[Improvement-16754][DataX] Support DataX writer parameter batchSize

[leocook]

Was this PR generated or assisted by AI?

YES — used Claude (Sonnet 4.6 / Opus 4.7) to help review the original design, simplify the implementation (removing per-database dynamic defaults that were the wrong abstraction), and resolve rebase conflicts against dev. All design decisions, the final approach, and verification were reviewed by me.

Purpose of the pull request

DataX writer currently does not expose the batchSize parameter, so users are stuck with the DataX default of 2048. This is too small for some target databases — e.g. the ClickHouse plugin recommends 65536. This PR makes batchSize configurable from the task UI.

Closes #16754

Brief change log

Backend (dolphinscheduler-task-datax):

• Add batchSize field to DataxParameters (lombok @Data generates accessors)
• In DataxTask, write batchSize into the writer JSON only when value > 0, so the DataX upstream default still applies when the user picks 0 (unlimited)
• Extend DataxParametersTest to cover the new field

Frontend (dolphinscheduler-ui):

• Add a batchSize select control on the DataX task form
• Static option list: 0 / 1024 / 2048 / 4096 / 8192 / 16384 / 32768 / 65536 / 131072
• Default 2048 (matches DataX upstream); ClickHouse / Databend users can pick 65536 / 131072 from the same list
• Add zh_CN and en_US i18n entries (datax_writer_batch_size)

Design note: an earlier draft switched the option list and default based on target database type (see issue discussion). That was dropped after review — batchSize optima depend on row width, network, and target hardware, not just on the database, so hard-coding database-specific defaults in the UI is the wrong abstraction. A static list keeps the UI consistent with surrounding fields (jobSpeedByte / jobSpeedRecord / memoryLimit).

Verify this pull request

This change added tests and can be verified as follows:

• Added testBatchSize in DataxParametersTest covering the new field (default 0, 2048, 65536)
• Updated the existing toString assertion in DataxParametersTest to include batchSize=0
• Manually verified locally:
  • Created a DataX task targeting MySQL with batchSize=2048 — generated JSON contains "batchSize": 2048 under writer.parameter
  • Set batchSize=0 — generated JSON omits the field, DataX falls back to its own default
  • Switched UI between values, persisted task, reloaded — value preserved

Screenshots

Pull Request Notice

Pull Request Notice