Audit sources and questions
We profile the source systems and the decisions the warehouse has to support. Grain, keys, late-arriving records, soft deletes and the true update frequency of each table are established before anything is designed.
Data warehousing
Data Warehouse Services
Appsierra designs, builds and modernises cloud data warehouses on Snowflake, BigQuery, Amazon Redshift and Azure Synapse. We model the warehouse layer properly — dimensional or Data Vault, depending on how volatile your sources are — then build ELT pipelines with dbt, change-data-capture ingestion, orchestration, lineage and automated data-quality tests so the numbers your business reports can be trusted.
Appsierra · Data warehouselive
Dimensional and Data Vault modelling
ELT with dbt and CDC ingestion
Snowflake, BigQuery, Redshift, Azure
Data-quality tests and lineage
dbttested ELT
Multi-cloudwarehousing
7 daysto start
Our process
How does a data warehouse project run?
Model first, load second. Reversing that order is how warehouses end up as expensive copies of the source systems.
Model the warehouse layer
Stable, well-governed sources get a Kimball dimensional model with conformed dimensions and slowly changing dimension handling. Volatile, many-source estates get Data Vault 2.0 hubs, links and satellites, with dimensional marts served on top.
Build ingestion and ELT
Batch and change-data-capture ingestion lands raw data; dbt transforms it in-warehouse with version-controlled models, tests and documentation; orchestration handles dependencies, retries and backfills — often alongside a wider cloud integration layer.
Govern, tune and hand over
Access control, row-level security, PII masking, lineage and cost guardrails go in before rollout, with runbooks and enablement so your team owns it — including on Azure Synapse and Microsoft Fabric estates via our Microsoft consulting services.
Why do enterprise data warehouse projects fail?
The usual failure is not technical capacity. Cloud warehouses will happily store and scan whatever you give them. The failure is that data is copied in without an agreed grain, without conformed dimensions, and without history handling — so every new report re-implements the same business logic slightly differently, two dashboards disagree, and confidence in the warehouse quietly collapses. Once that happens, teams route around it with extracts and spreadsheets, and the platform becomes an expensive staging area.
This page is specifically about the warehouse layer: how data is modelled, stored, transformed and validated. Two neighbouring disciplines matter and are covered separately. Our data analytics services cover what happens above the warehouse — business intelligence, dashboards, metrics definitions and analytical products built on the modelled data. Our data platform engineering services cover the surrounding platform: streaming, lakehouse storage, machine-learning feature pipelines and the operational tooling that a whole data estate runs on. If you need one modelled, trustworthy reporting layer, this is the page you want; if you need the wider platform or the analytics on top, follow those links instead.
Reports that disagree
Two dashboards giving different revenue figures is almost always a modelling problem: no conformed dimension, no agreed grain, and business logic duplicated in each report instead of held once.
Pipelines that break silently
A schema change upstream, a late-arriving file or a duplicated key can pass through an untested pipeline and reach a board pack before anyone notices.
Costs nobody predicted
Oversized warehouses, unpartitioned scans, always-on clusters and full refreshes of tables that only need increments turn a consumption bill into a surprise.
History you cannot reconstruct
Overwriting records loses the ability to answer what the business looked like last quarter — an expensive gap when audit, regulation or trend analysis asks for it.
Coverage
What do our data warehouse services cover?
Modelling, ingestion, transformation, orchestration, governance and the tests that prove the numbers.
Warehouse design and data modelling
Star and snowflake schemas, conformed dimensions, fact grain definition, slowly changing dimensions, bridge tables for many-to-many relationships, and Data Vault 2.0 where source volatility makes raw-layer stability worth the extra structure.
Cloud platform build and migration
Greenfield builds and migrations onto Snowflake, Google BigQuery, Amazon Redshift, Azure Synapse and Microsoft Fabric, including lift-and-reshape moves off ageing on-premise appliances and legacy SQL Server or Oracle warehouses.
Ingestion and change data capture
Batch, incremental and log-based CDC ingestion using tools such as Fivetran, Airbyte and Debezium, with schema-drift handling, watermarking, replay and idempotent loads so a re-run does not duplicate a day of data.
ELT engineering with dbt
Version-controlled transformation models in staging, intermediate and mart layers, with incremental materialisations, snapshots for history, macros for reuse, and generated documentation and lineage graphs the analytics team can actually read.
Orchestration and reliability
Dependency-aware scheduling in Airflow, Dagster or Azure Data Factory, with retries, alerting on freshness and volume anomalies, and backfill procedures that do not require someone to hand-edit production data at midnight.
Data quality and validation testing
Automated tests for uniqueness, referential integrity, nullability, accepted values, row-count deltas and reconciliation against source — the discipline we extend into full big data testing on large estates.
How do we control warehouse cost and prove the data is right?
Consumption pricing rewards good design and punishes lazy design immediately. An always-on cluster, a nightly full refresh of a table that only gains a few thousand rows, or an unpartitioned scan across years of history will each show up on the bill within a month. We treat cost as an engineering constraint with a target attached, then design to it: right-sized compute with auto-suspend, incremental models, partitioning and clustering on the columns queries actually filter, and materialised aggregates where the same heavy query runs repeatedly.
