Storage overview

Mastra storage is organized into domains. Each domain owns a set of tables or collections. Depending on your adapter and configuration, you may use all domains or only a subset.

Storage domains

MastraCompositeStore can route the following domain keys:

Not every storage adapter implements every domain. Composite storage lets you mix adapters per domain when the adapter packages export the corresponding domain classes.

Domain	Description
memory	Conversation persistence: messages, threads, and resources (including working memory).
workflows	Workflow run snapshots used for suspend and resume.
scores	Evaluation score records from eval runs.
observability	Traces and spans used by observability exporters and Studio.
datasets	Dataset records, versioned items, and dataset versions used by experiments.
experiments	Experiment runs and per-item experiment results.

The schema definitions below cover the built-in database-backed tables documented for memory, workflows, scores, and observability. Other domains, and non-database adapters, use implementation-specific storage structures.

Core schema

Messages

Stores conversation messages and their metadata. Each message belongs to a thread and contains the actual content along with metadata about the sender role and message type.

id

uuidv4

PRIMARYKEY

NOT NULL

Unique identifier for the message (format: xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx)

thread_id

uuidv4

FK → threads.id

NOT NULL

Parent thread reference

resourceId

uuidv4

CAN BE NULL

ID of the resource that owns this message

content

text

NOT NULL

JSON of the message content in V2 format. Example: { format: 2, parts: [...] }

role

text

NOT NULL

Enum of user | assistant

createdAt

timestamp

NOT NULL

Used for thread message ordering

The message content column contains a JSON object conforming to the MastraMessageContentV2 type, which is designed to align closely with the AI SDK UIMessage message shape.

format

integer

NOT NULL

Message format version (currently 2)

parts

array (JSON)

NOT NULL

Array of message parts (text, tool-invocation, file, reasoning, etc.). The structure of items in this array varies by type.

experimental_attachments

array (JSON)

CAN BE NULL

Optional array of file attachments

content

text

CAN BE NULL

Optional main text content of the message

toolInvocations

array (JSON)

CAN BE NULL

Optional array summarizing tool calls and results

reasoning

object (JSON)

CAN BE NULL

Optional information about the reasoning process behind the assistant's response

annotations

object (JSON)

CAN BE NULL

Optional additional metadata or annotations

Threads

Groups related messages together and associates them with a resource. Contains metadata about the conversation.

id

uuidv4

PRIMARYKEY

NOT NULL

Unique identifier for the thread (format: xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx)

resourceId

text

NOT NULL

Primary identifier of the external resource this thread is associated with. Used to group and retrieve related threads.

title

text

NOT NULL

Title of the conversation thread

metadata

text

Custom thread metadata as stringified JSON. Example:

{
  "category": "support",
  "priority": 1
}

createdAt

timestamp

NOT NULL

updatedAt

timestamp

NOT NULL

Used for thread ordering history

Resources

Stores user-specific data for resource-scoped working memory. Each resource represents a user or entity, allowing working memory to persist across all conversation threads for that user.

id

text

PRIMARYKEY

NOT NULL

Resource identifier (user or entity ID) - same as resourceId used in threads and agent calls

workingMemory

text

CAN BE NULL

Persistent working memory data as Markdown text. Contains user profile, preferences, and contextual information that persists across conversation threads.

metadata

jsonb

CAN BE NULL

Additional resource metadata as JSON. Example:

{
  "preferences": {
    "language": "en",
    "timezone": "UTC"
  },
  "tags": [
    "premium",
    "beta-user"
  ]
}

createdAt

timestamp

NOT NULL

When the resource record was first created

updatedAt

timestamp

NOT NULL

When the working memory was last updated

Workflows

When suspend() is called on a workflow, its state is saved in the following format. When resume() is called, that state is rehydrated.

workflow_name

text

NOT NULL

Name of the workflow

run_id

uuidv4

NOT NULL

Unique identifier for the workflow execution. Used to track state across suspend/resume cycles (format: xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx)

snapshot

text

NOT NULL

Serialized workflow state as JSON. Example:

{
  "value": {
    "currentState": "running"
  },
  "context": {
    "stepResults": {},
    "attempts": {},
    "triggerData": {}
  },
  "activePaths": [],
  "runId": "550e8400-e29b-41d4-a716-446655440000",
  "timestamp": 1648176000000
}

createdAt

timestamp

NOT NULL

updatedAt

timestamp

NOT NULL

Last modification time, used to track state changes during workflow execution

Evals

Stores eval results from running metrics against agent outputs.

input

text

NOT NULL

Input provided to the agent

output

text

NOT NULL

Output generated by the agent

result

jsonb

NOT NULL

Eval result data that includes score and details. Example:

{
  "score": 0.95,
  "details": {
    "reason": "Response accurately reflects source material",
    "citations": [
      "page 1",
      "page 3"
    ]
  }
}

agent_name

text

NOT NULL

metric_name

text

NOT NULL

e.g Faithfulness, Hallucination, etc.

instructions

text

NOT NULL

System prompt or instructions for the agent

test_info

jsonb

NOT NULL

Additional test metadata and configuration

global_run_id

uuidv4

NOT NULL

Groups related evaluation runs (e.g. all unit tests in a CI run)

run_id

uuidv4

NOT NULL

Unique identifier for the run being evaluated (format: xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx)

created_at

timestamp

NOT NULL

Traces

Captures OpenTelemetry traces for monitoring and debugging.

id

text

NOT NULL

PRIMARYKEY

Unique trace identifier

parentSpanId

text

ID of the parent span. Null if span is top level

name

text

NOT NULL

Hierarchical operation name (e.g. workflow.myWorkflow.execute, http.request, database.query)

traceId

text

NOT NULL

Root trace identifier that groups related spans

scope

text

NOT NULL

Library/package/service that created the span (e.g. @mastra/core, express, pg)

kind

integer

NOT NULL

INTERNAL (0, within process), CLIENT (1, outgoing calls), SERVER (2, incoming calls), PRODUCER (3, async job creation), CONSUMER (4, async job processing)

attributes

jsonb

User defined key-value pairs that contain span metadata

status

jsonb

JSON object with code (UNSET=0, ERROR=1, OK=2) and optional message. Example:

{
  "code": 1,
  "message": "HTTP request failed with status 500"
}

events

jsonb

Time-stamped events that occurred during the span

links

jsonb

Links to other related spans

other

text

Additional OpenTelemetry span fields as stringified JSON. Example:

{
  "droppedAttributesCount": 2,
  "droppedEventsCount": 1,
  "instrumentationLibrary": "@opentelemetry/instrumentation-http"
}

startTime

bigint

NOT NULL

Nanoseconds since Unix epoch when span started

endTime

bigint

NOT NULL

Nanoseconds since Unix epoch when span ended

createdAt

timestamp

NOT NULL