How to Fix PostgreSQL Error: Value Too Long for Type

The "Value too long for type" error occurs when attempting to insert or update a value that exceeds the defined length limit of a character column (VARCHAR(n), CHAR(n), or similar types).

Impact

This error prevents data insertion or updates, causing application failures and data loss if not handled properly. It indicates a mismatch between application expectations and database schema.

Common Causes

Column defined with insufficient length
User input exceeding expected limits
Data from external sources longer than expected
Missing input validation in application
Schema not updated for new requirements
Concatenation producing longer strings
Multi-byte characters (UTF-8) using more storage

Troubleshooting and Resolution Steps

Identify the column and limit:

-- Check column definitions
\d table_name

-- Query column lengths
SELECT
    column_name,
    character_maximum_length,
    data_type
FROM information_schema.columns
WHERE table_name = 'users';

Increase column length:

-- Increase VARCHAR length
ALTER TABLE users ALTER COLUMN email TYPE VARCHAR(255);

-- Change to TEXT for unlimited length
ALTER TABLE users ALTER COLUMN description TYPE TEXT;

-- For multiple columns
ALTER TABLE users
    ALTER COLUMN first_name TYPE VARCHAR(100),
    ALTER COLUMN last_name TYPE VARCHAR(100);

Truncate data before insertion:

-- Truncate in INSERT
INSERT INTO users (name, description)
VALUES (
    LEFT('Very Long Name...', 50),
    LEFT('Long description...', 500)
);

-- Truncate in UPDATE
UPDATE users
SET description = LEFT(description, 500)
WHERE LENGTH(description) > 500;

Find oversized data:

-- Find rows with long values
SELECT id, email, LENGTH(email) AS email_length
FROM users
WHERE LENGTH(email) > 100
ORDER BY email_length DESC;

-- Check before altering column type
SELECT MAX(LENGTH(column_name)) AS max_length
FROM table_name;

Application-level validation:

# Python validation
def validate_input(text, max_length):
    if len(text) > max_length:
        # Option 1: Truncate
        return text[:max_length]
        # Option 2: Raise error
        # raise ValueError(f"Text exceeds {max_length} characters")
        # Option 3: Truncate with ellipsis
        # return text[:max_length-3] + '...'
    return text

# Usage
email = validate_input(user_email, 255)
cursor.execute(
    "INSERT INTO users (email) VALUES (%s)",
    (email,)
)

Handle multi-byte characters:

-- UTF-8 characters can use multiple bytes
-- LENGTH counts characters, octet_length counts bytes
SELECT
    name,
    LENGTH(name) AS char_length,
    OCTET_LENGTH(name) AS byte_length
FROM users;

-- For byte-limited columns
ALTER TABLE users ALTER COLUMN name TYPE VARCHAR(100);
-- Stores up to 100 characters, regardless of byte count

Use CHECK constraints for validation:

-- Prevent overly long values at database level
ALTER TABLE users
ADD CONSTRAINT name_length_check
CHECK (LENGTH(name) <= 100);

-- Combined with NOT NULL
ALTER TABLE users
ADD CONSTRAINT email_valid
CHECK (LENGTH(email) > 0 AND LENGTH(email) <= 255);

Handle truncation safely:

-- Create function for safe truncation
CREATE OR REPLACE FUNCTION safe_insert_text(
    text_value TEXT,
    max_length INTEGER
) RETURNS VARCHAR AS $$
BEGIN
    IF text_value IS NULL THEN
        RETURN NULL;
    END IF;
    IF LENGTH(text_value) <= max_length THEN
        RETURN text_value::VARCHAR;
    END IF;
    RETURN SUBSTRING(text_value FROM 1 FOR max_length)::VARCHAR;
END;
$$ LANGUAGE plpgsql IMMUTABLE;

-- Usage
INSERT INTO users (name)
VALUES (safe_insert_text('Very long name...', 50));

Batch update for existing data:

-- Update oversized values
UPDATE users
SET description = LEFT(description, 500)
WHERE LENGTH(description) > 500;

-- Then adjust column size
ALTER TABLE users ALTER COLUMN description TYPE VARCHAR(500);

Schema design best practices:

-- Good: Reasonable limits based on requirements
CREATE TABLE users (
    id SERIAL PRIMARY KEY,
    email VARCHAR(255),      -- Standard email length
    name VARCHAR(100),       -- Reasonable name length
    phone VARCHAR(20),       -- Standard phone length
    bio TEXT,               -- Unlimited for long content
    notes TEXT              -- Unlimited for variable content
);

-- Avoid overly restrictive limits unless necessary
-- Use TEXT for unknown/variable length content

Additional Information

TEXT type has no length limit (up to 1GB)
VARCHAR without length specification behaves like TEXT
Consider business requirements when setting limits
Multi-byte UTF-8 characters count as 1 character in LENGTH()
CHAR(n) pads with spaces, VARCHAR(n) doesn't
Validate data in application before database insertion
Document column length requirements
Consider future growth when sizing columns

Frequently Asked Questions

Q: What's the maximum length for VARCHAR?
A: Technically up to ~1GB, but practical limit with length specification is VARCHAR(10485760). For unlimited, use TEXT.

Q: Should I use VARCHAR or TEXT?
A: Use VARCHAR(n) when you have a known maximum length. Use TEXT for variable or unlimited length. Both have similar performance in PostgreSQL.

Q: Does VARCHAR(255) vs VARCHAR(1000) affect performance?
A: No, PostgreSQL stores actual string length. The limit only enforces maximum size. Storage is the same for same actual content.

Q: How do I change VARCHAR(50) to TEXT?
A: ALTER TABLE table_name ALTER COLUMN column_name TYPE TEXT; - this is safe and doesn't require table rewrite in most cases.

Q: Can I truncate automatically instead of getting an error?
A: Not by default. Use application validation or CREATE a BEFORE INSERT trigger to truncate.

Q: What's the difference between LENGTH and OCTET_LENGTH?
A: LENGTH counts characters, OCTET_LENGTH counts bytes. In UTF-8, multi-byte characters have different values for each.

Q: How do I handle data that's occasionally too long?
A: Either increase column size, use TEXT type, or implement truncation in application with user notification.

Q: Does this error occur with TEXT type?
A: No, TEXT has no enforced length limit. You'd only hit storage limits (1GB).