Doc: note enforce_batch_size_in_joins only applies to symmetric hash join

datafusion/common/src/config.rs

@@ -1116,6 +1116,7 @@ config_namespace! {
         /// DataFusion will not enforce batch size in joins. Enforcing batch size
         /// in joins can reduce memory usage when joining large
         /// tables with a highly-selective join filter, but is also slightly slower.
+        /// Note: this option currently only applies to the symmetric hash join.
         pub enforce_batch_size_in_joins: bool, default = false
 
         /// Size (bytes) of data buffer DataFusion uses when writing output files.

datafusion/sqllogictest/test_files/information_schema.slt

@@ -381,7 +381,7 @@ datafusion.execution.enable_ansi_mode false Whether to enable ANSI SQL mode. The
 datafusion.execution.enable_file_stream_work_stealing true When `true` (the default), DataFusion's built-in file scans dynamically rebalance files across partitions at query execution time: a partition that goes idle reads files (or byte-range morsels) originally assigned to a sibling partition, which keeps all partitions busy in a single process. Executors that depend on the plan-time partition assignment — such as Ballista and datafusion-distributed, which run each partition as an isolated task and never poll the siblings — should set this to `false` so each partition reads only its own file group and no runtime reassignment occurs.
 datafusion.execution.enable_migration_aggregate true Temporary switch for aggregate stream implementations that are being migrated from `GroupedHashAggregateStream`. When set to true, DataFusion tries the migrated implementations when their preconditions are satisfied. When set to false, grouped aggregation falls back to `GroupedHashAggregateStream`. This option will be removed after the migration is finished. See <https://github.com/apache/datafusion/issues/22710> for details.
 datafusion.execution.enable_recursive_ctes true Should DataFusion support recursive CTEs
-datafusion.execution.enforce_batch_size_in_joins false Should DataFusion enforce batch size in joins or not. By default, DataFusion will not enforce batch size in joins. Enforcing batch size in joins can reduce memory usage when joining large tables with a highly-selective join filter, but is also slightly slower.
+datafusion.execution.enforce_batch_size_in_joins false Should DataFusion enforce batch size in joins or not. By default, DataFusion will not enforce batch size in joins. Enforcing batch size in joins can reduce memory usage when joining large tables with a highly-selective join filter, but is also slightly slower. Note: this option currently only applies to the symmetric hash join.
 datafusion.execution.hash_join_buffering_capacity 0 How many bytes to buffer in the probe side of hash joins while the build side is concurrently being built. Without this, hash joins will wait until the full materialization of the build side before polling the probe side. This is useful in scenarios where the query is not completely CPU bounded, allowing to do some early work concurrently and reducing the latency of the query. Note that when hash join buffering is enabled, the probe side will start eagerly polling data, not giving time for the producer side of dynamic filters to produce any meaningful predicate. Queries with dynamic filters might see performance degradation. Disabled by default, set to a number greater than 0 for enabling it.
 datafusion.execution.keep_partition_by_columns false Should DataFusion keep the columns used for partition_by in the output RecordBatches
 datafusion.execution.listing_table_factory_infer_partitions true Should a `ListingTable` created through the `ListingTableFactory` infer table partitions from Hive compliant directories. Defaults to true (partition columns are inferred and will be represented in the table schema).

docs/source/user-guide/configs.md

@@ -140,7 +140,7 @@ The following configuration settings are available:
 | datafusion.execution.skip_partial_aggregation_probe_ratio_threshold     | 0.8                       | Aggregation ratio (number of distinct groups / number of input rows) threshold for skipping partial aggregation. If the value is greater then partial aggregation will skip aggregation for further input                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
 | datafusion.execution.skip_partial_aggregation_probe_rows_threshold      | 100000                    | Number of input rows partial aggregation partition should process, before aggregation ratio check and trying to switch to skipping aggregation mode                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
 | datafusion.execution.use_row_number_estimates_to_optimize_partitioning  | false                     | Should DataFusion use row number estimates at the input to decide whether increasing parallelism is beneficial or not. By default, only exact row numbers (not estimates) are used for this decision. Setting this flag to `true` will likely produce better plans. if the source of statistics is accurate. We plan to make this the default in the future.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |
-| datafusion.execution.enforce_batch_size_in_joins                        | false                     | Should DataFusion enforce batch size in joins or not. By default, DataFusion will not enforce batch size in joins. Enforcing batch size in joins can reduce memory usage when joining large tables with a highly-selective join filter, but is also slightly slower.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
+| datafusion.execution.enforce_batch_size_in_joins                        | false                     | Should DataFusion enforce batch size in joins or not. By default, DataFusion will not enforce batch size in joins. Enforcing batch size in joins can reduce memory usage when joining large tables with a highly-selective join filter, but is also slightly slower. Note: this option currently only applies to the symmetric hash join.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
 | datafusion.execution.objectstore_writer_buffer_size                     | 10485760                  | Size (bytes) of data buffer DataFusion uses when writing output files. This affects the size of the data chunks that are uploaded to remote object stores (e.g. AWS S3). If very large (>= 100 GiB) output files are being written, it may be necessary to increase this size to avoid errors from the remote end point.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |
 | datafusion.execution.enable_ansi_mode                                   | false                     | Whether to enable ANSI SQL mode. The flag is experimental and relevant only for DataFusion Spark built-in functions When `enable_ansi_mode` is set to `true`, the query engine follows ANSI SQL semantics for expressions, casting, and error handling. This means: - **Strict type coercion rules:** implicit casts between incompatible types are disallowed. - **Standard SQL arithmetic behavior:** operations such as division by zero, numeric overflow, or invalid casts raise runtime errors rather than returning `NULL` or adjusted values. - **Consistent ANSI behavior** for string concatenation, comparisons, and `NULL` handling. When `enable_ansi_mode` is `false` (the default), the engine uses a more permissive, non-ANSI mode designed for user convenience and backward compatibility. In this mode: - Implicit casts between types are allowed (e.g., string to integer when possible). - Arithmetic operations are more lenient — for example, `abs()` on the minimum representable integer value returns the input value instead of raising overflow. - Division by zero or invalid casts may return `NULL` instead of failing. # Default `false` — ANSI SQL mode is disabled by default.                          |
 | datafusion.execution.hash_join_buffering_capacity                       | 0                         | How many bytes to buffer in the probe side of hash joins while the build side is concurrently being built. Without this, hash joins will wait until the full materialization of the build side before polling the probe side. This is useful in scenarios where the query is not completely CPU bounded, allowing to do some early work concurrently and reducing the latency of the query. Note that when hash join buffering is enabled, the probe side will start eagerly polling data, not giving time for the producer side of dynamic filters to produce any meaningful predicate. Queries with dynamic filters might see performance degradation. Disabled by default, set to a number greater than 0 for enabling it.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |