# EventStore The append-only log every aggregate and view model is built on. Each event belongs to a stream, identified by aggregate name and id, and has two coordinates: a `version` that orders it inside its stream and a `position` that orders it across the whole store. Writers use the version for optimistic concurrency, readers use the position as a durable cursor. ## Classes ### ConcurrencyConflict Defined in: [src/EventStore.ts:43](https://github.com/davidnussio/effect-cqrs/blob/9d66af7141782f3f89655e6868abe3f141c97632/src/EventStore.ts#L43) #### Extends * `object` & `YieldableError`<`this`> #### Constructors ##### Constructor > **new ConcurrencyConflict**(…`args`): [`ConcurrencyConflict`](https://effect-cqrs.dambox.ch/reference/api/eventstore/#concurrencyconflict) Defined in: node_modules/.pnpm/effect\@4.0.6/node_modules/effect/dist/Schema.d.ts:10979 ###### Parameters ###### args …\[`props`: `object`, `options?`: `MakeOptions`] ###### Returns [`ConcurrencyConflict`](https://effect-cqrs.dambox.ch/reference/api/eventstore/#concurrencyconflict) ###### Inherited from `Schema.TaggedError()("ConcurrencyConflict", { aggregateName: Schema.String, aggregateId: Schema.String, expectedVersion: Schema.Int }).constructor` #### Properties ##### aggregateId > `readonly` **aggregateId**: `string` = `Schema.String` Defined in: [src/EventStore.ts:45](https://github.com/davidnussio/effect-cqrs/blob/9d66af7141782f3f89655e6868abe3f141c97632/src/EventStore.ts#L45) ###### Inherited from `Schema.TaggedError()("ConcurrencyConflict", { aggregateName: Schema.String, aggregateId: Schema.String, expectedVersion: Schema.Int }).aggregateId` ##### aggregateName > `readonly` **aggregateName**: `string` = `Schema.String` Defined in: [src/EventStore.ts:44](https://github.com/davidnussio/effect-cqrs/blob/9d66af7141782f3f89655e6868abe3f141c97632/src/EventStore.ts#L44) ###### Inherited from `Schema.TaggedError()("ConcurrencyConflict", { aggregateName: Schema.String, aggregateId: Schema.String, expectedVersion: Schema.Int }).aggregateName` ##### expectedVersion > `readonly` **expectedVersion**: `number` = `Schema.Int` Defined in: [src/EventStore.ts:46](https://github.com/davidnussio/effect-cqrs/blob/9d66af7141782f3f89655e6868abe3f141c97632/src/EventStore.ts#L46) ###### Inherited from `Schema.TaggedError()("ConcurrencyConflict", { aggregateName: Schema.String, aggregateId: Schema.String, expectedVersion: Schema.Int }).expectedVersion` *** ### EventStore Defined in: [src/EventStore.ts:139](https://github.com/davidnussio/effect-cqrs/blob/9d66af7141782f3f89655e6868abe3f141c97632/src/EventStore.ts#L139) #### Extends * `Shape`<`"effect-cqrs/EventStore"`, { `afterCommit?`: <`R`>(`effect`) => `Effect`<`void`, `never`, `R`>; `changes`: `Stream`<`number`>; `head`: `Effect`<`number`, [`EventStoreError`](https://effect-cqrs.dambox.ch/reference/api/eventstore/#eventstoreerror)>; `append`(`input`): `Effect`\; `read`(`filter?`): `Stream`<{ `aggregateId`: `string`; `aggregateName`: `string`; `causationId`: `string` | `null`; `correlationId`: `string` | `null`; `metadata`: {\[`key`: `string`]: `Json`; }; `payload`: `Json`; `position`: `number`; `schemaVersion`: `number`; `timestamp`: `Utc`; `type`: `string`; `version`: `number`; }, [`EventStoreError`](https://effect-cqrs.dambox.ch/reference/api/eventstore/#eventstoreerror)>; `subscribe`(`filter?`): `Stream`<{ `aggregateId`: `string`; `aggregateName`: `string`; `causationId`: `string` | `null`; `correlationId`: `string` | `null`; `metadata`: {\[`key`: `string`]: `Json`; }; `payload`: `Json`; `position`: `number`; `schemaVersion`: `number`; `timestamp`: `Utc`; `type`: `string`; `version`: `number`; }, [`EventStoreError`](https://effect-cqrs.dambox.ch/reference/api/eventstore/#eventstoreerror)>; }, `this`> #### Constructors ##### Constructor > **new EventStore**(`_`): [`EventStore`](https://effect-cqrs.dambox.ch/reference/api/eventstore/#eventstore) Defined in: node_modules/.pnpm/effect\@4.0.6/node_modules/effect/dist/Context.d.ts:121 ###### Parameters ###### \_ `never` ###### Returns [`EventStore`](https://effect-cqrs.dambox.ch/reference/api/eventstore/#eventstore) ###### Inherited from Context.Service\, ConcurrencyConflict | EventStoreError> /\*\* Reads the events stored so far, ordered by position, then completes. \*/ read(filter?: EventFilter): Stream.Stream\ /\*\* Reads the events stored so far, then keeps following new ones. Never completes. \*/ subscribe(filter?: EventFilter): Stream.Stream\ /\*\* The position of the latest event, \`0\` when the store is empty. \*/ readonly head: Effect.Effect\ /\*\* \* Emits the current latest position, then each newer one. Consumers can treat an \* element as “there may be something new”. Appends from this process are always \* observed, appends from other processes when the backend announces them or the \* store polls for them: see \`MakeOptions\`. \*/ readonly changes: Stream.Stream\ /\*\* \* Runs an effect once what was just appended can be read by everyone: at once, \* or when the caller’s transaction commits, and never if it rolls back. Services \* that keep what they read or wrote in memory go through it, so they don’t keep \* what a rollback undid. Missing on stores without transactions. \*/ readonly afterCommit?: (\(effect: Effect.Effect\) => Effect.Effect\) | undefined }>()(“effect-cqrs/EventStore”).constructor *** ### EventStoreError Defined in: [src/EventStore.ts:38](https://github.com/davidnussio/effect-cqrs/blob/9d66af7141782f3f89655e6868abe3f141c97632/src/EventStore.ts#L38) #### Extends * `object` & `YieldableError`<`this`> #### Constructors ##### Constructor > **new EventStoreError**(…`args`): [`EventStoreError`](https://effect-cqrs.dambox.ch/reference/api/eventstore/#eventstoreerror) Defined in: node_modules/.pnpm/effect\@4.0.6/node_modules/effect/dist/Schema.d.ts:10979 ###### Parameters ###### args …\[`props`: `object`, `options?`: `MakeOptions`] ###### Returns [`EventStoreError`](https://effect-cqrs.dambox.ch/reference/api/eventstore/#eventstoreerror) ###### Inherited from `Schema.TaggedError()("EventStoreError", { operation: Schema.String, cause: Schema.Defect() }).constructor` #### Properties ##### cause > **cause**: `unknown` Defined in: [src/EventStore.ts:40](https://github.com/davidnussio/effect-cqrs/blob/9d66af7141782f3f89655e6868abe3f141c97632/src/EventStore.ts#L40) ###### Inherited from `Schema.TaggedError()("EventStoreError", { operation: Schema.String, cause: Schema.Defect() }).cause` ##### operation > `readonly` **operation**: `string` = `Schema.String` Defined in: [src/EventStore.ts:39](https://github.com/davidnussio/effect-cqrs/blob/9d66af7141782f3f89655e6868abe3f141c97632/src/EventStore.ts#L39) ###### Inherited from `Schema.TaggedError()("EventStoreError", { operation: Schema.String, cause: Schema.Defect() }).operation` ## Interfaces ### AppendInput Defined in: [src/EventStore.ts:75](https://github.com/davidnussio/effect-cqrs/blob/9d66af7141782f3f89655e6868abe3f141c97632/src/EventStore.ts#L75) #### Properties ##### aggregateId > `readonly` **aggregateId**: `string` Defined in: [src/EventStore.ts:77](https://github.com/davidnussio/effect-cqrs/blob/9d66af7141782f3f89655e6868abe3f141c97632/src/EventStore.ts#L77) ##### aggregateName > `readonly` **aggregateName**: `string` Defined in: [src/EventStore.ts:76](https://github.com/davidnussio/effect-cqrs/blob/9d66af7141782f3f89655e6868abe3f141c97632/src/EventStore.ts#L76) ##### causationId? > `readonly` `optional` **causationId?