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Data Platform

Databricks, Spark, lakehouse, Data Factory, Fabric, Power BI, warehouses, Kafka, Airflow and dbt. 161 posts.

Warehouses / Runbook

Sev1: a Snowflake network policy locked out every user and integration

After activating or editing an account-level network policy, logins fail with "IP is not allowed to access Snowflake" for users, BI tools and pipelines. Find a path back in, unset or fix the policy, then roll network rules out safely with user-level testing.

4 min readAdvanced

Airflow / Runbook

Sev1: after a deploy, Airflow DAGs disappear or fail to import and nothing runs

A release changed shared code, a requirement or a provider version, and now many DAGs show import errors, vanish from the UI or never get scheduled. Find the broken import, roll back or hotfix, catch up missed runs safely, and add the CI checks that stop it recurring.

4 min readAdvanced

Streaming & CDC / How-to

Advisory: batch, micro-batch or streaming - deciding how fresh data really needs to be

Real-time pipelines cost more to build and run, and many requests for "real time" don't need it. Turn freshness requests into explicit latency requirements, map them to batch, micro-batch or streaming, account for the operational cost of each, and use hybrid designs where only part of the data must be fast.

3 min readIntermediate

Governance / How-to

Advisory: cost allocation and showback for shared data platforms

Shared warehouses, clusters and capacities make it hard to see who drives cost. Choose allocation keys per platform, tag or separate compute by team, split shared costs fairly, start with showback before any chargeback, and use the numbers to drive optimisation rather than arguments.

3 min readIntermediate

Governance / Checklist

Advisory: running a well-architected review of a data platform

A structured review across reliability, security, cost, performance and operations finds the risks that build up in a data platform over time. Scope it, gather evidence before the workshop, use a question set tailored to data workloads, rate risks, and turn findings into a short, owned improvement plan.

3 min readIntermediate

Fabric & Power BI / How-to

Advisory: semantic layer and BI strategy - one definition of each metric across tools

When "revenue" means three things in three dashboards, trust in data drops. Decide where metric definitions live (BI semantic models, a headless semantic layer or platform metric views), how many BI tools to support, and how certified datasets, ownership and change control keep numbers consistent.

3 min readIntermediate

dbt & Quality / Cheat sheet

Advisory: structuring dbt projects - layers, naming, one project or many, and ownership

A dbt project that grows without structure becomes slow to build and hard to change. Use clear staging, intermediate and mart layers with naming rules, decide between a monolith and several projects with cross-project references, set ownership and access per group, and keep CI and environments consistent.

3 min readIntermediate

Fabric & Power BI / How-to

Optimization: faster Power BI semantic models - star schema, VertiPaq size and DAX

Slow Power BI reports usually come from a model that's too big or badly shaped, not from capacity. Measure with Performance Analyzer and VertiPaq Analyzer, move to a star schema, cut columns and cardinality, fix relationships, rewrite the slowest DAX, and use aggregations or Direct Lake where they fit.

3 min readIntermediate

Streaming & CDC / How-to

Optimization: Kafka Connect throughput - tasks, batching, converters and dead-letter queues

Connectors running one task, tiny batches and verbose JSON converters move far less data than the cluster can handle. Measure per-connector throughput and lag, raise tasks to match partitions, tune connector and client batch settings, pick efficient converters, use DLQs instead of stopping on bad records, and size the worker cluster.

3 min readIntermediate

Streaming & CDC / How-to

Optimization: Kafka producer and consumer tuning for throughput and latency

Most Kafka performance problems are client settings, not broker size. Measure where time goes, tune producer batching, linger and compression, keep idempotence and acks safe, tune consumer fetch and poll settings, scale consumers to partitions and check the broker side last.

3 min readAdvanced

Fabric & Power BI / How-to

Optimization: right-sizing Microsoft Fabric capacity - smoothing, workload placement and pause/resume

Fabric capacity sizing is about understanding capacity units (CU) over time, not peak minutes. Read the Capacity Metrics app correctly, find the items and operations that consume most, optimise them, separate workloads across capacities, set surge protection, pause non-production capacities and only then choose the SKU and commitment.

3 min readIntermediate

Streaming & CDC / How-to

Optimization: sizing Azure Event Hubs - tiers, throughput units, auto-inflate and partitions

Event Hubs namespaces are often sized once for a launch and never revisited, or throttle because partitions were chosen badly. Measure ingress, egress and events per second, choose the tier, set throughput units with auto-inflate and a plan to scale down, pick partition counts for consumer parallelism, and review Capture and retention costs.

