{
  "id": "causal-consistency",
  "title": "Enable causal consistency",
  "url": "https://redis.io/docs/latest/operate/rs/7.8/databases/active-active/causal-consistency/",
  "summary": "Enable causal consistency in an Active-Active database.",
  "content": "When you enable causal consistency in Active-Active databases,\nthe order of operations on a specific key are maintained across all Active-Active database instances.\n\nFor example, if operations A and B were applied on the same key and the effect of A was observed by the instance that initiated B before B was applied to the key.\nAll instances of an Active-Active database would then observe the effect of A before observing the effect of B.\nThis way, any causal relationship between operations on the same key is also observed and maintained by every replica.\n\n### Enable causal consistency\n\nWhen you create an Active-Active database, you can enable causal consistency in the Cluster Manager UI:\n\n1. In the **Participating clusters** section of the **Create Active-Active database** screen, locate **Causal Consistency**:\n\n    \n\n1. Click **Change** to open the **Causal Consistency** dialog.\n\n1. Select **Enabled**:\n\n    \n\n1. Click **Change** to confirm your selection.\n\nAfter database creation, you can only turn causal consistency on or off using the REST API or `crdb-cli`.\nThe updated setting only affects commands and operations received after the change.\n\n### Causal consistency side effects\n\nWhen the causal consistency option is enabled, each instance maintains the order of operations it received from another instance\nand relays that information to all other N-2 instances,\nwhere N represents the number of instances used by the Active-Active database.\n\nAs a result, network traffic is increased by a factor of (N-2).\nThe memory consumed by each instance and overall performance are also impacted when causal consistency is activated.\n\n",
  "tags": ["docs","operate","rs"],
  "last_updated": "2026-04-01T08:10:08-05:00"
}