**: `string` Defined in: [src/EventStore.ts:82](https://github.com/davidnussio/effect-cqrs/blob/9d66af7141782f3f89655e6868abe3f141c97632/src/EventStore.ts#L82) ##### correlationId? > `readonly` `optional` **correlationId?**: `string` Defined in: [src/EventStore.ts:81](https://github.com/davidnussio/effect-cqrs/blob/9d66af7141782f3f89655e6868abe3f141c97632/src/EventStore.ts#L81) ##### events > `readonly` **events**: readonly [`NewEvent`](https://effect-cqrs.dambox.ch/reference/api/eventstore/#newevent)\[] Defined in: [src/EventStore.ts:80](https://github.com/davidnussio/effect-cqrs/blob/9d66af7141782f3f89655e6868abe3f141c97632/src/EventStore.ts#L80) ##### expectedVersion > `readonly` **expectedVersion**: `number` Defined in: [src/EventStore.ts:79](https://github.com/davidnussio/effect-cqrs/blob/9d66af7141782f3f89655e6868abe3f141c97632/src/EventStore.ts#L79) The stream version the writer based its decision on, `0` for a new stream. ##### metadata? > `readonly` `optional` **metadata?**: `JsonObject` Defined in: [src/EventStore.ts:84](https://github.com/davidnussio/effect-cqrs/blob/9d66af7141782f3f89655e6868abe3f141c97632/src/EventStore.ts#L84) Recorded on every event of the append. Defaults to `{}`. *** ### Backend Defined in: [src/EventStore.ts:165](https://github.com/davidnussio/effect-cqrs/blob/9d66af7141782f3f89655e6868abe3f141c97632/src/EventStore.ts#L165) What a storage adapter implements. [make](https://effect-cqrs.dambox.ch/reference/api/eventstore/#make) builds the rest on top. #### Properties ##### afterCommit? > `readonly` `optional` **afterCommit?**: <`R`>(`effect`) => `Effect`<`void`, `never`, `R`> Defined in: [src/EventStore.ts:185](https://github.com/davidnussio/effect-cqrs/blob/9d66af7141782f3f89655e6868abe3f141c97632/src/EventStore.ts#L185) Runs an effect once an append made now can be read by everyone: at once, or when the caller’s transaction commits, and never if it rolls back. `SqlClient.afterCommit` is one. Without it appends are announced as soon as they return, which makes subscribers skip those of a transaction that is still open. ###### Type Parameters ###### R `R` ###### Parameters ###### effect `Effect`<`void`, `never`, `R`> ###### Returns `Effect`<`void`, `never`, `R`> ##### append > `readonly` **append**: (`input`) => `Effect`\ Defined in: [src/EventStore.ts:166](https://github.com/davidnussio/effect-cqrs/blob/9d66af7141782f3f89655e6868abe3f141c97632/src/EventStore.ts#L166) Appends atomically, failing if the stream moved past `expectedVersion`. ###### Parameters ###### input [`AppendInput`](https://effect-cqrs.dambox.ch/reference/api/eventstore/#appendinput) ###### Returns `Effect`\ ##### changes? > `readonly` `optional` **changes?**: `Stream`<`number`, [`EventStoreError`](https://effect-cqrs.dambox.ch/reference/api/eventstore/#eventstoreerror), `never`> Defined in: [src/EventStore.ts:178](https://github.com/davidnussio/effect-cqrs/blob/9d66af7141782f3f89655e6868abe3f141c97632/src/EventStore.ts#L178) Head positions written by other processes, as the database announces them. It should start with the head once it listens, so nothing between two runs is missed. When it fails or ends, the store logs it and runs it again a second later. ##### head > `readonly` **head**: `Effect`<`number`, [`EventStoreError`](https://effect-cqrs.dambox.ch/reference/api/eventstore/#eventstoreerror)> Defined in: [src/EventStore.ts:172](https://github.com/davidnussio/effect-cqrs/blob/9d66af7141782f3f89655e6868abe3f141c97632/src/EventStore.ts#L172) ##### readBatch > `readonly` **readBatch**: (`filter`, `afterPosition`, `limit`) => `Effect`\ Defined in: [src/EventStore.ts:167](https://github.com/davidnussio/effect-cqrs/blob/9d66af7141782f3f89655e6868abe3f141c97632/src/EventStore.ts#L167) ###### Parameters ###### filter [`EventFilter`](https://effect-cqrs.dambox.ch/reference/api/eventstore/#eventfilter) ###### afterPosition `number` ###### limit `number` ###### Returns `Effect`\ *** ### EventFilter Defined in: [src/EventStore.ts:121](https://github.com/davidnussio/effect-cqrs/blob/9d66af7141782f3f89655e6868abe3f141c97632/src/EventStore.ts#L121) Selects events by stream, type and time. Omitted fields match everything. `startTime` is inclusive and `finishTime` is exclusive, so adding one millisecond to a history timestamp selects up to and including that event. #### Properties ##### afterPosition? > `readonly` `optional` **afterPosition?**: `number` Defined in: [src/EventStore.ts:127](https://github.com/davidnussio/effect-cqrs/blob/9d66af7141782f3f89655e6868abe3f141c97632/src/EventStore.ts#L127) ##### afterVersion? > `readonly` `optional` **afterVersion?**: `number` Defined in: [src/EventStore.ts:132](https://github.com/davidnussio/effect-cqrs/blob/9d66af7141782f3f89655e6868abe3f141c97632/src/EventStore.ts#L132) For a filter on one stream: where to continue in it. Versions follow the stream’s own index, so resuming there costs the same however far the log has moved on. ##### aggregateIds? > `readonly` `optional` **aggregateIds?**: readonly `string`\[] Defined in: [src/EventStore.ts:123](https://github.com/davidnussio/effect-cqrs/blob/9d66af7141782f3f89655e6868abe3f141c97632/src/EventStore.ts#L123) ##### aggregateNames? > `readonly` `optional` **aggregateNames?**: readonly `string`\[] Defined in: [src/EventStore.ts:122](https://github.com/davidnussio/effect-cqrs/blob/9d66af7141782f3f89655e6868abe3f141c97632/src/EventStore.ts#L122) ##### eventTypes? > `readonly` `optional` **eventTypes?**: readonly `string`\[] Defined in: [src/EventStore.ts:124](https://github.com/davidnussio/effect-cqrs/blob/9d66af7141782f3f89655e6868abe3f141c97632/src/EventStore.ts#L124) ##### finishTime? > `readonly` `optional` **finishTime?**: `Utc` Defined in: [src/EventStore.ts:126](https://github.com/davidnussio/effect-cqrs/blob/9d66af7141782f3f89655e6868abe3f141c97632/src/EventStore.ts#L126) ##### startTime? > `readonly` `optional` **startTime?**: `Utc` Defined in: [src/EventStore.ts:125](https://github.com/davidnussio/effect-cqrs/blob/9d66af7141782f3f89655e6868abe3f141c97632/src/EventStore.ts#L125) *** ### MakeOptions Defined in: [src/EventStore.ts:188](https://github.com/davidnussio/effect-cqrs/blob/9d66af7141782f3f89655e6868abe3f141c97632/src/EventStore.ts#L188) #### Properties ##### batchSize? > `readonly` `optional` **batchSize?**: `number` Defined in: [src/EventStore.ts:190](https://github.com/davidnussio/effect-cqrs/blob/9d66af7141782f3f89655e6868abe3f141c97632/src/EventStore.ts#L190) Events per read. Defaults to 500. ##### pollInterval? > `readonly` `optional` **pollInterval?