Dbcc traceflags

With dbcc traceflags you can do many different things, like change the behaviour of the server, see why a certain query plan is choosen or fine-tune the optimizer. This page shows you how to use them and provides a list of known traceflags.

Using traceflags

You can set a traceflag in two ways

At boottime

Usually a server is booted through the runserver file. In this file (default location is $SYBASE/$SYBASE_ASE/install) you can add a traceflag by specifying a -T flag and one or more comma separated values.

At run time

When you are logged in to ASE you can set a traceflag with the dbcc traceon command. Example:

dbcc traceon(3604)

You can specify multiple values, comma separated. To turn a traceflag off, use traceoff

dbcc traceoff(3604)

Which traceflags are active

To see which traceflags are active for your own session use the dbcc traceflags command

dbcc traceflags

To see the traceflags of other sessions as well

dbcc traceflags(2)

List of known traceflags

Below you will find a list of currently known traceflags. But beware of the following:

WARNING

• Most traceflags are undocumented and not supported by Sybase, use at your own risk. Certain traceflags can severely harm your databases.
• Some traceflags are obsolete and are replaced by configuration parameters.
• Certain traceflags should be used when you start the server, others are meant for a specific session, when known this is indicated in the list.
• Experiment first on a test server, use only on production systems when either the traceflag is documented by Sybase or when you have consulted Sybase Technical Support.

