SQL Server Sp_msforeachdb query character llimitation

Question

Recently I wrote a bigger query than I usually write and I got a SQL query error using the Sp_msforeachdb. This query is running for every database in the instance of SQL Server. In addition the query is working if I make it smaller and I noticed that the Sp_msforeachdb has a character limitation of 2000 chars.

I tried to place it first in a variable nvarchar, varchar but without any luck.

So is there any way to increase this limitation and execute my full query?

Answer 1

SQL Server Sp_msforeachdb query character without limitation

When we write a query than is running for every database in the instance of SQL Server, we use Sp_msforeachdb.

If your query is bigger than 2000 chars, the query cannot work because Sp_msforeachdb has a character limitation of 2000 chars.

The solution is to re-create MySp_myforeachdb. We use sp_helptext to see the definition of sp_MSforeachdb and sp_MSforeach_worker, and we change to a new character limitation of 262144 chars.

USE master;
GO
/*
 * This is the worker proc for all of the "for each" type procs.  Its function is to read the
 * next replacement name from the cursor (which returns only a single name), plug it into the
 * replacement locations for the commands, and execute them.  It assumes the cursor "hCForEach***"
 * has already been opened by its caller.
 * worker_type is a parameter that indicates whether we call this for a database (1) or for a table (0)
 */
create proc dbo.sp_Myforeach_worker
    @command1 nvarchar(max), @replacechar nchar(1) = N'?', @command2 nvarchar(max) = null, @command3 nvarchar(max) = null, @worker_type int =1
as

    create table #qtemp (   /* Temp command storage */
        qnum                int             NOT NULL,
        qchar               nvarchar(max)   COLLATE database_default NULL
    )

    set nocount on
    declare @name nvarchar(517), @namelen int, @q1 nvarchar(max), @q2 nvarchar(max)
   declare @q3 nvarchar(max), @q4 nvarchar(max), @q5 nvarchar(max)
    declare @q6 nvarchar(max), @q7 nvarchar(max), @q8 nvarchar(max), @q9 nvarchar(max), @q10 nvarchar(max)
    declare @cmd nvarchar(max), @replacecharindex int, @useq tinyint, @usecmd tinyint, @nextcmd nvarchar(max)
   declare @namesave nvarchar(517), @nametmp nvarchar(517), @nametmp2 nvarchar(258)

    declare @local_cursor cursor
    if @worker_type=1   
        set @local_cursor = hCForEachDatabase
    else
        set @local_cursor = hCForEachTable

    open @local_cursor
    fetch @local_cursor into @name

    /* Loop for each database */
    while (@@fetch_status >= 0) begin
        /* Initialize. */

      /* save the original dbname */
      select @namesave = @name
        select @useq = 1, @usecmd = 1, @cmd = @command1, @namelen = datalength(@name)
        while (@cmd is not null) begin      /* Generate @q* for exec() */
            /*
             * Parse each @commandX into a single executable batch.
             * Because the expanded form of a @commandX may be > OSQL_MAXCOLLEN_SET, we'll need to allow overflow.
             * We also may append @commandX's (signified by '++' as first letters of next @command).
             */
            select @replacecharindex = charindex(@replacechar, @cmd)
            while (@replacecharindex <> 0) begin

            /* 7.0, if name contains ' character, and the name has been single quoted in command, double all of them in dbname */
            /* if the name has not been single quoted in command, do not doulbe them */
            /* if name contains ] character, and the name has been [] quoted in command, double all of ] in dbname */
            select @name = @namesave
            select @namelen = datalength(@name)
            declare @tempindex int
            if (substring(@cmd, @replacecharindex - 1, 1) = N'''') begin
               /* if ? is inside of '', we need to double all the ' in name */
               select @name = REPLACE(@name, N'''', N'''''')
            end else if (substring(@cmd, @replacecharindex - 1, 1) = N'[') begin
               /* if ? is inside of [], we need to double all the ] in name */
               select @name = REPLACE(@name, N']', N']]')
            end else if ((@name LIKE N'%].%]') and (substring(@name, 1, 1) = N'[')) begin
               /* ? is NOT inside of [] nor '', and the name is in [owner].[name] format, handle it */
               /* !!! work around, when using LIKE to find string pattern, can't use '[', since LIKE operator is treating '[' as a wide char */
               select @tempindex = charindex(N'].[', @name)
               select @nametmp  = substring(@name, 2, @tempindex-2 )
               select @nametmp2 = substring(@name, @tempindex+3, len(@name)-@tempindex-3 )
               select @nametmp  = REPLACE(@nametmp, N']', N']]')
               select @nametmp2 = REPLACE(@nametmp2, N']', N']]')
               select @name = N'[' + @nametmp + N'].[' + @nametmp2 + ']'
            end else if ((@name LIKE N'%]') and (substring(@name, 1, 1) = N'[')) begin
               /* ? is NOT inside of [] nor '', and the name is in [name] format, handle it */
       /* j.i.c., since we should not fall into this case */
               /* !!! work around, when using LIKE to find string pattern, can't use '[', since LIKE operator is treating '[' as a wide char */
               select @nametmp = substring(@name, 2, len(@name)-2 )
               select @nametmp = REPLACE(@nametmp, N']', N']]')
               select @name = N'[' + @nametmp + N']'
            end
            /* Get the new length */
            select @namelen = datalength(@name)

            /* start normal process */
                if (datalength(@cmd) + @namelen - 1 > 262144) begin
                    /* Overflow; put preceding stuff into the temp table */
                    if (@useq > 9) begin
                        close @local_cursor
                        if @worker_type=1   
                            deallocate hCForEachDatabase
                        else
                            deallocate hCForEachTable

