@mastra/pg

PostgreSQL implementation for Mastra, providing both vector similarity search (using pgvector) and general storage capabilities with connection pooling and transaction support.

Installation

npm install @mastra/pg

Prerequisites

• PostgreSQL server with pgvector extension installed (if using vector store)
• PostgreSQL 11 or higher

Usage

Vector Store

Basic Configuration

PgVector supports multiple connection methods:

1. Connection String (Recommended)

import { PgVector } from '@mastra/pg';

const vectorStore = new PgVector({
  connectionString: 'postgresql://user:pass@localhost:5432/db',
});

2. Host/Port/Database Configuration

const vectorStore = new PgVector({
  host: 'localhost',
  port: 5432,
  database: 'mydb',
  user: 'postgres',
  password: 'password',
});

Note: PgVector also supports advanced configurations like Google Cloud SQL Connector via pg.ClientConfig.

Advanced Options

const vectorStore = new PgVector({
  connectionString: 'postgresql://user:pass@localhost:5432/db',
  schemaName: 'custom_schema', // Use custom schema (default: public)
  max: 30, // Max pool connections (default: 20)
  idleTimeoutMillis: 60000, // Idle timeout (default: 30000)
  pgPoolOptions: {
    // Additional pg pool options
    connectionTimeoutMillis: 5000,
    allowExitOnIdle: true,
  },
});

Usage Example

// Create a new table with vector support
await vectorStore.createIndex({
  indexName: 'my_vectors',
  dimension: 1536,
  metric: 'cosine',
  // Optional: Configure index type and parameters
  indexConfig: {
    type: 'hnsw',  // 'ivfflat' (default), 'hnsw', or 'flat'
    hnsw: {
      m: 16,              // Number of connections per layer (default: 8)
      efConstruction: 64  // Size of dynamic list (default: 32)
    }
  }
});

// Add vectors
const ids = await vectorStore.upsert({
  indexName: 'my_vectors',
  vectors: [[0.1, 0.2, ...], [0.3, 0.4, ...]],
  metadata: [{ text: 'doc1' }, { text: 'doc2' }],
});

// Query vectors
const results = await vectorStore.query({
  indexName: 'my_vectors',
  queryVector: [0.1, 0.2, ...],
  topK: 10, // topK
  filter: { text: 'doc1' }, // filter
  includeVector: false, // includeVector
  minScore: 0.5, // minScore
});

// Clean up
await vectorStore.disconnect();

Storage

import { PostgresStore } from '@mastra/pg';

const store = new PostgresStore({
  host: 'localhost',
  port: 5432,
  database: 'mastra',
  user: 'postgres',
  password: 'postgres',
});

// Create a thread
await store.saveThread({
  thread: {
    id: 'thread-123',
    resourceId: 'resource-456',
    title: 'My Thread',
    metadata: { key: 'value' },
    createdAt: new Date(),
  },
});

// Add messages to thread
await store.saveMessages({
  messages: [
    {
      id: 'msg-789',
      threadId: 'thread-123',
      role: 'user',
      content: { content: 'Hello' },
      resourceId: 'resource-456',
      createdAt: new Date(),
    },
  ],
});

// Query threads and messages
const savedThread = await store.getThreadById({ threadId: 'thread-123' });
const messages = await store.listMessages({ threadId: 'thread-123' });

Configuration

Connection Methods

Both PgVector and PostgresStore support multiple connection methods:

1. Connection String

   {
     connectionString: 'postgresql://user:pass@localhost:5432/db';
   }

2. Host/Port/Database

   {
     host: 'localhost',
     port: 5432,
     database: 'mydb',
     user: 'postgres',
     password: 'password'
   }

Advanced: Also supports pg.ClientConfig for use cases like Google Cloud SQL Connector with IAM authentication.

Optional Configuration

• schemaName: Custom PostgreSQL schema (default: public)
• ssl: Enable SSL or provide custom SSL options (true | false | ConnectionOptions)
• max: Maximum pool connections (default: 20)
• idleTimeoutMillis: Idle connection timeout (default: 30000)
• pgPoolOptions: Additional pg pool options (PgVector only)

Default Connection Pool Settings

• Maximum connections: 20
• Idle timeout: 30 seconds
• Connection timeout: 2 seconds

Features

Vector Store Features

• Vector similarity search with cosine, euclidean, and dot product (inner) metrics
• Advanced metadata filtering with MongoDB-like query syntax
• Minimum score threshold for queries
• Automatic UUID generation for vectors
• Table management (create, list, describe, delete, truncate)
• Configurable vector index types:
  • IVFFlat (default): Balanced speed/accuracy, auto-calculates optimal lists parameter
  • HNSW: Fastest queries, higher memory usage, best for large datasets
  • Flat: No index, 100% accuracy, best for small datasets (<1000 vectors)

Storage Features

• Thread and message storage with JSON support
• Atomic transactions for data consistency
• Efficient batch operations
• Rich metadata support
• Timestamp tracking
• Cascading deletes

Supported Filter Operators

The following filter operators are supported for metadata queries:

