Based on the knowledge sources provided, I can answer your question about experiment IDs in GrowthBook. Experiment IDs in GrowthBook are intended to be unique identifiers, but they are not automatically guaranteed to be unique across all projects. Here's what we can conclude from the available information: 1. Experiment IDs are meant to be unique within the context of GrowthBook. As mentioned in the [Experiment Assignment Queries](https://docs.growthbook.io/app/datasources#experiment-assignment-queries) documentation, the experiment_id is "a unique identifier, usually a string like 'my-cool-experiment', for an experiment within GrowthBook." 2. However, there is no automatic system-wide enforcement of uniqueness across all projects. This is evident from a conversation where a user encountered a warning when trying to create an experiment with an ID that already existed:

Warning: An experiment with that id already exists. To continue anyway, click 'Save' again.

[Source](https://linen.growthbook.io/t/14155545/hi-i-m-seeing-this-when-trying-to-add-a-new-experiment-with-) 3. The fact that GrowthBook allows users to proceed with creating an experiment with a duplicate ID (after showing a warning) suggests that uniqueness is not strictly enforced across the entire system. 4. It's worth noting that while experiment IDs may not be automatically unique across all projects, it's generally a good practice to keep them unique to avoid confusion and potential issues with data analysis. To ensure uniqueness, especially when working across multiple projects, it's recommended to use a naming convention that includes project-specific identifiers or to double-check for existing IDs before creating new experiments.