Error: "SQL Dialect does not support Symmetric Aggregates with percentiles, field ignored"

[sam8]

Knowledge Drop

Last Tested: March 2021

Looker’s percentile and median measure types employ some complex sql to perform percentile logic at the aggregate level rather than in a window function. To prevent fanout through joins, Looker needs to employ percentile_distinct, but this hasn't yet been built out for every database we support.

Docs has an up to date list of what databases this is supported for, and there is a feature request in Pendo to support this globally.

Workarounds

1. Use `median` or `percentile` function in table calculations.
2. Create a derived table which computes the median.

This content is subject to limited support.