Arrays

HEAVY.AI supports arrays in dictionary-encoded text and number fields (TINYINT, SMALLINT, INTEGER, BIGINT, FLOAT, and DOUBLE). Data stored in arrays are not normalized. For example, {green,yellow} is not the same as {yellow,green}. As with many SQL-based services, OmniSci array indexes are 1-based.

HEAVY.AI supports NULL variable-length arrays for all integer and floating-point data types, including dictionary-encoded string arrays. For example, you can insert NULL into BIGINT[ ], DOUBLE[ ], or TEXT[ ] columns. HEAVY.AI supports NULL fixed-length arrays for all integer and floating-point data types, but not for dictionary-encoded string arrays. For example, you can insert NULL into BIGINT[2] DOUBLE[3], but not into TEXT[2] columns.

ExpressionDescription

ArrayCol[n] ...

Returns value(s) from specific location n in the array.

UNNEST(ArrayCol)

Extract the values in the array to a set of rows. Requires GROUP BY; projecting UNNEST is not currently supported.

test = ANY ArrayCol

ANY compares a scalar value with a single row or set of values in an array, returning results in which at least one item in the array matches. ANY must be preceded by a comparison operator.

test = ALL ArrayCol

ALL compares a scalar value with a single row or set of values in an array, returning results in which all records in the array field are compared to the scalar value. ALL must be preceded by a comparison operator.

CARDINALITY()

Returns the number of elements in an array. For example:

heavysql> \d arr
CREATE TABLE arr (
sia SMALLINT[])
omnisql> select sia, CARDINALITY(sia) from arr;
sia|EXPR$0
NULL|NULL
{}|0
{NULL}|1
{1}|1
{2,2}|2
{3,3,3}|3

Examples

The following examples show query results based on the table test_array created with the following statement:

CREATE TABLE test_array (name TEXT ENCODING DICT(32),colors TEXT[] ENCODING DICT(32), qty INT[]);
omnisql> SELECT * FROM test_array;
name|colors|qty
Banana|{green, yellow}|{1, 2}
Cherry|{red, black}|{1, 1}
Olive|{green, black}|{1, 0}
Onion|{red, white}|{1, 1}
Pepper|{red, green, yellow}|{1, 2, 3}
Radish|{red, white}|{}
Rutabaga|NULL|{}
Zucchini|{green, yellow}|{NULL}

The following queries use arrays in an INTEGER field:

omnisql> SELECT name, qty FROM test_array WHERE qty[2] >1;
name|qty
Banana|{1, 2}
Pepper|{1, 2, 3}

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