SYBASE ASE修复identity 类型字段数据的跳跃（译）

ehxz

免费乐捐，感谢支持

内容提要

1、引言
2、dbcc object_atts
3、下载'sp_identity' 存储过程
4、使用sp_identity显示使用identity 类型字段的表
5  使用sp_identity显示当前表的 identity 数字
6、使用sp_identity 修改表的 identity数字

1引言
在sybase 中，有一个使用未公开的dbcc 命令 ，即 dbcc object_atts 快速修复identity 跳跃的方法，因为 dbcc

object_atts 比较难于使用,而存储过程 sp_identity 更容易完成你的问题
警告：本文的方法没有出现在sybase 发布的文档中，并且没有被 sybase 支持，使用与否取决定你自己，如果出现问题，不能从
sybase 技术支持那里得到帮助



2、dbcc object_atts
dbcc object_atts 命令提供了 一个访问 OAM 页的后门，在 OMA 中，保存了表的 identity 计数器。
不幸的是，这个命令在文档中几乎没有任何说明，并且很难使用，其语法如下：
  dbcc object_atts (table_name, 0, subcommand, [ new_value ] )
第一个参数 ：表名，第二个参数 0，
第三个参数：   get  ---显示 保存在 OMA 中的 identity 值
           或put  ---设置 OMA 中的 identity 值，设置的具体数据为 第四个参数数据
第四个参数 ：新设置的数

主要的问题是 dbcc object_atts 显示的数据为 16字节的 16进制字符，你必须自己解释为10进制，并且，如何解释依赖于

identity 列的长度，同样，设置它也是。在实际环境中，很少作为首选。
幸运的是，有一个存储过程 sp_identity 能够处理编码与解码， 并且给出所有含 identity 列的表的情况

下载 'sp_identity'
sp_identity 只支持 11。0 以后版本，下载文件中包含两个版本，一个用于 ASE 11.9/11.5/11.0 的叫  

,sp_identity.119.sql，另外一个用于ASE 12.0及以后版本(sp_identity.120.sql)

4、使用sp_identity显示使用identity 类型字段的表
sp_identity 有几个不同的功能，不带任何参数运行，只显示当前数据库中 包含 identity 列的表，
以及最大可能的 identity 跳跃

1>; sp_identity
2>; go
Tables with an identity column in database '':

Owner.Table.Column datatype     Maximum Identity Gap
------------------------------- -------------------------------
dbo.invoices.inv_nr numeric(18) 500000000000000 (burn)
dbo.small_gap_tab.a numeric(30) 10 (identity_gap)
dbo.my_table.n numeric(6)       500 (burn)


(burn) 表示 identity列的 一次取数由系统参数"identity burning set factor" 决定，而
(identity_gap) 表示 该表有自定义的identity_gap 属性


5  使用sp_identity显示当前表的 identity 数字
确定当前特定表的  OAM 页的identity 值，必须按照以下三步过程：
  首先 打开跟踪标志 3604 (运行 dbcc traceon(3604) )
  运行 指定特定表名运行 sp_identity

  1>; sp_identity invoices
  2>; go
  Table             = invoices (id=1804533462)
  Identity column   = a numeric(18)
  Max. Identity Gap = 500000000000000
         ("identity burning set factor" = 5000 = 0.05%)

  Reading identity value from OAM page...
  object_atts:get:return value=1
  0207E20C: 0001c6bf 52634001 00000000 00000000 ....Rc@.........
  0207E21C: .
  DBCC execution completed. If DBCC printed error messages,
  contact a user with System Administrator (SA) role.
  
  这个 16字节的 16进制字符串是 OAM 中保存的 identity 值 （0001c6bf 52634001 00000000 00000000）

  再次运行 sp_identity ,并且 指定这个字符串参数

  1>; sp_identity invoices, "0001c6bf 52634001 00000000 0000000"
  2>; go
  Table             = invoices (id=1804533462)
  Identity column   = a numeric(18)
  Max. Identity Gap = 500000000000000
         ("identity burning set factor" = 5000 = 0.05%)

  Decoded identity value on OAM page = 500000000000001
  (hex=0001c6bf52634001)

  现在，我们得到并解码了 OAM 中的 identity 值，但它意味着什么呢？
  首先，如果你用 "with nowait" 停止服务器，这个 identity 列将跳跃多少。而不是表中数据的下一个。
  而是保存在 OAM 中的数据加上 identity 种子设顶数(在 ASE 12.0, 为identity_gap 选项)
  另外，当你运行 ASE 12.0, 可以通过运行 dbcc listoam看到这个数据   