**: `Input` Defined in: [src/EventStore.ts:195](https://github.com/davidnussio/effect-cqrs/blob/9d66af7141782f3f89655e6868abe3f141c97632/src/EventStore.ts#L195) Reads the head this often, to notice appends from other processes when the backend doesn’t announce them, or as a safety net when it does. Off by default. *** ### Migration Defined in: [src/EventStore.ts:32](https://github.com/davidnussio/effect-cqrs/blob/9d66af7141782f3f89655e6868abe3f141c97632/src/EventStore.ts#L32) A schema change for a SQL table, with the table names filled in. Each module that keeps a table exports its migrations in the order to apply them, for teams that run them with their own tooling and turn off `migrate`. #### Properties ##### id > `readonly` **id**: `number` Defined in: [src/EventStore.ts:33](https://github.com/davidnussio/effect-cqrs/blob/9d66af7141782f3f89655e6868abe3f141c97632/src/EventStore.ts#L33) ##### name > `readonly` **name**: `string` Defined in: [src/EventStore.ts:34](https://github.com/davidnussio/effect-cqrs/blob/9d66af7141782f3f89655e6868abe3f141c97632/src/EventStore.ts#L34) ##### statements > `readonly` **statements**: readonly `string`\[] Defined in: [src/EventStore.ts:35](https://github.com/davidnussio/effect-cqrs/blob/9d66af7141782f3f89655e6868abe3f141c97632/src/EventStore.ts#L35) *** ### NewEvent Defined in: [src/EventStore.ts:68](https://github.com/davidnussio/effect-cqrs/blob/9d66af7141782f3f89655e6868abe3f141c97632/src/EventStore.ts#L68) #### Properties ##### payload > `readonly` **payload**: `Json` Defined in: [src/EventStore.ts:70](https://github.com/davidnussio/effect-cqrs/blob/9d66af7141782f3f89655e6868abe3f141c97632/src/EventStore.ts#L70) ##### schemaVersion? > `readonly` `optional` **schemaVersion?**: `number` Defined in: [src/EventStore.ts:72](https://github.com/davidnussio/effect-cqrs/blob/9d66af7141782f3f89655e6868abe3f141c97632/src/EventStore.ts#L72) Defaults to `1`. ##### type > `readonly` **type**: `string` Defined in: [src/EventStore.ts:69](https://github.com/davidnussio/effect-cqrs/blob/9d66af7141782f3f89655e6868abe3f141c97632/src/EventStore.ts#L69) ## Type Aliases ### StoredEvent > **StoredEvent** = *typeof* `StoredEvent.Type` Defined in: [src/EventStore.ts:49](https://github.com/davidnussio/effect-cqrs/blob/9d66af7141782f3f89655e6868abe3f141c97632/src/EventStore.ts#L49) ## Variables ### groupCommit > `const` **groupCommit**: (…`args`) => `Effect`<(`input`) => `Effect`\, `never`, `Scope`> Defined in: [src/EventStore.ts:331](https://github.com/davidnussio/effect-cqrs/blob/9d66af7141782f3f89655e6868abe3f141c97632/src/EventStore.ts#L331) Group commit for a backend. An append that finds nothing being written goes straight through `appendGroup`, in its own fiber. Appends that arrive meanwhile wait, then go together into the next call, which writes them in one transaction and returns an exit for each, in order: however many wait, they pay for one commit. A group holds at most one append per stream, so they can’t conflict with each other, and at most `maxEvents` events unless a single append has more. An append left out waits for the next group, where it comes first, so appends to a stream are written in the order they came. Groups of waiting appends are written by a fiber of the `Scope`. An append interrupted while it waits is not written, while one interrupted once its group is being written may be: a caller that times out should retry with a `commandId`, which finds the first result if there is one. The others in its group are written and answered as if nothing happened. #### Parameters ##### args …\[`appendGroup`: (`inputs`) => `Effect`\, `options?