Dbcc traceflags
From SybaseWiki
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.
Contents
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.
| 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 | |||
| 116 | Print the text of the abstract query plan. Supported by Sybase, see documentation | ||||
| 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 | ||||
| 217 | Display a warning message for using the T-SQL extension of queries with grouped aggregates and columns in the select list which are not in the GROUP BY clause. | 15.0.2 ESD 2 | |||
| 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. When Msg 511 is incorrectly raised with this flag on, upgrade to 15.0.2 ESD 6. | ||||
| 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, supported by Sybase, see documentation | 12.5 unless using compatibility mode in ASE 15 | 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. Supported by Sybase see documentation | 12.5 unless using compatibility mode in ASE 15 | Y | ||
| 311 | Display optimizers expected I/O cost | 12.5 unless using compatibility mode in ASE 15 | Y | ||
| 317 | Show all considered plans. Supported by Sybase, see documentation | 12.5 unless using compatibility mode in ASE 15 | Y | ||
| 319 | Display optimizer reformatting strategy | 12.5 unless using compatibility mode in ASE 15. | Y | ||
| 320 | Turn off join order heuristics | 12.5 | |||
| 321 | Display optimizers reformatting strategy briefly | 12.5 unless using compatibility mode in ASE 15. | |||
| 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 unless using compatibility mode in ASE 15. | |||
| 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 | 12.0 | 12.5 unless using compatibility mode in ASE 15. | ||
| 396 | Use min-max optimization for single table queries. | ||||
| 441 | queries where literal autoparametrization applies will be processed in full compatibility mode when enabled. Supported by Sybase, see documentation | 15.0.3 ESD 1 | |||
| 446 | Disable restricted compatibility mode. Supported by Sybase, see documentation | 15.0.3 ESD 1 | |||
| 450 | Sort a group by operation in the order of the groups | 15 | |||
| 457 | Try to use worktables for a select in a cursor in order to isolate the selected data from the base table (12.5 behaviour) | 15.0.2 ESD 6 | |||
| 467 | Do not cache a statement in the statement cache when a temp tables is referenced. | 15.0.2 ESD 5 | |||
| 477 | When using compatibility mode, print a message about the type being used. Supported by Sybase, see documentation | 15.0.3 ESD 1 | |||
| 516 | Print mapping between xchg operators and worker processes when using parallel execution. Supported by Sybase, see documentation | 15 | |||
| 526 | Print semi-graphical execution operator tree when showplan is enabled. Supported by Sybase, see documentation | ||||
| 589 | Close a cursor implicitly during a cursor fetch and after an error was hit. | 15.0.2 ESD 2 | |||
| 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 | |
| 625 | When hitting Msg 12328, do not regenerate the row-offset table | 12.5.4 ESD 10 | |||
| 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. Supported by Sybase, see documentation | ||||
| 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. | 12.5.3 ESD 5 and 15.0 ESD 2 | Y | N | |
| 1642 | Reserve one third of the sockets for EJB. | ||||
| 1648 | Enable DIRECT IO for block devices under on Linux | ||||
| 1649 | (linux on Intel, amd and IBM P) When set ASE uses Linux Kernel Asynchronous IO, rather than POSIX AIO | 12.5.4 ESD 10 | |||
| 1656 | (Sun only) ASE will not boot when Intimate Shared Memory is not available. | 12.5.4 ESD 10, 15.0.2 ESD 6 | |||
| 2205 | Show HA debugging output, supported by Sybase see documentation | ||||
| 2209 | Used when upgrading ASE configured with high availability | ||||
| 2511 | Suppress Msg 15082 during DBCC checks | 12.5.4 ESD 10 | |||
| 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. Supported by Sybase, see documentation | ||||
| 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 | |||
| 2716 | Generate statistics for private temp tables | 15.0.3 ESD 3 | |||
| 2720 | When set, do not allow "update statistics" to be run within a multi-statement transaction | 15.0.3 ESD 3 | |||
| 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. Supported by Sybase see documentation | Y | |||
| 3605 | Send trace output to the errorlog of the server. Supported by Sybase see documentation | 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. | ||||
| 3637 | Connection time averages for LDAPUA are printed | 12.5.4 ESD 10 | |||
| 3706 | Performance improvement of drop table in tempdb. | 15.0 ESD 2 | Y | Y | |
| 3710 | Improve the performance of DROP INDEX and CREATE INDEX by releasing the system catalog locks when not in DDL-IN-TRAN mode after the commit of the transaction but before post commit work started. | 12.5.4 ESD 10, 15.0.2 ESD 4 | 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. | 12.5.3 ESD 5 + 15.0 ESD 2 | |||
| 4082 | When set printing messages to console is made non-blocking | 12.5.4 ESD 10 | |||
| 4083 | Disable SQLDBGR. | 12.5.4 ESD 10 | Y | N | |
| 4084 | Console logging will be disabled if setting console to nonblocking fails. | 12.5.4 ESD 10, 15.0.2 ESD 5 | Y | N | |
| 4413 | Trace queries in a 12.5 server that are join-order dependent. | ||||
