Update

Author: sgrebnov

datafusion/sqllogictest/test_files/information_schema.slt

@@ -233,6 +233,7 @@ datafusion.optimizer.filter_null_join_keys false
 datafusion.optimizer.hash_join_single_partition_threshold 1048576
 datafusion.optimizer.hash_join_single_partition_threshold_rows 131072
 datafusion.optimizer.max_passes 3
+datafusion.optimizer.optimize_projections_preserve_existing_projections false
 datafusion.optimizer.prefer_existing_sort false
 datafusion.optimizer.prefer_existing_union false
 datafusion.optimizer.prefer_hash_join true
@@ -326,6 +327,7 @@ datafusion.optimizer.filter_null_join_keys false When set to true, the optimizer
 datafusion.optimizer.hash_join_single_partition_threshold 1048576 The maximum estimated size in bytes for one input side of a HashJoin will be collected into a single partition
 datafusion.optimizer.hash_join_single_partition_threshold_rows 131072 The maximum estimated size in rows for one input side of a HashJoin will be collected into a single partition
 datafusion.optimizer.max_passes 3 Number of times that the optimizer will attempt to optimize the plan
+datafusion.optimizer.optimize_projections_preserve_existing_projections false When set to true, the `optimize_projections` rule will not attempt to move, add, or remove existing projections. This flag helps maintain the original structure of the `LogicalPlan` when converting it back into SQL via the `unparser` module. It ensures the query layout remains simple and readable, relying on the underlying SQL engine to apply its own optimizations during execution.
 datafusion.optimizer.prefer_existing_sort false When true, DataFusion will opportunistically remove sorts when the data is already sorted, (i.e. setting `preserve_order` to true on `RepartitionExec`  and using `SortPreservingMergeExec`) When false, DataFusion will maximize plan parallelism using `RepartitionExec` even if this requires subsequently resorting data using a `SortExec`.
 datafusion.optimizer.prefer_existing_union false When set to true, the optimizer will not attempt to convert Union to Interleave
 datafusion.optimizer.prefer_hash_join true When set to true, the physical plan optimizer will prefer HashJoin over SortMergeJoin. HashJoin can work more efficiently than SortMergeJoin but consumes more memory

docs/source/user-guide/configs.md

@@ -115,6 +115,7 @@ Environment variables are read during `SessionConfig` initialisation so they mus
 | datafusion.optimizer.default_filter_selectivity                         | 20                        | The default filter selectivity used by Filter Statistics when an exact selectivity cannot be determined. Valid values are between 0 (no selectivity) and 100 (all rows are selected).                                                                                                                                                                                                                                                                                                                                                                                    |
 | datafusion.optimizer.prefer_existing_union                              | false                     | When set to true, the optimizer will not attempt to convert Union to Interleave                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
 | datafusion.optimizer.expand_views_at_output                             | false                     | When set to true, if the returned type is a view type then the output will be coerced to a non-view. Coerces `Utf8View` to `LargeUtf8`, and `BinaryView` to `LargeBinary`.                                                                                                                                                                                                                                                                                                                                                                                               |
+| datafusion.optimizer.optimize_projections_preserve_existing_projections | false                     | When set to true, the `optimize_projections` rule will not attempt to move, add, or remove existing projections. This flag helps maintain the original structure of the `LogicalPlan` when converting it back into SQL via the `unparser` module. It ensures the query layout remains simple and readable, relying on the underlying SQL engine to apply its own optimizations during execution.                                                                                                                                                                         |
 | datafusion.explain.logical_plan_only                                    | false                     | When set to true, the explain statement will only print logical plans                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
 | datafusion.explain.physical_plan_only                                   | false                     | When set to true, the explain statement will only print physical plans                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |
 | datafusion.explain.show_statistics                                      | false                     | When set to true, the explain statement will print operator statistics for physical plans                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |