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INNER JOIN ON predicates are flattened into WHERE. Cost-based AND reordering could evaluate a[i] before a cardinality/bounds guard, raising ARRAY_ELEMENT_ERROR for indexes the join would exclude. Prefer AND sides that cannot raise array element errors first so short-circuit skips out-of-range array access. JSON accessors still return null; bare out-of-range array[index] still errors. Fixes h2database#4364
katzyn
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Aug 1, 2026
katzyn
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Unfortunately, this is not a proper solution, it's just a workaround.
The proper fix is to move a premature query transformation from Parser.parseSelectFromPart() into place when we can determine whether transformation is possible or not.
Determination of unsafe expressions also should be performed by a new type of ExpressionVisitor, because array element reference is not the only one dangerous operation, so we need more flexibility here.
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Summary
Fixes #4364.
H2 flattens
INNER JOIN ... ONpredicates into the queryWHEREclause.ConditionAndOrthen reorders AND sides by cost. A cheaperarray[i]comparison could therefore run before a more expensive cardinality/bounds guard from the join, raisingARRAY_ELEMENT_ERRORfor indexes the join would have excluded (e.g. Hibernate-style unnest withsystem_range).This change keeps cost-based reordering, then for AND only moves expressions that may raise SQL array element errors to the right so short-circuit can skip them when a safer guard already failed. JSON array accessors still return
NULLfor missing indexes; bare out-of-rangearray[index]still raises as documented/SQL-standard.Changes
ConditionAndOr.optimize: after cost reorder, if left may raise array element error and right does not, swapConditionAndOrN.optimize: for AND, stable-sort so may-raise expressions are lastdatatypes/array.sql(issue Unnecessary WHERE condition evaluation leading to error #4364 repro + related forms)Test plan
= 2returns rowARRAY[1,2,3][4]still raisesARRAY_ELEMENT_ERROR_2TestScript:datatypes/array.sql,indexes.sql,range_table.sql,queries/joins.sql,queries/query-optimisations.sql,other/conditions.sql,predicates/null.sql,functions/system/array-get.sql— green