6、使用sp_identity 修改表的 identity数字
使用 sp_identity ， OAM 中identity 的 数字可以被设置为任意数. 这个需要如下步骤：
1、确认你要设置的数据（查看表中identity 的数据应该到多少,比如 10033 ）
2、正常停止服务器
3  重新启动服务器，以单用户模式，或者不让用户访问
4、 运行 sp_identity table_name, null, new_value ;
  1>; sp_identity invoices, null, 10032
  2>; go
  Table             = invoices (id=1804533462)
  Identity column   = a numeric(18)
  Max. Identity Gap = 500000000000000
       ("identity burning set factor" = 5000 = 0.05%)

  object_atts:put:return value=1
  DBCC execution completed. If DBCC printed error messages,
  contact a user with System Administrator (SA) role.

  Identity value on OAM page has been set to 10032
  (hex=0x00000000000027300000000000000000)
  You should now do a 'shutdown with nowait' immediately.
  After restarting the server, the value assigned to the
  next row inserted into 'invoices' will be 10033.

5  然后立即运行 'shutdown with nowait' ，这样 表的下一个  identity 数字是 10033
6  重新正常启动sybase 服务


说明：如果你应用了 identity 数据类型，并且要求identity 列保持连续，并且数据量很大，那么，用这个方法需要的时间可能比较短
否则不推荐使用。



下面是SP_IDENTITY.120.SQL，用于  12.0 以后版本
/*
* SP_IDENTITY.120.SQL - version for ASE 12.0 or later
* (when running ASE 11.9/11.5/11.0, install SP_IDENTITY.119.SQL instead)
*
* Description
* ===========
* This file contains the stored procedure 'sp_identity', which performs some
* useful functions w.r.t. identity columns:
*
*   - displays all tables with an identity column in the current database
*   - displays the identity value stored on a table's OAM page
*   - resets the identity value stored on a table's OAM page
*
* For details and background, see http://www.sypron.nl/idfix.html .
*
*
* Installation
* ============
* Execute this script using "isql", using a login having both "sa_role"
* and "sso_role".
* The stored procedure will be created in the sybsystemprocs database.
*
*
* Notes
* =====
* - Traceflag 3604 should be enabled before running sp_identity for a
*   specific table ("dbcc traceon(3604)"); if omitted, you won't see
*   any output.
*
* - To run sp_identity for a specific table, sa_role and sybase_ts_role
*   are required.
*
* - sp_identity was successfully tested on ASE versions 11.0.3, 11.5,
*   11.9.2 and 12.0 on various platforms.
*
* - sp_identity will not work on ASE 11.0 because this version
*   does not support the 'case' expression.
*
* - sp_identity was not tested on a 64-bit ASE version.
*
*
* Revision History
* ================
* Version 1.0  17-Dec-2000  First version
* Version 1.1  Oct-2002  Handle identity_gap=NULL (thanks to Alan Cooper),
*                        and some small improvements for installation
* Version 1.2  Apr-2003  Improved installation
*
*
* Copyright Note & Disclaimer :
* =============================
* This software is provided "as is"; there is no warranty of any kind.
* While this software is believed to work accurately, it may not work
* correctly and/or reliably in a production environment. In no event shall  
* Rob Verschoor and/or Sypron B.V. be liable for any damages resulting
* from the use of this software.
* You are allowed to use this software free of charge for your own
* professional, non-commercial purposes.
* You are not allowed to sell or bundle this software or use it for any
* other commercial purpose without prior written permission from
* Rob Verschoor/Sypron B.V.
* You may (re)distribute only unaltered copies of this software, which
* must include this copyright note, as well as the copyright note in
* the header of each stored procedure.
*
* Note: All trademarks are acknowledged.
*
* Please send any comments, bugs, suggestions etc. to the below email
* address.
*
* Copyright (c) 2000-2002 Rob Verschoor/Sypron B.V.
*                    P.O.Box 10695
*                    2501 HR Den Haag
*                    The Netherlands
*
*                    Email: rob@sypron.nl
*                    WWW  : http://www.sypron.nl/
*----------------------------------------------------------------------------
*/

set nocount on
go
set flushmessage on
go

use sybsystemprocs
go

-- we need to be at ASE 12.0 or later; if not, abort this script
if isnull(object_id("master.dbo.sysqueryplans"),99) >;= 99
begin
   print ""
   print ""
   print "********************************************"
   print "********************************************"
   print " This script is for ASE 12.0 or later."
   print " Please install SP_IDENTITY.119.SQL instead."
   print "********************************************"
   print "********************************************"
   print " "
   print " "
   print ""
   set background on  -- terminate this script now
end
go

