Implicit Type Conversion for Temporal Types

[Song-Quan]

support query like SELECT ta.ID, date FROM ta right join tb on ta.ID = tb.ID where '2025-04-23 12:25:42' < ta.date;

[gemini-code-assist]

Hello @Song-Quan, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

Summary of Changes

This pull request introduces implicit type conversion for temporal types. Specifically, it allows string representations of dates (YYYY-MM-DD and YYYY-MM-DD HH:MM:SS) to be implicitly converted to Unix timestamps (milliseconds since epoch) when used as constants in expressions. This is achieved by adding functions to check if a string is a date and to convert it to a Unix timestamp. The translator is modified to use these functions to convert string constants to int64 when appropriate.

Highlights

• Implicit Type Conversion: Implements implicit type conversion from string to Unix milliseconds for date/time constants.
• Date String Detection: Adds a utility function to detect if a string is in a valid date/time format (YYYY-MM-DD or YYYY-MM-DD HH:MM:SS).
• String to Unix Milliseconds Conversion: Adds a utility function to convert a date/time string to Unix milliseconds.

Changelog

• pkg/interpreter/translator/translator.go
  • Imports the stringutil package.
  • Adds logic to getTensorFromExpression to check if a constant is a date string and convert it to Unix milliseconds if it is.
• pkg/util/stringutil/string_util.go
  • Adds IsDateString function to check if a string is a date.
  • Adds StringToUnixMilli function to convert a date string to Unix milliseconds.
• pkg/util/stringutil/string_util_test.go
  • Adds tests for IsDateString function.
  • Adds tests for StringToUnixMilli function.

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---

A string of time,
To numbers we must climb,
Convert with care.

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[gemini-code-assist]

Code Review

The pull request introduces implicit type conversion for temporal types, specifically handling date strings by converting them to Unix milliseconds. This enhancement could be beneficial for systems that rely on numerical representations of time. However, there are several areas that need improvement, particularly around error handling, input validation, and code clarity.

Summary of Findings

• Error Handling: The StringToUnixMilli function could benefit from more robust error handling, especially when parsing dates. The current implementation returns 0 and an error for unsupported formats, which might not be the best approach. Consider returning a specific error value or using a more descriptive error message.
• Input Validation: The IsDateString function uses regular expressions to validate date strings. While this approach works, it might be too restrictive. Consider allowing for more flexible date formats or providing a mechanism to configure the supported formats.
• Code Clarity: The logic in getTensorFromExpression could be simplified to improve readability. Consider extracting the date parsing logic into a separate function or using a more concise way to check the string value and convert it to Unix milliseconds.
• Potential Overflow: Converting date strings to Unix milliseconds using UnixNano() / 1e6 could lead to potential overflow issues. Consider using UnixMilli() which is available in newer versions of Go.

Merge Readiness

The pull request is not ready for merging. There are several issues that need to be addressed before merging, including error handling, input validation, and code clarity. I recommend addressing these issues before merging. I am unable to approve this pull request, and users should have others review and approve this code before merging.

[tongke6]

please add some query test cases

[fucangfy]

why is this kind of format not correct?

[Song-Quan]

UnixMilli() can only deal with the string which format is YYYY-MM-DD hh:mm:ss

[fucangfy]

do we need the cast between float32 and float64?

[Song-Quan]

I'm not sure, conversions in this map is a temporary solution. Maybe we can add more conversions as needed