--- id: known-issues title: SQL-based ingestion known issues sidebar_label: Known issues --- > This page describes SQL-based batch ingestion using the [`druid-multi-stage-query`](../multi-stage-query/index.md) > extension, new in Druid 24.0. Refer to the [ingestion methods](../ingestion/index.md#batch) table to determine which > ingestion method is right for you. ## Multi-stage query task runtime - Fault tolerance is not implemented. If any task fails, the entire query fails. - Worker task stage outputs are stored in the working directory given by `druid.indexer.task.baseDir`. Stages that generate a large amount of output data may exhaust all available disk space. In this case, the query fails with an [UnknownError](./reference.md#error_UnknownError) with a message including "No space left on device". ## SELECT - SELECT from a Druid datasource does not include unpublished real-time data. - GROUPING SETS and UNION ALL are not implemented. Queries using these features return a [QueryNotSupported](reference.md#error_QueryNotSupported) error. - For some COUNT DISTINCT queries, you'll encounter a [QueryNotSupported](reference.md#error_QueryNotSupported) error that includes `Must not have 'subtotalsSpec'` as one of its causes. This is caused by the planner attempting to use GROUPING SETs, which are not implemented. - The numeric varieties of the EARLIEST and LATEST aggregators do not work properly. Attempting to use the numeric varieties of these aggregators lead to an error like `java.lang.ClassCastException: class java.lang.Double cannot be cast to class org.apache.druid.collections.SerializablePair`. The string varieties, however, do work properly. ## INSERT and REPLACE - INSERT and REPLACE with column lists, like `INSERT INTO tbl (a, b, c) SELECT ...`, is not implemented. - `INSERT ... SELECT` and `REPLACE ... SELECT` insert columns from the SELECT statement based on column name. This differs from SQL standard behavior, where columns are inserted based on position. - INSERT and REPLACE do not support all options available in [ingestion specs](../ingestion/ingestion-spec.md), including the `createBitmapIndex` and `multiValueHandling` [dimension](../ingestion/ingestion-spec.md#dimension-objects) properties, and the `indexSpec` [`tuningConfig`](../ingestion/ingestion-spec.md#tuningconfig) property. ## EXTERN - The [schemaless dimensions](../ingestion/ingestion-spec.md#inclusions-and-exclusions) feature is not available. All columns and their types must be specified explicitly using the `signature` parameter of the [EXTERN function](reference.md#extern). - EXTERN with input sources that match large numbers of files may exhaust available memory on the controller task. - EXTERN does not accept `druid` input sources. Use FROM instead.