collection

pig build pkg pgcollection         # 构建 RPM / DEB 包

pig repo add pgsql -u          # 添加仓库并更新缓存

CREATE EXTENSION collection;

CREATE EXTENSION collection;

DECLARE
    c1  collection('date');
    ic1 icollection('int4');

DO $$
DECLARE t_capital collection;
BEGIN
    t_capital['USA'] := 'Washington, D.C.';
    t_capital['Japan'] := 'Tokyo';
    RAISE NOTICE '%', t_capital['USA'];  -- Washington, D.C.
END $$;

DO $$
DECLARE t_capital collection;
BEGIN
    t_capital['USA'] := 'Washington, D.C.';
    t_capital['United Kingdom'] := 'London';
    t_capital['Japan'] := 'Tokyo';

    t_capital := first(t_capital);
    WHILE NOT isnull(t_capital) LOOP
        RAISE NOTICE 'Capital of % is %', key(t_capital), value(t_capital);
        t_capital := next(t_capital);
    END LOOP;
END $$;

DECLARE sparse icollection;
BEGIN
    sparse[1] := 'first';
    sparse[1000000] := 'millionth';  -- 间隙不会浪费内存
END;