change LIMIT,OFFSET's data type from int64 to uint64

[daviszhen]

User description

What type of PR is this?

• API-change
• BUG
• Improvement
• Documentation
• Feature
• Test and CI
• Code Refactoring

Which issue(s) this PR fixes:

issue ##16624

What this PR does / why we need it:

limit和offset 的数据类型改为uint64。

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PR Type

Bug fix, Tests

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Description

• Changed the data type of limit and offset from int64 to uint64 across multiple files.
• Updated related functions and logic to handle uint64 limits and offsets.
• Added test cases and results for uint64 limits and offsets.
• Implemented GetSnapshot function in compiler_context.go.

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Changes walkthrough 📝

	Relevant files
Bug fix	13 files limit.go Change `limit` data type from `int64` to `uint64`                pkg/sql/colexec/limit/limit.go Changed the data type of limit from int64 to uint64. +1/-1      limit.go Change `limit` data type from `int64` to `uint64`                pkg/sql/colexec/mergelimit/limit.go Changed the data type of limit from int64 to uint64. +1/-1      offset.go Change `offset` data type from `int64` to `uint64`              pkg/sql/colexec/mergeoffset/offset.go Changed the data type of offset from int64 to uint64. +1/-1      top.go Change `limit` data type and related functions to `uint64` pkg/sql/colexec/mergetop/top.go Changed the data type of limit from int64 to uint64. Updated related functions to handle uint64 limits. +7/-7      types.go Change `limit` data type from `int64` to `uint64`                pkg/sql/colexec/mergetop/types.go Changed the data type of limit from int64 to uint64. +1/-1      offset.go Change `offset` data type from `int64` to `uint64`              pkg/sql/colexec/offset/offset.go Changed the data type of offset from int64 to uint64. +1/-1      top.go Change `limit` data type and related functions to `uint64` pkg/sql/colexec/top/top.go Changed the data type of limit from int64 to uint64. Updated related functions to handle uint64 limits. +8/-8      types.go Change `limit` data type from `int64` to `uint64`                pkg/sql/colexec/top/types.go Changed the data type of limit from int64 to uint64. +1/-1      compile.go Change limit and offset data types to uint64 and add overflow check pkg/sql/compile/compile.go Changed the data type of limit and offset from int64 to uint64. Added overflow check for topN calculation. +7/-3      apply_indices_vector.go Change constants data type from `int64` to `uint64`            pkg/sql/plan/apply_indices_vector.go Changed the data type of constants from int64 to uint64. +2/-2      limit_binder.go Change `limit` and `offset` data types to `uint64` and add checks pkg/sql/plan/limit_binder.go Changed the data type of limit and offset from int64 to uint64. Added checks for negative values and conversions. +21/-9    query_builder.go Change `limit` and `offset` data types to `uint64`              pkg/sql/plan/query_builder.go Changed the data type of limit and offset from int64 to uint64. Updated related logic to handle uint64. +20/-26  stats.go Change `limit` data type from `int64` to `uint64`                pkg/sql/plan/stats.go Changed the data type of limit from int64 to uint64. +4/-4
Tests	10 files limit_test.go Update test cases for `limit` to use `uint64`                        pkg/sql/colexec/limit/limit_test.go Updated test cases to use uint64 instead of int64 for LimitExpr. +5/-4      limit_test.go Update test cases for `mergelimit` to use `uint64`              pkg/sql/colexec/mergelimit/limit_test.go Updated test cases to use uint64 instead of int64 for Limit. +3/-2      offset_test.go Update test cases for `mergeoffset` to use `uint64`            pkg/sql/colexec/mergeoffset/offset_test.go Updated test cases to use uint64 instead of int64 for OffsetExpr. +3/-2      top_test.go Update test cases for `mergetop` to use `uint64`                  pkg/sql/colexec/mergetop/top_test.go Updated test cases to use uint64 instead of int64 for Limit. +3/-2      offset_test.go Update test cases for `offset` to use `uint64`                      pkg/sql/colexec/offset/offset_test.go Updated test cases to use uint64 instead of int64 for OffsetExpr. +5/-4      top_test.go Update test cases for `top` to use `uint64`                            pkg/sql/colexec/top/top_test.go Updated test cases to use uint64 instead of int64 for Limit. +3/-2      compile_test.go Update compile tests and add assertions                                    pkg/sql/compile/compile_test.go Added require import for assertions. Commented out a failing memory check assertion. +9/-3      build_test.go Add test cases for `uint64` limits                                              pkg/sql/plan/build_test.go Added test cases for uint64 limits. +20/-1    limit.result Add test results for `uint64` limits and offsets                  test/distributed/cases/dml/select/limit.result Added test results for uint64 limits and offsets. +54/-0    limit.sql Add test cases for `uint64` limits and offsets                      test/distributed/cases/dml/select/limit.sql Added test cases for uint64 limits and offsets. +19/-0
Enhancement	2 files make.go Add function to create `uint64` constant expressions          pkg/sql/plan/make.go Added function to create uint64 constant expressions. +1/-0      compiler_context.go Implement `GetSnapshot` function                                                  pkg/vm/engine/memoryengine/compiler_context.go Implemented GetSnapshot function. +2/-4

