PG_SIZE_PRETTY

Format a byte count as a human-readable size string (bytes, kB, MB, GB, TB).

Category: miscReturns: STRINGDialect: PostgreSql

Syntax

PG_SIZE_PRETTY(size)

Description

## Overview Formats a byte count as a short human-readable string using the nearest unit from bytes, kB, MB, GB, or TB. Use this function for diagnostic and monitoring output where an exact byte count would be hard to read. ## Behavior - Returns NULL if the input is NULL. - Units are base-1024: 1 kB = 1024 bytes, 1 MB = 1,048,576 bytes, and so on. - Units use the PG-compat spellings `bytes`, `kB`, `MB`, `GB`, `TB`. - Negative values are formatted with a leading minus sign. - Deterministic and side effect free. ## Compatibility - PG-compat alias with the same output format.

Parameters

Name	Type	Description
`size`		Specifies the size in bytes to format as a human-readable string. Accepts any signed 64-bit integer.

Examples

-- Format a kilobyte
SELECT PG_SIZE_PRETTY(1024);  -- '1 kB'

-- Format a megabyte
SELECT PG_SIZE_PRETTY(1048576);  -- '1 MB'

-- Format a terabyte
SELECT PG_SIZE_PRETTY(1099511627776);  -- '1 TB'

-- Use alongside PG_COLUMN_SIZE in an information_schema report
SELECT column_name, PG_SIZE_PRETTY(PG_COLUMN_SIZE(column_name)) AS readable_size
FROM information_schema.columns
WHERE table_name = 'orders';

-- NULL propagation
SELECT PG_SIZE_PRETTY(NULL);  -- NULL

Pitfalls

PG_SIZE_PRETTY uses base-1024 units, which are conventionally called KiB/MiB by IEC rules. The output uses the PG-compat spellings `kB`, `MB`, etc. Do not conflate with base-1000 (SI) units.
Output is a STRING; do not parse it back into a numeric for arithmetic. Keep the original byte count in a separate column if you need to compute with it.
The function rounds to the nearest printable magnitude and may display the same text for nearby byte counts. Use the exact byte count for precise comparisons.
Very large values (exabytes) still render as a TB count; the function does not add PB/EB units.