For this article, we'll use some terms you won't see in the product. They describe how to think about and set up bases when you link records across Airtable bases.

• Hub base - A base that collects data synced in from several other bases.

• Spoke base - A base that syncs a view into a hub base. A hub-and-spoke setup has one hub and several spokes.

• Reporting base - A hub base used mainly to answer questions across its sources, usually with rollups rather than day-to-day record editing.

Linking records across synced bases overview

A hub-and-spoke setup syncs several spoke bases into one hub base. The records come over, but the links between them often don't. A linked record field arrives as plain text unless its linked table is synced too (using the Sync linked tables option). And any link field you create in the hub belongs to the hub only. It doesn't sync back to the spokes. Most of the work in a hub base is rebuilding those relationships on purpose.

This article covers the three patterns that come up most often:

• Turning synced text back into real links in the hub.

• Joining two independently synced tables so you can roll values up across them.

• Reporting in a spoke base's source on which downstream bases use its records.

If you're setting up the sync itself, start with Getting started with Airtable sync instead.

Before you start setting things up

Decide early whether a hub table needs more than one source. Multi-source syncing and linked-record syncing can't be used on the same table, and switching later is more difficult.

• A synced table can't have more than one source if it contains a synced linked record field, or if a synced linked record field in another synced table links to it. When that's the case, Add records from another source doesn't appear for that table.

• So if two synced tables in the same destination base are connected by a synced linked record field, neither table can add another source.

• It works the other way too: a table that already has multiple sources can't be the linked table for a synced linked record field.

• Turning linked records on is hard to undo. When you change plain text fields to linked records during sync setup, Airtable warns that this can't be undone after import. The restriction follows the linked record fields, not the setting. Turning off "Sync linked tables" in the source won't make the table eligible for multi-source syncing while those synced linked record fields still exist in the destination.

For the full picture, see Multi-source syncing in Airtable.

Turning synced text back into links in the hub

When a linked record field syncs without its linked table, the hub gets the linked records' primary field values as plain text. To turn them back into links, sync the linked table into the hub too, then convert the text field.

1. Sync the linked table into the hub

   1. In the spoke base, open the table the linked record field points to. Create a view with the records and fields the hub needs, and turn on syncing for that view. Records left out of the view can't be linked.

   2. In the hub base, sync that view in as its own table.

2. Convert the text field

   1. In the hub, open the table with the synced text field. Open the field's menu and choose Convert to linked records.

3. Review anything that used the text values - Filters, sorts, formulas, and automations that treated the field as text may behave differently now that it holds linked records. Check them after converting. You can also add lookups and rollups through the new linked record field.

Joining two synced tables in a reporting base

When two tables sync into the same reporting base from different sources, they aren't connected. Link them, then summarize across the link.

1. Sync both sources in

   1. In each source base, create a view with the records and fields the reporting base needs, and turn on syncing for that view. If the report needs every record, leave the view unfiltered.

   2. In the reporting base, sync each view in as its own table.

2. Link the two synced tables

   1. In the detail table, find the field that holds the summary table's primary field value as text. For example, a content record that stores its objective's name.

   2. Add a field to the detail table, set its type to Link to another record, and choose the summary table.

   3. Copy the text values and paste them into the new field to create the links. A value only links if it matches a primary field value in the summary table.

3. Roll up the value

   1. On the summary table, add a Rollup field that uses the link you just created and summarizes a field from the detail table. For example, the sum of engagements across each objective's content.

   2. One link takes one rollup. You need a second rollup only when the value lives one more link away. In that case, roll it up onto the detail table first, then roll that field up onto the summary table.

4. Limit the rollup to a condition

   1. Open the rollup field's settings.

   2. Turn on Only include linked records from the {Insert your table here} table that meet certain conditions.

   3. Add a condition based on a field in the detail table. For example, a date field that is within this calendar year.

      1. There's no fiscal-year option. To filter by fiscal year, add a formula field to the detail table that marks records in the current fiscal year, then use that field in the condition.

For the full set of options, see Applying conditions to count, lookup, or rollup fields in Airtable.

Reporting on downstream usage from the source base

In this setup, Airtable sync moves data one way. Linked record fields, lookups, and rollups built on synced records in a destination base exist only in that base, and the source base has no record of them. A hub that syncs a library to eight team bases can't see which team linked to which library record.

To answer that from the hub, each spoke has to send usage information back. You have two options outlined in the table below.

Whichever you choose, have each spoke stamp its own identity onto the records it sends back — a formula or single select naming the spoke base — so the hub can tell the sources apart after they land in 1 table.

If you take the automation route, see Two-way syncing in Airtable for what a destination is allowed to write back to its source.

Limitations

• Linked-record syncing and multi-source syncing can't be used on the same synced table.

• Links, lookups, and rollups created in a destination base aren't visible in the source base.

• If you sync linked records, links are kept by record, not by name. If you instead change a synced text field into a linked record field, values match on the linked table's primary field. Duplicate names can match the wrong record, and values with no match create new records.

• Records can't be created through two-way sync in a multi-source synced table.

• A rollup reads across one link. To summarize across two hops, add a rollup or lookup in the middle table, then roll up that field.

• Sync limits vary by plan. See Sync limitations in Getting started with Airtable sync.

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