pg-mem

library3.0.14jsnpmunverified

pg-mem v3.0.14 is an experimental in-memory emulation of a PostgreSQL database for Node.js and browser environments, released under active development with weekly commits. It supports SQL syntax parsing via a custom parser (pgsql-ast-parser), provides adapters for popular ORMs/query builders such as TypeORM, MikroORM, Knex, Kysely, pg-promise, Slonik, and postgres.js, and offers unique features like immutable restore points for zero-cost rollback in unit tests. Key differentiators include browser compatibility, custom function registration, and no native dependencies. However, it is not a full PostgreSQL replacement; many advanced features are missing (e.g., some data types, triggers, window functions) and the SQL parser may reject valid PostgreSQL syntax. It ships TypeScript types and is primarily used for testing and development.

testing

npm install pg-mem

github ↗package ↗homepage ↗

INSTALL

IMPORT

SIG · PG-MEM

pg-mem

testingjavascriptv3.0.14

harness data pending

Install & Compatibility

Where this runs

No compatibility data collected yet for this library.

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

newDb

✓ import { newDb } from 'pg-mem'

✗ const pgmem = require('pg-mem'); const db = pgmem.newDb()

ESM-only since v3; named import required.

DataType

✓ import { DataType } from 'pg-mem'

✗ import DataType from 'pg-mem'

Named export, not default.

IDb

✓ import type { IDb } from 'pg-mem'

Type import for TypeScript; only available since v3.

Creates an in-memory database, runs SQL schema and inserts, queries data, then demonstrates restore point rollback.

import { newDb } from 'pg-mem'; const db = newDb(); db.public.none(`CREATE TABLE users (id SERIAL PRIMARY KEY, name TEXT NOT NULL)`); db.public.none(`INSERT INTO users (name) VALUES ('Alice'), ('Bob')`); const rows = db.public.many(`SELECT * FROM users`); console.log(rows); // [{ id: 1, name: 'Alice' }, { id: 2, name: 'Bob' }] // Create restore point and rollback const backup = db.backup(); db.public.none(`UPDATE users SET name = 'Charlie' WHERE id = 1`); backup.restore(); const afterRestore = db.public.many(`SELECT * FROM users`); console.log(afterRestore); // [{ id: 1, name: 'Alice' }, { id: 2, name: 'Bob' }]

Debug

Known issues

gotchapg-mem does not implement all PostgreSQL features; some SQL syntax or functions may fail silently or throw unexpected errors.

fix

Before relying on pg-mem, test your SQL against it. For unsupported features, consider filing an issue or using alternative mocking strategies.

affects: >=0.0.0

breakingIn v3, the package is ESM-only. Using require() will fail.

fix

Switch to ES module imports: import { newDb } from 'pg-mem'.

affects: >=3.0.0

breakingThe default export was removed in v3; only named exports are available.

fix

Use named imports: import { newDb, DataType, IDb } from 'pg-mem'.

affects: >=3.0.0

gotchaRestore points are only valid within the same db session; creating a second db instance will not share restore points.

fix

Always use the same db instance for restore points.

affects: >=0.0.0

gotchaCustom function return values are not type-checked; returning an incompatible type can cause runtime errors.

fix

Ensure the implementation returns a value compatible with the declared DataType.

affects: >=0.0.0

Errors

Common errors & fixes

TypeError: pg_mem_1.newDb is not a function

Using default import on ESM-only package v3

fix

Change to named import: import { newDb } from 'pg-mem'

SyntaxError: Unexpected token 'export'

Using require() on ESM-only package

fix

Set type: 'module' in package.json or use dynamic import: const { newDb } = await import('pg-mem')

Error: unsupported statement type: <some specific SQL>

pg-mem's SQL parser does not recognize that statement

fix

Simplify the SQL or split into multiple statements; consider using pgsql-ast-parser separately.

Upgrade

Version history

3.0.14latest on npm

Audit

Dependencies

typeormoptionalOptional adapter for TypeORM integration

@mikro-orm/coreoptionalOptional adapter for MikroORM integration

@mikro-orm/postgresqloptionalOptional adapter for MikroORM PostgreSQL driver

knexoptionalOptional adapter for Knex query builder

kyselyoptionalOptional adapter for Kysely query builder

pg-promiseoptionalOptional adapter for pg-promise

slonikoptionalOptional adapter for Slonik

postgresoptionalOptional adapter for postgres.js

pg-serveroptionalOptional adapter for pg-server

Agent activity

15 hits · last 30 days

node

Resources

githubhttps://github.com/oguimbal/pg-mem ↗

packagepg-mem ↗

homepagehttps://github.com/oguimbal/pg-mem#readme ↗