[IMPALA-7338] Test coverage for codegen with CHAR type

• Type: Sub-task
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: Impala 3.0, Impala 2.12.0
• Component/s: Backend
• Labels: codegen
• Target Version: Product Backlog
• Epic Color: ghx-label-2
• Assignee: Unassigned
• Reporter: Michael Ho
• Created: 23/Jul/18 20:58
• Updated: 19/May/20 21:15

Description

Until IMPALA-3207 is fixed, we will disable codegen for operators if CHAR is involved. Our test coverage for these cases is not very comprehensive. For instance, we still hit cases such as IMPALA-7032, IMPALA-7288. This Jira aims to track the effort to boost the test coverage for these cases.

Some ideas:

• augment existing test cases to make sure we cover all built-in expressions which can take char type as argument or return type. This should help catch cases such as IMPALA-7032
• exercise the bail out path in codegen functions (e.g. hash tables, exec nodes, expressions) by injecting faults in expression codegen functions to fail codegen. This should help catch cases such as IMPALA-7288.
• Make sure our query generator will generate all possible combination of built-in expressions (with CHAR type) and all exec nodes which may codegen.

cc'ing mikesbrown for query generator idea