User Guide

Everything you need to install, configure, and build with Montycat — from getting started to governance, advanced operations, and security.

Snapshots

Snapshots overview

Montycat provides snapshotting capabilities for in-memory keyspaces, enabling you to persist their state to disk without sacrificing performance.
Snapshots are incremental and efficient—they are only triggered when changes (insertions, updates, or deletions) occur within a keyspace.
Snapshots serve as periodic checkpoints: they capture the current state of a keyspace according to the interval you configure.
On startup, in-memory indexes are not loaded from snapshots but reconstructed in the background, ensuring full data consistency.

You control snapshotting with two levels of configuration:

  • Global snapshot rate: Defines the system-wide interval (in seconds) at which Montycat checks for changes and writes updated snapshots to disk.
  • Per-keyspace snapshot settings: Enable, disable, or clean snapshots on a per-keyspace basis.

montycat snapshot-rate 60

or

montycat console
> snapshot-rate 60

exit

or set it in Docker:

FROM montygovernance/montycat:latest

# MONTYCAT_SNAPSHOT_RATE default is 0 seconds (snapshot disabled)
# Override it by setting it to your desired value in seconds
# Setting it to 0 will disable snapshots
# It's recommended to set it to at least 60 seconds for production systems

ENV MONTYCAT_SNAPSHOT_RATE=60

You can also set the snapshot rate directly from the client (requires superowner credentials):

# Set the DB-wide snapshot rate in seconds (0 disables snapshots).
# Requires superowner credentials.
await connection.set_snapshot_rate(60)

# {"status": True, "payload": "Snapshot rate updated", "error": None}

Enable snapshots

You can enable snapshotting for individual in-memory keyspaces.

montycat console
> do-snapshots-for-keyspace store <store name> keyspace <keyspace name>

exit
from montycat import Keyspace
from connection import connection #connection.py

class EmployeesInMem(Keyspace.InMemory):
    keyspace = "EmployeesInMem"

EmployeesInMem.connect_engine(connection)

res = await EmployeesInMem.do_snapshots_for_keyspace()

Disable snapshots

You can selectively disable snapshotting for some keyspaces while keeping it enabled for others.
When disabled, Montycat preserves the last saved snapshot but does not create new ones.

montycat console
> stop-snapshots-for-keyspace store <store name> keyspace <keyspace name>

exit
from montycat import Keyspace
from keyspaces import EmployeesInMem

res = await EmployeesInMem.stop_snapshots_for_keyspace()

Cleaning up snapshots

Cleaning snapshots removes the last saved state of a keyspace from disk.
This operation is destructive, so it should be used with caution.

montycat console
> clean-snapshots-for-keyspace store <store name> keyspace <keyspace name>

exit
from keyspaces import EmployeesInMem #keyspaces.py

res = await EmployeesInMem.clean_snapshots_for_keyspace()