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2.2 Managing Sedna

  2.2.1 Running Sedna
  2.2.2 Stopping Sedna
  2.2.3 Configuring Sedna
2.2.1 Running Sedna

To start the Sedna server one should start Governor by executing the se_gov command. This starts the main server component. After that Administrator can run databases (as discussed in Section 2.3.4).

Important note: since version 3.5 Sedna server by default listens on ’localhost’ and allows only local clients. If you want to work with Sedna remotely make sure that -listen-address parameter value is adjusted properly.

The usage of the se_gov command is as follows:

Usage: se_gov [options]  
 
options:  
  --help                     display this help and exit  
  -help                      display this help and exit  
  -version                   display product version and exit  
  -background-mode on/off    start the server in the background mode  
                             (default on)  
  -listen-address address    local address Sedna listens for client  
                             connections (default localhost)  
  -port-number <int>         socket listening port  
                             (default 5050)  
  -el-level level            event logging level (default 3):  
                               0 - event logging is off  
                               1 - log only fatal errors  
                               2 - log all errors/warnings  
                               3 - system operational messages  
                               4 - log everything (+debug messages)  
  -alive-timeout timeout     session keep alive timeout  
                             (default 0 - infinite timeout)  
  -stack-depth depth         maximum executor stack depth  
                             (default 4000)

--help and -help options provide the exhaustive information about the se_gov command.

-version option allows getting the version of the Governor.

-background-mode option allows Administrator to start Governor in the background mode.

-listen-address specifies the address on which the server is to listen for connections from client applications. The value takes the form of a numeric IP address or host name (it must be resolvable by your system, check your host file). The value 0.0.0.0 corresponds to all available IP interfaces. The default value is localhost, which allows only local ”loopback” connections to be made. If value is not specified Sedna server tries to find the sednaconf.xml configuration file file and uses the address specified as listen_address parameter (see section 2.2.3, Configuring Sedna). If there is no configuration file or listen_address parameter is not specified Sedna would listen on localhost.

Note, if you want to make Sedna work in the old-fashioned (prior version 3.5) way you should set -listen-address option to 0.0.0.0 — that would force Sedna to listen on every interface in your system as it worked in older versions.

-port-number option specifies the port number on which Sedna listens for connections from clients. If port number is not specified Governor tries to find the sednaconf.xml file and use port number specified as listener_port parameter (see section 2.2.3, Configuring Sedna). If it still cannot find port number it will use default 5050 value.

-el-level option specifies the event log severity level. For details refer to the section 2.6, Event Log.

-alive-timeout option specifies number of seconds to wait for the next request from the some client on the same connection. Session keep alive timeout can be defined also in the sednaconf.xml file. Value provided via command ine overrides value (if any) defined in the sednaconf.xml file.

-stack-depth option specifies the maximum safe depth of the session’s physical operations stack. Setting the parameter higher than the actual process stack may fit will mean that a runaway recursive function can crash an individual session (and server in the current architecture). The default setting is 4000, which is unlikely to risk crashes. However, it may be too small to allow execution of complex functions. Value provided via command line overrides value (if any) defined in the sednaconf.xml file.

To get the information about which Sedna components are run use se_rc command.

The usage of the se_rc command is as follows:

Usage: se_rc [options]  
 
options:  
  --help           display this help and exit  
  -help            display this help and exit  
  -version         display product version and exit  
  -sm-list         display running databases list

2.2.2 Stopping Sedna

To stop Sedna, Administrator should use the se_stop command. This command stops all Sedna components including all databases, which are run. Command has several optional parameters.

The usage of the se_stop command is as follows:

Usage: se_stop [options]  
 
options:  
  --help       display this help and exit  
  -help        display this help and exit  
  -version     display product version and exit  
  -hard        attempt to roll back transactions immediately

The first and second options are straightforward, typing these options Administrator can get the exhaustive information about the se_stop command. Option -version allows getting the version of the se_stop.

Note, se_stop may cause a rollback of some active transactions in the system. However, Sedna waits for the last statement in each transaction is completed. Option -hard causes Sedna to attempt to roll back transactions as soon as possible (except bulk load and update transactions).

2.2.3 Configuring Sedna

Sedna configuration parameters are stored in the file sednaconf.xml located in:

[win:] SEDNA_INSTALL\etc  
[nix:] SEDNA_INSTALL/etc

The file is optional. If there is no such file, the default values are used. The file is an XML document, which satisfies the following DTD:

<!ELEMENT sednaconf (sedna_data, os_primitives_id_min_bound,  
                     listener_port, ping_port,  
                     event_log_level, keep_alive_timeout,  
                     session_stack_depth)>  
<!ELEMENT sedna_data (#PCDATA)>  
<!ELEMENT os_primitives_id_min_bound (#PCDATA)>  
<!ELEMENT listen_address (#PCDATA)>  
<!ELEMENT listener_port (#PCDATA)>  
<!ELEMENT ping_port (#PCDATA)>  
<!ELEMENT event_log_level (#PCDATA)>  
<!ELEMENT keep_alive_timeout (#PCDATA)>  
<!ELEMENT session_stack_depth (#PCDATA)>

The sedna_data element contains the path to the directory where database configuration files (in the cfg subdirectory) and databases (in the data subdirectory) are stored. Path must be absolute and exist. The path by default is SEDNA_INSTALL.

The os_primitives_id_min_bound element defines the minimal value for identifiers of OS resources (e.g. semaphores) used in Sedna. In order to run several Sedna instances on one machine Administrator should configure this parameter in a such way that identifiers belonging to different Sedna instances does not intersect. In a standard configuration one Sedna instance acquires a range of identifiers which length is equal to 150.

The listen_address element specifies the address on which the server is to listen for connections from client applications. The value takes the form of a host name or numeric IP address. The value 0.0.0.0 corresponds to all available IP interfaces. The default value is localhost, which allows only local ”loopback” connections to be made.

The listener_port element defines the port number for listening for connection requests from a client.

The ping_port element defines the port number of Sedna ping server that is an internal kernel mechanism. It is used to stop all Sedna processes in case of crash.

The event_log_level defines event log severity level (0-4). For full description see section 2.6, Event Log.

The keep_alive_timeout defines session keep alive timeout, i.e. number of seconds to wait for the next request from the some client on the same connection.

The session_stack_depth defines the maximum safe depth of the session’s physical operations stack. Setting the parameter higher than the actual process stack may fit will mean that a runaway recursive function can crash an individual session (and server in the current architecture). The default setting is 4000, which is unlikely to risk crashes. However, it may be too small to allow execution of complex functions.

To tune the Sedna configuration, Administrator should edit the proper elements of the Sedna configuration file. Note, in order for new configuration to take effect you must restart Sedna server (se_gov).