SQL Server 2005 DBCC Command Reference

New, Undocumented and Retired DBCC Commands in SQL Server 2005

Microsoft’s SQL Server development team has introduced seven new DBCC commands. Unfortunately little or no documentation is available on the new commands listed below, though some of them may be documented in the RTM release.

Those that are listed as being documented do not require a trace flag to be set before using them. However, to use the undocumented commands, you will need to turn on trace flag 2588. This has changed since SQL Server 7.0/2000, where the trace flag was 2520.

Please note that the following is a result of investigations with the beta 2 release of SQL Server 2005, the final RTM release may differ slightly. As always, never use an undocumented DBCC command on a production server unless advised by Microsoft, and never use a documented one unless you understand how it may affect the performance of your server.

DBCC Commands New to SQL Server 2005

Documented New Commands

• freesessioncache () -- no parameters

• requeststats ({clear} | {setfastdecayrate, rate} | {setslowdecayrate, rate})

Undocumented New Commands

• mapallocunit (I8AllocUnitId | {I4part, I2part})

• metadata ({'print' [, printopt = {0 |1}] | 'drop' | 'clone' [, '' | ....]}, {'object' [, 'type',...}, {Id | Name}, [{Ownerid | Ownername}], [{Dbid | Dbname}]])

• optimizer_whatif property, value

• persiststackhash (hashfile, BUFLATCH_TIMEOUT | ATTENTION | OUTOFLOCKS | LATCH_ATTN | OUTOFLOG | OUTOFMEM | SOS [, SKIPLAST | INCLUDELAST])

• semetadata (object id | name, index id | name [, partition id])

DBCC Commands Altered Since SQL Server 2000

The following is presented as a list of pairs of commands. The first command is the old syntax, as used in SQL Server 2000. The second of each pair is the altered syntax new to SQL Server 2005. In most cases the commands have been extended to take advantage of passing an object ID instead of a name, but if your scripts use any of these commands, it's probably worth checking them out before you migrate to SQL Sever 2005.

• 2000 : checkalloc [('database_name'[, NOINDEX | REPAIR])] [WITH NO_INFOMSGS[, ALL_ERRORMSGS][, ESTIMATEONLY]]

• 2005 : checkalloc [('dbname'|dbid[, NOINDEX | REPAIR])] [WITH NO_INFOMSGS[,ALL_ERRORMSGS][, ESTIMATEONLY]]

• Changes : SQL Server 2005 now accepts the dbid as well as the dbname

 

• 2000 : checkdb [('database_name'[, NOINDEX | REPAIR])] [WITH NO_INFOMSGS[, ALL_ERRORMSGS][, PHYSICAL_ONLY] [, ESTIMATEONLY][, TABLOCK]

• 2005 : checkdb [('dbname | dbid'[, NOINDEX | REPAIR])] [WITH NO_INFOMSGS[,ALL_ERRORMSGS][, PHYSICAL_ONLY] [, ESTIMATEONLY][, TABLOCK]]

• Changes : SQL Server 2005 now accepts the dbid as well as the dbname

 

• 2000 : checkident ('table_name'[, { NORESEED | {RESEED [, new_reseed_value] } } ] )

• 2005 : checkident ('table_name'[, { NORESEED | {RESEED [, new_reseed_value] } } ] )

• Changes : Although the syntax is identical for SQL Server 2000 and 2005, there is a subtle change in the behaviour of this command. In SQL Server 7.0 and 2000, running checkident would cause the identity column to be re-seeded, even if the table was empty. In SQL Server 2005, if the table is empty when dbcc checkident is run, the reseed value will be ignored.

 

• 2000 : dbrepair ('dbname', DROPDB [, NOINIT])

• 2005 : dbrepair ('dbname', markdirty | {dropdevice, int} | {repairindex, int, int})

• Changes : dropdevice syntax changed ; markdirty and repairindex options added NB : It seems odd that this command has been extended with this release, as in the SQL Server 2005 setup help file, setupsql9.chm, it states that DROP DATABASE should be used instead of this command. It was included in SQL Server 2000 for backward compatibility only.

