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。
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
之前我还没有尝试过代码:在下面我张贴 Klaus和user457226解决方案的sql代码版本 它在我的电脑上运行(Postgres 8.3),只做了一些小调整 克劳斯的版本和我的user457226版本。
克劳斯解决方案:
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
constraint_column_usage.table_name as tablename,
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
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 ||' restart with ' || c;
END LOOP;
RETURN 1; END;
$body$ LANGUAGE plpgsql;
select rebuilt_sequences();
User457226解决方案:
--drop function IF EXISTS reset_sequence (text,text) RESTRICT;
CREATE OR REPLACE FUNCTION "reset_sequence" (tablename text,columnname text) RETURNS bigint --"pg_catalog"."void"
AS
$body$
DECLARE seqname character varying;
c integer;
BEGIN
select tablename || '_' || columnname || '_seq' into seqname;
EXECUTE 'SELECT max("' || columnname || '") FROM "' || tablename || '"' into c;
if c is null then c = 0; end if;
c = c+1; --because of substitution of setval with "alter sequence"
--EXECUTE 'SELECT setval( "' || seqname || '", ' || cast(c as character varying) || ', false)'; DOES NOT WORK!!!
EXECUTE 'alter sequence ' || seqname ||' restart with ' || cast(c as character varying);
RETURN nextval(seqname)-1;
END;
$body$ LANGUAGE 'plpgsql';
select sequence_name, PG_CLASS.relname, PG_ATTRIBUTE.attname,
reset_sequence(PG_CLASS.relname,PG_ATTRIBUTE.attname)
from PG_CLASS
join PG_ATTRIBUTE on PG_ATTRIBUTE.attrelid = PG_CLASS.oid
join information_schema.sequences
on information_schema.sequences.sequence_name = PG_CLASS.relname || '_' || PG_ATTRIBUTE.attname || '_seq'
where sequence_schema='public';
其他回答
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;
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;
重置所有公共序列
CREATE OR REPLACE FUNCTION "reset_sequence" (tablename text) RETURNS "pg_catalog"."void" AS
$body$
DECLARE
BEGIN
EXECUTE 'SELECT setval( '''
|| tablename
|| '_id_seq'', '
|| '(SELECT id + 1 FROM "'
|| tablename
|| '" ORDER BY id DESC LIMIT 1), false)';
END;
$body$ LANGUAGE 'plpgsql';
select sequence_name, reset_sequence(split_part(sequence_name, '_id_seq',1)) from information_schema.sequences
where sequence_schema='public';
试着重建索引。
更新:正如评论中指出的,这是对最初问题的回答。
我找不到Rails的明确答案。
从rails控制台
ActiveRecord::Base.connection.execute("SELECT setval(pg_get_serial_sequence('table_name', 'id'), MAX(id)) FROM table_name;")
例如将table_name替换为users。