HASH¶
HASH(A, B, C, ...)
Takes in a variable number of arguments of any type and returns a hash value that considers the values in each column. The hash function is deterministic across multiple ranks or multiple sessions.
Also supports the syntactic sugar forms HASH(*)
and HASH(T.*)
as shortcuts for referencing all of the columns in a table, or multiple tables.
For example, if T1
has columns A
and B
, and T2
has columns
A
, E
and I
, then the following query:
SELECT HASH(*), HASH(T1.*) FROM T1 INNER JOIN T2 ON T1.A=T2.I
Would be syntactic sugar for the following:
SELECT HASH(T1.A, T1.B, T2.A, T2.E, T2.I), HASH(T1.A, T1.B) FROM T1 INNER JOIN T2 ON T1.A=T2.I