sql/analyzer: fix use of declared aliases in the same projection #609
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src-d#590] Signed-off-by: Manuel Carmona <manu.carmona90@gmail.com>
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asking for a code review to the new awesome @src-d/data-processing team |
| @@ -27,6 +27,7 @@ var DefaultRules = []Rule{ | |||
| var OnceBeforeDefault = []Rule{ | |||
| {"resolve_subqueries", resolveSubqueries}, | |||
| {"resolve_tables", resolveTables}, | |||
| {"check_aliases", checkAliases}, | |||
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this should be a validation rule
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validation rules are executed after regular rules, this must be executed on the parsed plan before transformations
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But it's a validation rule. Why can't it be run in validation phase?
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Since validation phase runs after the default rules, the plan to be validated could be modified enough to not keep this alias case.
An alias defined and used in the same projection in the original query, it couldn't be there in the plan after the transformations (reorder/remove/pushdown/joins...) (that's the case of the issue).
To be sure that a query which is making this is not allowed, the check must be done on the parsed plan or on a plan near to it.
Fixes #590
Since this is just a SQL syntax issue finally I've just added a new rule to check the aliases usage at the beginning of the analysis phase that runs once before the default rules. This way it doesn't interfere with the transformations made by the rest of the rules.