fix(stream): reset tableScan operator

[wangmm0220]

Description

Please briefly describe the code changes in this pull request.

Checklist

Please check the items in the checklist if applicable.

• Is the user manual updated?
• Are the test cases passed and automated?
• Is there no significant decrease in test coverage?

[gemini-code-assist]

Summary of Changes

Hello @wangmm0220, 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!

This pull request significantly enhances the robustness and correctness of stream processing by implementing comprehensive state reset mechanisms for various scan operators. By introducing specific reset functions for TableScan, TableMergeScan, and SysTableScan operators, it ensures that their internal states are properly cleared and reinitialized when a stream task is reset, preventing issues related to stale data or resource leaks. The changes also include minor improvements to logging and null pointer handling.

Highlights

• Improved Operator State Reset: Introduced dedicated state reset functions for TableScan, TableMergeScan, and SysTableScan operators, ensuring proper cleanup and reinitialization of operator states when a stream task is reset.
• Refined Stream Task Reset Logic: The vnodeProcessStreamFetchMsg function now correctly distinguishes between creating a new stream execution task and resetting an existing one, utilizing the new qResetTableScan and operator-specific reset functions.
• Enhanced Debugging and Logging: Added informative qInfo logging for meta data fetching and loading in system table scans, and adjusted a debug flag for data block printing to a more appropriate level.
• NULL Pointer Safety: A NULL pointer check was added to the blockDataEmpty function to prevent potential crashes.

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[gemini-code-assist]

Code Review

This pull request refactors the stream operator reset logic by introducing a polymorphic resetStateFn function pointer. This is a good design improvement. The implementation is applied to TableScan, TableMergeScan, and SysTableScan operators. My review includes a suggestion to refactor some duplicated code and to remove a large block of commented-out code for better maintainability.

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