[v25.3.x] iceberg: set MAP logical type on parquet map columns#30458
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wdberkeley merged 2 commits intoMay 13, 2026
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Without the LogicalType.MAP annotation, strict parquet readers (Spark via SparkParquetReaders) fail with "Not a struct type" when reading the column, even though `describe` reports the column as a map. The declared type lives in the iceberg metadata and is unaffected by the missing annotation; only column read-back was broken. Mirror the LIST converter and stamp the annotation on the map root element. Cover with a unit-test assertion that the annotation is present and an end-to-end ducktape test that exercises map read-back via both Spark and Trino. (cherry picked from commit 4ae42da)
Trino's parquet reader is permissive enough to accept a map column written without the LogicalType.MAP annotation, so the engine-side assertion alone misses regressions that only show up in stricter readers. Add a pyiceberg read-back step that scans the column via arrow; pyiceberg rejects the malformed file (different failure mode than Spark) which gives us coverage independent of the query engine. (cherry picked from commit 5bfb4d3)
wdberkeley
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May 13, 2026
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CI test resultstest results on build#84385
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Backport of PR #30454