CREATE FUNCTION inherit_template_properties (p_parent_table text, p_child_schema text, p_child_tablename text) RETURNS boolean
    LANGUAGE plpgsql SECURITY DEFINER
    AS $$
DECLARE

v_child_relkind         char;
v_child_schema          text;
v_child_tablename       text;
v_fk_list               record;
v_index_list            record;
v_inherit_fk            boolean;
v_parent_oid            oid;
v_parent_table          text;
v_sql                   text;
v_template_oid          oid;
v_template_table        text;
v_template_tablespace   text;

BEGIN
/*
 * Function to inherit the properties of the template table to newly created child tables.
 * Currently used for PostgreSQL 10 to inherit indexes and FKs since that is not natively available
 */

SELECT parent_table, template_table, inherit_fk
INTO v_parent_table, v_template_table, v_inherit_fk
FROM @extschema@.part_config
WHERE parent_table = p_parent_table;
IF v_parent_table IS NULL THEN
    RAISE EXCEPTION 'Given parent table has no configuration in pg_partman: %', p_parent_table;
ELSIF v_template_table IS NULL THEN
    RAISE EXCEPTION 'No template table set in configuration for given parent table: %', p_parent_table;
END IF;
 
SELECT c.oid INTO v_parent_oid
FROM pg_catalog.pg_class c
JOIN pg_catalog.pg_namespace n ON c.relnamespace = n.oid
WHERE n.nspname = split_part(p_parent_table, '.', 1)::name
AND c.relname = split_part(p_parent_table, '.', 2)::name;
    IF v_parent_oid IS NULL THEN
        RAISE EXCEPTION 'Unable to find given parent table in system catalogs: %', p_parent_table;
    END IF;
 
SELECT n.nspname, c.relname, c.relkind INTO v_child_schema, v_child_tablename, v_child_relkind
FROM pg_catalog.pg_class c
JOIN pg_catalog.pg_namespace n ON c.relnamespace = n.oid
WHERE n.nspname = p_child_schema::name
AND c.relname = p_child_tablename::name;
    IF v_child_tablename IS NULL THEN
        RAISE EXCEPTION 'Unable to find given child table in system catalogs: %.%', v_child_schema, v_child_tablename;
    END IF;
       
IF v_child_relkind = 'p' THEN
    -- Subpartitioned parent, do not apply properties
    RAISE DEBUG 'inherit_template_properties: found given child is subpartition parent, so properties not inherited';
    RETURN false;
END IF;

SELECT c.oid, ts.spcname INTO v_template_oid, v_template_tablespace
FROM pg_catalog.pg_class c
JOIN pg_catalog.pg_namespace n ON c.relnamespace = n.oid
LEFT OUTER JOIN pg_catalog.pg_tablespace ts ON c.reltablespace = ts.oid
WHERE n.nspname = split_part(v_template_table, '.', 1)::name
AND c.relname = split_part(v_template_table, '.', 2)::name;
    IF v_template_oid IS NULL THEN
        RAISE EXCEPTION 'Unable to find configured template table in system catalogs: %', v_template_table;
    END IF;

-- Index creation (only required in 10)
IF current_setting('server_version_num')::int > 100000 AND current_setting('server_version_num')::int < 110000 THEN
    FOR v_index_list IN 
        SELECT
        array_to_string(regexp_matches(pg_get_indexdef(indexrelid), ' USING .*'),',') AS statement
        , i.indisprimary
        , ( SELECT array_agg( a.attname ORDER by x.r )
            FROM pg_catalog.pg_attribute a
            JOIN ( SELECT k, row_number() over () as r
                    FROM unnest(i.indkey) k ) as x
            ON a.attnum = x.k AND a.attrelid = i.indrelid
        ) AS indkey_names
        , c.relname AS index_name
        FROM pg_catalog.pg_index i
        JOIN pg_catalog.pg_class c ON i.indexrelid = c.oid
        WHERE i.indrelid = v_template_oid
        AND i.indisvalid
        ORDER BY 1
    LOOP

        IF v_index_list.indisprimary THEN
            v_sql := format('ALTER TABLE %I.%I ADD PRIMARY KEY (%s)'
                            , v_child_schema
                            , v_child_tablename
                            , '"' || array_to_string(v_index_list.indkey_names, '","') || '"');
            RAISE DEBUG 'Create pk: %', v_sql;
            EXECUTE v_sql;
        ELSE
            -- statement column should be just the portion of the index definition that defines what it actually is
            v_sql := format('CREATE INDEX ON %I.%I %s', v_child_schema, v_child_tablename, v_index_list.statement);
            RAISE DEBUG 'Create index: %', v_sql;
            EXECUTE v_sql;

        END IF;

    END LOOP;
END IF; 
-- End index creation

-- Foreign key creation
IF v_inherit_fk THEN
    FOR v_fk_list IN 
        SELECT pg_get_constraintdef(con.oid) AS constraint_def
        FROM pg_catalog.pg_constraint con
        JOIN pg_catalog.pg_class c ON con.conrelid = c.oid
        WHERE c.oid = v_template_oid
        AND contype = 'f'
    LOOP
        v_sql := format('ALTER TABLE %I.%I ADD %s', v_child_schema, v_child_tablename, v_fk_list.constraint_def);
        RAISE DEBUG 'Create FK: %', v_sql;
        EXECUTE v_sql;
    END LOOP;
END IF;
-- End foreign key creation

-- Tablespace inheritance
IF v_template_tablespace IS NOT NULL THEN
    v_sql := format('ALTER TABLE %I.%I SET TABLESPACE %I', v_child_schema, v_child_tablename, v_template_tablespace);
    EXECUTE v_sql;
    RAISE DEBUG 'Alter tablespace: %', v_sql;
END IF;

RETURN true;

END
$$;