Many wasteful copies of `Settings`
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- C++
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Description
Enhancement
The size of Settings is 2976 bytes in the current master codebase.
However, there are many wasteful copies of Settings.
For example, the Settings is copied in ExpressionAnalyzer, ExpressionActionsChain, and ExpressionActions.
Settings in ExpressionActionsChain is just used to copy to ExpressionActions.
And only two variables in Settings are used in ExpressionActions which are max_temporary_columns and max_temporary_non_const_columns.
In view of the fact that ExpressionActions has a high frequency of use during compiling, we should avoid copying Settings.
Contributor guide
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First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start by tracing how Settings is copied through ExpressionAnalyzer, ExpressionActionsChain, and ExpressionActions. Confirm which Settings values ExpressionActions actually uses, especially max_temporary_columns and max_temporary_non_const_columns. Done means redundant Settings copies are avoided while preserving the existing behavior.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- cpp
- Domain
- backend, performance
- Issue type
- Refactor
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 35/100