LENGTH

Return the number of characters in the input string.

Category: stringReturns: INTEGERDialect: Standard

Syntax

LENGTH(str)

Description

## Overview Returns the number of characters in the input string. In DeltaForge, LENGTH is a character count, not a byte count, so multi-byte UTF-8 characters each contribute 1 to the result. This aligns with CHAR_LENGTH and CHARACTER_LENGTH and matches how most application code counts characters. Use LENGTH for validation (enforcing maximum length for a name, ensuring a code is exactly N characters), for computing summary statistics, and as input to SUBSTRING-based slicing. For byte-accurate storage estimates, use OCTET_LENGTH; for bit counts, use BIT_LENGTH. ## Behavior - Returns NULL when the input is NULL. - Returns 0 for an empty string. - Each Unicode code point counts as one character. Multi-byte UTF-8 sequences are not double-counted. - Combining sequences (for example a base letter plus an accent mark) count as the number of code points, not grapheme clusters. 'e\u0301' has LENGTH 2 even though it visually renders as one character. - LENGTH never returns a negative value. - CHAR_LENGTH and CHARACTER_LENGTH are strict synonyms for LENGTH when applied to string types. ## Compatibility - Conforms to the SQL standard definition when applied to character strings. - For VARBINARY or BYTEA inputs, some dialects define LENGTH as a byte count. DeltaForge requires explicit use of OCTET_LENGTH for byte counting.

Parameters

Name	Type	Description
`str`		Specifies the input string whose character count is returned. Accepts any VARCHAR or CHAR value.

Examples

-- Basic ASCII length
SELECT LENGTH('hello');  -- 5

-- Empty string
SELECT LENGTH('');  -- 0

-- NULL propagates
SELECT LENGTH(CAST(NULL AS VARCHAR));  -- NULL

-- Multi-byte characters count as one character each
SELECT LENGTH('éèê');  -- 3

-- Validate that no customer name exceeds 100 characters
SELECT customer_id, full_name
FROM retail.customers.profiles
WHERE LENGTH(full_name) > 100;

-- Average description length per category
SELECT category, AVG(LENGTH(description)) AS avg_len
FROM retail.products.catalog
GROUP BY category;

Pitfalls

LENGTH is a character count, not a byte count. A column containing emoji or CJK characters will have smaller LENGTH than OCTET_LENGTH. Use OCTET_LENGTH for storage-size decisions.
LENGTH counts code points, not grapheme clusters. A base letter plus a combining accent is 2 characters even though it renders as one. Apply NORMALIZE NFC first if you need a stable visual-character count.
LENGTH of a trailing-padded CHAR(n) value can differ between dialects: some count trailing pad spaces, others strip them. DeltaForge counts every character including trailing spaces.
LENGTH(arr) applied to an ARRAY type is the array length, not a string length. Be explicit about casts if a column's type is ambiguous.