REVERSE command format, parameters, and return value - MaxCompute

Syntax

STRING|BINARY|ARRAY REVERSE(STRING|BINARY|ARRAY <value>)

Parameters

Parameter	Required	Type	Description
`value`	Yes	STRING, BINARY, or ARRAY	The value to reverse. Values of data types such as BIGINT, DOUBLE, DECIMAL, and DATETIME are implicitly converted to STRING before the operation. If the value cannot be converted to STRING, BINARY, or ARRAY, an error is returned. If the value is null, null is returned.

Return value

Returns the reversed value. The return type matches the input type: STRING input returns STRING, BINARY returns BINARY, and ARRAY returns ARRAY.

Encoding behavior

By default, REVERSE operates byte by byte regardless of input type.

In BigQuery compatibility mode (SET odps.sql.bigquery.compatible=true;), the behavior differs by type:

Input type	Default mode	BigQuery compatibility mode
STRING	Reversed byte by byte	Reversed by UTF-8 character
BINARY	Reversed byte by byte	Reversed byte by byte
ARRAY	Reversed byte by byte	Reversed byte by byte

Why this matters for multi-byte characters: In default mode, REVERSE treats each byte as an independent unit. Multi-byte Unicode characters (such as characters from languages like Chinese, Japanese, or Arabic) span multiple bytes, so reversing byte by byte produces garbled results. In BigQuery compatibility mode, REVERSE treats each UTF-8 encoded Unicode code point as a single unit, which correctly reverses strings containing these characters.

Examples

Reverse a string

SELECT REVERSE('I love aliyun very much');

Result
`hcum yrev nuyila evol I`

Return null for a null input

SELECT REVERSE(null);

Result
`NULL`

Reverse an array

SELECT REVERSE(ARRAY(2, 1, 4, 3));

Result
`[3, 4, 1, 2]`

Reverse binary data

SELECT REVERSE(UNHEX('FA34E10293CB42848573A4E39937F479'));

Result
`y=F47=99=E3=A4s=85=84B=CB=93=02=E14=FA`

Reverse a string in BigQuery compatibility mode

Use this example to test multi-byte character reversal via the SQL code editor in the MaxCompute client.

Important

Run the following steps from the bin folder of the MaxCompute client.

In the bin folder, create a file named reverse_func.sql with the following content:
```
SET odps.sql.bigquery.compatible=true;
SELECT REVERSE("<Emoji character>");
```
Open a command-line window and run the following command:
```
odpscmd -s reverse_func.sql
```
View the reversed result on the Result tab in Logview.

Related functions

REVERSE is a string function. For other string search and conversion functions, see String functions.