So you've got some data that's needed in several docs but you don't want to copy/paste it every time there's an update, cross-doc might be the answer.
What is Cross-doc?
Cross-doc creates a connection between two docs and tables so data can be copied from the source to a sync doc. Think of the two tables as separate from each other, each living in their own doc, and cross-doc as the connection that lets you pull data over from one to the other. This can happen on either be a time-based or manual trigger.
Where Cross-doc Works Best
One doc sends data to many other docs
Example: A company roster used across other company docs
Where Cross-doc may not be the best fit
Many docs send data to one doc
This is doable, but it takes few more steps to merge data in the resulting doc since each table synced in will be its own separate table.
Are the two tables synced?
Not really. Cross-doc copies the data over from one table to the other, but there is not real-time communication back and forth between the two tables. There is a source doc and a sync doc and data only moves one way.
Can I update the Source Doc from the Sync Doc?
You can with Cross-doc Actions. This is a connection that allows you to update information in the Source Doc from the Sync Doc, usually through the use of a button.
Is data available in real-time?
No. Cross-doc pulls data from one table into another table based on either a time trigger or a manual click to re-sync. The data is also pulled from the most recent snapshot, which is how docs are saved as backups on regular intervals. This happens in seconds, not hours, but the larger a doc gets, the longer it will take to snapshot.
Can I delete rows in a sync table?
No. Rows can't be added or deleted in a sync table. This is data that is copied over from the source table.
Can I add columns to a sync table?
Yes! You can add columns to a cross-doc sync table. This allows you to extend a more simplified data set and customize it to your needs.
One caveat is if the table ever becomes disconnected, you may lose the data in these extra columns when it re-syncs. To avoid this, there is a toggle in the cross-doc settings to "Keep un-synced rows" which will keep what was there before when the re-sync happens. There is also an extra hidden checkbox column called "Synced" that will let you see which rows are actively synced over and which ones were disconnected.