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CHECKSUM

Calculates a hash value known as a checksum operation on a list of arguments. When * is specified as an argument - calculates checksum over all columns in the input. Performing a checksum operation is useful for warming up table data or to check if the same values exist in two different tables.

Syntax

CHECKSUM( <expr1> [, <expr2>] [, <expr3>] [, ...<exprN>] )
CHECKSUM(*)

Example

For this example, we’ll create a new table albums as shown below.

CREATE DIMENSION TABLE albums (year INT, artist TEXT, title TEXT);

INSERT INTO
	albums
VALUES
	(1982, 'Michael Jackson', 'Thriller'),
	(1973, 'Pink Floyd', 'The Dark Side of the Moon'),
	(1969, 'The Beatles', 'Abbey Road'),
	(1976, 'Eagles', 'Hotel California');

The example below calculates a checksum based on all columns in the table albums.

SELECT CHECKSUM(*) FROM albums;

Returns: 1630068993470241196

The next example calculates a checksum based on columns year and title only.

SELECT CHECKSUM(year, title) FROM albums;

Returns: 4056287705143712538