Amazon Redshift will no longer support the use of Python UDFs after June 30, 2026.
We will start enforcing it in phases. For more information on the details of Python end of life
and migration options, see the
blog post
HLL_CARDINALITY function
The HLL_CARDINALITY function returns the cardinality of the input HLLSKETCH data type.
Syntax
HLL_CARDINALITY (hllsketch_expression)
Argument
- hllsketch_expression
-
Any valid expression that evaluates to an HLLSKETCH type, such as a column name. The input value is the HLLSKETCH data type.
Return type
The HLL_CARDINALITY function returns a BIGINT or INT8 value.
Examples
The following example returns the cardinality of column sketch in table
hll_table.
CREATE TABLE a_table(an_int INT, b_int INT); INSERT INTO a_table VALUES (1,1), (2,1), (3,1), (4,1), (1,2), (2,2), (3,2), (4,2), (5,2), (6,2); CREATE TABLE hll_table (sketch HLLSKETCH); INSERT INTO hll_table select hll_create_sketch(an_int) from a_table group by b_int; SELECT hll_cardinality(sketch) AS cardinality FROM hll_table; cardinality ------------- 6 4 (2 rows)