`: `object`] #### Returns `Effect`<(`input`) => `Effect`\, `never`, `Scope`> *** ### layerMemory > `const` **layerMemory**: `Layer.Layer`<[`EventStore`](https://effect-cqrs.dambox.ch/reference/api/eventstore/#eventstore), [`EventStoreError`](https://effect-cqrs.dambox.ch/reference/api/eventstore/#eventstoreerror)> Defined in: [src/EventStore.ts:540](https://github.com/davidnussio/effect-cqrs/blob/9d66af7141782f3f89655e6868abe3f141c97632/src/EventStore.ts#L540) Keeps events in process memory. They do not survive a restart. *** ### make > `const` **make**: (…`args`) => `Effect`<{ `afterCommit?`: <`R`>(`effect`) => `Effect`<`void`, `never`, `R`>; `changes`: `Stream`<`number`>; `head`: `Effect`<`number`, [`EventStoreError`](https://effect-cqrs.dambox.ch/reference/api/eventstore/#eventstoreerror)>; `append`(`input`): `Effect`\; `read`(`filter?`): `Stream`<{ `aggregateId`: `string`; `aggregateName`: `string`; `causationId`: `string` | `null`; `correlationId`: `string` | `null`; `metadata`: {\[`key`: `string`]: `Json`; }; `payload`: `Json`; `position`: `number`; `schemaVersion`: `number`; `timestamp`: `Utc`; `type`: `string`; `version`: `number`; }, [`EventStoreError`](https://effect-cqrs.dambox.ch/reference/api/eventstore/#eventstoreerror)>; `subscribe`(`filter?`): `Stream`<{ `aggregateId`: `string`; `aggregateName`: `string`; `causationId`: `string` | `null`; `correlationId`: `string` | `null`; `metadata`: {\[`key`: `string`]: `Json`; }; `payload`: `Json`; `position`: `number`; `schemaVersion`: `number`; `timestamp`: `Utc`; `type`: `string`; `version`: `number`; }, [`EventStoreError`](https://effect-cqrs.dambox.ch/reference/api/eventstore/#eventstoreerror)>; }, [`EventStoreError`](https://effect-cqrs.dambox.ch/reference/api/eventstore/#eventstoreerror), `Scope`> Defined in: [src/EventStore.ts:208](https://github.com/davidnussio/effect-cqrs/blob/9d66af7141782f3f89655e6868abe3f141c97632/src/EventStore.ts#L208) Builds a store on a backend. Watching for appends from other processes takes fibers that live as long as the `Scope`, which `Layer.effect` provides. #### Parameters ##### args …\[`backend`: [`Backend`](https://effect-cqrs.dambox.ch/reference/api/eventstore/#backend), `options?`: [`MakeOptions`](https://effect-cqrs.dambox.ch/reference/api/eventstore/#makeoptions)] #### Returns `Effect`<{ `afterCommit?`: <`R`>(`effect`) => `Effect`<`void`, `never`, `R`>; `changes`: `Stream`<`number`>; `head`: `Effect`<`number`, [`EventStoreError`](https://effect-cqrs.dambox.ch/reference/api/eventstore/#eventstoreerror)>; `append`(`input`): `Effect`\; `read`(`filter?`): `Stream`<{ `aggregateId`: `string`; `aggregateName`: `string`; `causationId`: `string` | `null`; `correlationId`: `string` | `null`; `metadata`: {\[`key`: `string`]: `Json`; }; `payload`: `Json`; `position`: `number`; `schemaVersion`: `number`; `timestamp`: `Utc`; `type`: `string`; `version`: `number`; }, [`EventStoreError`](https://effect-cqrs.dambox.ch/reference/api/eventstore/#eventstoreerror)>; `subscribe`(`filter?`): `Stream`<{ `aggregateId`: `string`; `aggregateName`: `string`; `causationId`: `string` | `null`; `correlationId`: `string` | `null`; `metadata`: {\[`key`: `string`]: `Json`; }; `payload`: `Json`; `position`: `number`; `schemaVersion`: `number`; `timestamp`: `Utc`; `type`: `string`; `version`: `number`; }, [`EventStoreError`](https://effect-cqrs.dambox.ch/reference/api/eventstore/#eventstoreerror)>; }, [`EventStoreError`](https://effect-cqrs.dambox.ch/reference/api/eventstore/#eventstoreerror), `Scope`> *** ### makeMemory > `const` **makeMemory**: `Effect.Effect`<[`EventStore`](https://effect-cqrs.dambox.ch/reference/api/eventstore/#eventstore)\[`"Service"`], [`EventStoreError`](https://effect-cqrs.dambox.ch/reference/api/eventstore/#eventstoreerror)> Defined