Tuesday, 11 June 2013

usp_Util_TruncatePartition: trancate a specified partition from a partitioned table

-- published at
-- http://www.sqlservercentral.com/articles/partition+switch/100013/

USE TEST
GO
IF EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[usp_Util_TruncatePartition]') AND type in (N'P', N'PC'))
 DROP PROCEDURE [usp_Util_TruncatePartition]
GO
--
-- By Steven Rao
-- Date: June 13, 2013
-- StevenZRAO@gmail.com
-- declare @code int
-- A generic procedure to truncate any given partition from a partitioned table
-- Limitation: cannot deal with some data types, such as xml
-- Basic assumption and current limitation: (some minor changes are needed to extend the functionality of this sp)
-- 1) partition parameter has integer type
-- Change history
-- Date Description
-- 2013-07-26 Fix schema name and computed column issues
-- It is now also working both left and right partition type

CREATE PROCEDURE [usp_Util_TruncatePartition]
@tableName varchar(255)
,@partitionValue int
,@schemaName varchar(255)='dbo'
AS
BEGIN
--
-- Is table partitioned at all?
declare @error int, @rowsCount int, @errMsg varchar(1024)
declare @partitionSchema varchar(255), @partitionFunction varchar(255), @partitionColumn varchar(255), @tableStorageType varchar(16), @partitionFunctionID int
declare @partitionFileGroupName varchar(255), @databaseName varchar(255), @partitionNumber int, @cloneTableName varchar(255), @compression tinyint, @compressionQuery varchar(256)
declare @LogHeader varchar(23), @Now datetime
select @tableName=ltrim(rtrim(isnull(@tableName, ''))), @schemaName=ltrim(rtrim(isnull(@schemaName, ''))), @databaseName=db_name(), @schemaName=ltrim(rtrim(@schemaName)), @tableName=ltrim(rtrim(@tableName)), @compressionQuery=''

--
-- find the partition number for the partion value and other information for table partition
SELECT
@tableStorageType=i.type_desc
,@partitionSchema=ps.name
,@partitionFunction=pf.name
,@partitionFunctionID=pf.function_id
-- partition FOR RIGHT and boundary_id begins with id 1
,@partitionNumber=case when pf.boundary_value_on_right=1 then rv.boundary_id+1 else rv.boundary_id end
,@partitionColumn=c.name
,@partitionFileGroupName=fg.name
-- compression can be 0: no compresson, 1: row level compression 2: page level compression
-- only apply to clustered index?
,@compression=case when i.index_id=1 then p.data_compression else 0 end
FROM sys.schemas s
INNER JOIN sys.tables t
ON t.schema_id=s.schema_id
-- check table storage type
INNER JOIN  sys.indexes i
ON (i.object_id = t.object_id
-- 0: heap
-- 1: clusterd
and i.index_id in (0,1))
INNER JOIN sys.partitions p
ON p.object_id = i.object_id
AND p.index_id = i.index_id
INNER JOIN  sys.index_columns  ic
ON (-- identify partioned column
ic.partition_ordinal > 0
and ic.index_id = i.index_id
and ic.object_id = t.object_id)
INNER JOIN  sys.columns c
ON c.object_id = ic.object_id and c.column_id = ic.column_id
INNER JOIN sys.system_internals_allocation_units au
ON p.partition_id = au.container_id
INNER JOIN sys.partition_schemes ps
ON ps.data_space_id = i.data_space_id
INNER JOIN sys.partition_functions pf
ON pf.function_id = ps.function_id
INNER JOIN sys.destination_data_spaces dds
ON dds.partition_scheme_id = ps.data_space_id AND dds.destination_id = p.partition_number
INNER JOIN sys.filegroups fg
ON dds.data_space_id = fg.data_space_id
INNER JOIN sys.partition_range_values rv
ON pf.function_id = rv.function_id AND p.partition_number = rv.boundary_id
WHERE -- only look for heap or clustered index
i.index_id IN (0, 1)
AND s.name=@schemaName
AND t.name=@tableName
-- need exact match
AND cast(rv.value as int)=@partitionValue