List of dbcc traceflags

	Explanation	Since version	Untill Version	Boot time	Run time
100	Display a parse tree for each command
108	Allow dynamic and host variables in create view statements	12.5
200	Display messages about the before image of the query-tree
201	Display messages about the after image of the query tree
208	Show types of locks taken
241	Compress all query-trees when ASE is started
243	Do not expand select * to column names when creating a compiled object
244	When set, the maximum length of the returned value of str_replace() is 16384, otherwise it is 255
260	Reduce TDS (Tabular Data Stream) overhead in stored procedures. Turn off done-in-behaviour packets. See also Send doneinproc tokens.
291	Changes the hierarchy and casting of datatypes to pre-11.5.1 behaviour. There was an issue is some very rare cases where a wrong result could occur, but that's been cleared up in 11.9.2 and above.		11.9.2
292	Never send doneinproc tokens. See also Send doneinproc tokens.
298	Display an error message when a query uses a correlated variable as an inner or outer member of an outer join.
299	Do not recompile a stored procedure that inherits a temp table from a parent procedure.
302	Print trace information on index selection		12.5		Y
303	Display optimizer OR strategy		12.5		Y
304	Revert special "or" optimizer strategy to the strategy used in pre-System 11 (this traceflag resolved several bug issues in System 11, most of these bugs are fixed in ASE 11.0.3.2)
310	Show the plan as choosen by the optimizer, as well as I/O costs.		12.5		Y
311	Display optimizers expected I/O cost		12.5		Y
317	Show all considered plans		12.5		Y
319	Display optimizer reformatting strategy		12.5		Y
320	Turn off join order heuristics		12.5
321	Display optimizers reformatting strategy briefly		12.5
324	Turn off the like optimization for ad-hoc queries using local variables		12.5
326	Instructs the server to use arithmetic averaging when calculating density instead of a geometric weighted average when updating statistics. Useful for building better stats when an index has skew on the leading column. Use only for updating the stats of a table/index with known skewed data.		11.5
329	Turns on a strategy for fast first row return for queries using cursors with an ORDERBY.	15.0 ESD 2		Y	N
333	Disables min-max optimization		12.5
334	Enable merge joins		12.5
353	Turn off transitive closure
364	Use range density instead of total density
370	Use min-max index as an alternative to the table scan for single table queries. Does not perform aggregation optimization for joins.
384	Enable JTC
396	Use min-max optimization for single table queries.
450	Sort a group by operation in the order of the groups	15
516	Print mapping between xchg operators and worker processes when using parallel execution	15
526	Print semi-graphical execution operator tree when showplan is enabled.
602	Prints out diagnostic information for deadlock prevention.
603	Prints out diagnostic information when avoiding deadlock.
615	When a read of a page does not indicate it's right identity a second read is done. When the identity is now correct the related device is suspect and ASE turns on additional diagnostic checks. The check can be turned off with the traceflag.	12.5.3 ESD 5 and 15.0 ESD 2		Y	Y
646	Turn off the new space allocation method as introduced in 12.5.3 for partitioned DOL tables	12.5.3
699	Turn off transaction logging
712	Disable procedure cache optimisation
722	ASE (debug version) will perform additional checks on the heap memory to detect possible memory corruption.	15.0 ESD 2		Y	N
833	Do not report Msg 880 "Your query is blocked because it tried to write and database '<dbname>' is in quiesce state. Your query will proceed after the DBA performs QUIESCE DATABASE RELEASE.".	15.0 ESD 2	Y	N
990	Allow only access to the server with the "sa" account.
1116	Suppress Msg 1131. (The OAM page does not belong to object with index.....)
1202	Also show the blocked lock requests in master..syslocks
1204	Print deadlock information into errorlog
1205	Prints deadlock information by printing stacktraces.
1206	Disable lock promotion.
1212	Shows info about locks granted and released
1213	Used with dbcc object_stats
1217	Show info about locks being acquired
1603	Turns off async i/o and forces standard unix io. Can be useful if symptoms include transient corruption errors that may be caused by bad drives or controllers.
1605	Start secondary engines by hand
1606	Create a debug engine start file. This allows you to start up a debug engine which can access the server's shared memory for running diagnostics.
1608	Instructs server engine 0 to not on-line any other dataserver engines
1610	Boot the server with TCP_NODELAY enabled.			Y
1611	If possible, pin shared memory -- check errorlog for success/failure.
1613	Set affinity of the ASE engine's onto particular CPUs usually pins engine 0 to processor 0, engine 1 to processor 1, etc
1615	SGI only: turn on recoverability to filesystem devices.
1625	Linux only: Revert to using cached filesystem I/O. By default, ASE on Linux opens filesystem devices using O_SYNC, unlike other Unix based releases, which means it is safe to use filesystems devices for production systems.	11.9.2
1630	SuSE 32 bit Linux (SuSE 9 SP1 or later), ASE incorrectly identifies AIO to be KAIO while using Posix AIO. Can lead to ASE hang. Start with this trace flag.	15.0 ESD 2		Y	N
1642	Reserve one third of the sockets for EJB.
2205	Show HA debugging output
2209	Used when upgrading ASE configured with high availability
2512	Instructs dbcc checkalloc to skip the syslogs table during processing.
2513	Instructs dbcc checkalloc, tablealloc and indexalloc to check for whether foreign objects are stranded on a particular segment within a database.
2703	When using update statistics with sampling and the index/column does not have existing statistics, set join density and total density to values from the sample rather then to defaults.	15.0 ESD 2
