Hologres:Presto functions

Prerequisites

Before you begin, ensure that you have:

• A Hologres instance running V3.1 or later

• Superuser access to the target database

Install the extension

Run the following statement as a Superuser. Run it once per database — if you create a new database, run it again.

CREATE EXTENSION hg_presto_funcs;

Call Presto functions

All Presto functions live in the hg_presto_funcs schema. To call them, either prefix each function name or set the search path once per session:

-- Option 1: prefix each call
SELECT hg_presto_funcs.array_cum_sum(b) FROM public.presto_test;

-- Option 2: set search path for the session
SET search_path = hg_presto_funcs;
SELECT array_cum_sum(b) FROM public.presto_test;

Sample table

The examples in this topic use the following table:

CREATE TABLE public.presto_test(
  a INT, b INT[], c TEXT, d TEXT, e TEXT, f TEXT, g TEXT,
  h TEXT, i TEXT, j TEXT, k TEXT, l TEXT, m TEXT, n TEXT,
  o TEXT, p TEXT, r TEXT, s TEXT, t FLOAT, u TEXT
);

INSERT INTO public.presto_test
  VALUES (
    3, ARRAY[1, 2, 3, 2], 'A', '10010', 'SGVsbG8gV29ybGQh',
    '\x00000001', '\x0000000000000001', '48656C6C6F',
    '\x40490FD0', '\x400921FB54442D18', '\x48656C6C6F',
    '"dwdw"', '[1,2,3,4,5,6]', '{"x": {"a": 1, "b": 2}}',
    'café', 'apple,banana,cherry', 'ABCDA', 'running',
    3.1415926, '[1.0,2.0]'
  );

Supported functions

The tables below list all supported functions, grouped by category. Each entry shows the function signature with parameter and return types.

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What's next

• Hologres functions overview

• Velox function reference