print ""
print "Installing 'sp_identity'..."
print ""
go

if object_id("sp_identity_help") <>; NULL
begin
   drop proc sp_identity_help
end
go

create proc sp_identity_help
/* Copyright (c) 2000-2002 Rob Verschoor/Sypron B.V. */
as
begin
   print " "
   print " Usage: sp_identity table_name, ""hex-string-from-OAM-page"", new-identity-value "
   print " Notes: "
   print " - specifying only parameter 1 retrieves the current identity value for"
   print "   that table from the OAM page as a hexadecimal string."
   print " - specifying this hexadecimal string as the second parameter (in quotes)"
   print "   will decode the hex value to a numeric value."
   print " - specifying a numeric value for the third parameter will set that"
   print "   value as the new identity value for this table."
   print " - parameters 2 and 3 cannot be specified together: one of them must be NULL."
   print " - ""dbcc traceon(3604)"" must be run before using option 2 or 3"
   print " "
   print " Copyright (c) 2000-2002 Rob Verschoor/Sypron B.V."
   print " See http://www.sypron.nl/idfix.html for background information & updates."
   print " "
end
go

grant execute on sp_identity_help to public
dump tran sybsystemprocs with truncate_only
go

if object_id("sp_identity") <>; NULL
begin
   drop proc sp_identity
end
go

create proc sp_identity
/* Copyright (c) 2000-2002 Rob Verschoor/Sypron B.V. */
@p0 varchar(50) = NULL, -- table name
@p1 varchar(50) = NULL, -- hex value to decode
@p2 numeric(38) = NULL  -- new value to set
as
begin
set nocount on
declare @n numeric(38), @j numeric(38), @n256 numeric(3), @n10 numeric(38)
declare @i int, @max int, @idlen int, @idlenb int, @ib int, @len int
declare @p0_id int, @b int, @b1 binary(1), @lsb int
declare @idgap int, @idburn int, @maxidgap numeric(38), @max1 int, @max2 int
declare @idburnpct numeric(5,2), @v int, @ntab int
declare @c2 char(2), @doampg int, @indid int, @dbname varchar(32)
declare @vc50 varchar(50), @colname varchar(32), @vb16 varbinary(16)

select @dbname = db_name()

-- check version
select @v = 0
if exists (select * from sysobjects
           where name = "sysqueryplans" and type = "S")
begin
    select @v = 12
end

if @p0 = '?'
begin
   exec sp_identity_help
   return 0
end

-- numeric values
select @n256 = 256
select @n10 = 10

-- id burning set factor
select @idburn = value from master.dbo.syscurconfigs where config=141
select @idburnpct = convert(numeric(5,2), @idburn * 0.00001)

-- figure out msb/lsb
select @lsb = 0
if substring(convert(binary(4), 1), 1 ,1) = 0x01 select @lsb = 1
if substring(convert(binary(4), 1), 2 ,1) = 0x01 select @lsb = 2
if substring(convert(binary(4), 1), 3 ,1) = 0x01 select @lsb = 3
if substring(convert(binary(4), 1), 4 ,1) = 0x01 select @lsb = 4

-- get all tables containing identity columns in this database
select id = so.id, owner = su.name, uid = so.uid, so.name, si.doampg, si.indid, idgap =

isnull(si.identitygap,0),
       colname = sc.name, sc.prec, maxgap = convert(numeric(38), ceiling((@idburn * 0.0000001) *

power(@n10,prec)))
into #id
from sysindexes si, syscolumns sc, sysobjects so, sysusers su
where si.indid < 2
  and so.type = "U"
  and sc.status & 128 = 128
  and so.id = sc.id
  and so.id = si.id
  and so.uid = su.uid
select @ntab = @@rowcount

set arithabort numeric_truncation off

if @p0 = null
begin
   -- display all tables with identity columns in the current DB
   if @ntab = 0
   begin
      print " There are no tables with an identity column in database '%1!'", @dbname
          return 0
   end
   print " Tables with an identity column in database '%1!':", @dbname
   print " "
   select @max1 = max(char_length(owner + "." + name + "." + colname)) + 12 from #id
   select @max2 = max(char_length(convert(varchar(38), maxgap))) + 7 from #id

   if @max1 <= 52 and @max2 <= 24
   begin
     select convert(varchar(52), owner + "." + name + "." + colname + " numeric(" +

convert(varchar(2),prec) + ")") "Owner.Table.Column datatype",
                    convert(varchar(24), case when idgap = 0 then convert(varchar(38),maxgap) + "