3100	Load a database even when the characterset or sort order of a dump file is incompatible with the server.
3199	When ONLINE DATABASE fails with Msg 2610 (Could not find leaf row in nonclustered index partition ...) after a cross-platform database load, set the traceflag on, reload the dump and online again.	15.0 ESD 2			Y
3300	Display each log record that is being processed during recovery. You may wish to redirect stdout because it can be a lot of information.
3500	Disable checkpointing.
3502	Write an entry in the errorlog when a databases is checkpointed
3601	Write a stacktrace to the errorlog every time an error is raised.
3604	Send trace output to the session of the client				Y
3605	Send trace output to the errorlog of the server				Y
3607	Do not start recovery when booting ASE.			Y
3608	Recover only the master database. Do not clear tempdb or start up checkpoint process.			Y
3609	Recover all databases. Do not clear tempdb or start up checkpoint process.
3610	Pre-System 10 behaviour: divide by zero to result in NULL instead of error
3620	Do not kill infected processes.
3706	Performance improvement of drop table in tempdb.	15.0 ESD 2		Y	Y
4001	Display a message in the errorlog when a loginrecord is recieved
4012	Don't spawn chkptproc.
4013	Write a message to the errorlog when a login takes place.
4020	Boot without recover.			Y
4044	Allows to log into ASE when the "sa" login is locked
4072	Disable the global login trigger	15
4073	Export the result of certain "set" command within a login trigger to the session.	15.0 ESD 2		Y
4080	When an UPDATE using tsequal() is done within a stored procedure, tsequal() no longer returns a timestamp value unless the trace flag is set.	15.0 ESD 2
4413	Trace queries in a 12.5 server that are join-order dependent.
5101	Forces all I/O requests to go through engine 0. This removes the contention between processors but could create a bottleneck if engine 0 becomes busy with non-I/O tasks.
5102	Prevents engine 0 from running any non-affinitied tasks.
7103	Disable table lock promotion for text columns.
7703	When assinging a value from a table into a local variable, go through the whole resultset rather than jump to last row and assing the value once.
7717	Disable check of client compatibility in ASE 15. See Version 15 client compatibility	15.0.1
7815	logs address connection requests and host / name lookups.
7841	Make ASE IPv6 aware
8003	prints info on RPC calls
8203	Display statement and transaction locks on a deadlock error.
8399	Instructs the dbcc monitor command to insert a valid description into the field_name column in the sysmonitors table. Not intended for use by users. Appears in the errorlog when sp_sysmon is used.
9217	When set, RepAgent will not stop after reporting error 9289 due to an inconsistent log record found. Instead it will attempt to continue after reporting error 9290 in the error log.	15.0 ESD 2
11201	Logs client connect events, disconnect events, and attention events.
11202	Logs client language, cursor declare, dynamic prepare, and dynamic execute-immediate text.
11203	Logs client rpc events.
11204	Logs all messages routed to client.
11205	Logs all interaction with remote server.
11206	Show messages about query processing for file access
11207	Log the processing of text and image datatypes from remote servers
11208	Prevents the create index and drop table statements from being transmitted to a remote server. sysindexes is updated anyway.
11209	When running "update statistics" on remote tables update only the rowcount
11210	Disables Component Integration Services enhanced remote query optimization.
11212	Prevents escape on underscores in table names.
11213	Prevents generation of column and table constraints.
11214	Disables Component Integration Services recovery at start-up.			Y
11215	Sets enhanced remote optimization for servers of class db2.
11216	For the session, disables enhanced remote optimization.				Y
11217	For the server, disables enhanced remote optimization.
11218	Any query that is part of a declare cursor command, and that references proxy tables, is read only by default.
11228	A 2762 error, "CREATE TABLE command is not allowed within multiple statement transaction" may be reported when executing a SQL INSERT..SELECT from proxy table mapped to a RPC. This traceflag has to be turned on to allow CREATE TABLE command in the remote procedure (for the session)	12.5.3. ESD 5 and 15.0 ESD 2
11229	Use pre-12.5.3 behaviour to import statistics for proxy tables	12.5.3
11231	CIS: Connections to remote servers are not disconnected and remain engine affinitied until the client session terminates. The connections can now be dropped and detached from an engine after executing a statement to the remote server by enabling this flag. Exceptions are when the statement is participating in cursor, transaction or stored procedure operations; or when ASE is in either HA failover or failback states.	15.0 ESD 2
11232	A 2762 error, "CREATE TABLE command is not allowed within multiple statement transaction" may be reported when executing a SQL INSERT..SELECT from proxy table mapped to a RPC. This traceflag has to be turned on to allow CREATE TABLE command in the remote procedure (serverwide)	12.5.3. ESD 5 and 15.0 ESD 2
11906	Informational messages from REORG will no longer be printed to the errorlog.	15.0 ESD 2
12628	Data insertion into DOL tables having nonclustered index will be done with the index prepend mode splits disabled, in order to improve disk space utilization.	15.0 ESD 2		Y	N
15302	When a subquery appears in the ON clause of an outer join query, the performance may not be efficient. ASE will do optimization for subquery attachment to achieve more favorable performance when turned on.	15.0 ESD 2
15303	Possible performance improvement on a SELECT statement when a BIT column is involved in the WHERE clause.	15.0 ESD 2
15556	Allow dump and load in ASE cluster edition with multiple instances active	cluster edition