Trust is the other half. A warehouse is only useful if people stop checking its figures against the source system by hand, and that confidence has to be earned with tests rather than asserted. Every model carries assertions on keys, nullability, accepted values and referential integrity; freshness checks fail the run when a source has not landed; and financial and volume totals are reconciled against source. When a check fails, the run stops and an owner is alerted, so a bad load is corrected before it reaches a board pack rather than after someone questions the number in a meeting.
Spend that matches workload
Right-sized virtual warehouses with auto-suspend, partitioning and clustering on the columns actually filtered, materialised aggregates for repeated heavy queries, and separation of loading from reporting compute.
Incremental by default
Full refreshes are the most common avoidable cost. Models are built incrementally with late-arriving-data handling, so a nightly run processes what changed rather than re-reading history.
Governance and lineage in place
Role-based access, row-level and column-level security, PII masking policies for non-production, and catalogued lineage so anyone can trace a reported figure back to its source table.
How we work
How does an Appsierra data warehouse engagement work?
Senior data engineers, agreed targets for freshness and cost, and a first modelled increment early.
Senior-led pods
A named senior data engineer owns the outcome, and you talk directly to the people modelling and building the warehouse.
Productive in about 7 days
Source access, environment setup and agreed scope happen in week one, with the first modelled and tested increment delivered from week two.
AI-accelerated, expert-supervised
AI tooling speeds up profiling, SQL migration and test scaffolding, and senior engineers review every model before it feeds a report.
Outcome-aligned scope
We agree measurable targets — freshness, reconciliation tolerance, query latency, cost ceiling — up front instead of billing open-ended hours.
Security and IP first
ISO 9001 and ISO 27001 certified, CMMI Level 3 aligned and NDA-first, with data handling and masking rules agreed before any source is connected.
Flexible engagement
Scale the pod up for a migration and down for steady-state maintenance, without a long lock-in on either side.
Data warehouse FAQs
What are data warehouse services?
Data warehouse services cover the design, build, migration and ongoing engineering of the central store where an organisation's reporting data lives. The work includes profiling source systems, choosing and implementing a data model, building ingestion and change-data-capture pipelines, transforming data with tested and version-controlled ELT code, orchestrating runs, applying access control and lineage, tuning storage and compute cost, and validating that the resulting figures reconcile with the systems they came from.
What is the difference between a data warehouse, a data lake and a lakehouse?
A data warehouse stores modelled, query-ready structured data with enforced schema and defined grain, which is what reliable reporting needs. A data lake stores raw files of any structure cheaply, which suits exploration, machine learning and retention but offers no guarantees about consistency. A lakehouse keeps lake-style open storage while adding warehouse-style table formats, transactions and schema enforcement through technologies such as Delta Lake, Apache Iceberg and Hudi. Most mature estates use a combination rather than choosing one.
Should we use dimensional modelling or Data Vault?
Dimensional modelling, in the Kimball style, is usually the right default: star schemas with conformed dimensions are fast to query, easy for analysts to understand, and map cleanly to business intelligence tools. Data Vault 2.0 earns its extra complexity when you integrate many volatile source systems, need full auditable history of every change, or face frequent source restructuring. A common answer is both: Data Vault in the raw and business layers for resilience, with dimensional marts served on top for consumption.
Which cloud data warehouse platform should we choose?
The honest answer depends on your existing estate and skills more than on a feature comparison, because the major platforms have converged. Snowflake separates storage from compute cleanly and runs across clouds. BigQuery suits Google-centric estates and serverless, ad-hoc scanning. Redshift fits deep AWS integration. Azure Synapse and Microsoft Fabric fit organisations already standardised on Microsoft. We assess workload shape, concurrency, data-residency obligations and the skills you can hire, then recommend one and explain the trade-off.
How do you keep data warehouse costs under control?
Cost problems are usually design problems. We right-size compute with auto-suspend so idle clusters stop billing, separate loading from reporting workloads, and partition and cluster tables on the columns queries actually filter. Transformations are built incrementally rather than as nightly full refreshes, repeated heavy aggregations are materialised, and unused tables and stale pipelines are retired. Spend is then monitored per workload with alerts, so a runaway query or an accidental full-table scan is caught in days rather than at the end of the billing cycle.
How do you test data quality in the warehouse?
Data-quality tests run as part of the pipeline, not as a separate manual check. Every model carries assertions for primary-key uniqueness, referential integrity, nullability and accepted values, plus freshness checks that fail if a source has not arrived. Row counts and financial totals are reconciled against the source system, and anomaly checks flag unexpected volume or distribution shifts. Failures stop the run and alert an owner, so a broken load is corrected before it reaches a dashboard rather than after someone questions a number.
Talk to a senior engineer
Get a free QA & engineering consult
Tell us what you're building, testing or scaling — a senior engineer sends a short, honest read and a low-risk way to start.
- Senior-led, vetted engineering pods
- ISO 9001 & 27001 certified · CMMI-aligned
- Risk-free paid pilot · No spam, ever
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Ready to build a warehouse the business trusts
Whether you are starting fresh, migrating off an ageing on-premise warehouse, or trying to make an existing cloud warehouse cheaper and more reliable, we will scope the model, the pipelines and the tests. Contact us to start with a short data audit.