in: [src/EventStore.ts:487](https://github.com/davidnussio/effect-cqrs/blob/9d66af7141782f3f89655e6868abe3f141c97632/src/EventStore.ts#L487) *** ### StoredEvent > `const` **StoredEvent**: `Struct`<{ `aggregateId`: `String`; `aggregateName`: `String`; `causationId`: `NullOr`<`String`>; `correlationId`: `NullOr`<`String`>; `metadata`: `$Record`<`String`, `Codec`<`Json`, `Json`, `never`, `never`>>; `payload`: `Codec`<`Json`, `Json`, `never`, `never`>; `position`: `Int`; `schemaVersion`: `Int`; `timestamp`: `DateTimeUtcFromMillis`; `type`: `String`; `version`: `Int`; }> Defined in: [src/EventStore.ts:49](https://github.com/davidnussio/effect-cqrs/blob/9d66af7141782f3f89655e6868abe3f141c97632/src/EventStore.ts#L49) ## Functions ### eventId() > **eventId**(`event`): `string` Defined in: [src/EventStore.ts:92](https://github.com/davidnussio/effect-cqrs/blob/9d66af7141782f3f89655e6868abe3f141c97632/src/EventStore.ts#L92) Identifies an event wherever it is stored, as the `causationId` of what it causes: `account/alice@4`. Name and id are URI-encoded, so a `/` or `@` inside one can’t make two events look alike. #### Parameters ##### event `Pick`<[`StoredEvent`](https://effect-cqrs.dambox.ch/reference/api/eventstore/#storedevent), `"aggregateName"` | `"aggregateId"` | `"version"`> #### Returns `string` *** ### isOneStream() > **isOneStream**(`__namedParameters`): `boolean` Defined in: [src/EventStore.ts:136](https://github.com/davidnussio/effect-cqrs/blob/9d66af7141782f3f89655e6868abe3f141c97632/src/EventStore.ts#L136) A filter on exactly one stream, which a store can read through that stream’s index. #### Parameters ##### \_\_namedParameters [`EventFilter`](https://effect-cqrs.dambox.ch/reference/api/eventstore/#eventfilter) #### Returns `boolean` *** ### toStored() > **toStored**(`input`, `event`, `index`, `position`, `timestamp`): `object` Defined in: [src/EventStore.ts:96](https://github.com/davidnussio/effect-cqrs/blob/9d66af7141782f3f89655e6868abe3f141c97632/src/EventStore.ts#L96) The columns every adapter stores for a new event, with the defaults filled in. #### Parameters ##### input [`AppendInput`](https://effect-cqrs.dambox.ch/reference/api/eventstore/#appendinput) ##### event [`NewEvent`](https://effect-cqrs.dambox.ch/reference/api/eventstore/#newevent) ##### index `number` ##### position `number` ##### timestamp `Utc` #### Returns ##### aggregateId > `readonly` **aggregateId**: `string` = `Schema.String` ##### aggregateName > `readonly` **aggregateName**: `string` = `Schema.String` ##### causationId > `readonly` **causationId**: `string` | `null` What directly caused the command that recorded the event: a request, a command or another event. ##### correlationId > `readonly` **correlationId**: `string` | `null` Shared by everything that follows from one original request. ##### metadata > `readonly` **metadata**: `object` = `Schema.JsonObject` What the command carried beside its payload, see `Metadata`. Events from before metadata existed have `{}`. ###### Index Signature \[`key`: `string`]: `Json` ##### payload > `readonly` **payload**: `Json` = `Schema.Json` ##### position > `readonly` **position**: `number` = `Schema.Int` ##### schemaVersion > `readonly` **schemaVersion**: `number` = `Schema.Int` The version of the event’s schema the payload was written with. Events from before versions existed are `1`. ##### timestamp > `readonly` **timestamp**: `Utc` = `Schema.DateTimeUtcFromMillis` ##### type > `readonly` **type**: `string` = `Schema.String` ##### version > `readonly` **version**: `number` = `Schema.Int`