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+# 5. Use TupleKey store data cache
+
+Date: 2023-04-27
+
+## Status
+
+Accepted
+
+## Context
+
+- Multiple accounts login at the same time in the same browser. The accounts will use the same database (`IndexDatabase`).
+
+## Decision
+
+- Use unique parameters (`AccountId`, `UserName`, `ObjectId(MailboxId/EmailId/StateType`) to form a unique `key` for storage (called `TupleKey`).
+- TupleKey has the format: `ObjectId | AccountId | User`;
+- `HiveDatabase` includes many `Box`. Each box is a `Map<Key, Object>` with `key=TupleKey`.
+
+## Consequences
+
+- The correct `mailbox` and `email` lists are obtained for each account