supported-for-i","errorCode":null,"errorMessage":"ALTER TABLE SET PARALLELISM is not supported for iceberg table: {}.{}","messagePattern":"ALTER TABLE SET PARALLELISM is not supported for iceberg table: (.+?)\\.(.+?)","errorType":"error_code","errorClass":null,"httpStatus":null,"severity":"error","filePath":"src/frontend/src/handler/mod.rs","lineNumber":1774,"sourceCode":"        AlterTableOperation::RenameColumn { .. }\n        | AlterTableOperation::ChangeColumn { .. }\n        | AlterTableOperation::AlterColumn { .. } => {\n            bail!(\n                \"ALTER TABLE {} is not supported for iceberg table: {}.{}. Existing column schema mutation is not supported currently\",\n                operation,\n                schema_name,\n                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            );","sourceCodeStart":1756,"sourceCodeEnd":1792,"githubUrl":"https://github.com/risingwavelabs/risingwave/blob/6469eb736d691e8e9b8a419a57edd6429ca77417/src/frontend/src/handler/mod.rs#L1756-L1792","documentation":"Changing streaming parallelism (`ALTER TABLE ... SET PARALLELISM`) is rejected for Iceberg-backed tables. Iceberg table DDL on RisingWave does not support parallelism adjustment on the underlying streaming job.","triggerScenarios":"Executing `ALTER TABLE <iceberg_table> SET PARALLELISM ...` where the table is backed by an Iceberg sink.","commonSituations":"Tuning throughput after increased load; copy-pasted parallelism tuning scripts applied to all tables including Iceberg ones.","solutions":["Recreate the table and Iceberg sink with the desired parallelism option in the DDL.","Tune parallelism on the Iceberg side/external compute if applicable, not via RisingWave ALTER TABLE.","Skip the SET PARALLELISM statement for Iceberg tables in automation scripts."],"exampleFix":"// before\nALTER TABLE iceberg_t SET PARALLELISM = 8;\n// after\n-- recreate: CREATE TABLE ... WITH (parallelism = 8) plus Iceberg sink","handlingStrategy":"validation","validationCode":"-- Skip SET PARALLELISM for iceberg-backed tables\nSELECT relation_kind FROM rw_catalog.rw_relations WHERE name = 't';\n-- only issue SET PARALLELISM for non-iceberg tables","typeGuard":"fn is_parallelism_change(op: &AlterTableOperation) -> bool {\n    matches!(op, AlterTableOperation::SetParallelism {..})\n}","tryCatchPattern":"match client.alter_table_set_parallelism(table, p).await {\n    Err(e) if e.message().contains(\"SET PARALLELISM is not supported for iceberg\") => {\n        // recreate table/sink with desired parallelism if needed\n    }\n    other => other?,\n}","preventionTips":["Set parallelism at creation time for Iceberg tables.","Filter parallelism-tuning automation to non-Iceberg tables.","Capacity-plan Iceberg tables at creation to avoid later tuning."],"tags":["sql","iceberg","parallelism","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"}