DirectQueryCapabilities.From

In this article, we will delve into the M code behind this function, exploring its syntax, common use cases, and tips for optimizing its performance.

Syntax

The syntax for `DirectQueryCapabilities.From` is relatively simple. It takes in a single argument, which is a record that defines the capabilities of a DirectQuery source. The record has the following fields:

– `SupportsTop`: A boolean field that indicates whether the DirectQuery source supports the Top clause.

– `SupportsGroupBy`: A boolean field that indicates whether the DirectQuery source supports the Group By clause.

– `SupportsOrderBy`: A boolean field that indicates whether the DirectQuery source supports the Order By clause.

– `SupportsAggregates`: A boolean field that indicates whether the DirectQuery source supports aggregate functions such as SUM, AVG, MIN, and MAX.

– `SupportsJoin`: A boolean field that indicates whether the DirectQuery source supports Join operations.

– `SupportsInnerJoin`: A boolean field that indicates whether the DirectQuery source supports Inner Join operations.

– `SupportsLeftOuterJoin`: A boolean field that indicates whether the DirectQuery source supports Left Outer Join operations.

– `SupportsRightOuterJoin`: A boolean field that indicates whether the DirectQuery source supports Right Outer Join operations.

– `SupportsFullOuterJoin`: A boolean field that indicates whether the DirectQuery source supports Full Outer Join operations.

– `SupportsCrossJoin`: A boolean field that indicates whether the DirectQuery source supports Cross Join operations.

– `SupportsCount`: A boolean field that indicates whether the DirectQuery source supports the Count function.

– `SupportsDistinctCount`: A boolean field that indicates whether the DirectQuery source supports the Distinct Count function.

– `SupportsPercentile`: A boolean field that indicates whether the DirectQuery source supports the Percentile function.

– `SupportsMedian`: A boolean field that indicates whether the DirectQuery source supports the Median function.

– `SupportsMode`: A boolean field that indicates whether the DirectQuery source supports the Mode function.

– `SupportsVariance`: A boolean field that indicates whether the DirectQuery source supports the Variance function.

– `SupportsStandardDeviation`: A boolean field that indicates whether the DirectQuery source supports the Standard Deviation function.

Common Use Cases

`DirectQueryCapabilities.From` is often used when defining the capabilities of a custom data connector or when troubleshooting issues with an existing connector. By passing in a record that accurately describes the capabilities of the DirectQuery source, you can ensure that the query optimization engine is making the best decisions when generating SQL statements.

For example, if you know that the DirectQuery source does not support aggregate functions, you can set the `SupportsAggregates` field to `false`, which will prevent the query optimization engine from generating SQL statements that contain aggregate functions. This can significantly improve query performance and reduce the chances of encountering errors during query execution.

Similarly, if you know that the DirectQuery source supports Join operations but not Left Outer Joins, you can set the `SupportsJoin` and `SupportsLeftOuterJoin` fields accordingly, which will prevent the query optimization engine from generating SQL statements that contain Left Outer Join operations.

Performance Optimization

When using `DirectQueryCapabilities.From`, it is important to ensure that the record accurately reflects the capabilities of the DirectQuery source. Incorrect or incomplete information can lead to suboptimal query performance and errors during query execution.

One way to ensure the accuracy of the record is by testing the DirectQuery source using a tool such as SQL Server Management Studio or a similar database management tool. By executing sample queries against the DirectQuery source and observing the responses, you can determine which capabilities are supported and which are not.

Another way to optimize performance is by setting the `SupportsTop` field to `false` if the DirectQuery source does not support the Top clause. This can significantly improve query performance by preventing the query optimization engine from generating SQL statements that contain the Top clause.

`DirectQueryCapabilities.From` is a powerful function within Power Query that allows you to define the capabilities of a DirectQuery source. By accurately describing the capabilities of the source, you can optimize query performance and reduce the chances of encountering errors during query execution.

When using `DirectQueryCapabilities.From`, it is important to ensure that the record accurately reflects the capabilities of the DirectQuery source. Testing the source and setting the `SupportsTop` field to `false` if necessary can help improve performance.

Overall, `DirectQueryCapabilities.From` is a valuable tool for any data analyst or business intelligence professional working with Power Query.

Power Query and M Training Courses by G Com Solutions (0800 998 9248)

Upcoming Courses

Contact Us