CODEWITHSUNDEEP
firebasegoogle-cloud-firestore
mcliedtk
mcliedtk

Reputation: 1031

Does Firebase remove collection indexes when a collection becomes empty?

When a collection is deleted from Cloud Firestore, its indexes are deleted along with it. I presume that when a collection goes from one or more documents to zero documents that its indexes are preserved. However, in the Cloud Firestore UI, when a collection goes from one document to zero the collection disappears from the root collections tree. Again, I presume this is an artifact of the Cloud Firestore UI, but it got me wondering whether something more happens when a collection becomes empty (as opposed to the collection being deleted outright).

Can you please help clarify what happens (if anything) when a collection goes from one or more documents to zero in Cloud Firestore? Do I need to be worried about losing any indexes when this occurs?

Upvotes: 1

Views: 1004

Answers (3)

Frank van Puffelen
Frank van Puffelen

Reputation: 599716

Some great answers by LeadDreamer and Doug already, but one more thing you seem to be curious about: deleting all documents from a collection does not affect the index definitions for that collection. So if you later add documents to the collection again, the same index definitions will still apply.

Upvotes: 1

Doug Stevenson
Doug Stevenson

Reputation: 317750

When a collection goes from 1 to 0 documents, all that happens is that the document is gone, and nothing else. The UI sees no reason to display a collection when there is nothing to show.

Collections don't really "exist". They are just ways to organize documents for the purpose of making queries. What you see in the console is just there to help you visualize the contents of the database. Collections will apparently spring into "existence" when a document is first created, and just as quickly disappear when there are none. They do not work like directories in a filesystem.

An index is just a way of telling Firestore that you have special query needs for documents in a certain named collection or collection group. The index simply enables the query against the documents in the collection or collection group that you name. The index works without requiring any documents to index, and it will continue working no matter how many documents exist.

Upvotes: 1

LeadDreamer
LeadDreamer

Reputation: 3499

I'm neither Googler nor Firebaser, BUT...

Firestore indexes documents, not collections - the collection paths are an organizing principle more than physical entities. The "collections" are part of the path to documents, and it's the paths and the document fields that end up indexed.

Case in point: you can actually delete a collection while child documents remain, and they will still be indexed with the collection name/ID as part of their path - you'll see this in the console with the collection (and any interstitial document) names italicized.

Upvotes: 2

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