fix(sql): fix a bug when planning semi- or antijoins#20990
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aalexandrov wants to merge 1 commit intoapache:mainfrom
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fix(sql): fix a bug when planning semi- or antijoins#20990aalexandrov wants to merge 1 commit intoapache:mainfrom
aalexandrov wants to merge 1 commit intoapache:mainfrom
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Currently, the `exclude_using_columns` called from `expand_wildcard` doesn't consider the filtering semantics of semi- and antijoins when expanding wildcards on top of joins defined via `USING(<columns>)` syntax. From each set of columns equated by a `USING(<column>)` expression, the code currently (1) sorts the set entries, and (2) retains only the first entry from each set. Because of that, the columns surviving the `exclude_using_columns` call might be wrongly chosen from the filtering side if the table qualifier from that side is lexicographically before the filtered side qualifier. For example, given this schema of two identical tables: ```sql create table s(x1 int, x2 int, x3 int); create table t(x1 int, x2 int, x3 int); ``` One would expect that the schema of queries where the `s` and `t` names are swapped will be identical. However, currently this is not the case: ```sql -- Q1 schema: x1 int, x2 int, x3 int (because s < t) select * from s left semi join t using (x1); -- Q2 schema: x2 int, x3 int (because t < s) select * from t left semi join s using (x1); ``` This commit fixes the issue and adds some regression tests.
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exclude_using_columnsmight wrongly retain columns from a projected join input #20989.Rationale for this change
The planner should be consistent with the expected SQL behavior—swapping the names of tables that have identical structure in a SQL query should not affect the schema for that query.
What changes are included in this PR?
exclude_using_columnshelper method indatafusion/expr/src/utils.rsthat ensures that we don't retain columns from the projected side when deciding which USING columns to exclude and which to retain on top of semi- or antijoins.test_using_join_wildcard_schema_semi_anti.Are these changes tested?
Are there any user-facing changes?
Yes, the change is user facing, but I doubt that this behavior is expected and is documented anywhere.
If existing docs need to be updated, please point me to the concrete places and I can take a look.