Database Blocks
1. Problem
The system causes database blocks when you perform operations.
Cause
This problem occurs when multiple operations such as “Running of Filters”, and “Property Saves” are performed concurrently.
Solution
To avoid database blocks, follow these steps:
a. Start SQL Server Management Studio, and run the following command:
sp_who2
The name of the SPID that is causing the Database block is displayed.
b. Run the following command in SQL Server Management Studio, by specifying the name of the SPID that is causing the database block, in place of <Blocking SPID>.
DBCC INPUTBUFFER(<Blocking SPID>)
The SPROC/SQL statements are displayed.
c. Check which SPROC/SQL statement is causing the block. Also analyze the select, update, or delete statements in the SPROC/SQL script, and optimize the statements appropriately.
For example, if a select statement is taking a long time to execute, analyze the query using SQL Execution Plan, and take appropriate actions such as creating an index, or altering the SQL query to improve its performance.
Solution
To collect additional information about a Blocking SPID:
◦ Compile the sp_blocker_pss80.
The following code snippet refers to sp_blocker_pss80 script:
/*
Note: This script is meant to have 2 creations of the same stored procedure and one of them will fail
with either 207 errors or a 2714 error.
*/
use master
GO
if exists (select * from sysobjects where id = object_id('dbo.sp_blocker_pss80') and sysstat & 0xf = 4)
drop procedure dbo.sp_blocker_pss80
GO
create procedure sp_blocker_pss80 (@latch int = 0, @fast int = 1)
as
--version 15SP3
set nocount on
declare @spid varchar(6)
declare @blocked varchar(6)
declare @time datetime
declare @time2 datetime
declare @dbname nvarchar(128)
declare @status sql_variant
declare @useraccess sql_variant
set @time = getdate()
declare @probclients table(spid smallint, ecid smallint, blocked smallint, waittype binary(2), dbid smallint,
ignore_app tinyint, primary key (blocked, spid, ecid))
insert @probclients select spid, ecid, blocked, waittype, dbid,
case when convert(varchar(128),hostname) = 'PSSDIAG' then 1 else 0 end
from sysprocesses where blocked!=0 or waittype != 0x0000
if exists (select spid from @probclients where ignore_app != 1 or waittype != 0x020B)
begin
set @time2 = getdate()
print ''
print '8.2 Start time: ' + convert(varchar(26), @time, 121) + ' ' + convert(varchar(12), datediff(ms,@time,@time2))
insert @probclients select distinct blocked, 0, 0, 0x0000, 0, 0 from @probclients
where blocked not in (select spid from @probclients) and blocked != 0
if (@fast = 1)
begin
print ''
print 'SYSPROCESSES ' + ISNULL (@@servername,'(null)') + ' ' + str(@@microsoftversion)
select spid, status, blocked, open_tran, waitresource, waittype,
waittime, cmd, lastwaittype, cpu, physical_io,
memusage, last_batch=convert(varchar(26), last_batch,121),
login_time=convert(varchar(26), login_time,121),net_address,
net_library, dbid, ecid, kpid, hostname, hostprocess,
loginame, program_name, nt_domain, nt_username, uid, sid,
sql_handle, stmt_start, stmt_end
from master..sysprocesses
where blocked!=0 or waittype != 0x0000
or spid in (select blocked from @probclients where blocked != 0)
or spid in (select spid from @probclients where blocked != 0)
print 'ESP ' + convert(varchar(12), datediff(ms,@time2,getdate()))
print ''
print 'SYSPROC FIRST PASS'
select spid, ecid, waittype from @probclients where waittype != 0x0000
if exists(select blocked from @probclients where blocked != 0)
begin
print 'Blocking via locks at ' + convert(varchar(26), @time, 121)
print ''
print 'SPIDs at the head of blocking chains'
select spid from @probclients
where blocked = 0 and spid in (select blocked from @probclients where spid != 0)
if @latch = 0
begin
print 'SYSLOCKINFO'
select @time2 = getdate()
