[Solved] What will happen if you try to write a document with the same ID twice in Firestore on GCP? — Ans: The second write overwrites the first document | GCP

GCP - Cloud Firestore and Bigtable

What will happen if you try to write a document with the same ID twice in Firestore on GCP?

AFirestore throws an error and rejects the second write

BThe second write overwrites the first document

CFirestore creates a duplicate document with a new ID

DThe first document is deleted automatically

Step-by-Step Solution

Solution:

Step 1: Understand Firestore document ID uniqueness
Document IDs are unique keys; writing with the same ID replaces the existing document.
Step 2: Confirm Firestore behavior on duplicate IDs
Firestore does not throw an error but overwrites the existing document with new data.
Final Answer:
The second write overwrites the first document -> Option B
Quick Check:
Same document ID write = overwrite [OK]

Quick Trick: Same ID write replaces document in Firestore [OK]

Common Mistakes:

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