• Comparison: $eq, $ne, $gt, $gte, $lt, $lte
• Logical: $and, $or
• Array: $in, $nin
• Text: $regex, $like

Example filter:

{
  $and: [{ age: { $gt: 25 } }, { tags: { $in: ['tag1', 'tag2'] } }];
}

Vector Index Configuration

pgvector supports three index types, each with different performance characteristics:

IVFFlat Index (Default)

IVFFlat groups vectors into clusters for efficient searching:

await vectorStore.createIndex({
  indexName: 'my_vectors',
  dimension: 1536,
  metric: 'cosine',
  indexConfig: {
    type: 'ivfflat',
    ivf: {
      lists: 1000, // Number of clusters (default: auto-calculated as sqrt(rows) * 2)
    },
  },
});

• Best for: Medium to large datasets (10K-1M vectors)
• Build time: Minutes for millions of vectors
• Query speed: Fast (tens of milliseconds)
• Memory: Moderate
• Accuracy: ~95-99%

HNSW Index

HNSW builds a graph structure for extremely fast searches:

await vectorStore.createIndex({
  indexName: 'my_vectors',
  dimension: 1536,
  metric: 'dotproduct', // Recommended for normalized embeddings (OpenAI, etc.)
  indexConfig: {
    type: 'hnsw',
    hnsw: {
      m: 16, // Connections per layer (default: 8, range: 2-100)
      efConstruction: 64, // Dynamic list size (default: 32, range: 4-1000)
    },
  },
});

• Best for: Large datasets (100K+ vectors) requiring fastest searches
• Build time: Can take hours for large datasets
• Query speed: Very fast (milliseconds even for millions)
• Memory: High (can be 2-3x vector size)
• Accuracy: ~99%

Tuning HNSW:

• Higher m: Better accuracy, more memory (16-32 for high accuracy)
• Higher efConstruction: Better index quality, slower builds (64-200 for quality)

Flat Index (No Index)

Uses sequential scan for 100% accuracy:

await vectorStore.createIndex({
  indexName: 'my_vectors',
  dimension: 1536,
  metric: 'cosine',
  indexConfig: {
    type: 'flat',
  },
});

• Best for: Small datasets (<1000 vectors) or when 100% accuracy is required
• Build time: None
• Query speed: Slow for large datasets (linear scan)
• Memory: Minimal (just vectors)
• Accuracy: 100%

Distance Metrics

Choose the appropriate metric for your embeddings:

• cosine (default): Angular similarity, good for text embeddings
• euclidean: L2 distance, for unnormalized embeddings
• dotproduct: Dot product, optimal for normalized embeddings (OpenAI, Cohere)

Index Recreation

The system automatically detects configuration changes and only rebuilds indexes when necessary, preventing the performance issues from unnecessary recreations.

Important behaviors:

• If no indexConfig is provided, existing indexes are preserved as-is
• If indexConfig is provided, indexes are only rebuilt if the configuration differs
• New indexes default to IVFFlat with cosine distance when no config is specified

Vector Store Methods

• createIndex({indexName, dimension, metric?, indexConfig?, buildIndex?}): Create a new table with vector support
• buildIndex({indexName, metric?, indexConfig?}): Build or rebuild vector index
• upsert({indexName, vectors, metadata?, ids?}): Add or update vectors
• query({indexName, queryVector, topK?, filter?, includeVector?, minScore?}): Search for similar vectors
• updateVector({ indexName, id?, filter?, update }): Update a single vector by ID or metadata filter
• deleteVector({ indexName, id }): Delete a single vector by ID
• deleteVectors({ indexName, ids?, filter? }): Delete multiple vectors by IDs or metadata filter
• listIndexes(): List all vector-enabled tables
• describeIndex(indexName): Get table statistics and index configuration
• deleteIndex(indexName): Delete a table
• truncateIndex(indexName): Remove all data from a table
• disconnect(): Close all database connections

Storage Methods

Thread Operations

• saveThread({ thread }): Create or update a thread
• getThreadById({ threadId }): Get a thread by ID
• updateThread({ id, title, metadata }): Update thread title and/or metadata
• deleteThread({ threadId }): Delete a thread and its messages
• listThreadsByResourceId({ resourceId, offset, limit, orderBy? }): List paginated threads for a resource

Message Operations

• saveMessages({ messages }): Save multiple messages in a transaction
• listMessages({ threadId, resourceId?, perPage?, page?, orderBy?, filter? }): Get messages for a thread with pagination
• listMessagesById({ messageIds }): Get specific messages by their IDs
• updateMessages({ messages }): Update existing messages
• deleteMessages(messageIds): Delete specific messages

Resource Operations

• getResourceById({ resourceId }): Get a resource by ID
• saveResource({ resource }): Create or save a resource
• updateResource({ resourceId, workingMemory }): Update resource working memory

Workflow Operations

• persistWorkflowSnapshot({ workflowName, runId, snapshot }): Save workflow state
• loadWorkflowSnapshot({ workflowName, runId }): Load workflow state
• listWorkflowRuns({ workflowName, pagination }): List workflow runs with pagination
• getWorkflowRunById({ workflowName, runId }): Get a specific workflow run
• updateWorkflowState({ workflowName, runId, state }): Update workflow state
• updateWorkflowResults({ workflowName, runId, results }): Update workflow results