select spid = convert (smallint, req_spid),
ecid = convert (smallint, req_ecid),
rsc_dbid As dbid,
rsc_objid As ObjId,
rsc_indid As IndId,
Type = case rsc_type when 1 then 'NUL'
when 2 then 'DB'
when 3 then 'FIL'
when 4 then 'IDX'
when 5 then 'TAB'
when 6 then 'PAG'
when 7 then 'KEY'
when 8 then 'EXT'
when 9 then 'RID'
when 10 then 'APP' end,
Resource = substring (rsc_text, 1, 16),
Mode = case req_mode + 1 when 1 then NULL
when 2 then 'Sch-S'
when 3 then 'Sch-M'
when 4 then 'S'
when 5 then 'U'
when 6 then 'X'
when 7 then 'IS'
when 8 then 'IU'
when 9 then 'IX'
when 10 then 'SIU'
when 11 then 'SIX'
when 12 then 'UIX'
when 13 then 'BU'
when 14 then 'RangeS-S'
when 15 then 'RangeS-U'
when 16 then 'RangeIn-Null'
when 17 then 'RangeIn-S'
when 18 then 'RangeIn-U'
when 19 then 'RangeIn-X'
when 20 then 'RangeX-S'
when 21 then 'RangeX-U'
when 22 then 'RangeX-X'end,
Status = case req_status when 1 then 'GRANT'
when 2 then 'CNVT'
when 3 then 'WAIT' end,
req_transactionID As TransID, req_transactionUOW As TransUOW
from master.dbo.syslockinfo s,
@probclients p
where p.spid = s.req_spid
print 'ESL ' + convert(varchar(12), datediff(ms,@time2,getdate()))
end -- latch not set
end
else
print 'No blocking via locks at ' + convert(varchar(26), @time, 121)
print ''
end -- fast set
else
begin -- Fast not set
print ''
print 'SYSPROCESSES ' + ISNULL (@@servername,'(null)') + ' ' + str(@@microsoftversion)
select spid, status, blocked, open_tran, waitresource, waittype,
waittime, cmd, lastwaittype, cpu, physical_io,
memusage, last_batch=convert(varchar(26), last_batch,121),
login_time=convert(varchar(26), login_time,121),net_address,
net_library, dbid, ecid, kpid, hostname, hostprocess,
loginame, program_name, nt_domain, nt_username, uid, sid,
sql_handle, stmt_start, stmt_end
from master..sysprocesses
print 'ESP ' + convert(varchar(12), datediff(ms,@time2,getdate()))
print ''
print 'SYSPROC FIRST PASS'
select spid, ecid, waittype from @probclients where waittype != 0x0000
if exists(select blocked from @probclients where blocked != 0)
begin
print 'Blocking via locks at ' + convert(varchar(26), @time, 121)
print ''
print 'SPIDs at the head of blocking chains'
select spid from @probclients
where blocked = 0 and spid in (select blocked from @probclients where spid != 0)
if @latch = 0
begin
print 'SYSLOCKINFO'
select @time2 = getdate()
select spid = convert (smallint, req_spid),
ecid = convert (smallint, req_ecid),
rsc_dbid As dbid,
rsc_objid As ObjId,
rsc_indid As IndId,
Type = case rsc_type when 1 then 'NUL'
when 2 then 'DB'
when 3 then 'FIL'
when 4 then 'IDX'
when 5 then 'TAB'
when 6 then 'PAG'
when 7 then 'KEY'
when 8 then 'EXT'
when 9 then 'RID'
when 10 then 'APP' end,
Resource = substring (rsc_text, 1, 16),
Mode = case req_mode + 1 when 1 then NULL
when 2 then 'Sch-S'
when 3 then 'Sch-M'
when 4 then 'S'
when 5 then 'U'
when 6 then 'X'
when 7 then 'IS'
when 8 then 'IU'
when 9 then 'IX'
when 10 then 'SIU'
when 11 then 'SIX'
when 12 then 'UIX'
when 13 then 'BU'
when 14 then 'RangeS-S'
when 15 then 'RangeS-U'
when 16 then 'RangeIn-Null'
when 17 then 'RangeIn-S'
when 18 then 'RangeIn-U'
when 19 then 'RangeIn-X'
when 20 then 'RangeX-S'
when 21 then 'RangeX-U'
when 22 then 'RangeX-X'end,
Status = case req_status when 1 then 'GRANT'
when 2 then 'CNVT'
when 3 then 'WAIT' end,
req_transactionID As TransID, req_transactionUOW As TransUOW
from master.dbo.syslockinfo
print 'ESL ' + convert(varchar(12), datediff(ms,@time2,getdate()))
end -- latch not set
end
else
print 'No blocking via locks at ' + convert(varchar(26), @time, 121)
print ''
end -- Fast not set
print 'DBCC SQLPERF(WAITSTATS)'
dbcc sqlperf(waitstats)
Print ''
Print '*********************************************************************'
Print 'Print out DBCC Input buffer for all blocked or blocking spids.'
