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JsonFileWriter fails with NPE after VectorSchemaRoot syncSchema #390
Description
Hey there :)
Repro:
-
Open VSR
-
Do something that'll change the
Fieldof one of the vectors in the VSR (promotable writer, etc) -
vsr.syncSchema() -
Open JsonFileWriter,
start,write-> NPELooks like the cause is that the
fieldVectorsMapcache isn't updated insyncSchema? Possibly a few other places -addVector/removeVectortoo?Cheers,
James
Reporter: James Henderson / @jarohen
Note: This issue was originally created as ARROW-11385. Please see the migration documentation for further details.
Activity
hutiefang76 commentedon Oct 24, 2026
I can take this. The current
syncSchema()still leaves the Field-keyed lookup using the old schema. I'll refresh that lookup when the schema changes and add regressions for child-type promotion and a real JSON write/read round trip, while preserving the existing vector objects and row count.I've checked the related add/remove ownership and name-lookup PRs; they do not cover this cache refresh. I'll keep this change scoped to schema synchronization and its tests.
AI-generated coordination comment; investigation and implementation assisted by Codex and DeepSeek.