What are Join Types?
When you blend data in Whatagraph, you’re combining information from different sources (like Facebook Ads, Google Ads, or Google Analytics) into one report.
The way these sources are combined depends on the join type you choose. Think of join types as “rules” that decide:
Which data stays in the report
Which data gets left out
Whatagraph offers 4 join types. If you’re new, we recommend starting with the Full Outer Join, as it works for most use cases.
The 4 Join Types Explained
1. Full Outer Join (Best for beginners)
What it does: Includes all data from both sources, even if something doesn’t match.
Example: You connect Facebook Ads and Google Ads by Date. Even if one platform is missing a date, it still shows up in your report (with empty values filled as “null”).
Important: Start with this join type if you’re unsure which one to use. It’s the most flexible.
2. Left Outer Join
What it does: Keeps everything from your first source (left table), and only adds matching data from the second source.
Example: You want to show ad spend from Facebook Ads and Google Ads by Date. If Google Ads has a date that Facebook Ads doesn’t, that Google Ads value won’t appear in the report.
Tip: Use this when one source is your “main” dataset, and you only want extra details from the second.
3. Inner Join
What it does: Shows only matching data between both sources. Anything that doesn’t match is excluded.
Example: You track users in Google Analytics by User ID. You only want to see users who logged in on both Mobile and Desktop. Users who only used one device will be left out.
Note: This join type is stricter. It’s best when you only care about overlaps between sources.
4. Cross Join
What it does: Creates all possible combinations between two sources. This join doesn’t require a shared field (like Date).
Example: You want to calculate a sales ratio:
Total Purchases (Google Analytics) ÷ Total Spend (Facebook Ads).
This creates one combined value instead of matching by a shared dimension.
Important: Cross Join is more advanced, so use it only for special calculations.
Quick Summary
Full Outer Join → All data from both sources (recommended starting point).
Left Outer Join → All data from the first source, matching data from the second.
Inner Join → Only matching data from both sources.
Cross Join → All combinations, no shared field needed.