Print '*********************************************************************'
declare ibuffer cursor fast_forward for
select cast (spid as varchar(6)) as spid, cast (blocked as varchar(6)) as blocked
from @probclients
where (spid <> @@spid) and
((blocked!=0 or (waittype != 0x0000 and ignore_app = 0))
or spid in (select blocked from @probclients where blocked != 0))
open ibuffer
fetch next from ibuffer into @spid, @blocked
while (@@fetch_status != -1)
begin
print ''
print 'DBCC INPUTBUFFER FOR SPID ' + @spid
exec ('dbcc inputbuffer (' + @spid + ')')
fetch next from ibuffer into @spid, @blocked
end
deallocate ibuffer
Print ''
Print '*******************************************************************************'
Print 'Print out DBCC OPENTRAN for active databases for all blocked or blocking spids.'
Print '*******************************************************************************'
declare ibuffer cursor fast_forward for
select distinct cast (dbid as varchar(6)) from @probclients
where dbid != 0
open ibuffer
fetch next from ibuffer into @spid
while (@@fetch_status != -1)
begin
print ''
set @dbname = db_name(@spid)
set @status = DATABASEPROPERTYEX(@dbname,'Status')
set @useraccess = DATABASEPROPERTYEX(@dbname,'UserAccess')
print 'DBCC OPENTRAN FOR DBID ' + @spid + ' ['+ @dbname + ']'
if @Status = N'ONLINE' and @UserAccess != N'SINGLE_USER'
dbcc opentran(@dbname)
else
print 'Skipped: Status=' + convert(nvarchar(128),@status)
+ ' UserAccess=' + convert(nvarchar(128),@useraccess)
print ''
if @spid = '2' select @blocked = 'Y'
fetch next from ibuffer into @spid
end
deallocate ibuffer
if @blocked != 'Y'
begin
print ''
print 'DBCC OPENTRAN FOR DBID 2 [tempdb]'
dbcc opentran ('tempdb')
end
print 'End time: ' + convert(varchar(26), getdate(), 121)
end -- All
else
print '8 No Waittypes: ' + convert(varchar(26), @time, 121) + ' '
+ convert(varchar(12), datediff(ms,@time,getdate())) + ' ' + ISNULL (@@servername,'(null)')
GO
create proc sp_blocker_pss80 (@latch int = 0, @fast int = 1)
as
--version 15
set nocount on
declare @spid varchar(6)
declare @blocked varchar(6)
declare @time datetime
declare @time2 datetime
declare @dbname nvarchar(128)
declare @status sql_variant
declare @useraccess sql_variant
set @time = getdate()
declare @probclients table(spid smallint, ecid smallint, blocked smallint, waittype binary(2), dbid smallint,
ignore_app tinyint, primary key (blocked, spid, ecid))
insert @probclients select spid, ecid, blocked, waittype, dbid,
case when convert(varchar(128),hostname) = 'PSSDIAG' then 1 else 0 end
from sysprocesses where blocked!=0 or waittype != 0x0000
if exists (select spid from @probclients where ignore_app != 1 or waittype != 0x020B)
begin
set @time2 = getdate()
print ''
print '8 Start time: ' + convert(varchar(26), @time, 121) + ' ' + convert(varchar(12), datediff(ms,@time,@time2))
insert @probclients select distinct blocked, 0, 0, 0x0000, 0, 0 from @probclients
where blocked not in (select spid from @probclients) and blocked != 0
if (@fast = 1)
begin
print ''
print 'SYSPROCESSES ' + ISNULL (@@servername,'(null)') + ' ' + str(@@microsoftversion)
select spid, status, blocked, open_tran, waitresource, waittype,
waittime, cmd, lastwaittype, cpu, physical_io,
memusage,last_batch=convert(varchar(26), last_batch,121),
login_time=convert(varchar(26), login_time,121), net_address,
net_library, dbid, ecid, kpid, hostname, hostprocess,
loginame, program_name, nt_domain, nt_username, uid, sid