AI Observability Operations

• createSpan(span): Create a single AI span
• batchCreateSpans({ records }): Create multiple AI spans
• updateSpan({ traceId, spanId, updates }): Update an AI span
• batchUpdateSpans({ updates }): Update multiple AI spans
• getTrace(traceId): Get an trace by ID
• getTracesPaginated({ ...filters, pagination }): Get paginated traces with filtering
• batchDeleteTraces({ traceIds }): Delete multiple traces

Evaluation/Scoring Operations

• getScoreById({ id }): Get a score by ID
• saveScore(score): Save an evaluation score
• listScoresByScorerId({ scorerId, pagination }): List scores by scorer with pagination
• listScoresByRunId({ runId, pagination }): List scores by run with pagination
• listScoresByEntityId({ entityId, entityType, pagination }): List scores by entity with pagination
• listScoresBySpan({ traceId, spanId, pagination }): List scores by span with pagination

Index Management

The PostgreSQL store provides comprehensive index management capabilities to optimize query performance.

Automatic Performance Indexes

PostgreSQL storage automatically creates composite indexes during initialization for common query patterns:

• mastra_threads_resourceid_createdat_idx: (resourceId, createdAt DESC)
• mastra_messages_thread_id_createdat_idx: (thread_id, createdAt DESC)
• mastra_traces_name_starttime_idx: (name, startTime DESC)
• mastra_evals_agent_name_created_at_idx: (agent_name, created_at DESC)

These indexes significantly improve performance for filtered queries with sorting.

Creating Custom Indexes

Create additional indexes to optimize specific query patterns:

// Basic index for common queries
await store.createIndex({
  name: 'idx_threads_resource',
  table: 'mastra_threads',
  columns: ['resourceId'],
});

// Composite index with sort order for filtering + sorting
await store.createIndex({
  name: 'idx_messages_composite',
  table: 'mastra_messages',
  columns: ['thread_id', 'createdAt DESC'],
});

// GIN index for JSONB columns (fast JSON queries)
await store.createIndex({
  name: 'idx_traces_attributes',
  table: 'mastra_traces',
  columns: ['attributes'],
  method: 'gin',
});

For more advanced use cases, you can also use:

• unique: true for unique constraints
• where: 'condition' for partial indexes
• method: 'brin' for time-series data
• storage: { fillfactor: 90 } for update-heavy tables
• concurrent: true for non-blocking creation (default)

Managing Indexes

// List all indexes
const allIndexes = await store.listIndexes();

// List indexes for specific table
const threadIndexes = await store.listIndexes('mastra_threads');

// Get detailed statistics for an index
const stats = await store.describeIndex('idx_threads_resource');
console.log(stats);
// {
//   name: 'idx_threads_resource',
//   table: 'mastra_threads',
//   columns: ['resourceId', 'createdAt'],
//   unique: false,
//   size: '128 KB',
//   definition: 'CREATE INDEX idx_threads_resource...',
//   method: 'btree',
//   scans: 1542,           // Number of index scans
//   tuples_read: 45230,    // Tuples read via index
//   tuples_fetched: 12050  // Tuples fetched via index
// }

// Drop an index
await store.dropIndex('idx_threads_status');

Index Types and Use Cases

| Index Type | Best For | Storage | Speed | | ------------------- | --------------------------------------- | ---------- | -------------------------- | | btree (default) | Range queries, sorting, general purpose | Moderate | Fast | | hash | Equality comparisons only | Small | Very fast for = | | gin | JSONB, arrays, full-text search | Large | Fast for contains | | gist | Geometric data, full-text search | Moderate | Fast for nearest-neighbor | | spgist | Non-balanced data, text patterns | Small | Fast for specific patterns | | brin | Large tables with natural ordering | Very small | Fast for ranges |

Index Options

• name (required): Index name
• table (required): Table name
• columns (required): Array of column names (can include DESC/ASC)
• unique: Create unique index (default: false)
• concurrent: Non-blocking index creation (default: true)
• where: Partial index condition
• method: Index type ('btree' | 'hash' | 'gin' | 'gist' | 'spgist' | 'brin')
• opclass: Operator class for GIN/GIST indexes
• storage: Storage parameters (e.g., { fillfactor: 90 })
• tablespace: Tablespace name for index placement

Monitoring Index Performance

// Check index usage statistics
const stats = await store.describeIndex('idx_threads_resource');

// Identify unused indexes
if (stats.scans === 0) {
  console.log(`Index ${stats.name} is unused - consider removing`);
  await store.dropIndex(stats.name);
}

// Monitor index efficiency
const efficiency = stats.tuples_fetched / stats.tuples_read;
if (efficiency < 0.5) {
  console.log(`Index ${stats.name} has low efficiency: ${efficiency}`);
}

Related Links

• pgvector Documentation
• PostgreSQL Documentation