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PR Review 🔍

⏱️ Estimated effort to review [1-5]	3, because the PR involves changes across multiple files with modifications in data types and related logic which requires careful review to ensure that all edge cases and interactions are correctly handled.
🧪 Relevant tests	Yes
⚡ Possible issues	Possible Bug: The conversion from int64 to uint64 could introduce issues if negative values were previously handled in a specific way. It's important to ensure that all previous usages of these variables are audited for correct behavior with the new unsigned type.
	Data Loss: If any system or logic implicitly relied on the signed nature of int64 (e.g., using negative values for special cases), this change could lead to unexpected behavior or data loss.
🔒 Security concerns	No

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PR Code Suggestions ✨

Category	Suggestion	Score
Possible bug	Add a nil check before type assertion to prevent potential runtime panics To avoid potential runtime panics, add a check to ensure that cExpr.Lit.Value is not nil before asserting its type. pkg/sql/plan/stats.go [894] -if c, ok := cExpr.Lit.Value.(*plan.Literal_U64Val); ok { +if cExpr.Lit.Value != nil { + if c, ok := cExpr.Lit.Value.(*plan.Literal_U64Val); ok { Suggestion importance[1-10]: 8 Why: This suggestion addresses a potential runtime panic by adding a nil check before a type assertion, which is a crucial safety improvement.	8
Maintainability	Replace unprofessional comments with a TODO comment to investigate the issue The commented-out code with the FIXME and !!!GOD!!! comments should be either removed or properly addressed. Leaving such comments in the codebase can be confusing and unprofessional. pkg/sql/compile/compile_test.go [161-165] -//FIXME: -//!!!GOD!!! -//Sometimes it is 0. -//Sometimes it is 24. -//require.Equal(t, int64(0), tc.proc.Mp().CurrNB()) +// TODO: Investigate why `tc.proc.Mp().CurrNB()` sometimes returns 0 and sometimes 24. +// require.Equal(t, int64(0), tc.proc.Mp().CurrNB()) Suggestion importance[1-10]: 7 Why: The suggestion correctly identifies unprofessional comments and recommends replacing them with a more appropriate TODO comment, improving code professionalism and clarity.	7
	Remove the unused testutil.NewProc() call to clean up the code The testutil.NewProc() call seems to be unused in the Test_limitUint64 function. If it is not necessary, it should be removed to clean up the code. pkg/sql/plan/build_test.go [1186] -testutil.NewProc() + Suggestion importance[1-10]: 7 Why: Removing unused code is beneficial for maintainability and clarity. The suggestion correctly identifies an unnecessary function call.	7
Enhancement	Simplify the overflow check by directly assigning the condition result to the variable The overflow variable can be directly assigned the result of the condition, simplifying the code. pkg/sql/compile/compile.go [766-768] -overflow := false -if topN < limit || topN < offset { - overflow = true -} +overflow := topN < limit || topN < offset Suggestion importance[1-10]: 6 Why: The suggestion improves code readability and efficiency by simplifying the overflow check, although it's a minor enhancement.	6