[khaledh]

fixes #40188

messageFromMap resolves every field with Descriptor.findFieldByName, which concatenates and hashes the fully qualified name on each call. This records each field's ordinal in SchemaInformation and uses it as a lookup hint, verified by name, with findFieldByName as the fallback.

• No cache, no shared state, no public API change.
• Required-field validation and diagnostics unchanged.
• JMH: 1.575 → 1.084 ms/op (−31%). Dataflow, production workload: −15.7% CPU/record with this change alone.

Tests: reordered descriptor (exact bytes), ordinal beyond descriptor length (fallback), required-field validation, concurrent conversion. GCP IO suite green on JDK 11 and 17.

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[github-actions]

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R: @chamikaramj for label java.

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[github-actions]

Reminder, please take a look at this pr: @chamikaramj

[github-actions]

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[github-actions]

Reminder, please take a look at this pr: @Abacn

[Abacn]

BQIO storage write is a popular connector. Need to understand the implication of this optimization, if this new assumption introduced could break schema updates feature

[github-actions]

Reminder, please take a look at this pr: @Abacn

[derrickaw]

Hi @khaledh, friendly ping to resolve merge conflict and address @Abacn comment. Thanks.

[khaledh]

BQIO storage write is a popular connector. Need to understand the implication of this optimization, if this new assumption introduced could break schema updates feature

@Abacn The ordinal is only a hint. We still compare fields by name after retrieving it by ordinal to make sure it's the same field (a descriptor can't have two fields with the same name). On mismatch we fall back to findFieldByName. The tests cover this.

Is there a particular feature/case I haven't considered? Happy to amend the PR if necessary.