select @error=@@ERROR, @rowsCount=@@ROWCOUNT, @Now=getdate(), @LogHeader=convert(char(23), @Now, 126)
if (@rowsCount<=0)
begin
print @LogHeader+' table '+@tableName+' on db '+@databaseName+' with schema '+@schemaName
+' is not partitioned or @partitionValue='+cast(@partitionValue as varchar(16))
+' is not in exsiting partition range. will return.'
return 100
end else
begin
print @LogHeader+' table '+@tableName+' on db '+@databaseName+' with schema '
+@schemaName+' is partitioned: @partitionSchema='+@partitionSchema
+', @partitionFunction='+@partitionFunction
+', @partitionFunctionID='+cast(@partitionFunctionID as varchar(16))
+', @partitionColumn='+ @partitionColumn
+', @tableStorageType='+@tableStorageType
+', @partitionValue='+cast(@partitionValue as varchar(16))
+', @partitionNumber='+cast(@partitionNumber as varchar(16))
+', @partitionFileGroupName='+@partitionFileGroupName
+', @compression='+cast(@compression as varchar(16))
end

--
-- create clone table on same file group, drop it if already exists
-- we don't need to take care of FK and no clustered for our case
-- No clustered index is not needed
-- taking care of columns and primary key
-- Ironically you could drop a table without droping its primary key!! suprise suprise
-- Now we know the primary key name, we can generate the drop statement

declare @dropCloneTable varchar(8000),
        @createCloneTable varchar(8000),
        @primaryKeyName varchar(255),
        @dropPrimaryKey varchar(8000),
        @primayKeyNamePlaceHolder varchar(255),
        @hasPrimaryKey tinyint,
        @switchPartition varchar(1024)

select
-- A place holder for primary key which will be replace when the value is known
  @primayKeyNamePlaceHolder='$$PK_NAME$$'
 ,@cloneTableName=@tableName+'_'+cast(@partitionNumber as varchar(16))
 ,@dropCloneTable='IF EXISTS (SELECT 1 FROM sys.objects WHERE object_id = OBJECT_ID(N'+''''+@schemaName+'.'+@cloneTableName+''''+') AND type in (N'+''''+'U'+''''+'))'+char(13)
 +'BEGIN'+char(13)+'DROP TABLE '+@schemaName+'.'+@cloneTableName+char(13) +'END'
 ,@dropPrimaryKey='IF EXISTS (SELECT 1 FROM sys.indexes WHERE object_id = OBJECT_ID(N'+''''+@schemaName+'.'+@cloneTableName+''''+') AND name = N'+''''+@primayKeyNamePlaceHolder+''''+')'+char(13)
 +'BEGIN'+char(13)+'ALTER TABLE '+@schemaName+'.'+@cloneTableName+' DROP CONSTRAINT '+@primayKeyNamePlaceHolder+char(13)+'END'
 ,@switchPartition='ALTER TABLE '+@schemaName+'.'+@tableName +' SWITCH PARTITION '+cast(@partitionNumber as varchar(16))+' TO '+@schemaName+'.'+@cloneTableName

