[I] [Bug]: Go SDK row coder encodes negative INT32 schema fields as 10 byte varints that Java and Python reject [beam]

["Eliaaazzz (via GitHub)" <gi...@apache.org>]

Eliaaazzz opened a new issue, #40159:
URL: https://github.com/apache/beam/issues/40159

   ### What happened?
   
   The Go SDK reflection row coder encodes `int32` struct fields with `EncodeVarInt(rv.Int())`, the signed 64 bit varint, so a negative value takes 10 bytes: `-1` becomes `ff ff ff ff ff ff ff ff ff 01` (`sdks/go/pkg/beam/core/graph/coder/row_encoder.go`, the `reflect.Int32` case shared with the other int kinds).
   
   The other SDKs encode the INT32 schema type as the varint of the unsigned 32 bit form of the value, 5 bytes at most:
   
   - Java `VarIntCoder` calls `VarInt.encode(int)`, which masks with `0xFFFFFFFFL`, so `-1` is `ff ff ff ff 0f`. `VarInt.decodeInt` throws `varint overflow` for the Go bytes because they decode to a negative long.
   - Python `VarInt32Coder` writes `v & 0xFFFFFFFF` (`write_var_int32` in `slow_stream.py`) and `read_var_int32` packs the decoded value with `struct.pack('<I', v)`, which raises for the negative value produced by the Go bytes.
   
   So a Go row with a negative `int32` field cannot be read by the Java or Python SDK. Positive values are unaffected, and Go can already read the 5 byte form because `reflect.Value.SetInt` truncates to 32 bits.
   
   This is the INT32 counterpart of #40151 (INT16). Found while working on #39684.
   
   ### Issue Priority
   
   Priority: 2 (default / most bugs should be filed as P2)
   
   ### Issue Components
   
   - [ ] Component: Python SDK
   - [ ] Component: Java SDK
   - [x] Component: Go SDK
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Re: [I] [Bug]: Go SDK row coder encodes negative INT32 schema fields as 10 byte varints that Java and Python reject [beam]

["Eliaaazzz (via GitHub)" <gi...@apache.org>]

Eliaaazzz commented on issue #40159:
URL: https://github.com/apache/beam/issues/40159#issuecomment-5715399157

   .take-issue


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Re: [I] [Bug]: Go SDK row coder encodes negative INT32 schema fields as 10 byte varints that Java and Python reject [beam]

["alisha-1000 (via GitHub)" <gi...@apache.org>]

alisha-1000 commented on issue #40159:
URL: https://github.com/apache/beam/issues/40159#issuecomment-6364543431

   Hello, @Eliaaazzz !
   
   I’ve reviewed the issue and understand the cross-SDK compatibility problem: the Go row coder currently encodes negative `INT32` values using signed 64-bit varint encoding, whereas Java and Python expect the 32-bit unsigned representation of the value.
   
   I’d be interested in contributing to the investigation and validation of a fix, particularly by examining the existing `INT16` counterpart and identifying the appropriate regression tests to ensure consistent encoding across the Go, Java, and Python SDKs.
   
   Would additional help with cross-SDK regression testing or related edge cases be useful for this issue?


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