 

• 2000 : indexdefrag ({dbid | dbname | 0}, {tableid | tablename}, {indid | indname})

• 2005 : indexdefrag ({dbname | dbid | 0}, {tableid | tablename} [, {indid | indname} [, partition_number]])

• Changes : An extra optional parameter has been added, partition_number

 

• 2000 : inputbuffer (spid)

• 2005 : inputbuffer (spid, [batchid])

• Changes : An extra optional parameter has been added, batch_id

 

• 2000 : outputbuffer (spid)

• 2005 : outputbuffer (spid, [batchid])

• Changes : An extra optional parameter has been added, batch_id

 

• 2000 : proccache

• 2005 : proccache ([compplan_ticks_threshold])

• Changes : An optional parameter has been added, compplan_ticks_threshold

 

• 2000 : sqlperf (LOGSPACE)({IOSTATS | LRUSTATS | NETSTATS | RASTATS [, CLEAR]} | {THREADS} | {LOGSPACE})

• 2005 : sqlperf (LOGSPACE | IOSTATS | NETSTATS | RASTATS [, CLEAR]} | [THREADS] )

• Changes : As for +2000, but LRUSTATS has been removed as an option. NB : Microsoft only document the LOGSPACE parameter of this command - use any others at your own discretion.

 

• 2000 : updateusage ({'database_name'| 0} [, 'table_name' [, index_id]]) [WITH [NO_INFOMSGS] [,] COUNT_ROWS]

• 2005 : updateusage ({'dbname' | dbid | 0} [, {'table_name' | table_id} [,{index_id | 'index_name'}]]) [WITH [NO_INFOMSGS] [,] COUNT_ROWS]

• Changes : Can now specify db_id, table_id, or the index name as parameters, instead of just the db/table/index name. Also note that there is a problem with the output generated by the dbcc showcontig command under certain conditions in the beta version of SQL Server 2005, where more than one block of information per index is generated for tables that contain text columns.

DBCC Commands Retired Since SQL Server 2000

Many of us have used them at one time or another and a few might even depend upon them. However, we can't say we have not been warned, and Microsoft has finally retired a whole raft of dbcc commands in SQL Server 2005. Most of these were not particularly useful, but thoughtfully retained right up to SQL Server 2000 for backward compatibility with SQL Server 6.5 and earlier scripts.

The following dbcc commands are now dead and buried from SQL Server 2005 onwards:

• adduserobject (name)

• balancefactor (variance_percent)

• bufcount [(number_of_buffers)]

• cacheprofile [( {actionid} [, bucketid])

• checkdbts (dbid, newTimestamp)]

• des [( {'dbname' | dbid} [, {'objname' | objid} ])

• dropuserobject ('object_name')

• getvalue (name)

• iotrace ( { 'dbname' | dbid | 0 | -1 }, { fileid | 0 }, bufsize, [ { numIOs | -1 } [, { timeout (sec) | -1 } [, printopt={ 0 | 1 }]]] )

• lockobjectschema ('object_name')

• matview ({'PERSIST' | 'ENDPERSIST' | 'FREE' | 'USE' | 'ENDUSE'})

• memospy

• memusage ([IDS | NAMES], [Number of rows to output])

• monitorevents ('sink' [, 'filter-expression'])

• newalloc (previously retired, use of checkalloc recommended instead)

• perflog

• pglinkage (dbid, startfile, startpg, number, printopt={0|1|2}, targetfile, targetpg, order={1|0})

• procbuf [({'dbname' | dbid}[, {'objname' | objid}[, nbufs[, printopt = { 0 | 1 } ]]] )]

• rebuild_log (dbname [, filename])

• row_lock (dbid, tableid, set) - Not Needed

• shrinkdb (previously retired, use of shrinkdatabase recommended instead)

• tab ( dbid, objid )

• tape_control {'query' | 'release'}[,('\\.\tape')]

• textall [({'database_name'|database_id}[, 'FULL' | FAST] )]

• textalloc ({'table_name'|table_id}[, 'FULL' | FAST])

• upgradedb (db) usagegovernor (command, value)

• wakeup (spid)

DBCC Commands Included in SQL Server 2005, which will be Retired at a Later Date

dbreindex
This will be replaced with the REBUILD option of the ALTER INDEX statement.

indexdefrag
This will be replaced with the REORGANIZE option of the ALTER INDEX statement.

showcontig
This command will be replace by the system function fn_indexinfo.