select
  @hasPrimaryKey=CASE WHEN tc.Constraint_Name IS NULL THEN 0 ELSE 1 END
 ,@primaryKeyName=CASE WHEN @hasPrimaryKey=1 THEN replace(replace(@CloneTableName, @schemaName, ''), '.', '')+'_'+tc.Constraint_Name ELSE '' END
 ,@createCloneTable= 'CREATE TABLE ' +@schemaName+'.'+@CloneTableName
  + '(' + o.list + ')'
  + ' ON ['+@partitionFileGroupName+']'
  + CASE WHEN @hasPrimaryKey=0 THEN '' ELSE char(13)
  +'ALTER TABLE ' +@schemaName+'.'+ @CloneTableName + ' ADD CONSTRAINT ' + @primaryKeyName + ' PRIMARY KEY '
  + CASE WHEN i.index_id IS NULL THEN 'NONCLUSTERED ' ELSE 'CLUSTERED ' END
  + ' (' + LEFT(j.List, Len(j.List)-1) + ')' END
 from sys.schemas s
  inner join sys.objects so
   on s.schema_id=so.schema_id
  cross apply
   (SELECT
' ['+column_name+'] '
-- deal with computed columns
+ case when cc.is_computed=1 then ' AS ('+cc.definition+')'+case when cc.is_persisted=1 then ' PERSISTED' else '' end + ', ' else
-- non computed columns case
data_type+
case data_type
when 'sql_variant' then ''
when 'text' then ''
when 'decimal' then '(' + cast(numeric_precision as varchar) + ', ' + cast(numeric_scale as varchar) + ')'
else coalesce('('+case when character_maximum_length = -1 then 'MAX' else cast(character_maximum_length as varchar) end +')','') end
+ ' '
+ case when exists (
 select id
  from syscolumns
  where object_name(id)='TestTruncatePartition'
  and name=column_name
  and columnproperty(id,name,'IsIdentity') = 1
)
 then 'IDENTITY(' + cast(ident_seed('TestTruncatePartition') as varchar) + ',' + cast(ident_incr('TestTruncatePartition') as varchar) + ')'
 else '' end
+ ' '
+ (case when c.IS_NULLABLE = 'No' then 'NOT ' else '' end ) + 'NULL '
+ case when c.COLUMN_DEFAULT IS NOT NULL THEN 'DEFAULT '+ c.COLUMN_DEFAULT ELSE '' END + ', '
end
from information_schema.columns c left join sys.computed_columns cc on
OBJECT_ID(c.TABLE_SCHEMA+'.'+c.TABLE_NAME)=cc.object_id and c.COLUMN_NAME=cc.name
where c.table_name = so.name AND c.TABLE_SCHEMA=@schemaName
 order by ordinal_position
 FOR XML PATH('')
  ) o (list)
 left join information_schema.table_constraints tc
  on tc.Table_name = so.Name
  AND tc.Constraint_Type = 'PRIMARY KEY'
  AND tc.TABLE_SCHEMA=@schemaName
 cross apply
  (select '[' + Column_Name + '], '
   FROM information_schema.key_column_usage kcu
   WHERE kcu.Constraint_Name = tc.Constraint_Name and kcu.TABLE_SCHEMA=@schemaName
   ORDER BY ORDINAL_POSITION
   FOR XML PATH('')
   ) j (list)
  -- find out if the primary key is clustered
  left join sys.indexes i
   on so.object_id=i.object_id
   -- index_id 1 means clustered
   -- constraint name is primary key name which is same as the index name
   AND i.index_id=1 AND tc.CONSTRAINT_NAME=i.name and tc.TABLE_SCHEMA=@schemaName
 where s.name=@SchemaName
and so.type = 'U'
and so.name NOT IN ('dtproperties')
and so.name=@TableName

select @error=@@ERROR,
       @rowsCount=@@ROWCOUNT,
       @Now=getdate(),
       @LogHeader=convert(char(23), @Now, 126)

print @LogHeader+' @hasPrimaryKey='+cast(@hasPrimaryKey as varchar(16))

if (@hasPrimaryKey=1)
 begin
  select @dropPrimaryKey=replace(@dropPrimaryKey, @primayKeyNamePlaceHolder, @primaryKeyName)
 end

