pg_map

Overview

This packaged provider is Snowflake pg_lake pg_map 3.4, not the unrelated semenikhind/pg_map 1.0 array-mapping extension. The catalog name is unique, so the packaged provider supersedes that source-only row and is reassigned with the pg_lake family to OLAP ID 2563. Extension SQL/control version is 3.4; source and DEB/RPM package version is 3.4.0.

Version

Build

You can build the RPM / DEB packages for pg_lake using pig build:

pig build pkg pg_lake         # build RPM / DEB packages

Install

You can install pg_lake directly. First, make sure the PGDG and PIGSTY repositories are added and enabled:

pig repo add pgsql -u          # Add repo and update cache

Install the extension using pig or apt/yum/dnf:

• Install
• pig
• dnf
• apt

pig install pg_lake;          # Install for current active PG version

pig ext install -y pg_lake -v 18  # PG 18
pig ext install -y pg_lake -v 17  # PG 17
pig ext install -y pg_lake -v 16  # PG 16

dnf install -y pg_lake_18       # PG 18
dnf install -y pg_lake_17       # PG 17
dnf install -y pg_lake_16       # PG 16

apt install -y postgresql-18-pg-lake   # PG 18
apt install -y postgresql-17-pg-lake   # PG 17
apt install -y postgresql-16-pg-lake   # PG 16

Create Extension:

CREATE EXTENSION pg_map;

Usage

Sources:

• pg_map README at the reviewed commit
• pg_map install SQL at the reviewed commit
• pg_map C implementation at the reviewed commit

pg_map applies a one-argument PostgreSQL function to every element of an array and returns an array of the function results. Its two overloads identify the mapped function by OID or by text; a text signature containing parentheses is resolved as a specific regprocedure, while a bare name is resolved as regproc.

Map a Function over an Array

CREATE EXTENSION pg_map;

SELECT pg_map(
  'upper(text)',
  ARRAY['alpha', 'beta', 'gamma']::text[]
);

The example applies upper(text) to each element and returns an uppercase text array. Supplying a full signature avoids ambiguity when a function name is overloaded.

Caveats

• Upstream only claims compatibility with PostgreSQL 9.6devel. It does not document support for modern PostgreSQL releases.
• The version 1.0 C implementation uses PostgreSQL internal array, catalog, and function-manager APIs. Build and regression-test it against the exact server source before use.
• The mapped function must accept one argument. The implementation attempts an element-type cast when the array element type differs from the function argument type and errors if no cast function is available.
• Upstream publishes no license or release compatibility matrix.