Data Engineers
Free Data Engineering Ebooks & Courses
Show more📈 Analytical overview of Telegram channel Data Engineers
Channel Data Engineers (@sql_engineer) in the English language segment is an active participant. Currently, the community unites 10 545 subscribers, ranking 18 735 in the Education category and 37 618 in the India region.
📊 Audience metrics and dynamics
Since its creation on невідомо, the project has demonstrated rapid growth, gathering an audience of 10 545 subscribers.
According to the latest data from 13 July, 2026, the channel demonstrates stable activity. Although there has been a change in the number of participants by 136 over the last 30 days and by 1 over the last 24 hours, overall reach remains high.
- Verification status: Not verified
- Engagement rate (ER): The average audience engagement rate is 10.05%. Within the first 24 hours after publication, content typically collects 3.73% reactions from the total number of subscribers.
- Post reach: On average, each post receives 1 059 views. Within the first day, a publication typically gains 393 views.
- Reactions and interaction: The audience actively supports content: the average number of reactions per post is 3.
- Thematic interests: Content is focused on key topics such as sql, learning, analytic, engineer, link:-.
📝 Description and content policy
The author describes the resource as a platform for expressing subjective opinions:
“Free Data Engineering Ebooks & Courses”
Thanks to the high frequency of updates (latest data received on 14 July, 2026), the channel maintains relevance and a high level of publication reach. Analytics show that the audience actively interacts with content, making it an important point of influence in the Education category.
dbt test --store-failures --alert slack.
📊 1️⃣2️⃣ What is the medallion architecture? Bronze/Silver/Gold layers
✅ Answer:
Medallion (Databricks): Raw → Clean → Curated.
- Bronze: Raw landing zone (schema-on-read).
- Silver: Cleaned, deduplicated, enriched.
- Gold: Business-ready marts (aggregations, joins).
Example: bronze_events → silver_events (dedup) → gold_customer_daily (business KPIs).
🧠 1️⃣3️⃣ Compare ACID transactions across different data systems
✅ Answer:
- Traditional RDBMS: Full ACID.
- Data Lakes: None (eventual consistency).
- Delta Lake/Iceberg: ACID via transaction log.
- Snowflake: Time Travel ACID (query past states).
- Kafka: Exactly-once with idempotent producers.
Choose based on consistency vs scale needs.
📈 1️⃣4️⃣ How do you optimize Spark jobs for cost and performance?
✅ Answer:
Cost: Auto-scaling clusters, spot instances, partition pruning.
Performance:
- Cache/persist intermediate results
- Broadcast small tables for JOINs
- Predicate pushdown (filter before join)
- Adaptive query execution (AQE)
- Z-order clustering
Monitor: Spark UI, Ganglia, query profiles.
📊 1️⃣5️⃣ What tools and tech stack do you use daily?
✅ Answer:
- Orchestration: Airflow, Prefect, Dagster
- Processing: PySpark, dbt, DuckDB
- Storage: S3, Snowflake, Delta Lake, PostgreSQL
- Streaming: Kafka, Flink, Kinesis
- Cloud: AWS/GCP/Azure (EMR, Databricks, VertexAI)
- Monitoring: Datadog, Grafana, Great Expectations
💼 1️⃣6️⃣ Describe a challenging data engineering problem you solved
✅ Answer:
"Production pipeline failed silently dropping 30% events due to Kafka consumer lag (7-day backlog). Root cause: Spark Structured Streaming micro-batch outpacing consumer group.
Fix: Dynamic partitioning by watermark, exactly-once semantics, consumer group rebalancing. Added dead letter queue, lag monitoring alerts.
Result: 99.99% delivery guarantee, processing resumed in 4 hours vs 7 days. Implemented chaos testing for future resilience."
Double Tap ❤️ For MoreMERGE target t USING staging s ON t.id = s.id WHEN MATCHED THEN UPDATE WHEN NOT MATCHED THEN INSERT
📊 6️⃣ What is Apache Airflow? Key components and DAG best practices
✅ Answer:
Airflow: Workflow orchestration platform. DAGs (Directed Acyclic Graphs) define pipeline dependencies.
Components: Scheduler, Webserver, Metadata DB, Workers (Celery/Kubernetes).
Best practices:
- Small, focused tasks (<15min)
- Idempotent tasks
- Retry logic + SLAs
- XComs for lightweight data passing
- Dynamic DAGs via Jinja templating
📉 7️⃣ Explain partitioning vs bucketing vs clustering in big data systems
✅ Answer:
Partitioning: Split data by column values (date, region) → directory structure. Prunes I/O for queries.
Bucketing: Hash-based file grouping within partitions. Optimizes JOINs (same bucket).
Clustering: Multi-dimensional sorting (Snowflake Z-order). Dynamic, query-optimized.
Example: PARTITIONED BY (year, month) CLUSTERED BY (customer_id) balances prune + sort.
📊 8️⃣ How do you handle schema evolution in data pipelines?
✅ Answer:
Schema evolution: Handle changing upstream data structures.
Strategies:
- Avro/Protobuf (schema in file metadata)
- dbt schema.yml + tests
- Delta Lake/Apache Iceberg (ACID + schema evolution)
- Flexible staging layer (JSON → structured)
- Versioned tables (table_v1, table_v2)
🧠 9️⃣ What is Spark? Compare DataFrames vs RDDs vs Datasets
✅ Answer:
Spark: Distributed data processing engine.
RDD: Low-level, resilient distributed datasets (Python objects).
DataFrame: Structured, optimized (Tungsten + Catalyst).
Dataset: Type-safe DataFrame (Scala/Java only\