3 min readIntermediate

dbt & Quality / Runbook

Sev1: a dbt --full-refresh wiped history from an incremental model

Recover an incremental dbt model that lost years of history because someone ran --full-refresh against a source that only keeps recent data. Restore from warehouse time travel, protect the model with full_refresh=false and fix the run process.

2 min readIntermediate

Streaming & CDC / Runbook

Sev1: Kafka offline and under-replicated partitions after a broker loss

Restore a Kafka cluster where partitions are offline or under-replicated after one or more brokers failed. Find affected partitions, bring brokers back, decide on unclean leader election only as a last resort, and rebalance safely.

2 min readAdvanced

Databricks & Spark / How-to

Transformation: Cloudera/Hortonworks Hadoop to a Databricks lakehouse

Plan the move from CDH/HDP/CDP clusters to Databricks on Azure or AWS. Map every Hadoop component to its lakehouse equivalent, migrate data to Delta, convert Hive/Impala SQL and Spark jobs, replace Oozie and Ranger, and run both in parallel before switching.

3 min readAdvanced

Streaming & CDC / How-to

Transformation: from nightly SFTP file drops to event-driven ingestion

Replace cron jobs that poll SFTP folders once a night with ingestion that reacts to each file as it lands. Use managed SFTP into object storage, storage events, Auto Loader or Snowpipe, file validation and a quarantine path.

3 min readIntermediate

Streaming & CDC / Runbook

Transformation: migrate a Kafka cluster from ZooKeeper to KRaft

Move a production Kafka cluster off ZooKeeper before ZooKeeper support disappears. Pre-checks, deploying KRaft controllers in migration mode, moving brokers, finalising, and the rollback window you get before finalisation.

2 min readAdvanced

Warehouses / Runbook

Transformation: Teradata or Netezza data warehouse to Snowflake

A practical migration plan from an appliance data warehouse to Snowflake. Inventory and usage analysis, schema and SQL conversion, historical data transfer, rebuilding loads, testing with reconciliation, cutover of BI tools and decommissioning.

2 min readAdvanced

Databricks & Spark / How-to

Databricks cost optimisation with system tables: find, attribute and cut DBU spend

Use system.billing tables to see where DBUs go by workspace, SKU, job, warehouse and team, then apply the levers that usually cut 20–40% — job compute instead of all-purpose, auto-termination, right-sizing, Photon where it pays, serverless, spot, and tags with budgets.

3 min readIntermediate

Databricks & Spark / How-to

Databricks operations monitoring: system tables, alerts and an ops dashboard

Build day-2 monitoring for a Databricks platform from system tables. Covers job failures and SLA misses, long-running and stuck jobs, cluster start failures, warehouse queueing, security events from the audit log, data freshness, and how to route alerts.

3 min readIntermediate

Databricks & Spark / Checklist

Databricks production go-live readiness checklist for pipelines and workloads

The checks to pass before a new Databricks pipeline, job or data product goes into production. Covers code and deployment, compute, data quality, security and access, reliability, monitoring and alerting, cost, documentation and handover to operations.

3 min readIntermediate

Databricks & Spark / How-to

Databricks tenant-to-tenant migration: strategy, scope and approach

Plan a move of Azure Databricks (or a Databricks account on AWS) from one tenant or account to another after a merger, divestiture or tenant consolidation. Covers why workspaces can't simply be moved, what has to be rebuilt versus copied, the target design, phases and the main risks.

3 min readAdvanced

Databricks & Spark / How-to

Delta tables on autopilot: liquid clustering and predictive optimization in Databricks

Replace hand-tuned partitioning, Z-ORDER and scheduled OPTIMIZE/VACUUM jobs with liquid clustering and predictive optimization. Covers choosing clustering keys, converting existing tables, automatic clustering, enabling predictive optimization by catalog, and checking what it did.

2 min readIntermediate

Airflow / Troubleshooting

Airflow tasks failing randomly: zombies, SIGKILL and retries

Read Airflow task logs and worker events to tell code failures from killed workers, zombie tasks and timeouts, and set retries, timeouts and resources so jobs recover on their own.

2 min readIntermediate

Warehouses / Troubleshooting

Snowflake queries are slow: queuing, spilling and pruning

Use query history and the query profile to tell warehouse queuing from spilling and poor partition pruning, then fix it with multi-cluster scaling, sizing or clustering.

2 min readIntermediate

Data Factory / Runbook

Azure Data Factory pipeline failure runbook

Find failed runs across factories with KQL, read activity error codes, fix self-hosted integration runtime problems and rerun from the point of failure.

3 min readIntermediate