Make ASTSelectQuery::formatImpl() more robust #46889
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Fixes #45204 The problem is that ASTSelectQuery::group_by_with_grouping_sets == true implies ASTSelectQuery::groupBy() but sometimes this wasn't the case. I added a sanity check a few months ago but had no idea how the AST became corrupt. All crashes/exceptions were during AST fuzzing. Looking at Client/QueryFuzzer.cpp, there is a very small chance to run into the issue. In detail: 1. In QueryFuzzer::fuzz(), we find that the AST is a ASTSelectQuery and groupBy() returns true. 2. With small probability, we do select->group_by_with_grouping_sets = !select->group_by_with_grouping_sets; where the (default false) group_by_with_grouping_sets flips true. 3. With small probability, we change the expression type in the following WHERE or PREWHERE if-branches. This situation is illegal. One possibility is changing the fuzzing code to not generate it. The fuzzing code is however generic, and doesn't really care about such details. Therefore, instead add an (theoretically unnecessary) extra check to ASTSelectQuery::formatImpl() for robustness.
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Feb 25, 2023
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Fixes #45204
The problem is that
ASTSelectQuery::group_by_with_grouping_sets == trueshould implyASTSelectQuery::groupBy()but sometimes this wasn't the case. I added a sanity check a few months ago but had no idea how the AST became corrupt.All crashes/exceptions were during AST fuzzing. Looking at Client/QueryFuzzer.cpp, there is a very small chance to run into the issue. In detail:
In
QueryFuzzer::fuzz(), we find that the AST is aASTSelectQueryandgroupBy()returns true.With small probability, we do
select->group_by_with_grouping_sets = !select->group_by_with_grouping_sets;where the (default false)group_by_with_grouping_setsflips true.With small probability, we change the expression type in the following WHERE or PREWHERE if-branches.
This situation is illegal. One possibility is changing the fuzzing code to not generate it. The fuzzing code is however generic, and doesn't really care about such details. Therefore, instead add an (theoretically unnecessary) extra check to
ASTSelectQuery::formatImpl()for robustness.Changelog category (leave one):