Without explicit bqstorage_client parameter, to_arrow_iterable() silently
falls back to REST API pagination (~5K rows/sec). With explicit client,
it uses parallel gRPC streams via BQ Storage API (~300K rows/sec).
No temp table materialization - BQ already writes query results to an
internal temp table automatically. We just tell the reader to use the
fast gRPC path instead of slow HTTP pagination.
QueryJob only has to_arrow(), not to_arrow_iterable().
Must call query_job.result() first to get RowIterator,
which has the streaming to_arrow_iterable() method.
Replace to_arrow() (loads entire result into RAM) with
to_arrow_iterable() (streams RecordBatches). Each batch is written
directly to disk via ParquetWriter - constant memory regardless
of table size. Prevents OOM on 8GB server for multi-million row tables.
BigQuery connector that syncs BQ tables to local Parquet files via PyArrow
(no CSV intermediate step). Supports full refresh, timestamp-based
incremental (via incremental_column), and partition-based sync strategies.
- connectors/bigquery/client.py: BQ API wrapper with ADC auth, parameterized
queries, metadata cache, cross-project support (job project != data project)
- connectors/bigquery/adapter.py: DataSource implementation with merge/dedup
- src/config.py: Add incremental_column field to TableConfig
- 72 unit tests (mocked, no GCP SDK required)