Complete List of Documented SQL Server 2005 DBCC Commands

• checkalloc [('dbname'|dbid[, NOINDEX | REPAIR])] [WITH NO_INFOMSGS[, ALL_ERRORMSGS][, ESTIMATEONLY]]

• checkcatalog [('dbname'|dbid)] [WITH NO_INFOMSGS]

• checkconstraints [( 'tab_name' | tab_id | 'constraint_name' | constraint_id )] [WITH ALL_CONSTRAINTS | ALL_ERRORMSGS]

• checkdb [('dbname | dbid'[, NOINDEX | REPAIR])] [WITH NO_INFOMSGS[, ALL_ERRORMSGS][, PHYSICAL_ONLY][, ESTIMATEONLY] [, TABLOCK]]

• checkfilegroup [( [ {'filegroup_name' | filegroup_id} ] [, NOINDEX] )] [WITH NO_INFOMSGS[, ALL_ERRORMSGS][, PHYSICAL_ONLY] [, ESTIMATEONLY][, TABLOCK]]

• checkident ('table_name'[, { NORESEED | {RESEED [, new_reseed_value] } } ] )

• checktable ('table_name'[, {NOINDEX | index_id | REPAIR}]) [WITH NO_INFOMSGS[, ALL_ERRORMSGS][, PHYSICAL_ONLY] [, ESTIMATEONLY][, TABLOCK]]

• cleantable ('dbname'|dbid, 'table_name'|table_id [, batch_size])

• concurrencyviolation (reset | display | startlog | stoplog)

• dbreindex ('table_name' [, index_name [, fillfactor]]) [WITH NO_INFOMSGS]

• dbrepair ('dbname', markdirty | {dropdevice, int} | {repairindex, int, int})

• dropcleanbuffers

• free dll_name (FREE) e.g. DBCC xp_sample (FREE)

• freeproccache

• freesessioncache

• help ('dbcc_command' | '?')

• indexdefrag ({dbname | dbid | 0}, {tableid | tablename} [, {indid | indname} [, partition_number]])

• inputbuffer (spid, [batchid])

• opentran [({'dbname'| dbid})] [WITH TABLERESULTS[,NO_INFOMSGS]]

• outputbuffer (spid, [batchid])

• perfmon

• pintable (database_id, table_id)

• proccache ([compplan_ticks_threshold])

• requeststats ({clear} | {setfastdecayrate, rate} | {setslowdecayrate, rate})

• show_statistics ('table_name'[, 'target_name'])

• showcontig ([table_id | table_name [, index_id | index_name]] [WITH FAST, ALL_INDEXES, TABLERESULTS [,ALL_LEVELS]])

• shrinkdatabase ({'dbname'|dbid}, [freespace_percentage [, {NOTRUNCATE | TRUNCATEONLY}]])

• shrinkfile ({fileid | 'filename'} {[, EMPTYFILE] | [[, compress_size] [, {NOTRUNCATE | TRUNCATEONLY}]]})

• sqlperf (LOGSPACE)

• traceoff [( tracenum [, tracenum ... ] )]

• traceon [( tracenum [, tracenum ... ] )]

• tracestatus (trace# [, ...trace#])

• unprintable (dbid, table_id)

• updateusage ({'dbname' | dbid | 0} [, {'table_name' | table_id} [, {index_id | 'index_name'}]]) [WITH [NO_INFOMSGS] [,] COUNT_ROWS]
• useroptions

Complete List of Undocumented SQL Server 2005 DBCC Commands

• activecursors [(spid)]

• addextendedproc (function_name, dll_name)

• addinstance (objectname, instancename)

• auditevent (eventclass, eventsubclass, success, loginname, rolename, dbusername, loginid, objname, servername, providername)

• autopilot (typeid [, dbid [, {maxQueryCost | tabid [, indid [, pages [, flag [, rowcounts]]]]} ]])

• buffer ( {'dbname' | dbid} [, objid [, number [, printopt={0|1|2} ][, dirty | io | kept | rlock | ioerr | hashed ]]])

• bytes ( startaddress, length )

• cacheprofile ( actionid [, bucketid])

• cachestats

• callfulltext - system sp use only

• checkprimaryfile ( {'FileName'} [, opt={0|1|2|3} ])

• clearspacecaches ('dbname'|dbid, 'table_name'|table_id, 'index_name'|index_id [, partition_number])

• collectstats (on | off)

• cursorstats ([spid [,'clear']])

• dbrecover (dbname [, IgnoreErrors])

• dbreindexall (dbname|dbid[, type_bitmap])

• debugbreak

• deleteinstance (objectname, instancename)

• detachdb ( 'dbname' [, fKeep_Fulltext_Index_File (0 | 1)] )

• dropextendedproc (function_name)

• config

• dbinfo [('dbname')]

• dbtable [({'dbname' | dbid})]

• lock ([{'DUMPTABLE' | 'DUMPSTATS' | 'RESETSTATS' | 'HASH'}]|[{'STALLREPORTTHESHOLD', stallthreshold}])

• log (dbname | dbid [,{0|1|2|3|4}[,['lsn','[0x]x:y:z']|['numrecs',num]|['xdesid','x:y']|['extent','x:y']|['pageid','x:y']| ['objid',{x,'y'}]|['logrecs',{'lop'|op}...]|['output',x,['filename','x']]...]]])

