Pgsql实现雪花算法

创建方法

创建一个序列
CREATE SEQUENCE table_id_seq increment by 1 maxvalue 999999999999999 minvalue 1 start 1 cycle;

创建一个函数
create function snow_next_id(OUT result bigint) returns bigint
    language plpgsql
as
$$
DECLARE
   our_epoch bigint := 1483200000000;
   seq_id bigint;
   now_millis bigint;
   shard_id int := 5;
BEGIN
   seq_id := nextval('table_id_seq') % 1024;
   SELECT FLOOR(EXTRACT(EPOCH FROM clock_timestamp()) * 1000) INTO now_millis;
   result := (now_millis - our_epoch) << 23;
   result := result | (shard_id << 10);
   result := result | (seq_id);
END;
$$;

如何使用？

SELECT SNOW_NEXT_ID() AS ID