This error occurs when a database query through Prisma Pulse fails to return a response within the configured query timeout limit. Common causes include slow queries, insufficient database connections during high traffic, or database resource contention.
The P6004 error indicates that a database query routed through Prisma Pulse failed to complete within the allowed time window. Prisma enforces a default query timeout of 10 seconds to ensure responsive application performance and prevent resource exhaustion. This timeout encompasses several components: the time waiting for an available connection from the connection pool, network latency between your application and the database, and the actual query execution time. When a query exceeds this limit, Prisma cancels the operation and returns the P6004 error to prevent indefinite blocking of your application threads. This protective mechanism helps maintain overall system stability and prevents long-running queries from consuming connection resources indefinitely.
First, configure Prisma Client to log query performance and duration:
import { PrismaClient } from '@prisma/client';
const prisma = new PrismaClient({
log: [
{ emit: 'event', level: 'query' },
{ emit: 'stdout', level: 'error' },
{ emit: 'stdout', level: 'warn' },
],
});
// Listen to query events
prisma.$on('query', (e) => {
console.log('Query: ' + e.query);
console.log('Duration: ' + e.duration + 'ms');
if (e.duration > 5000) {
console.warn('SLOW QUERY WARNING: Query took ' + e.duration + 'ms');
}
});Monitor your logs to identify queries that are approaching or exceeding the 10-second limit. Pay special attention to queries that fetch large amounts of data or perform complex operations. Once you identify the culprit, focus your optimization efforts there.
Use Prisma's select clause to retrieve only the fields your application needs:
// Before: Fetching all fields (slow)
const users = await prisma.user.findMany({
where: { isActive: true }
});
// After: Fetch only required fields (fast)
const users = await prisma.user.findMany({
where: { isActive: true },
select: {
id: true,
email: true,
name: true,
}
});Avoiding unnecessary fields, especially JSONB columns or text fields with large content, can dramatically reduce query execution time. This also reduces network transfer time and database I/O.
Break large queries into smaller chunks using cursor-based pagination:
// Cursor-based pagination (recommended for large datasets)
const pageSize = 100;
let cursor = undefined;
while (true) {
const users = await prisma.user.findMany({
take: pageSize,
skip: cursor ? 1 : 0,
cursor: cursor ? { id: cursor } : undefined,
orderBy: { id: 'asc' },
});
if (users.length === 0) break;
// Process this batch
await processBatch(users);
// Move to next cursor
cursor = users[users.length - 1].id;
}Pagination prevents fetching thousands of records in a single query, which easily exceeds timeout limits. This is especially important for reporting, exports, and batch operations.
Ensure your database has indexes on fields used in WHERE, ORDER BY, and JOIN clauses:
model User {
id String @id @default(cuid())
email String @unique
createdAt DateTime @default(now())
status String
department String
@@index([status])
@@index([createdAt])
@@index([status, createdAt])
@@index([department])
}Apply the migration to your database:
npx prisma migrate dev --name add-indexesIndexes can reduce query time from seconds to milliseconds by allowing the database to quickly locate relevant rows instead of scanning the entire table.
If timeouts occur because queries wait too long for available connections, increase the pool_timeout in your database URL:
# PostgreSQL example
DATABASE_URL="postgresql://user:password@localhost:5432/mydb?connection_limit=20&pool_timeout=20"
# The pool_timeout is in seconds (default is 10)
# Increase it to allow queries to wait longer for a free connectionHowever, only increase this if the timeout is truly due to connection pool exhaustion (not slow queries). Monitor your connection utilization to confirm this is the issue. Setting pool_timeout too high can mask other performance problems.
Ensure your connection pool is large enough to handle your application's concurrent load:
# Calculate: (number_of_app_instances * 2) to start
# E.g., 5 app instances = 10 connections
DATABASE_URL="postgresql://user:password@localhost:5432/mydb?connection_limit=15"Check your database's maximum connection limit first:
-- PostgreSQL: Check max connections
SHOW max_connections;
-- If you have connection pooling (e.g., PgBouncer), check its settingsMore connections allows more concurrent queries, but be careful not to exceed your database's limit. Restart your application after changing the connection limit.
Refactor queries to reduce unnecessary database roundtrips and improve efficiency:
// Before: N+1 query problem (slow)
const users = await prisma.user.findMany();
const usersWithPosts = await Promise.all(
users.map(user =>
prisma.post.findMany({ where: { userId: user.id } })
)
);
// After: Use include/join (fast)
const usersWithPosts = await prisma.user.findMany({
include: {
posts: {
select: { id: true, title: true }
}
}
});Also consider using findRaw() for complex aggregations that would be slow with ORM methods:
// For complex analytics
const results = await prisma.$queryRaw`
SELECT status, COUNT(*) as count
FROM users
GROUP BY status
`;Pulse-Specific Considerations: Prisma Pulse is the real-time data synchronization feature. The P6004 timeout specifically applies to queries executed through Pulse subscriptions and streaming. If you're using Pulse for real-time updates, consider separating your analytics/batch queries to use direct connections instead.
Direct Connection for Long Queries: Create a separate PrismaClient instance with a direct database connection string (not through Pulse) for long-running queries:
const realtimeClient = new PrismaClient({
datasources: { db: { url: process.env.DATABASE_URL_PULSE } }
});
const analyticsClient = new PrismaClient({
datasources: { db: { url: process.env.DATABASE_URL_DIRECT } }
});
// Use realtimeClient for responsive user-facing queries
// Use analyticsClient for long-running reports/exportsTransaction Timeout: If your timeout occurs within an interactive transaction, increase the transaction timeout:
await prisma.$transaction(
async (tx) => {
// Your queries here
},
{ timeout: 30000 } // 30 seconds
);Database Query Analysis: Use your database's native tools to identify bottlenecks:
PostgreSQL:
SELECT query, calls, mean_exec_time FROM pg_stat_statements
ORDER BY mean_exec_time DESC LIMIT 10;This shows your slowest queries on average. Focus optimization efforts there first.
Monitoring and Alerts: Implement application-level monitoring using Prisma's query events or APM tools like DataDog, New Relic, or Sentry. Set alerts for queries approaching 8-9 seconds so you can catch issues before users experience timeouts.
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