• page ( {'dbname' | dbid}, filenum, pagenum [, printopt={0|1|2|3} ]) pss [(uid[, spid[, printopt = { 1 | 0 }]] )]

• resource

• dumptrigger ({'BREAK', {0 | 1}} | 'DISPLAY' | {'SET', exception_number} | {'CLEAR', exception_number})

• errorlog

• extentinfo [({'dbname'| dbid | 0} [, {'tablename' | tableid} [, {'indexname' | indexid | -1} [, partition_number]]])]

• fileheader [( {'dbname' | dbid} [, fileid])

• fixallocation [({'ADD' | 'REMOVE'}, {'PAGE' | 'SINGLEPAGE' | 'EXTENT' | 'MIXEDEXTENT'}, filenum, pagenum [, objectid, indexid, partitionid, allocUnitId])

• flush ('data' | 'log', dbname | dbid)

• flushprocindb (dbid)

• freeze_io (dbname | dbid)

• icecapquery ('dbname' [, stored_proc_name [, #_times_to_icecap (-1 infinite, 0 turns off)]])
  • Use 'dbcc icecapquery (printlist)' to see list of stored procs to profile.
  • Use 'dbcc icecapquery (icecapall)' to profile all stored procs.

• incrementinstance (objectname, countername, instancename, value)

• ind ( { 'dbname' | dbid }, { 'objname' | objid }, { indid | 0 | -1 | -2 } [, partition_number] )

• invalidate_textptr (textptr)

• invalidate_textptr_objid (objid) latch ( address [, 'owners'] [, 'stackdumps'])

• loginfo [({'dbname' | dbid})]

• mapallocunit (I8AllocUnitId | {I4part, I2part})

• memobjlist [(memory object)]

• memorymap

• memorystatus

• metadata ({'print' [, printopt = {0 |1}] | 'drop' | 'clone' [, '' | ....]}, {'object' [, 'type',...}, {Id | Name}, [{Ownerid | Ownername}], [{Dbid | Dbname}]])

• no_textptr (table_id , max_inline)

• optimizer_whatif property, value

• persiststackhash (hashfile, BUFLATCH_TIMEOUT | ATTENTION | OUTOFLOCKS | LATCH_ATTN | OUTOFLOG | OUTOFMEM | SOS [, SKIPLAST | INCLUDELAST])

• prtipage (dbname | dbid, objid | objname, indexid | indexname [, partition_number [, level]]).
  • No partition specified uses the first partition.
  • No level specified prints root page.

• readpage ({'dbname'|dbid}, fileid, pageid, formatstr [, printopt = { 0 | 1} ])

• renamecolumn (object_name, old_name, new_name)

• ruleoff ({ rulenum | rulestring } [, { rulenum | rulestring } ]+)

• ruleon ( rulenum | rulestring } [, { rulenum | rulestring } ]+)

• semetadata (object id | name, index id | name [, partition id])

• setcpuweight (weight)

• setinstance (objectname, countername, instancename, value)

• setioweight (weight)

• showdbaffinity

• showfilestats [(file_num)]

• showoffrules

• showonrules

• showtableaffinity (table_id | table_name [, partition_number])

• showtext ('dbname' | dbid, {textpointer | {fileid, pageid, slotid [,option]}})

• showweights

• sqlmgrstats

• stackdump [( {uid[, spid [, batchid [, ecid]]} | {threadId, 'THREADID'}] )] tec [( uid[, spid[, batchid[, ecid]] )]

• thaw_io (dbname | dbid)

• useplan [(number_of_plan)]

• writepage ({'dbname' | dbid}, fileid, pageid, offset, length, data)

Acknowledgements and References

• Except where noted below, the above investigation was carried out on the Beta 2 release of SQL Server 2005 Express Edition. At the time of writing (November 2004) this product was available as a free download at www.microsoft.com/sql.
• SQL Server 2005 Setup Help © Microsoft Corporation 2004.
• SQL Server 2005 Express Edition.

End of Essential Guide

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