A CUBRID database user can have members with the same authorization. If authorization A is granted to a user, the same authorization is also granted to all members belonging to the user. A database user and its members are called a "group."; a user who has no members is called a "user."
CUBRID provides DBA and PUBLIC users by default.
- DBA can access every object in the database, that is, it has authorization at the highest level. Only DBA has sufficient authorization to add, alter and delete the database users.
- All users including DBA are members of PUBLIC. Therefore, all database users have the authorization granted to PUBLIC . For example, if authorization B is added to PUBLIC group, all database members will automatically have the B authorization.
CUBRID stores information on the locations of all existing databases in the databases.txt file. This file is called the "database location file." A database location file is used when CUBRID executes utilities for creating, renaming, deleting or replicating databases; it is also used when CUBRID runs each database. By default, this file is located in the databases directory under the installation directory. The directory is located through the environment variable CUBRID_DATABASES.
db_name db_directory server_host logfile_directory
The format of each line of a database location file is the same as defined by the above syntax; it contains information on the database name, database path, server host and the path to the log files. The following example shows how to check the contents of a database location file.
% more databases.txt dist_testdb /home1/user/CUBRID/bin d85007 /home1/user/CUBRID/bin dist_demodb /home1/user/CUBRID/bin d85007 /home1/user/CUBRID/bin testdb /home1/user/CUBRID/databases/testdb d85007 /home1/user/CUBRID/databases/testdb demodb /home1/user/CUBRID/databases/demodb d85007 /home1/user/CUBRID/databases/demodb
By default, the database location file is stored in the databases directory under the installation directory. You can change the default directory by modifying the value of the CUBRID_DATABASES environment variable. The path to the database location file must be valid so that the cubrid utility for database management can access the file properly. You must enter the directory path correctly and check if you have write permission on the file. The following example shows how to check the value configured in the CUBRID_DATABASES environment variable.
% set | grep CUBRID_DATABASES CUBRID_DATABASES=/home1/user/CUBRID/databases
An error occurs if an invalid directory path is set in the CUBRID_DATABASES environment variable. If the directory path is valid but the database location file does not exist, a new location information file is created. If the CUBRID_DATABASES environment variable has not been configured at all, CUBRID retrieves the location information file in the current working directory.
The volumes of CUBRID database are classified as permanent volume, temporary volume and backup volume.
- In the permanent volumes,
- there are generic, data, index and temp volumes in database volumes.
- there are an active log, an archiving log and a background archiving log in log volumes.
- In temporary volume, there is a temporary temp volume.
For more details on volumes, see Database Volume Structure.
The following is an example of files related to the database when testdb database operates.
|testdb||40MB||generic||Database volume||The firstly created volume when DB is created. This is used as generic volume and includes the meta information of DB. The file size is 40M because "cubrid createdb" is executed after db_volume_size in cubrid.conf is specified as 40M or the option of "cubrid createdb", --db-volume-size is specified as 40M.|
|testdb_x001||40MB||one of generic, data and index||Automatically created generic file or a file created by the user's command for adding a volume. The size of generic file which was automatically created became 40MB because DB was started after specifying db_volume_size in cubrid.conf as 40M.|
|testdb_x002||40MB||one of generic, data and index||Automatically created generic file or a file created by the user's command for adding a volume.|
|testdb_x003||40MB||one of generic, data and index||Automatically created generic file or a file created by the user's command for adding a volume.|
|testdb_x004||40MB||one of generic, data and index||Automatically created generic file or a file created by the user's command for adding a volume.|
|testdb_x005||40MB||one of generic, data and index||Automatically created generic file or a file created by the user's command for adding a volume.|
|testdb_x006||2GB||one of generic, data and index||Automatically created generic file or a file created by the user's command for adding a volume. The size became 2GB because DB was restarted after specifying db_volume_size in cubrid.conf as 2G or the option of "cubrid addvoldb", --db-volume-size is specified as 2G.|
|testdb_t32766||360MB||temporary temp||Temp Volume||a file created temporarily when the space of temp volume is insufficient during running the temp volume required query(e.g.: sorting, scanning, index creation). This is removed when DB is restarted. But, this should not be deleted arbitrarily.|
|testdb_lgar_t||40MB||background archiving||Log volume||A log file which is related to the background archiving feature. This is used when storing the archiving log.|
|testdb_lgar224||40MB||archiving||Archiving logs are continuously archived and the files ending with three digits are created. At this time, archiving logs from 001~223 seem to be removed normally by "cubrid backupdb" -r option or the setting of log_max_archives in cubrid.conf. When archiving logs are removed, you can see the removed archiving log numbers in the REMOVE section of lginf file. See Managing Archive Logs.|
|testdb_lgat||40MB||active||Active log file|
- Database volume file
- In the above, testdb, testdb_x001 ~ testdb_x006 are classified as the database volume files.
- File size is determined by "db_volume_size" in cubrid.conf or the "--db-volume-size" option of "cubrid createdb" and "cubrid addvoldb".
- The type of an automatically created volume is always generic.
- Log volume file
- In the above, testdb_lgar_t, testdb_lgar224 and testdb_lgat are classified as the log volume files.
- File size is determined by "log_volume_size" in cubrid.conf or the "--log-volume-size" option of "cubrid createdb".
Temp volume is a space where the intermediate and final results of query processing and sorting are temporarily stored; this is separated as temporary temp volume and permanent temp volume.
The examples of queries that can use permanent temp volume or temporary temp volume are as follows:
- Queries creating the resultset like SELECT
- Queries including GROUP BY or ORDER BY
- Queries including a subquery
- Queries executing sort-merge join
- Queries including the CREATE INDEX statement
When executing the queries above, the temp volume is used after exhausting the memory space (the space size is determined by the system parameter temp_file_memory_size_in_pages specified in cubrid.conf) assigned to store SELECT results or sort the data. The order in which the storage space is used to store the results of query processing and sorting is as follows: when the current storage space is exhausted, the next storage space is used.
- temp_file_memory_size_in_pages memory secured by the system parameter
- Permanent temp volume
- Temporary temp volume (for details, see the below)
To prevent the system from insufficient disk space (as the size of temporary temp volume is increased than expected because a query which requires a big-sized temp space is executed), we recommend that you should;
- secure the expected permanent temp volume in advance and
- limit the size of the space used in the temporary temp volume when a query is executed.
Permanent temp volume secures this space as running "cubrid addvoldb -p temp", and the maximum temporary temp space which is occupied during a query runs can be limited by the temp_file_max_size_in_pages (default is -1, which means infinite) parameter in cubrid.conf.