databricks-spark-structured-streaming

Spark Structured Streaming

Production-ready streaming pipelines with Spark Structured Streaming. This skill provides navigation to detailed patterns and best practices.

Quick Start

from pyspark.sql.functions import col, from_json

# Basic Kafka to Delta streaming
df = (spark
    .readStream
    .format("kafka")
    .option("kafka.bootstrap.servers", "broker:9092")
    .option("subscribe", "topic")
    .load()
    .select(from_json(col("value").cast("string"), schema).alias("data"))
    .select("data.*")
)

df.writeStream \
    .format("delta") \
    .outputMode("append") \
    .option("checkpointLocation", "/Volumes/catalog/checkpoints/stream") \
    .trigger(processingTime="30 seconds") \
    .start("/delta/target_table")

Core Patterns

Pattern	Description	Reference
Kafka Streaming	Kafka to Delta, Kafka to Kafka, Real-Time Mode	See references/kafka-streaming.md
Real-Time Mode (RTM)	Sub-second E2E latency — cluster setup, slot math, supported ops (incl. stream-stream inner join on DBR 18+), transformWithState, observability, error classes, delivery semantics	See references/real-time-mode.md
Lakebase Sink	Write streaming records into Lakebase Postgres with transactional upserts. Native format("postgresql") sink (DBR 18.3+) and manual foreach sink as a fallback	See references/lakebase-sink-python.md
Stream Joins	Stream-stream joins, stream-static joins	See references/stream-stream-joins.md, references/stream-static-joins.md
Multi-Sink Writes	Write to multiple tables, parallel merges	See references/multi-sink-writes.md
Merge Operations	MERGE performance, parallel merges, optimizations	See references/merge-operations.md

Configuration

Topic	Description	Reference
Checkpoints	Checkpoint management and best practices	See references/checkpoint-best-practices.md
Stateful Operations	Watermarks, state stores, RocksDB configuration	See references/stateful-operations.md
Trigger & Cost	Trigger selection, cost optimization, RTM	See references/trigger-and-cost-optimization.md

Best Practices

Topic	Description	Reference
Production Checklist	Comprehensive best practices	See references/streaming-best-practices.md

Production Checklist

• Checkpoint location is persistent (UC volumes, not DBFS)
• Unique checkpoint per stream
• Fixed-size cluster (no autoscaling for streaming)
• Monitoring configured (input rate, lag, batch duration)
• Exactly-once verified (txnVersion/txnAppId)
• Watermark configured for stateful operations
• Left joins for stream-static (not inner)