feat: Add PostgreSQL REAL/FLOAT4 support to Sourcedb to Spanner template

[jsuhani-2026]

The Sourcedb_to_Spanner_Flex template previously lacked support for migrating data from PostgreSQL REAL (aliased as FLOAT4) columns when using the Spanner PostgreSQL dialect. This resulted in data not being populated in the target Spanner tables for columns of type FLOAT4 (Spanner's single-precision float type), causing failures in PostgreSQLDataTypesPGDialectIT for these type tests.

This PR addresses this by:

1. Adding Type Mapping: Introduced a type conversion mapping for Type.pgFloat4() in AvroToValueMapper.getPgMap(). This mapping utilizes the existing avroFieldToFloat32 function to correctly convert incoming Avro values (originating from PostgreSQL REAL columns) to Spanner Value.float32().
2. Unit Tests: Added new unit tests to AvroToValueMapperTest.java to specifically validate the Dialect.POSTGRESQL map entries for Type.pgFloat4(), ensuring the conversion logic is correctly wired.
3. Integration Tests: Re-enabled the integration test cases for REAL data types within PostgreSQLDataTypesPGDialectIT.java that were previously commented out. These tests now pass, confirming end-to-end functionality.

With these changes, the template now correctly handles PostgreSQL REAL/FLOAT4 types, mapping them to Spanner's float4 type in the PostgreSQL dialect.

Fixes: b/516973815

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 63.31%. Comparing base (d0ccc08) to head (466c250).
⚠️ Report is 11 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #3870      +/-   ##
============================================
+ Coverage     55.47%   63.31%   +7.84%     
+ Complexity     6962     2315    -4647     
============================================
  Files          1102      514     -588     
  Lines         67443    29932   -37511     
  Branches       7564     3298    -4266     
============================================
- Hits          37413    18952   -18461     
+ Misses        27587    10017   -17570     
+ Partials       2443      963    -1480     

Components	Coverage Δ
spanner-templates	88.72% <100.00%> (+0.92%)	⬆️
spanner-import-export	∅ <ø> (∅)
spanner-live-forward-migration	90.14% <100.00%> (-0.08%)	⬇️
spanner-live-reverse-replication	83.90% <100.00%> (+1.06%)	⬆️
spanner-bulk-migration	92.57% <100.00%> (-0.05%)	⬇️
gcs-spanner-dv	90.37% <100.00%> (+1.29%)	⬆️

Files with missing lines	Coverage Δ
.../v2/spanner/migrations/avro/AvroToValueMapper.java	94.24% <100.00%> (+0.07%)	⬆️

... and 621 files with indirect coverage changes

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[gemini-code-assist]

Summary of Changes

Hello, 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 enables support for migrating PostgreSQL REAL (FLOAT4) data types within the Sourcedb to Spanner template. By establishing the necessary type mappings and validating them through both unit and integration tests, the changes ensure that single-precision floating-point data is correctly processed and persisted in Spanner when using the PostgreSQL dialect.

Highlights

• Type Mapping Implementation: Added support for PostgreSQL REAL/FLOAT4 types by introducing a conversion mapping in AvroToValueMapper to correctly translate Avro values to Spanner float32.
• Unit Testing: Expanded AvroToValueMapperTest to include validation for the new pgFloat4 mapping, ensuring proper handling of float inputs.
• Integration Test Restoration: Re-enabled previously commented-out integration tests in PostgreSQLDataTypesPGDialectIT to verify end-to-end migration functionality for REAL data types.

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[gemini-code-assist]

Code Review

This pull request enables mapping support for PostgreSQL float4 (real) to Spanner float32 in AvroToValueMapper and re-enables the corresponding integration tests in PostgreSQLDataTypesPGDialectIT. Feedback suggests removing obsolete comments in the integration tests that claim the float4 tests are still commented out, and expanding the unit tests in AvroToValueMapperTest to cover null, NaN, and infinity values as described in the PR description.

[shreyakhajanchi]

LGTM

[sm745052]

LGTM