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Time Travel & History

Fluree's append-only architecture means every change is preserved. You can query data as it existed at any point in time.

How It Works​

Every transaction creates a new commit with a t value (transaction number). The data isn't overwritten—new commits build on previous ones.


t=1: Alice created with name="Alice"
t=2: Alice's email added
t=3: Alice's department changed to Engineering
t=4: Alice's email updated

Each commit is immutable. You can query any of these states.

Querying at a Specific Time​

Use the t option to query a historical state:


{
"from": "my-ledger",
"select": {"ex:alice": ["*"]},
"t": 2
}

Returns Alice as she existed after transaction 2.

Using Time Ranges​

Query a range of transactions:


{
"from": "my-ledger",
"select": {"ex:alice": ["*"]},
"t": {"from": 1, "to": 3}
}

History Queries​

See how an entity changed over time:


{
"from": "my-ledger",
"history": "ex:alice",
"t": {"from": 1}
}

Returns all changes to Alice from transaction 1 onward:


[
{
"f:t": 1,
"f:assert": [{"@id": "ex:alice", "name": "Alice"}],
"f:retract": []
},
{
"f:t": 2,
"f:assert": [{"@id": "ex:alice", "email": "alice@example.com"}],
"f:retract": []
},
{
"f:t": 4,
"f:assert": [{"@id": "ex:alice", "email": "alice.new@example.com"}],
"f:retract": [{"@id": "ex:alice", "email": "alice@example.com"}]
}
]

History of Specific Properties​

Track changes to a particular property:


{
"from": "my-ledger",
"history": ["ex:alice", "email"],
"t": {"from": 1}
}

Including Commit Details​

Get metadata about each commit:


{
"from": "my-ledger",
"history": "ex:alice",
"t": {"from": 1},
"commit-details": true
}

Returns commit timestamps, authors, and messages.

Use Cases​

Audit Trails​

Track who changed what and when for compliance.

Debugging​

See the exact state when a bug occurred.

Undo/Rollback​

Understand what to retract to reverse a change.

Analytics​

Analyze how data evolved over time.

Next Steps​