once now() is called in a statement, it forever returns the same value

[kmitchener]

Describe the bug
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select now();
-- ... 3 days later ...
select now(); -- returns same old value

It's correctly caching now() so it returns the same value when used multiple times in the same query, but it shouldn't be caching the value past statement execution, correct?

To Reproduce
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Expected behavior
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Would expect now() to return the same value for all instances in the same query, but a new value for a new statement in the same runtime context.

Additional context
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[andygrove]

It's correctly caching now() so it returns the same value when used multiple times in the same query, but it shouldn't be caching the value past statement execution, correct?

You are right. This is a bug.

[waitingkuo]

looks like now() is using the query_execution_start_time in session state which only created once per SessionContext

https://github.com/apache/arrow-datafusion/blob/master/datafusion/physical-expr/src/execution_props.rs#L32

[alamb]

Agree -- now() should update between each statement but stay the same within a statement