from master..sysprocesses
where blocked!=0 or waittype != 0x0000
or spid in (select blocked from @probclients where blocked != 0)
or spid in (select spid from @probclients where waittype != 0x0000)
print 'ESP ' + convert(varchar(12), datediff(ms,@time2,getdate()))
print ''
print 'SYSPROC FIRST PASS'
select spid, ecid, waittype from @probclients where waittype != 0x0000
if exists(select blocked from @probclients where blocked != 0)
begin
print 'Blocking via locks at ' + convert(varchar(26), @time, 121)
print ''
print 'SPIDs at the head of blocking chains'
select spid from @probclients
where blocked = 0 and spid in (select blocked from @probclients where spid != 0)
if @latch = 0
begin
print 'SYSLOCKINFO'
select @time2 = getdate()
select spid = convert (smallint, req_spid),
ecid = convert (smallint, req_ecid),
rsc_dbid As dbid,
rsc_objid As ObjId,
rsc_indid As IndId,
Type = case rsc_type when 1 then 'NUL'
when 2 then 'DB'
when 3 then 'FIL'
when 4 then 'IDX'
when 5 then 'TAB'
when 6 then 'PAG'
when 7 then 'KEY'
when 8 then 'EXT'
when 9 then 'RID'
when 10 then 'APP' end,
Resource = substring (rsc_text, 1, 16),
Mode = case req_mode + 1 when 1 then NULL
when 2 then 'Sch-S'
when 3 then 'Sch-M'
when 4 then 'S'
when 5 then 'U'
when 6 then 'X'
when 7 then 'IS'
when 8 then 'IU'
when 9 then 'IX'
when 10 then 'SIU'
when 11 then 'SIX'
when 12 then 'UIX'
when 13 then 'BU'
when 14 then 'RangeS-S'
when 15 then 'RangeS-U'
when 16 then 'RangeIn-Null'
when 17 then 'RangeIn-S'
when 18 then 'RangeIn-U'
when 19 then 'RangeIn-X'
when 20 then 'RangeX-S'
when 21 then 'RangeX-U'
when 22 then 'RangeX-X'end,
Status = case req_status when 1 then 'GRANT'
when 2 then 'CNVT'
when 3 then 'WAIT' end,
req_transactionID As TransID, req_transactionUOW As TransUOW
from master.dbo.syslockinfo s,
@probclients p
where p.spid = s.req_spid
print 'ESL ' + convert(varchar(12), datediff(ms,@time2,getdate()))
end -- latch not set
end
else
print 'No blocking via locks at ' + convert(varchar(26), @time, 121)
print ''
end -- fast set
else
begin -- Fast not set
print ''
print 'SYSPROCESSES ' + ISNULL (@@servername,'(null)') + ' ' + str(@@microsoftversion)
select spid, status, blocked, open_tran, waitresource, waittype,
waittime, cmd, lastwaittype, cpu, physical_io,
memusage,last_batch=convert(varchar(26), last_batch,121),
login_time=convert(varchar(26), login_time,121), net_address,
net_library, dbid, ecid, kpid, hostname, hostprocess,
loginame, program_name, nt_domain, nt_username, uid, sid
from master..sysprocesses
print 'ESP ' + convert(varchar(12), datediff(ms,@time2,getdate()))
print ''
print 'SYSPROC FIRST PASS'
select spid, ecid, waittype from @probclients where waittype != 0x0000
if exists(select blocked from @probclients where blocked != 0)
begin
print 'Blocking via locks at ' + convert(varchar(26), @time, 121)
print ''
print 'SPIDs at the head of blocking chains'
select spid from @probclients
where blocked = 0 and spid in (select blocked from @probclients where spid != 0)
if @latch = 0
begin
print 'SYSLOCKINFO'
select @time2 = getdate()
select spid = convert (smallint, req_spid),
ecid = convert (smallint, req_ecid),
rsc_dbid As dbid,
rsc_objid As ObjId,
rsc_indid As IndId,
Type = case rsc_type when 1 then 'NUL'
when 2 then 'DB'
when 3 then 'FIL'
when 4 then 'IDX'
when 5 then 'TAB'
when 6 then 'PAG'
when 7 then 'KEY'
when 8 then 'EXT'
when 9 then 'RID'
when 10 then 'APP' end,
Resource = substring (rsc_text, 1, 16),
Mode = case req_mode + 1 when 1 then NULL