(burn)"
                       else convert(varchar, idgap) + " (identity_gap)"
                     end) "Maximum Identity Gap"
        
     from #id
     order by name
   end
   else
   if @max1 <= 32 and @max2 <= 44
   begin
     select convert(varchar(32), owner + "." + name + "." + colname + " numeric(" +

convert(varchar(2),prec) + ")") "Owner.Table.Column datatype",
                    convert(varchar(44), case when idgap = 0 then convert(varchar(38),maxgap) + "

(burn)"
                       else convert(varchar, idgap) + " (identity_gap)"
                     end) "Maximum Identity Gap"
        
     from #id
     order by name
   end
   else
   begin
     select convert(varchar(78), owner + "." + name + "." + colname + " numeric(" +

convert(varchar(2),prec) + ")") "Owner.Table.Column datatype",
                    convert(varchar(50), case when idgap = 0 then convert(varchar(38),maxgap) + "

(burn)"
                       else convert(varchar, idgap) + " (identity_gap)"
                  end) "Maximum Identity Gap"
      from #id
      order by name
   end

   print " "
   print " Legend:"
   print "    (burn)         : gap size is determined by ""identity burning set factor"" "
   if @v = 12
   begin
   print "    (identity_gap) : gap size is determined by the ""identity_gap"" setting"
   end
   print " "
   print " Current value for ""identity burning set factor"" = %1! (=%2!%%)", @idburn, @idburnpct


   return 0
end

if charindex("sa_role", show_role()) = 0
begin
   print "You must have 'sa_role' to run this procedure."
   return -1
end

if charindex("sybase_ts_role", show_role()) = 0
begin
   print "You must have 'sybase_ts_role' to run this procedure."
   return -1
end

-- get some info on the object
select @p0_id = object_id(@p0)
if @p0_id = NULL
begin
   print " Error: '%1!' is not a user table.", @p0
   return -1
end

if @p0 not like "%.%"
begin
  select @ntab = count(*) from sysobjects where name = @p0 and type = "U"

  if @ntab >; 1
  begin
     print " %1! tables named '%2!' exist in this database:", @ntab, @p0
         print " "
     select owner + "." + name "owner.table_name"
         from #id where name = @p0 order by uid
         print " "
     print " Specify 'owner.table_name' to identify the table."
         return -1
  end
end

select @doampg = doampg, @indid = indid, @idgap = idgap
from #id where id = @p0_id

if not exists (select 1 from syscolumns where id = @p0_id and status & 128 = 128)  
begin
   print " Error: Table '%1!' does not have an identity column", @p0
   return -1
end

-- retrieve the length of the numeric identity column as declared when the
-- table was created
select @len = prec, @colname = name
from syscolumns where id = @p0_id and status & 128 = 128
if @@rowcount = 0
begin
   print " Error: Could not retrieve length of identity column for table '%1!'", @p0
   return -1
end

select @idlen = @len -- column precision (positions)
select @idlenb = (@idlen+1-((@idlen+5)/12)-(@idlen/12))/2 -- column length (bytes)

print " "
print " Table             = %1! (id=%2!)", @p0, @p0_id
print " Identity column   = %1! numeric(%2!)", @colname, @len
--print " OAM page          = %1!", @doampg
--print " Bytes on OAM page = %1!", @idlenb
if @idgap >; 0
begin
   print " Max. Identity Gap = %1! (""identity_gap"" = %2!)", @idgap, @idgap
end
else
begin
   set arithabort numeric_truncation off
   select @maxidgap = ceiling((convert(numeric(38),@idburn) * 0.0000001) * power(@n10,@len))
   print " Max. Identity Gap = %1!", @maxidgap
   print "                     (""identity burning set factor"" = %1! = %2!%%)", @idburn, @idburnpct
   if @v = 12
   begin
   print "                     (Note: ""identity_gap"" has not been set for this table !)"   
   end
end
print " "

if @p1 = NULL and @p2 = NULL -- retrieve current ID value
begin
   print " "
   print " Reading identity value from OAM page... (traceflag 3604 should be enabled !)"
   print " "
   dbcc object_atts (@p0, 0, get)
   print " "
   print " To decode this hexadecimal value, re-run 'sp_identity' with the hexadecimal"
   print " string as a quoted 2nd parameter (you can leave the spaces in). "
   print " Example:  sp_identity %1!, ""the-hex-string-from-the-above-output"" ", @p0
   print " "
   --
   -- only for 12.0+, dbcc listoam will display the values in the OAM and the DES
   --
   --dbcc listoam(@dbname, @p0_id, @indid)
   --
   return 0
end

if upper(@p1) like "[ 0-9A-F]%" -- entered a hex string, decode it
begin

if @p2 != NULL
begin
   print " Error: When decoding a hex value from the OAM page, parameter 3"
   print " (the new identity value) must be NULL."
   exec sp_identity_help
   return -1
end

select @ib = @idlenb -- counts bytes
select @i  = char_length(@p1) -- counts string
select @n = 0 -- holds result

while 1 = 1
begin
   select @c2 = substring(@p1, (char_length(@p1)-@i)+1, 2)