| 4419 | In some cases, outer join on view or derived table with CASE expression may perform slower due to view materialization.The workaround is to use traceflag 4419. | 12.5.4 ESD#6 | |||
| 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 | |||
| 7738 | Support plan sharing of cached statements across different users. | 15.0.2 ESD 2 | |||
| 7741 | Avoid Msg 257 when using statement cache and a parameterized statement without "dynamic prepare" and a incompatible parameter is specified as null. | 12.5.4 ESD 10 | |||
| 7815 | logs address connection requests and host / name lookups. | ||||
| 7841 | Make ASE IPv6 aware. No longer needed since 15.0.2 ESD 5 | 15.0.2 ESD 5 | |||
| 7844 | Enable/disable concurrent Kerberos authentication | ||||
| 7850 | When set, timeout after 60 s when no Kerberos security opaque token is received from client | 12.5.4 ESD 10 | |||
| 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. Supported by Sybase, see documentation | 15.0 ESD 2 | |||
| 9531 | Dump expensive buffer allocation analysis | 15.0.2 ESD 2 | |||
| 11201 | Logs client connect events, disconnect events, and attention events. Supported by Sybase, see documentation | ||||
| 11202 | Logs client language, cursor declare, dynamic prepare, and dynamic execute-immediate text. Supported by Sybase, see documentation | ||||
| 11203 | Logs client rpc events. Supported by Sybase, see documentation | ||||
| 11204 | Logs all messages routed to client. Supported by Sybase, see documentation | ||||
| 11205 | Logs all interaction with remote server. Supported by Sybase, see documentation | ||||
| 11206 | Show messages about query processing for file access. Supported by Sybase, see documentation | ||||
| 11207 | Log the processing of text and image datatypes from remote servers. Supported by Sybase, see documentation | ||||
| 11208 | Prevents the create index and drop table statements from being transmitted to a remote server. sysindexes is updated anyway. Supported by Sybase, see documentation | ||||
| 11209 | When running "update statistics" on remote tables update only the rowcount. Supported by Sybase, see documentation | ||||
| 11210 | Disables Component Integration Services enhanced remote query optimization. | ||||
| 11211 | Prevents the drop table syntax from being forwarded to remote servers if the table was created using the create table at location syntax. Supported by Sybase, see documentation | ||||
| 11212 | Prevents escape on underscores in table names. Supported by Sybase, see documentation | ||||
| 11213 | Prevents generation of column and table constraints. Supported by Sybase, see documentation | ||||
| 11214 | Disables Component Integration Services recovery at start-up. Supported by Sybase, see documentation | Y | |||
| 11215 | Sets enhanced remote optimization for servers of class db2. | ||||
| 11216 | For the session, disables enhanced remote optimization. Supported by Sybase, see documentation | Y | |||
| 11217 | For the server, disables enhanced remote optimization. Supported by Sybase, see documentation | ||||
| 11218 | Any query that is part of a declare cursor command, and that references proxy tables, is read only by default. Supported by Sybase, see documentation | ||||
| 11220 | Disables constraint checking of remote tables on the local server. This avoids duplicate checking. Setting this trace flag on ensures that queries are not rejected by the quickpass mode because of constraints. (spid) Supported by Sybase, see documentation | ||||
| 11221 | Disables alter table commands to the remote server when ON. This allows users to modify type, length, and nullability of columns in a local table without changing columns in the remote table. Use trace flag 11221 with caution. It may lead to tables that are “out of sync.” (spid). Supported by Sybase, see documentation | ||||
| 11223 | Disables proxy table index creation during create existing table or create proxy_table command execution. If this flag is set on, no index metadata is imported from the remote site referenced by the proxy table, and no indexes for the proxy table are created. This trace flag should be used with care and turned off when no longer necessary. (global) Supported by Sybase, see documentation | ||||
| 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. Supported by Sybase, see documentation | 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 | |||
| 11237 | Only for proxy tables to Oracle, do not append unneeded "null clause" to "alter table modify" command | 12.5.4 ESD 10 | |||
| 11299 | Allows connection information to be logged when a connection to a remote server fails. Supported by Sybase, see documentation | ||||
| 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 | |||
| 15322 | Use 12.5 behaviour when assigning variables in combination with subqueries. | 15.0.2 ESD 6 | |||
| 15371 | When set, bug fix for a sub-optimal plan is chosen when the query contains a subquery from an IF EXISTS clause. | 12.5.4 ESD 10 | |||
| 15381 | When set, the warning message 307, "Index <index_name> specified as optimizer hint in the FROM clause of table <table_name> does not exist. Optimizer will choose another index instead." is disabled. | 15.0.2 ESD 4 | |||
| 15382 | Disable "special OR strategy" (see release notes for the fine details) | 15.0.2 ESD 2 | |||
| 15556 | Allow dump and load in ASE cluster edition with multiple instances active | cluster edition |
