Error 42704 occurs when a query references a table, column, type, or other database object that does not exist. This commonly happens due to typos, case sensitivity issues, or missing schema qualifiers.
The "Undefined object" error (SQLSTATE 42704) in PostgreSQL indicates that your SQL statement is trying to access a database object that does not exist in the current database or schema. This object could be a table, column, index, constraint, type, function, or any other named database entity. PostgreSQL cannot find the referenced object in the catalog, so the query fails before execution. This is a strict requirement of SQL—all objects must exist before being used.
Check the SQL statement for typos in the object name. PostgreSQL error messages typically show which object is missing. For example:
-- WRONG: misspelled table name
SELECT * FROM user_table; -- Error: relation "user_table" does not exist
-- CORRECT: proper table name
SELECT * FROM users;Carefully compare the name in your query with the actual object definition.
PostgreSQL treats unquoted identifiers as lowercase. If you created an object with uppercase letters, you must quote it:
-- Created as uppercase
CREATE TABLE "Users" (id SERIAL);
-- WRONG: fails because it looks for "users" (lowercase)
SELECT * FROM users; -- Error: relation "users" does not exist
-- CORRECT: quote the identifier to preserve case
SELECT * FROM "Users";Best practice: use lowercase names without quoting to avoid these issues.
Use PostgreSQL system tables to check if the object exists:
-- Check if a table exists
SELECT EXISTS (
SELECT 1 FROM information_schema.tables
WHERE table_name = 'users'
);
-- Find which schema contains the object
SELECT table_schema FROM information_schema.tables
WHERE table_name = 'users';
-- List all tables in current schema
\dt
-- List all tables across all schemas
\dt *.*If the object does not exist, you need to create it with a CREATE TABLE, CREATE INDEX, etc. statement.
If the object exists in a different schema, you must include the schema name:
-- Object is in "public" schema
SELECT * FROM public.users;
-- Object is in "archive" schema
SELECT * FROM archive.users;Alternatively, add the schema to your search_path:
SET search_path TO public, archive;
SELECT * FROM users; -- Will find users in public or archiveIf this error occurs during migrations, ensure prerequisite objects are created first:
-- Migration 001: Create base table
CREATE TABLE users (
id SERIAL PRIMARY KEY,
email VARCHAR(255) UNIQUE
);
-- Migration 002: Create dependent table
CREATE TABLE posts (
id SERIAL PRIMARY KEY,
user_id INTEGER REFERENCES users(id) -- users must exist first
);Use transactions and IF NOT EXISTS to make migrations idempotent:
CREATE TABLE IF NOT EXISTS users (
id SERIAL PRIMARY KEY
);
CREATE TABLE IF NOT EXISTS posts (
id SERIAL PRIMARY KEY,
user_id INTEGER REFERENCES users(id)
);Related error codes: SQLSTATE 42P01 (undefined_table) for missing tables specifically, SQLSTATE 42703 (undefined_column) for missing columns, SQLSTATE 42883 (undefined_function) for missing functions. When using application ORMs or migrations tools, ensure they generate valid PostgreSQL syntax. Some frameworks (Laravel, Django) may need dialect-specific SQL. For distributed systems, confirm all replicas and standby servers have identical object definitions. Use pg_dump --schema-only to verify schema consistency across databases.
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