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title COMPRESS (Transact-SQL)
description The COMPRESS function compresses the input expression, using the Gzip algorithm.
author markingmyname
ms.author maghan
ms.reviewer randolphwest
ms.date 08/28/2025
ms.service sql
ms.subservice t-sql
ms.topic reference
ms.custom
ignite-2025
f1_keywords
COMPRESS
COMPRESS_TSQL
helpviewer_keywords
COMPRESS function
dev_langs
TSQL
monikerRange =azuresqldb-current || =azuresqldb-mi-current || >=sql-server-2016 || >=sql-server-linux-2017 || =azuresqledge-current || =azure-sqldw-latest || =fabric || =fabric-sqldb

COMPRESS (Transact-SQL)

[!INCLUDE sqlserver2016-asdb-asdbmi-asa-fabricse-fabricdw-fabricsqldb]

This function compresses the input expression, using the Gzip algorithm. The function returns a byte array of type varbinary(max).

:::image type="icon" source="../../includes/media/topic-link-icon.svg" border="false"::: Transact-SQL syntax conventions

Syntax

COMPRESS ( expression )

Arguments

expression

An expression of one of the following data types:

  • binary(n)
  • char(n)
  • nchar(n)
  • nvarchar(max)
  • nvarchar(n)
  • varbinary(max)
  • varbinary(n)
  • varchar(max)
  • varchar(n)

For more information, see Expressions.

Return types

varbinary(max), representing the compressed content of the input.

Remarks

Compressed data can't be indexed.

The COMPRESS function compresses the input expression data. You must invoke this function for each data section to compress. For more information about automatic data compression during storage at the row or page level, see Data compression.

Examples

A. Compress data during table insert

This example shows how to compress data inserted into a table:

INSERT INTO player (
    name,
    surname,
    info
)
VALUES (
    N'Ovidiu',
    N'Cracium',
    COMPRESS(N'{"sport":"Tennis","age": 28,"rank":1,"points":15258, "turn":17}')
);

INSERT INTO player (
    name,
    surname,
    info
)
VALUES (
    N'Michael',
    N'Raheem',
    COMPRESS(@info)
);

B. Archive compressed version of deleted rows

This statement first deletes old player records from the player table. To save space, it then stores the records in the inactivePlayer table, in a compressed format.

DELETE FROM player
OUTPUT
    deleted.id,
    deleted.name,
    deleted.surname,
    deleted.datemodifier,
    COMPRESS(deleted.info)
INTO dbo.inactivePlayers
WHERE datemodified < @startOfYear;

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