                        RAISERROR(55555, 16, 1); -- N'sp_MSforeach_worker assert failed:  command too long'
                        return 1
                    end
                    if (@replacecharindex < @namelen) begin
                        /* If this happened close to beginning, make sure expansion has enough room. */
                        /* In this case no trailing space can occur as the row ends with @name. */
                        select @nextcmd = substring(@cmd, 1, @replacecharindex)
                        select @cmd = substring(@cmd, @replacecharindex + 1, 262144)
                        select @nextcmd = stuff(@nextcmd, @replacecharindex, 1, @name)
                        select @replacecharindex = charindex(@replacechar, @cmd)
                        insert #qtemp values (@useq, @nextcmd)
                        select @useq = @useq + 1
                        continue
                    end
                    /* Move the string down and stuff() in-place. */
                    /* Because varchar columns trim trailing spaces, we may need to prepend one to the following string. */
                    /* In this case, the char to be replaced is moved over by one. */
                    insert #qtemp values (@useq, substring(@cmd, 1, @replacecharindex - 1))
                    if (substring(@cmd, @replacecharindex - 1, 1) = N' ') begin
                        select @cmd = N' ' + substring(@cmd, @replacecharindex, 262144)
                        select @replacecharindex = 2
                    end else begin
                        select @cmd = substring(@cmd, @replacecharindex, 262144)
                        select @replacecharindex = 1
                    end
                    select @useq = @useq + 1
                end
                select @cmd = stuff(@cmd, @replacecharindex, 1, @name)
                select @replacecharindex = charindex(@replacechar, @cmd)
            end

            /* Done replacing for current @cmd.  Get the next one and see if it's to be appended. */
            select @usecmd = @usecmd + 1
            select @nextcmd = case (@usecmd) when 2 then @command2 when 3 then @command3 else null end
            if (@nextcmd is not null and substring(@nextcmd, 1, 2) = N'++') begin
                insert #qtemp values (@useq, @cmd)
                select @cmd = substring(@nextcmd, 3, 262144), @useq = @useq + 1
                continue
            end

            /* Now exec() the generated @q*, and see if we had more commands to exec().  Continue even if errors. */
            /* Null them first as the no-result-set case won't. */
            select @q1 = null, @q2 = null, @q3 = null, @q4 = null, @q5 = null, @q6 = null, @q7 = null, @q8 = null, @q9 = null, @q10 = null
            select @q1 = qchar from #qtemp where qnum = 1
            select @q2 = qchar from #qtemp where qnum = 2
            select @q3 = qchar from #qtemp where qnum = 3
            select @q4 = qchar from #qtemp where qnum = 4
            select @q5 = qchar from #qtemp where qnum = 5
            select @q6 = qchar from #qtemp where qnum = 6
            select @q7 = qchar from #qtemp where qnum = 7
            select @q8 = qchar from #qtemp where qnum = 8
            select @q9 = qchar from #qtemp where qnum = 9
            select @q10 = qchar from #qtemp where qnum = 10
            truncate table #qtemp
            exec (@q1 + @q2 + @q3 + @q4 + @q5 + @q6 + @q7 + @q8 + @q9 + @q10 + @cmd)
            select @cmd = @nextcmd, @useq = 1
        end /* while @cmd is not null, generating @q* for exec() */

        /* All commands done for this name.  Go to next one. */
        fetch @local_cursor into @name
    end /* while FETCH_SUCCESS */
    close @local_cursor
    if @worker_type=1   
        deallocate hCForEachDatabase
    else
        deallocate hCForEachTable

    return 0

GO

GO
CREATE PROC sp_Myforeachdb
 @command1 nvarchar(max), @replacechar nchar(1) = N'?', @command2 nvarchar(max) = null, @command3 nvarchar(max) = null,  
 @precommand nvarchar(max) = null, @postcommand nvarchar(max) = null
 AS

 set deadlock_priority low  

 /* This proc returns one or more rows for each accessible db, with each db defaulting to its own result set */  
 /* @precommand and @postcommand may be used to force a single result set via a temp table. */  

 /* Preprocessor won't replace within quotes so have to use str(). */  
 declare @inaccessible nvarchar(12), @invalidlogin nvarchar(12), @dbinaccessible nvarchar(12)  
 select @inaccessible = ltrim(str(convert(int, 0x03e0), 11))  
 select @invalidlogin = ltrim(str(convert(int, 0x40000000), 11))  
 select @dbinaccessible = N'0x80000000'  /* SQLDMODbUserProf_InaccessibleDb; the negative number doesn't work in convert() */  

 if (@precommand is not null)  
  exec(@precommand)  

 declare @origdb nvarchar(128)  
 select @origdb = db_name()  

 /* If it's a single user db and there's an entry for it in sysprocesses who isn't us, we can't use it. */  
   /* Create the select */  
 exec(N'declare hCForEachDatabase cursor global for select name from master.dbo.sysdatabases d ' +  
   N' where (d.status & ' + @inaccessible + N' = 0)' +  
   N' and (DATABASEPROPERTYEX(d.name, ''UserAccess'') <> ''SINGLE_USER'' and (has_dbaccess(d.name) = 1))' )  

 declare @retval int  
 select @retval = @@error  
 if (@retval = 0)  
  exec @retval = dbo.sp_Myforeach_worker @command1, @replacechar, @command2, @command3, 1  

 if (@retval = 0 and @postcommand is not null)  
  exec(@postcommand)  

   declare @tempdb nvarchar(258)  
   SELECT @tempdb = REPLACE(@origdb, N']', N']]')  
   exec (N'use ' + N'[' + @tempdb + N']')  

 return @retval  
GO   

Answer 2

Seems that using the default Sp_msforeachdb we are limited to a string variable limitations. In any case we can use sql cursors.