[FLINK-15266] NPE in blink planner code gen

• Type: Bug
• Status: Resolved
• Priority: Blocker
• Resolution: Fixed
• Affects Version/s: 1.9.1
• Fix Version/s: 1.9.2, 1.10.0
• Component/s: Table SQL / Runtime
• Labels: pull-request-available
• Assignee: Benchao Li
• Reporter: Benchao Li
• Created: 16/Dec/19 02:17
• Updated: 05/May/23 18:46
• Resolved: 20/Dec/19 06:50

Description

`cast` function in blink planner and old planner are different:

in legacy planner:
cast('' as int) -> throw NumberFormatException
cast(null as int) -> throw NullPointerException
cast('abc' as int) -> throw NumberFormatException

but in blink planner:
cast('' as int) -> return null
cast(null as int) -> return null
cast('abc' as int) -> return null

A step forward:
```
create table source

{ age int, id varchar }

;
select case when age < 20 then cast(id as bigint) else 0 end from source;
```
queries like above will throw NPE because we will try assign a `null` to a `long` field when the input satisfy `age < 20`.

Issue Links

• links to: GitHub Pull Request #10594