Launch the CGE Server Using the cge-launch Command

Purpose, example, guidelines and troubleshooting tip for using the cge-launch command.

The cge-launch command launches the query engine and enables creating and building a database in a single step. It handles the details of allocating batch resources, setting up the launch environment, and composing a command line for the query engine on a given platform.

Following is an example of using cge-launch:
$ cge-launch -o pathtoResultsFile -d path -l logfile
In the preceding statement:
  • pathtoResultsFile - specifies the directory that will contain the results of queries and/or updates
  • path - specifies the path to the database directory
  • logfile - specifies the log file that will contain the command and server output.
The following options of the cage-launch command must be specified when launching the server:
  • The -d option that specifies the path to the directory where the data set resides.
  • The -o option that specifies the path to a directory where the result files produced by queries need to be placed.
Both the -d and -o options accept:
  • UNIX style pathnames as naming files on a POSIX compliant file system
  • URLs of the following forms:
    • file://unix_pathname - This form is the equivalent of the Unix Style Pathname in URL form
    • hdfs://name-server-address[:name-server-port-number]/HDFS_pathname - This type of format indicates that a Hadoop Distributed File System (HDFS) file or directory is known to the specified name server and is located within that name-server's name space at HDFS_pathname.
    Both the aforementioned forms must refer to a file/directory that is shared across and equally accessible from all nodes. CGE will determine where to look for this file/directory based on recognizing one of the aforementioned path formats.
When using checkpoints:
  • If a full URL is used, the checkpoint is written exactly as specified by the URL, which means that an HDFS URL will cause the checkpoint to be written to the path specified in the URL on the HDFS file system described by the rest of the URL, and a file URL (i.e. file:/path) will be written to the POSIX file system at the pathname specified in the URL.
  • If a relative path (i.e. a simple path with no leading / character) is used, the checkpoint will be written in a directory relative to the data directory used at CGE start up.
  • If a full pathname but not a URL is specified, the pathname will be interpreted within the space specified by the URL of the data directory used at CGE start up, so, if CGE was started using an HDFS URL, the checkpoint will be written at the specified path within HDFS, if CGE was started with a simple pathname or file URL, the checkpoint will be written at the specified path within the POSIX file space.
Tip: Relaunch CGE if the system displays an error message saying, "Server failed to start up” upon execution of the cge-launch command.

For more information, see the cge-launch(1) man page.