when 2 then 'Sch-S'
when 3 then 'Sch-M'
when 4 then 'S'
when 5 then 'U'
when 6 then 'X'
when 7 then 'IS'
when 8 then 'IU'
when 9 then 'IX'
when 10 then 'SIU'
when 11 then 'SIX'
when 12 then 'UIX'
when 13 then 'BU'
when 14 then 'RangeS-S'
when 15 then 'RangeS-U'
when 16 then 'RangeIn-Null'
when 17 then 'RangeIn-S'
when 18 then 'RangeIn-U'
when 19 then 'RangeIn-X'
when 20 then 'RangeX-S'
when 21 then 'RangeX-U'
when 22 then 'RangeX-X'end,
Status = case req_status when 1 then 'GRANT'
when 2 then 'CNVT'
when 3 then 'WAIT' end,
req_transactionID As TransID, req_transactionUOW As TransUOW
from master.dbo.syslockinfo
print 'ESL ' + convert(varchar(12), datediff(ms,@time2,getdate()))
end -- latch not set
end
else
print 'No blocking via locks at ' + convert(varchar(26), @time, 121)
print ''
end -- Fast not set
print 'DBCC SQLPERF(WAITSTATS)'
dbcc sqlperf(waitstats)
Print ''
Print '*********************************************************************'
Print 'Print out DBCC Input buffer for all blocked or blocking spids.'
Print '*********************************************************************'
declare ibuffer cursor fast_forward for
select cast (spid as varchar(6)) as spid, cast (blocked as varchar(6)) as blocked
from @probclients
where (spid <> @@spid) and
((blocked!=0 or (waittype != 0x0000 and ignore_app = 0))
or spid in (select blocked from @probclients where blocked != 0))
open ibuffer
fetch next from ibuffer into @spid, @blocked
while (@@fetch_status != -1)
begin
print ''
print 'DBCC INPUTBUFFER FOR SPID ' + @spid
exec ('dbcc inputbuffer (' + @spid + ')')
fetch next from ibuffer into @spid, @blocked
end
deallocate ibuffer
Print ''
Print '*******************************************************************************'
Print 'Print out DBCC OPENTRAN for active databases for all blocked or blocking spids.'
Print '*******************************************************************************'
declare ibuffer cursor fast_forward for
select distinct cast (dbid as varchar(6)) from @probclients
where dbid != 0
open ibuffer
fetch next from ibuffer into @spid
while (@@fetch_status != -1)
begin
print ''
set @dbname = db_name(@spid)
set @status = DATABASEPROPERTYEX(@dbname,'Status')
set @useraccess = DATABASEPROPERTYEX(@dbname,'UserAccess')
print 'DBCC OPENTRAN FOR DBID ' + @spid + ' ['+ @dbname + ']'
if @Status = N'ONLINE' and @UserAccess != N'SINGLE_USER'
dbcc opentran(@dbname)
else
print 'Skipped: Status=' + convert(nvarchar(128),@status)
+ ' UserAccess=' + convert(nvarchar(128),@useraccess)
print ''
if @spid = '2' select @blocked = 'Y'
fetch next from ibuffer into @spid
end
deallocate ibuffer
if @blocked != 'Y'
begin
print ''
print 'DBCC OPENTRAN FOR DBID 2 [tempdb]'
dbcc opentran ('tempdb')
end
print 'End time: ' + convert(varchar(26), getdate(), 121)
end -- All
else
print '8 No Waittypes: ' + convert(varchar(26), @time, 121) + ' '
+ convert(varchar(12), datediff(ms,@time,getdate())) + ' ' + ISNULL (@@servername,'(null)')
GO
Run the Check block script.
The following code snippet refers to Check Block script. Running this script will provide more details about the Blocking SPID. You can analyze the information available, and take appropriate actions.
Declare @val as int
Set @val=0
WHILE 1=1
BEGIN
EXEC master.dbo.sp_blocker_pss80
-- Or for fast mode
-- EXEC master.dbo.sp_blocker_pss80 @fast=1
-- Or for latch mode
-- EXEC master.dbo.sp_blocker_pss80 @latch=1
WAITFOR DELAY '00:00:15'
SET @val=@val+1
if @val=2 BREAK
END
GO