   --print "Step %1!, [%2!]", @ib, @c2
   if upper(substring(@c2,1,1)) = " " -- ignore single space pasted in by user
   begin
     select @i = @i - 1
         continue
   end

   if (upper(@c2) not like "[0-9A-F][0-9A-F]")
   begin
     print " Error: Invalid characters (%1!) in hex string", @c2
     break
   end

   -- add this byte to the result
   select @vc50 = @vc50 + @c2
   select @j = power(@n256, (@ib-1))
   select @n = @n + @j * hextoint("0x" + @c2)
   --print "Step %1!, exp= %2!, result = %3!", @ib, @j, @n

   -- next byte
   select @ib = @ib - 1
   if @ib = 0 break  -- ready

   -- next 2 chars
   select @i = @i - 2
   if @i = 0
   begin
      -- we shouldn't have got here, error
          print " Error: ID column length and specified hex string do not match !"
      break
   end
end

if @ib = 0
begin
   print " Decoded identity value on OAM page = %1!", @n
   print " (hex= %1!)", @vc50
   print " "
   return 0
end
else
begin
   print " Error: Aborted due to error."
   return -1
end
end

if @p2 != NULL -- entered a new ID value, set it
begin

if @p1 != NULL
begin
   print " Error: When setting a new identity value, parameter 2"
   print " (the hex string from the OAM page) must be NULL."
   exec sp_identity_help
   return -1
end

-- set the new ID value
if @p2 <= 0
begin
   print " Error: The new identity value must be >;= 0."
   print " "
   exec sp_identity_help
   return -1
end

if char_length(convert(varchar, @p2)) >; @idlen
begin
   select @vc50 = replicate("9", @idlen)
   print " Error: New identity value (%1!) is too large", @p2
   print "        for this identity column. The maximum possible value", @p2
   print "        is %1! (%2! positions).", @vc50, @idlen
   return -1
end

if @lsb = 0
begin
   print " "
   print "Internal error in 'sp_identity':"
   print "Cannot figure out byte order on this platform."
   print "Please send a note to 'rob@sypron.nl' with the text of this"
   print "error and your @@version string."
   return -1
end

-- convert the numeric value to hex
select @ib = @idlenb -- counts bytes
select @i  = 15

select @vc50 = NULL -- holds result
select @vb16 = NULL -- holds result
select @n256 = 256
select @n = @p2
set arithabort numeric_truncation off

while 1 = 1
begin
   select @j = power(@n256, @i)

   select @b = @n / @j
   select @n = @n - (@b * @j)
   select @c2 = right(inttohex(@b),2)
   select @b1 = substring(convert(binary(4), @b), @lsb,1)

   select @vb16 = @vb16 + @b1

   --print "Step %1!, @b=%2!, hex(c2)=%3!, hex(b1)=%5!, result=%4!", @i, @b, @c2, @vb16, @b1

   select @i = @i - 1
   if @i < 0 break  -- ready
end

if @i < 0
begin
   select @vb16 = substring(@vb16, 16 - (@idlenb) + 1, (@idlenb) ) + substring(@vb16, 1, 16 -

(@idlenb) )

   -- set the new ID value
   dbcc object_atts(@p0, 0, "put", @vb16)

   print " "
   print " Identity value on OAM page has been set to %1!", @p2
   print " (hex= %1!)", @vb16
   print " "
   select @p2 = @p2 + 1
   print " You should now do a 'shutdown with nowait' immediately."
   print " After restarting the server, the value assigned to the next row "
   print " inserted into '%1!' will be %2!.", @p0, @p2
   print " "
   return 0
end
else
begin
   print " Error: Aborted due to error."
   return -1
end
   
end

-- we should never get here
print "Internal error in 'sp_identity': Reached invalid end of procedure."
return -1
end
go

grant execute on sp_identity to public
dump tran sybsystemprocs with truncate_only
go


print "Ready. For usage information, run 'sp_identity ""?"" '."
print ""
go

/*
** end
*/