# How to address duplicate key value violates unique constraint "journal\_pkey" when remembering entities in Akka Cluster Sharding?

**URL:** <https://discuss.akka.io/t/how-to-address-duplicate-key-value-violates-unique-constraint-journal-pkey-when-remembering-entities-in-akka-cluster-sharding/8543>\
**Category:** Akka Cluster\
**Tags:** akka-typed\
**Created:** [July 22, 2021, 6:06am UTC](https://discuss.akka.io/t/how-to-address-duplicate-key-value-violates-unique-constraint-journal-pkey-when-remembering-entities-in-akka-cluster-sharding/8543 "2021-07-22T06:06:30Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![dmrolfs](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.akka.io/dmrolfs/32/873_2.png) [@dmrolfs](https://discuss.akka.io/u/dmrolfs)\
**Post date:** [July 22, 2021, 6:06am UTC](https://discuss.akka.io/t/how-to-address-duplicate-key-value-violates-unique-constraint-journal-pkey-when-remembering-entities-in-akka-cluster-sharding/8543/1 "2021-07-22T06:06:31Z")

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For my Akka Typed Persistence service, I’ve turned on remember entities for a couple of my entities. For the both of those actor types, I’m getting a PSQLException: ERROR: duplicate key value violates unique constraint “journal\_pkey” with the EventSourcedRememberEntitiesCoordinatorStore actors before the ShardCoordinator shuts down.

How do you recommend resolving this issue properly? How does this issue typically occur? I haven’t seen much guidance online on this issue, so any direction is appreciated.

Thanks!

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**Author:** ![octonato](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.akka.io/octonato/32/2885_2.png) [@octonato](https://discuss.akka.io/u/octonato)\
**Post date:** [July 22, 2021, 8:46am UTC](https://discuss.akka.io/t/how-to-address-duplicate-key-value-violates-unique-constraint-journal-pkey-when-remembering-entities-in-akka-cluster-sharding/8543/2 "2021-07-22T08:46:17Z")

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Hi @dmrolfs,

Which plugin are you using? The constraint in the [jdbc plugin](https://github.com/akka/akka-persistence-jdbc) is `journal_pk`. That may be just a typo on your side and not relevant here, but I want to check nevertheless.

In any case, I think this is happening because you have two instances of the same actor or two different actors that are sharing the same id. Could that be the case?

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<div class="post-metadata">

**Author:** ![dmrolfs](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.akka.io/dmrolfs/32/873_2.png) [@dmrolfs](https://discuss.akka.io/u/dmrolfs)\
**Post date:** [July 22, 2021, 10:35pm UTC](https://discuss.akka.io/t/how-to-address-duplicate-key-value-violates-unique-constraint-journal-pkey-when-remembering-entities-in-akka-cluster-sharding/8543/3 "2021-07-22T22:35:24Z")

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Hi @octonato,

We are using akka-persistence-jdbc plugin. We directly copied the schema.ddl. We’re using postgres.

Regarding same actor or difference actors using same key: We have two entities that are remembered, and I verified they have separate TypeKey’s during Cluster Shard Entity initialization (from which I believe the EventSourcedRememberEntitiesCoordinatorStore derives its identity).

We do have a deployment situation in which we’re deploying the service twice: once as a canary then the final deployment. Both reference the same database. Can the canary conflict with the final? Aside from the canary deployment, would deploying the service as a single-node cluster impact the behavior?

I’m seeing this duplicate key issue with both:

- [TypeKey]Shard (on EventSourcedRememberEntitiesShardStore$EntitiesStarted events); and,

```auto
 [2021-07-16 07:44:45,452] e[1;31mERRORe[0;39m e[36ma.c.s.i.EventSourcedRememberEntitiesShardStoree[0;39m [] [migration-akka.actor.default-dispatcher-16] - Failed to persist event type [akka.cluster.sharding.internal.EventSourcedRememberEntitiesShardStore$EntitiesStarted] with sequence number [33] for persistenceId [/sharding/MassSuspensionShard/0]. - MDC: {akkaAddress=akka://migration@127.0.0.1:2551, sourceThread=migration-akka.actor.default-dispatcher-12, akkaSource=akka://migration@127.0.0.1:2551/system/sharding/MassSuspension/0/RememberEntitiesStore, sourceActorSystem=migration, akkaTimestamp=07:44:45.452UTC}
org.postgresql.util.PSQLException: ERROR: duplicate key value violates unique constraint "journal_pkey"
  Detail: Key (persistence_id, sequence_number)=(/sharding/MassSuspensionShard/0, 33) already exists.

```

- [TypeKey]Coordinator actors (on String events).

```auto
[2021-07-21 02:00:06,980] e[1;31mERRORe[0;39m e[36ma.c.s.i.EventSourcedRememberEntitiesCoordinatorStoree[0;39m [] [migration-akka.actor.default-dispatcher-17] - Failed to persist event type [java.lang.String] with sequence number [7041] for persistenceId [/sharding/MassSuspensionCoordinator]. - MDC: {akkaAddress=akka://migration@127.0.0.1:2551, sourceThread=migration-akka.actor.default-dispatcher-15, akkaSource=akka://migration@127.0.0.1:2551/system/sharding/MassSuspensionCoordinator/singleton/coordinator/RememberEntitiesStore, sourceActorSystem=migration, akkaTimestamp=02:00:06.977UTC}
org.postgresql.util.PSQLException: ERROR: duplicate key value violates unique constraint "journal_pkey"
  Detail: Key (persistence_id, sequence_number)=(/sharding/MassSuspensionCoordinator, 7041) already exists.

```

Thanks for your perspective!