Data Engineers
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Show more๐ 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 10 421 subscribers, ranking 19 167 in the Education category and 38 949 in the India region.
๐ Audience metrics and dynamics
Since its creation on ะฝะตะฒัะดะพะผะพ, the project has demonstrated rapid growth, gathering an audience of 10 421 subscribers.
According to the latest data from 23 June, 2026, the channel demonstrates stable activity. Although there has been a change in the number of participants by 189 over the last 30 days and by 9 over the last 24 hours, overall reach remains high.
- Verification status: Not verified
- Engagement rate (ER): The average audience engagement rate is 14.46%. Within the first 24 hours after publication, content typically collects N/A% reactions from the total number of subscribers.
- Post reach: On average, each post receives 0 views. Within the first day, a publication typically gains 0 views.
- Reactions and interaction: The audience actively supports content: the average number of reactions per post is 0.
- Thematic interests: Content is focused on key topics such as sql, learning, analytic, engineer, link:-.
๐ Description and content policy
The author describes the resource as a platform for expressing subjective opinions:
โFree Data Engineering Ebooks & Coursesโ
Thanks to the high frequency of updates (latest data received on 24 June, 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.
๐ 1๏ธโฃ2๏ธโฃ What is the medallion architecture? Bronze/Silver/Gold layers
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Answer:
Medallion (Databricks): Raw โ Clean โ Curated.
- Bronze: Raw landing zone (schema-on-read).
- Silver: Cleaned, deduplicated, enriched.
- Gold: Business-ready marts (aggregations, joins).
Example: bronze_events โ silver_events (dedup) โ gold_customer_daily (business KPIs).
๐ง 1๏ธโฃ3๏ธโฃ Compare ACID transactions across different data systems
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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.
๐ 1๏ธโฃ4๏ธโฃ How do you optimize Spark jobs for cost and performance?
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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.
๐ 1๏ธโฃ5๏ธโฃ What tools and tech stack do you use daily?
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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
๐ผ 1๏ธโฃ6๏ธโฃ Describe a challenging data engineering problem you solved
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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 โค๏ธ For MoreMERGE target t USING staging s ON t.id = s.id WHEN MATCHED THEN UPDATE WHEN NOT MATCHED THEN INSERT
๐ 6๏ธโฃ What is Apache Airflow? Key components and DAG best practices
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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
๐ 7๏ธโฃ Explain partitioning vs bucketing vs clustering in big data systems
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Answer:
Partitioning: Split data by column values (date, region) โ 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.
๐ 8๏ธโฃ How do you handle schema evolution in data pipelines?
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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 โ structured)
- Versioned tables (table_v1, table_v2)
๐ง 9๏ธโฃ What is Spark? Compare DataFrames vs RDDs vs Datasets
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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\
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