这个答案是从毛罗那里抄来的。

drop function IF EXISTS rebuilt_sequences() RESTRICT;
CREATE OR REPLACE FUNCTION  rebuilt_sequences() RETURNS integer as
$body$
  DECLARE sequencedefs RECORD; c integer ;
  BEGIN
    FOR sequencedefs IN Select
      DISTINCT(constraint_column_usage.table_name) as tablename,
      constraint_column_usage.column_name as columnname,
      replace(replace(columns.column_default,'''::regclass)',''),'nextval(''','') as sequencename
      from information_schema.constraint_column_usage, information_schema.columns
      where constraint_column_usage.table_schema ='public' AND 
      columns.table_schema = 'public' AND columns.table_name=constraint_column_usage.table_name
      AND constraint_column_usage.column_name = columns.column_name
      AND columns.column_default is not null 
      ORDER BY sequencename
   LOOP    
      EXECUTE 'select max('||sequencedefs.columnname||') from ' || sequencedefs.tablename INTO c;
      IF c is null THEN c = 0; END IF;
      IF c is not null THEN c = c+ 1; END IF;
      EXECUTE 'alter sequence ' || sequencedefs.sequencename ||' minvalue '||c ||' start ' || c ||' restart  with ' || c;
   END LOOP;

   RETURN 1; END;
$body$ LANGUAGE plpgsql;

select rebuilt_sequences();

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;

在下例中，表名为users，模式名为public(默认模式)，请根据需要替换它。

1. 检查最大id:

SELECT MAX(id) FROM public.users;

2. 检查下一个值:

SELECT nextval('public."users_id_seq"');

3.如果下一个值小于最大id，重置它:

SELECT setval('public."users_id_seq"',
  (SELECT MAX(id) FROM public.users)
);

注意:

Nextval()将在返回当前值之前递增序列，而currval()将只返回当前值，如本文所述。

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;

还有另一个plpgsql -仅当max(att) >时重置lastval

do --check seq not in sync
$$
declare
 _r record;
 _i bigint;
 _m bigint;
begin
  for _r in (
    SELECT relname,nspname,d.refobjid::regclass, a.attname, refobjid
    FROM   pg_depend    d
    JOIN   pg_attribute a ON a.attrelid = d.refobjid AND a.attnum = d.refobjsubid
    JOIN pg_class r on r.oid = objid
    JOIN pg_namespace n on n.oid = relnamespace
    WHERE  d.refobjsubid > 0 and  relkind = 'S'
   ) loop
    execute format('select last_value from %I.%I',_r.nspname,_r.relname) into _i;
    execute format('select max(%I) from %s',_r.attname,_r.refobjid) into _m;
    if coalesce(_m,0) > _i then
      raise info '%',concat('changed: ',_r.nspname,'.',_r.relname,' from:',_i,' to:',_m);
      execute format('alter sequence %I.%I restart with %s',_r.nspname,_r.relname,_m+1);
    end if;
  end loop;

end;
$$
;

另外注释行——execute format('alter sequence将给出列表，而不是实际重置值

重置所有序列，除了每个表的主键是“id”外，对名称没有任何假设:

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

select table_name || '_' || column_name || '_seq', reset_sequence(table_name, column_name) from information_schema.columns where column_default like 'nextval%';