Python tutorials, tips, and best practices
Build a production data quality framework in PySpark. Eight validation checks (nulls, duplicates, range, regex, referential integrity, freshness, row count, type), the quarantine pattern, a reusable DQ class, DQ reports, integration with Medallion Architecture, and real-world DQ issues table.
Master every PySpark window function with real business scenarios. ROW_NUMBER, RANK, DENSE_RANK, LAG, LEAD, NTILE, running totals, moving averages, percent of group. Plus 5 real-world patterns: deduplication, gap detection, sessionization, YoY comparison, and top N per group.
Implement both SCD Type 1 and Type 2 using PySpark and Delta Lake MERGE in Databricks. Type 1: one MERGE with whenMatchedUpdate + whenNotMatchedInsertAll. Type 2: MERGE to expire + APPEND for new versions. Hash-based change detection, version numbering, idempotent tests, reusable functions, and complete Synapse Data Flow to PySpark MERGE mapping.
SCD Type 1 and Type 2 Using PySpark and Delta Lake MERGE in Azure Databricks Read More »
Master lazy evaluation — the most important PySpark concept nobody explains properly. Why Spark waits, how the Catalyst Optimizer rewrites your code, transformations vs actions with complete lists, predicate pushdown, column pruning, the DAG, narrow vs wide transformations, the cache trap, proving laziness with a hands-on experiment, and how it powers your SCD Type 2 pipeline.
The complete optimization playbook for Databricks. Small file problem and OPTIMIZE compaction, Z-ORDER for file skipping, conditional OPTIMIZE, VACUUM with retention and time travel interaction, partitioning strategy, AQE, broadcast joins, join best practices, caching, coalesce vs repartition, and the production checklist that turns 45-minute pipelines into 5-minute pipelines.
Master all 8 PySpark join types using the same two DataFrames. Inner, left, right, full outer, left_semi, left_anti, cross, and self joins with output tables, real-life analogies, SQL equivalents, broadcast optimization, duplicate column handling, and a decision table for choosing the right join.
Master managed vs external tables in Databricks. Complete setup: Access Connector, Storage Credential, External Location, and external table creation. Proves data persistence after DROP TABLE with step-by-step walkthrough. Covers Delta operations on external tables, partitioning, VACUUM, granting access, and the three-layer Unity Catalog security model.
Hands-on Delta Lake deep dive in Databricks. Every operation step by step: INSERT, UPDATE, DELETE, MERGE creating versions. Time travel three methods. Compare versions, track entities across history. RESTORE, VACUUM, Schema evolution, DeltaTable Python API.
Master Databricks to Azure SQL Database connectivity. JDBC connection setup, secure credentials with Key Vault, reading tables and custom queries, the ORDER BY subquery trap, write modes, upsert pattern, the three-notebook production architecture (Config + Functions + Operations), data quality functions, performance optimization with partitioned reads, and common JDBC errors.
Master PySpark foundations that every tutorial skips. SparkSession creation and configuration, SparkSession vs SparkContext history, every import you need, builder options, spark.conf.set vs builder config, stopping sessions, running PySpark locally, spark-submit, and environment comparison (Local vs Databricks vs Synapse).
PySpark Foundations: SparkSession, Imports, Configuration, and the Basics Nobody Teaches Read More »
