Overview

In some scenarios it’s desirable to change the “preferred code generator” Dremio uses to compile functions in a query execution. This article describes how to change this for select functions without changing the option system-wide.

Applies To

All currently supported Dremio Software.

Details

By default, Dremio uses the Gandiva compiler for functions compiled and sent to executors in fragments. In some cases, it is preferable to switch the code generator to compile using the native Java code compiler. This can be done system-wide with a support key change but may come with a performance tradeoff leading to query latency.

Cluster operators can disable specific SQL functions instead to limit the impact. To do this:

1. Navigate to the “Support” tab in the Dremio UI.
2. Enter the support key exec.disabled.gandiva-functions in the text box next to the “Show” button, then click the “Show” button.
3. In the text box that will appear with the support key as a label, enter one or more functions as a comma-separated list, and click the “Save” button.

Alternatively run the following SQL:
alter system SET "exec.disabled.gandiva-functions" = '<function>,<otherFunction>';

This can be verified on the “Support” tab in the Dremio UI.