Merge taking too much time and refresh is failing

Hi Anonymous,

Merging 7 million rows with another large table will always be slow in Power BI. Here are couple of options you can try:

Best approach - Merge at the source:

1. Use SQL/Database views: If both tables are from the same database, create a SQL view that joins them and import that single view into Power BI
2. Push the merge to the data source: This is 100x faster than Power Query merging

If you must merge in Power BI:

1. Reduce rows before merging: Apply filters to both tables BEFORE the merge step to reduce row count
2. Remove unnecessary columns: Keep only the columns you need from each table before merging
3. Check data types: Ensure join keys are the same data type (both text or both numbers) - mismatches cause performance issues
4. Use Table.Buffer: Before the merge step, add Table.Buffer(YourTable) to load the smaller table into memory first

Alternative architecture:

1. Use DirectQuery: Instead of importing, use DirectQuery mode - the database handles the join

7M x 7M rows is beyond Power Query's best practise. You really need database-level joining.

Best regards!

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