undocumented なものを見つけたので、調べてみる - その1 - - 都内で働くSEの技術的なひとりごと では、sp_MSforeachtable について触れました。今回は、sp_MSforeachtable で使用されている、sp_MSforeach_worker について調べてみたいと思います。早速下記のステートメントを実行して、内容を調べていきましょう。
exec sp_helptext sp_MSforeach_worker
create proc sys.sp_MSforeach_worker
@command1 nvarchar(2000),
@replacechar nchar(1) = N'?',
@command2 nvarchar(2000) = null,
@command3 nvarchar(2000) = null,
@worker_type int =1
as
create table #qtemp ( /* Temp command storage */
qnum int NOT NULL,
qchar nvarchar(2000) COLLATE database_default NULL
)
set nocount on
declare @name nvarchar(517), @namelen int, @q1 nvarchar(2000), @q2 nvarchar(2000)
declare @q3 nvarchar(2000), @q4 nvarchar(2000), @q5 nvarchar(2000)
declare @q6 nvarchar(2000), @q7 nvarchar(2000), @q8 nvarchar(2000), @q9 nvarchar(2000), @q10 nvarchar(2000)
declare @cmd nvarchar(2000), @replacecharindex int, @useq tinyint, @usecmd tinyint, @nextcmd nvarchar(2000)
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 > 2000) 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, 2000)
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, 2000)
select @replacecharindex = 2
end else begin
select @cmd = substring(@cmd, @replacecharindex, 2000)
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, 2000), @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
- @command1
指定されたステートメントを実行します。 - @replacechar
デフォルトは ? がテーブル名に置き換えられますが、他の文字にしたい場合replaccechar に変換したい文字を指定します。 - @command2
指定されたステートメントを実行します。 - @command3
指定されたステートメントを実行します。 - @worker_type
worker_type によって、どのタイプのカーソルを使用するか判断します。sp_MSforeach_worker は、呼び出し元でカーソルがオープンされている前提で動作します。デフォルトの 0 では、hCForEachDatabase が作成され、オープンされている状態を前提とします。1では、hCForEachTable が作成され、オープンされている状態を前提とします。もし、sp_MSforeach_worker を直接使用したい場合は、この部分に注意する必要があります。
例えば、以下のようなステートメントを実行したら、テーブル単位に、統計情報とCHECKTABLE をやってくれたりします。テーブル変換の文字は、! を指定したので、? → ! に変更しています。
exec sp_MSforeachtable @command1="print '!' select count(*) from !",
@whereand = "and o.name like '%State%'",
@precommand="print 'IroIroyaruyo' print ''",
@postcommand="print '' print 'IroIroOwattayo!'",
@replacechar = "!",
@command2 = "UPDATE STATISTICS !;",
@command3 = "DBCC CHECKTABLE ([!]);"
まだまだ、undocumented なストアドプロシージャはたくさんあります。undocumented なストアドプロシージャの内容見ているだけでも色々勉強になりますね。
