Interviewers and beginners both ask about the types of ETL testing. This guide lists the 12 main types with a one-line example each, then covers the related questions: types of validation, transformations, loads and defects in ETL testing.
12 Types of ETL Testing
| Type | What it checks | Example |
|---|---|---|
| Production validation (reconciliation) | Data in production matches the source | Daily total sales equal in source and warehouse |
| Source-to-target count testing | Row counts match after filters | 18 eligible orders → 18 fact rows |
| Source-to-target data testing | Values match for each key | Quantity and price identical per order |
| Data transformation testing | Business rules applied correctly | net_amount = quantity × price − discount |
| Data quality testing | Nulls, duplicates, ranges, formats | No negative amounts, valid emails |
| Metadata testing | Tables, columns, types, constraints | Column length matches the design |
| Data integration testing | Data from several sources combines correctly | Online and store sales merge without duplicates |
| Incremental load testing | Only changed data is loaded | Yesterday’s 50 new orders added once |
| Regression testing | New changes do not break old logic | Re-run all checks after a code change |
| Performance testing | Load finishes within the batch window | 10 million rows in under 2 hours |
| Report (BI) testing | Dashboards match the warehouse | Revenue by city equals a recalculation |
| User acceptance testing (UAT) | Business users confirm it meets needs | Finance signs off the monthly report |
Deeper guides: data transformation testing, data quality checks, metadata testing, ETL performance testing.
Types of Validation in ETL Testing
- Count validation: row counts by load date.
- Completeness validation: missing and extra keys (MINUS/EXCEPT).
- Field-level validation: column-by-column value comparison.
- Rule validation: derived columns recalculated from source.
- Referential validation: foreign keys exist in dimensions.
- Aggregate validation: sums and averages reconcile.
See data validation in ETL and data integrity testing.
Types of Transformations in ETL Testing
Common transformations you will test: filtering, cleansing (trim, case), standardisation (codes, units, currency), derivation (calculated columns), lookup (surrogate keys), aggregation, joining, splitting and merging columns, deduplication, type conversion and date/time-zone conversion. Each needs its own test; see data transformation testing.
Types of Load in ETL Testing
| Load type | What to test |
|---|---|
| Full (initial) load | Complete reconciliation of all history |
| Incremental (delta) load | Only new and changed rows; unchanged rows untouched |
| CDC (change data capture) | Inserts, updates and deletes all flow through |
| Reload / rerun | Rerunning a batch does not duplicate data |
Types of Defects (Bugs) in ETL Testing
Missing records, extra records, duplicates, wrong transformations, NULLs in mandatory columns, truncated values, wrong data types, wrong time zones, orphan foreign keys, wrong SCD history and report mismatches. Real examples with impact: ETL testing defect examples.
Learn Them Hands-On
Reading the list is easy; spotting these defects in real data is the skill. Try the free ETL testing end-to-end project, then build the full skill set with ETL Testing: From Beginners to Advanced.
ETL testing fundamentals: ETL testing scenarios · ETL testing techniques · ETL testing challenges · data transformation testing · data integrity testing · ETL test cases · ETL testing process
Frequently Asked Questions
What are the types of ETL testing?
The main types are production validation, source-to-target count and data testing, transformation testing, data quality testing, metadata testing, data integration testing, incremental load testing, regression, performance, report testing and UAT.
What are the types of validation in ETL testing?
Count, completeness, field-level, rule, referential and aggregate validation.
What are the types of loads in ETL?
Full (initial) load, incremental (delta) load, change data capture and reloads/reruns.
What types of defects are found in ETL testing?
Missing, extra or duplicate records, wrong transformations, NULLs, truncation, data type and time-zone errors, orphan keys, wrong SCD history and report mismatches.
Asim Noaman Lodhi
Certified Google Partner · QA Consultant · 12+ Years IT
QA consultant specializing in ETL testing and data quality. Trained 913+ students to transition into data testing roles through hands-on, real-world instruction.