-- 1: Row compression
-- 2: Page compression
if @compression=1
 begin
  set @compressionQuery='ALTER TABLE ' +@schemaName+'.'+@cloneTableName + ' REBUILD PARTITION = ALL WITH (DATA_COMPRESSION = ROW)';
 end
else if @compression=2
 begin
  set @compressionQuery='ALTER TABLE ' +@schemaName+'.'+@cloneTableName + ' REBUILD PARTITION = ALL WITH (DATA_COMPRESSION = PAGE)';
 end
--
-- taking care of clustered index
-- taking care of primary key is not enough since a primary key may not be clustered
-- so now we have to excludes clustered primary key index since they are already been taken care of
-- sample index create and drop statement
--
-- we may not need to drop the index? just in case
declare @indexColums varchar(256),
        @indexName varchar(256),
        @indexUnique varchar(8),
        @hasNonPrimaryKeyClusterdIndex tinyint,
        @createClusteredIndex varchar(8000),
        @dropClusteredIndex varchar(8000)

select @indexColums='(',
       @indexUnique='',
       @indexName='',
       @hasNonPrimaryKeyClusterdIndex=0,
       @dropClusteredIndex='',
       @createClusteredIndex=''

select
-- whenever we have result from here, we do have clusterd index
  @hasNonPrimaryKeyClusterdIndex=1
 ,@indexColums=@indexColums+ic.columnList
 ,@indexName=@cloneTableName+'_'+i.name
 ,@indexUnique=case when i.is_unique=0 then '' else 'UNIQUE ' end
 from sys.schemas s
  INNER JOIN sys.tables t
   ON t.schema_id=s.schema_id
  INNER JOIN sys.indexes i
   ON (i.object_id = t.object_id
   -- looking for clustered index ONLY
   and i.index_id=1
   -- ignore primary key, which is taken care of above already
   and i.is_primary_key=0)
  CROSS APPLY
   (
    select
      c.name+case when ic.is_descending_key=0 then ' ASC' else ' DESC' end+','
     from sys.index_columns ic
      INNER JOIN sys.columns c
       ON c.column_id=ic.column_id
      and c.object_id=ic.object_id
     where ic.index_id = i.index_id
       and ic.object_id = t.object_id
     order by ic.key_ordinal
    FOR XML PATH('')
    ) ic(columnList)
 where s.name=@schemaName
 and t.name=@tableName

select @error=@@ERROR,
       @rowsCount=@@ROWCOUNT,
       @Now=getdate(),
       @LogHeader=convert(char(23), @Now, 126),
       @hasNonPrimaryKeyClusterdIndex=isnull(@hasNonPrimaryKeyClusterdIndex, 0)

print @LogHeader+' @hasNonPrimaryKeyClusterdIndex='+cast(@hasNonPrimaryKeyClusterdIndex as varchar(16))

if (@hasNonPrimaryKeyClusterdIndex>=1)
 begin
  select @dropClusteredIndex='IF EXISTS (SELECT 1 FROM sys.indexes WHERE object_id = OBJECT_ID(N'+''''+@schemaName+'.'+@cloneTableName+''''+') AND name = N'+''''+@indexName+''''+')'
  +char(13)+'BEGIN'+char(13)
  +'DROP INDEX '+@indexName+' ON '+@schemaName+'.'+@cloneTableName
  +char(13)+'END'
  ,@createClusteredIndex='CREATE '+@indexUnique+'CLUSTERED INDEX '+@indexName+' ON '+@schemaName+'.'+@cloneTableName+left(@indexColums, len(@indexColums)-1)+')'
 end

select @error=@@ERROR, @rowsCount=@@ROWCOUNT, @Now=getdate(), @LogHeader=convert(char(23), @Now, 126)

print @LogHeader+' (@dropPrimaryKey, @dropClusteredIndex, @dropCloneTable, @createCloneTable, @createClusteredIndex, @compressionQuery, @switchPartition, @dropPrimaryKey, @dropCloneTable)'

print @dropPrimaryKey+char(13)+@dropClusteredIndex+char(13)+@dropCloneTable+char(13)+@createCloneTable+char(13)+@createClusteredIndex+char(13)+@compressionQuery+char(13)+@switchPartition+char(13)+@dropPrimaryKey+char(13)+@dropCloneTable

