我遇到了一个问题,我的主键序列与我的表行不同步。

也就是说,当我插入一个新行时,我得到一个重复的键错误,因为在串行数据类型中隐含的序列返回一个已经存在的数字。

这似乎是由于导入/恢复没有正确地维护序列造成的。


当前回答

ALTER SEQUENCE sequence_name RESTART WITH (SELECT max(id) FROM table_name); 是行不通的。

复制自@tardate答案:

SELECT setval(pg_get_serial_sequence('table_name', 'id'), MAX(id)) FROM table_name;

其他回答

Pg_get_serial_sequence可以用来避免任何关于序列名称的错误假设。这将在一个镜头中重置序列:

SELECT pg_catalog.setval(pg_get_serial_sequence('table_name', 'id'), (SELECT MAX(id) FROM table_name)+1);

或者更简洁地说:

SELECT pg_catalog.setval(pg_get_serial_sequence('table_name', 'id'), MAX(id)) FROM table_name;

然而,这个表单不能正确地处理空表,因为max(id)是空的,你也不能设置val 0,因为它超出了序列的范围。一种解决方法是使用ALTER SEQUENCE语法。

ALTER SEQUENCE table_name_id_seq RESTART WITH 1;
ALTER SEQUENCE table_name_id_seq RESTART; -- 8.4 or higher

但是ALTER SEQUENCE的用途有限,因为序列名和重启值不能是表达式。

似乎最好的通用解决方案是调用setval,将false作为第三个参数,允许我们指定“下一个要使用的值”:

SELECT setval(pg_get_serial_sequence('t1', 'id'), coalesce(max(id),0) + 1, false) FROM t1;

这符合我所有的条件:

避免硬编码实际的序列名 正确处理空表 使用现有数据处理表,并且不会留下 序列中的漏洞

最后,请注意,pg_get_serial_sequence仅在序列属于列时才有效。如果将递增列定义为串行类型,则会出现这种情况,但是如果手动添加序列,则需要确保ALTER sequence。“OWNED BY”也被执行。

例如,如果使用serial type来创建表,这应该都可以工作:

CREATE TABLE t1 (
  id serial,
  name varchar(20)
);

SELECT pg_get_serial_sequence('t1', 'id'); -- returns 't1_id_seq'

-- reset the sequence, regardless whether table has rows or not:
SELECT setval(pg_get_serial_sequence('t1', 'id'), coalesce(max(id),0) + 1, false) FROM t1;

但如果手动添加序列:

CREATE TABLE t2 (
  id integer NOT NULL,
  name varchar(20)
);

CREATE SEQUENCE t2_custom_id_seq
    START WITH 1
    INCREMENT BY 1
    NO MINVALUE
    NO MAXVALUE
    CACHE 1;

ALTER TABLE t2 ALTER COLUMN id SET DEFAULT nextval('t2_custom_id_seq'::regclass);

ALTER SEQUENCE t2_custom_id_seq OWNED BY t2.id; -- required for pg_get_serial_sequence

SELECT pg_get_serial_sequence('t2', 'id'); -- returns 't2_custom_id_seq'

-- reset the sequence, regardless whether table has rows or not:
SELECT setval(pg_get_serial_sequence('t2', 'id'), coalesce(max(id),0) + 1, false) FROM t1;

只需运行以下命令:

SELECT setval('my_table_seq', (SELECT max(id) FROM my_table));

这里有很多很好的答案。在重新加载Django数据库后,我也有同样的需求。

但我需要:

All in one功能 可以一次修复一个或多个模式吗 可以修复所有或只是一个表的时间 还想要一个很好的方式来确切地看到什么改变了,或没有改变

这似乎与最初的要求非常相似。 多亏了Baldiry和Mauro让我找到了正确的方向。

drop function IF EXISTS reset_sequences(text[], text) RESTRICT;
CREATE OR REPLACE FUNCTION reset_sequences(
    in_schema_name_list text[] = '{"django", "dbaas", "metrics", "monitor", "runner", "db_counts"}',
    in_table_name text = '%') RETURNS text[] as
$body$
  DECLARE changed_seqs text[];
  DECLARE sequence_defs RECORD; c integer ;
  BEGIN
    FOR sequence_defs IN
        select
          DISTINCT(ccu.table_name) as table_name,
          ccu.column_name as column_name,
          replace(replace(c.column_default,'''::regclass)',''),'nextval(''','') as sequence_name
          from information_schema.constraint_column_usage ccu,
               information_schema.columns c
          where ccu.table_schema = ANY(in_schema_name_list)
            and ccu.table_schema = c.table_schema
            AND c.table_name = ccu.table_name
            and c.table_name like in_table_name
            AND ccu.column_name = c.column_name
            AND c.column_default is not null
          ORDER BY sequence_name
   LOOP
      EXECUTE 'select max(' || sequence_defs.column_name || ') from ' || sequence_defs.table_name INTO c;
      IF c is null THEN c = 1; else c = c + 1; END IF;
      EXECUTE 'alter sequence ' || sequence_defs.sequence_name || ' restart  with ' || c;
      changed_seqs = array_append(changed_seqs, 'alter sequence ' || sequence_defs.sequence_name || ' restart with ' || c);
   END LOOP;
   changed_seqs = array_append(changed_seqs, 'Done');

   RETURN changed_seqs;
END
$body$ LANGUAGE plpgsql;

然后执行并查看更改运行:

select *
from unnest(reset_sequences('{"django", "dbaas", "metrics", "monitor", "runner", "db_counts"}'));

返回

activity_id_seq                          restart at 22
api_connection_info_id_seq               restart at 4
api_user_id_seq                          restart at 1
application_contact_id_seq               restart at 20
-- Login to psql and run the following

-- What is the result?
SELECT MAX(id) FROM your_table;

-- Then run...
-- This should be higher than the last result.
SELECT nextval('your_table_id_seq');

-- If it's not higher... run this set the sequence last to your highest id. 
-- (wise to run a quick pg_dump first...)

BEGIN;
-- protect against concurrent inserts while you update the counter
LOCK TABLE your_table IN EXCLUSIVE MODE;
-- Update the sequence
SELECT setval('your_table_id_seq', COALESCE((SELECT MAX(id)+1 FROM your_table), 1), false);
COMMIT;

来源- Ruby论坛

把它们放在一起

CREATE OR REPLACE FUNCTION "reset_sequence" (tablename text) 
RETURNS "pg_catalog"."void" AS
$body$
DECLARE
BEGIN
  EXECUTE 'SELECT setval( pg_get_serial_sequence(''' || tablename || ''', ''id''),
  (SELECT COALESCE(MAX(id)+1,1) FROM ' || tablename || '), false)';
END;
$body$  LANGUAGE 'plpgsql';

将修复给定表的'id'序列(通常在django中是必要的)。