update configs.md

docs/source/user-guide/configs.md

@@ -71,7 +71,7 @@ Environment variables are read during `SessionConfig` initialisation so they mus
 | datafusion.execution.parquet.bloom_filter_enabled          | false                     | Sets if bloom filter is enabled for any column                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
 | datafusion.execution.parquet.bloom_filter_fpp              | NULL                      | Sets bloom filter false positive probability. If NULL, uses default parquet writer setting                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |
 | datafusion.execution.parquet.bloom_filter_ndv              | NULL                      | Sets bloom filter number of distinct values. If NULL, uses default parquet writer setting                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |
-| datafusion.execution.parquet.allow_single_file_parallelism | true                      | Controls whether DataFusion will attempt to speed up writing large parquet files by first writing multiple smaller files and then stitching them together into a single large file. This will result in faster write speeds, but higher memory usage.                                                                                                                                                                                                                                                                                                                                                   |
+| datafusion.execution.parquet.allow_single_file_parallelism | false                     | Controls whether DataFusion will attempt to speed up writing large parquet files by first writing multiple smaller files and then stitching them together into a single large file. This will result in faster write speeds, but higher memory usage. Also currently unsupported are bloom filters and column indexes when single_file_parallelism is enabled.                                                                                                                                                                                                                                          |
 | datafusion.execution.aggregate.scalar_update_factor        | 10                        | Specifies the threshold for using `ScalarValue`s to update accumulators during high-cardinality aggregations for each input batch. The aggregation is considered high-cardinality if the number of affected groups is greater than or equal to `batch_size / scalar_update_factor`. In such cases, `ScalarValue`s are utilized for updating accumulators, rather than the default batch-slice approach. This can lead to performance improvements. By adjusting the `scalar_update_factor`, you can balance the trade-off between more efficient accumulator updates and the number of groups affected. |
 | datafusion.execution.planning_concurrency                  | 0                         | Fan-out during initial physical planning. This is mostly use to plan `UNION` children in parallel. Defaults to the number of CPU cores on the system                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
 | datafusion.execution.sort_spill_reservation_bytes          | 10485760                  | Specifies the reserved memory for each spillable sort operation to facilitate an in-memory merge. When a sort operation spills to disk, the in-memory data must be sorted and merged before being written to a file. This setting reserves a specific amount of memory for that in-memory sort/merge process. Note: This setting is irrelevant if the sort operation cannot spill (i.e., if there's no `DiskManager` configured).                                                                                                                                                                       |