Avoid boxing config keys #4762
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Avoid boxing config keys #4762
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alamb
reviewed
Dec 28, 2022
| @@ -134,9 +135,9 @@ pub const OPT_HASH_JOIN_SINGLE_PARTITION_THRESHOLD: &str = | |||
| /// Definition of a configuration option | |||
| pub struct ConfigDefinition { | |||
| /// key used to identifier this configuration option | |||
| key: String, | |||
| key: Cow<'static, str>, | |||
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What would you think about using Arc here instead?
Arc might would be more consistent with the rest of the DataFusion codebase as well as help systems like Ballista where the configuration was serialized / deserialized.
I believe with a Cow and without any extra work, the deserialized ConfigOptions will still be owned (and copied) Strings
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Hmm... You raise a good point r.e. serialization, perhaps we should just make ConfigOptions a struct... I'll leave this open if anyone else has any thoughts
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Closing in favour of #4771 |
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Which issue does this PR close?
Relates to #4517
Rationale for this change
Config keys are almost always static strings, currently we allocate a
Stringfor each of these, and clone these allocations when we cloneSessionConfig, which is done multiple times per query. Switching to useCow<'static, str>avoids this.I prevaricated about this change as we may eventually change
ConfigOptionsinto a struct, but thought I'd propose it anyway and see what people thoughtWhat changes are included in this PR?
This changes the definition of
ConfigOptionsto avoid boxing static strings.Are these changes tested?
Are there any user-facing changes?