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Should you use a data lake or a data warehouse?

Choose a data warehouse when the immediate need is repeated analysis of prepared tables. Use lake storage to retain varied records for questions that may develop later. A lakehouse combines lake storage with managed analytical tables. Choose by testing how the architecture supports a useful business workflow, including its preparation, permissions and continuing operation.

A monthly report uses established measures. When one changes unexpectedly, an analyst needs the detailed records behind it. Retaining those records also leaves room for later questions that the first report did not anticipate.

Those needs can be addressed through a first workflow that people can use. Its records show what must be retained, while its questions show what needs preparation. Later applications can extend that foundation.

The work the architecture serves

A useful architecture supports both a dependable answer and an investigation of its source records. Choosing the storage pattern settles part of that design. Source access, preparation, definitions and support determine whether the records become useful in daily work.

A recurring SQL report benefits from tables designed around its relationships and measures. Research may need more detailed records or files whose future use is still open. For either use, the access design distinguishes the people who may inspect source records from those who receive a prepared result.

The familiar lake and warehouse categories describe these tendencies. Products increasingly support several patterns, so the category alone cannot settle a purchase. The evaluation needs to follow the actual records through to the people who will use them.

Source records and prepared measures

Source records preserve detail for later questions. Prepared measures spare people from repeating the same calculations each time a report is needed. A lake commonly retains files and records while their future uses are still being explored. A warehouse organizes data for analytical queries, including regular business reporting.

Suppose an inventory review shows an unexpected change. The prepared measure gives the reviewer a consistent stock balance. The underlying movement records let an analyst examine receipts, transfers and adjustments separately. A correct balance alone cannot show which movement caused the change. The retained detail makes that investigation possible.

Retention still needs a purpose. Keeping every version indefinitely can increase storage and maintenance work without improving the investigation. The design should distinguish the history needed for explanation from intermediate data that can be reproduced.

Preparation also carries decisions. A stock movement may be recorded when goods leave a site or when they arrive elsewhere. A report needs a consistent treatment of goods in transit. Neither storage pattern decides that business meaning automatically.

What a lakehouse adds

A lakehouse organizes data in lake storage into managed tables for analysis. A tool reads a defined table state, and the wider architecture can retain both source records and prepared data. Reports can use prepared tables while engineers investigate the transformations behind them.

Apache Iceberg is one table format used for this purpose. Its metadata and snapshots describe the files belonging to a table. Compatible engines can work with those tables, allowing the stored format and the query engine to be separate choices.

The evaluation needs to test each required operation. A compatible read does not establish that the same engine can change the schema or write the required update. A planned engine and catalog combination must support the work that will run through it.

Open tables also need maintenance. The operating team must manage table changes and retained snapshots, and confirm how a new state becomes available to readers. The table format provides mechanisms for that work; the implementation determines how they serve a reporting deadline.

Definitions across tools and teams

Two tools can read the same table and answer different questions. A dashboard that excludes cancelled orders measures a different population from an analyst's query that includes them. The data can be identical while the reported measure differs.

A business model records those decisions together. It records the intended population, dates, relationships and calculations. Reports and plain-English questions can then use the same defined measure, with the underlying query available for investigation.

The tools may also refresh at different times. A reviewer needs the reporting period and refresh state to determine whether the apparent movement comes from the business or from different available records.

These details deserve attention during architecture selection because they affect trust in the result. A storage demonstration that omits business definitions leaves an important part of the delivery untested.

Test the complete reporting path

An architecture trial should show how a result survives an ordinary failure or correction. The useful test starts with source records, follows their preparation and ends with a recipient using the output. Query speed is one observation within that test.

Include a late source file and a corrected historical record. The trial should reveal whether the report shows its state, whether processing can resume and whether a correction changes the intended period. Those cases expose operating work that a clean demonstration can hide.

Access should also be tested through the intended interface. A successful administrator query does not establish what a department manager can see. Use the recipient's role to confirm that permitted records appear and restricted records remain inaccessible.

The trial needs an understandable acceptance decision. The business owner can judge whether the measure and explanation support the work. The delivery team supplies the technical evidence and resolves defects before the workflow becomes routine.

Plan for continuing operation

Someone must maintain the architecture as sources, definitions and users change. That responsibility includes recovering failed work and helping people interpret the result. These responsibilities exist whether the organization chooses a warehouse, a lakehouse or a combination.

Databasin combines its platform with the work of defining the outcome, building the workflow and helping people use it. Its team can operate the result, provide monthly support hours or remain on call. An existing Databricks, Snowflake or Fabric environment can remain part of the arrangement.

The organization also chooses how much operation it wants to own. An internal team with the required capacity may want direct control of the components. A team seeking an implemented business result may value a provider taking responsibility across the data, process and rollout.

That decision should remain connected to the first workflow. The architecture is useful when it supports today's result and a manageable path for the questions that follow.

Example: supporting a monthly stock review

This illustrative September stock review follows a closing balance back to receipts, transfers and adjustments, including an extract that arrives late.

StageData and timingWhat the review can establish
Retain inputsSeptember receipts, transfers and adjustments, measured in unitsTrace each month's balance to its receipts, transfers and adjustments
Prepare the measureClosing balance by site as of 30 SeptemberRead the closing balance for the same date at every site
Record an exceptionOne site's final extract arrives on 2 OctoberMark the review Incomplete until the late extract is processed
Publish the resultAll required sites pass the agreed checksMark the review Ready when all required sites are covered
Investigate a changeFollow a site total back to movement recordsInspect transfers and adjustments behind the changed site total

A warehouse or lakehouse can support the prepared measure. The design also preserves the detail and processing state needed to explain it.

Decisions before choosing storage

  1. Name the first workflowChoose the first report or investigation and agree who will accept it. That result gives the architecture trial a practical purpose.
  2. Decide what history mattersAgree which earlier periods and corrections the analysis must explain. Those decisions establish what source history the implementation needs to retain.
  3. Set acceptance conditionsApprove the measures, access rules and failure behavior the trial must demonstrate before the workflow enters regular use.
  4. Choose the operating arrangementDecide how much ongoing responsibility stays inside the organization and where a delivery partner should operate or support the work.

Sources

AWS, Data Lake vs Data Warehouse vs Data Mart, accessed 2026 · aws.amazon.com/compare/the-difference-between-a-data-warehouse-data-lake-and-data-mart

Apache Iceberg, Introduction, accessed 2026 · iceberg.apache.org/docs/latest

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