declare @returnCode int

if (@hasPrimaryKey=1)
 begin
  EXEC(@dropPrimaryKey)
  select @returnCode=300, @error=@@ERROR, @rowsCount=@@ROWCOUNT, @Now=getdate(), @LogHeader=convert(char(23), @Now, 126), @errMsg=@LogHeader+' [1] failed to drop primary key for clone table. will return.'
  if (@error<>0) goto ERROR
 end

if (@hasNonPrimaryKeyClusterdIndex=1)
 begin
  EXEC(@dropClusteredIndex)
  select @returnCode=310, @error=@@ERROR, @rowsCount=@@ROWCOUNT, @Now=getdate(), @LogHeader=convert(char(23), @Now, 126), @errMsg=@LogHeader+' [1] failed to drop clustered index for clone table. will return.'
  if (@error<>0) goto ERROR
 end

EXEC(@dropCloneTable)

select @returnCode=320, @error=@@ERROR, @rowsCount=@@ROWCOUNT, @Now=getdate(), @LogHeader=convert(char(23), @Now, 126), @errMsg=@LogHeader+' [1] failed to drop clone table. will return.'

if (@error<>0) goto ERROR

EXEC(@createCloneTable)

select @returnCode=330, @error=@@ERROR, @rowsCount=@@ROWCOUNT, @Now=getdate(), @LogHeader=convert(char(23), @Now, 126), @errMsg=@LogHeader+' failed to create clone table. will return.'

if (@error<>0) goto ERROR
 if (@hasNonPrimaryKeyClusterdIndex=1)
  begin
   EXEC(@createClusteredIndex)

   select @returnCode=340, @error=@@ERROR, @rowsCount=@@ROWCOUNT, @Now=getdate(), @LogHeader=convert(char(23), @Now, 126), @errMsg=@LogHeader+' failed to create clustered index for clone table. will return.'

   if (@error<>0) goto ERROR
  end

if (@compression IN (1,2))
 begin
  EXEC(@compressionQuery)
  select @returnCode=350, @error=@@ERROR, @rowsCount=@@ROWCOUNT, @Now=getdate(), @LogHeader=convert(char(23), @Now, 126), @errMsg=@LogHeader+' failed to adjust clone table compressoin option. will return.'
  if (@error<>0) goto ERROR
 end

--
-- now do the partition switch to truncate data
EXEC(@switchPartition)

select @returnCode=360, @error=@@ERROR, @rowsCount=@@ROWCOUNT, @Now=getdate(), @LogHeader=convert(char(23), @Now, 126), @errMsg=@LogHeader+' failed to switch partition to clone table. will return.'

if (@error<>0) goto ERROR

--
-- now drop the coloum table again
if (@hasPrimaryKey=1)
 begin
  EXEC(@dropPrimaryKey)
  select @returnCode=370, @error=@@ERROR, @rowsCount=@@ROWCOUNT, @Now=getdate(), @LogHeader=convert(char(23), @Now, 126), @errMsg=@LogHeader+' [2] failed to drop primary key for clone table. will return.'
  if (@error<>0) goto ERROR
 end
--
-- may not need to do this:
-- also this may have some performance issue since dropping clustered index means a heap will have to be created??
--if (@hasNonPrimaryKeyClusterdIndex=1)
--begin
--EXEC(@dropClusteredIndex)
--select @returnCode=380, @error=@@ERROR, @rowsCount=@@ROWCOUNT, @Now=getdate(), @LogHeader=convert(char(23), @Now, 126), @errMsg=@LogHeader+' [2] failed to drop clustered index for clone table. will return.'
--if (@error<>0) goto ERROR
--end
EXEC(@dropCloneTable)

select @returnCode=390, @error=@@ERROR, @rowsCount=@@ROWCOUNT, @Now=getdate(), @LogHeader=convert(char(23), @Now, 126), @errMsg=@LogHeader+' [2] failed to drop clone table. will return.'

if (@error<>0) goto ERROR

RETURN 0

ERROR:
print @errMsg

return @returnCode

END

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