Designing and diagnosing high-volume database ingestion from the JVM across PostgreSQL, MySQL, and SQL Server: JDBC batching and statement rewrite, native COPY/LOAD DATA/Bulk Copy, staging, transaction and partial-error semantics, idempotent restart, upsert races, logging, parallelism, and post-load validation. Use when a backfill, import, migration, or batch window is too slow or unsafe. Not routine ORM fetch/write tuning, which belongs to orm-fetch-and-batching-performance.
