Mimer SQL Documentation TOC PREV NEXT INDEX

Mimer SQL Developer Site


MULTIDEFS Parameters


Parameter
Definition
 Databanks
Specifies the maximum number of databank files that the database server can have open at any one time.
 Tables
Specifies the maximum number of tables that can be accessed simultaneously by the database server.
 ActTrans
Specifies the maximum number of transactions that can be active in the database server.
 SQLPool
Initial size of the SQLPool area in K bytes. This area contains information about each session, i.e. opened tables and databanks, compiled SQL programs, etc. The SQLPool area will expand automatically if it is too small, but it will not be larger than MaxSQLPool.
 RequestThreads
The number of threads in the database server that can serve client requests.
 BackgroundThreads
The number of background threads in the database server.
 Users
The maximum number of users that are allowed to connect to the database server. This parameter should not exceed the number of users specified in the Mimer SQL license key.
This number is also used to calculate the size of the shared memory region used for local database server communication. About 70 Kbytes of shared memory will be allocated for each user.
 DBCheck
A number which specifies what kind of check that should be performed when a databank is opened which previously was not closed properly.
0 - check index pages
Index pages only are checked in the foreground while applications that access the databank waits for the operation to complete.
1 - check data pages
A full databank check (involving index and data pages) provides for more secure operations, but may take much longer to execute than an index page check. When a full check is done, the index pages are checked in the foreground and the data pages are checked in the background so there is a smaller effect on performance.
2 - Immediate restart, no check
This options performs no checking when the file is opened. The system still verifies the integrity of each page through a checksum. A few pages may have been preallocated and these are not reclaimed when this option is used. If the option is subsequently changed these pages will be reclaimed the next time the databank is opened.
3 - Immediate restart, check index pages
This option performs a check of all index pages in the databank in the background. This is done concurrently with other operations on the system.
4 - Immediate restart, check all pages
This option performs a check of all pages in the databank in the background. This is done concurrently with other operations on the system.
The Immediate restart options require a license key called "Imm Restart".
Databank checks can be avoided by always shutting down the database server properly with the MIMCONTROL command, especially prior to shutting down the machine.
 Pages2K
The number of 2 Kbytes pages in the bufferpool area containing pages from the databank files. The default value of this parameter is 12.5% of the total RAM memory in the machine.
VMS: There may be an OpenVMS limit set for the amount of memory a process may allocate, this limit will not be exceeded. Among the various OpenVMS parameters, WSMAX is likely to be of primary interest in connection with this limit.
 Pages16K
The number of 16 Kbytes pages in the bufferpool area containing pages from the databank files. The default value of this parameter is 8.33% of the total RAM memory in the machine.
 Pages64K
The number of 64 Kbytes pages in the bufferpool area containing pages from the databank files. The default value of this parameter is 5% of the total RAM memory in the machine.
 Oper
This parameter gives a list of host system users, i.e. operators, or e-mail addresses that should receive e-mail notification of serious problems with the database server.
VMS: On OpenVMS, you can also specify OPER.
This will enable that notification messages are sent to the central operator, i.e. processes that have set:
$ REPLY/ENABLE=CENTRAL.
 DumpPath
This parameter may specify an alternate path for the dump directories. The default is to create dump directories under the database home directory.
 TCPPort
Specifies how the database server should handle incoming TCP/IP connection requests. If this parameter is set to - (a single dash), the TCP/IP capability will be disabled for the database server.
UNIX: On UNIX, the TCPPort parameter is, by default, set to inetd which means that the TCP/IP port server program, mimtcp, will be used for establishing a connection to any Mimer SQL version 8 database server. In this case clients may connect to the port to which mimtcp listens, usually 1360, and the handshake will be passed over to the requested Mimer SQL database server.
If a TCP/IP port number is specified, the database server will listen directly to that port.
VMS: On OpenVMS, the TCPPort parameter is, by default, set to the TCP/IP port number 1360. The TCP/IP port server program, MIMTCP, will automatically be started to listen to the given port, serving all Mimer SQL version 8 database servers set up to use that port.
 MaxSQLPool
The maximum size (in kilobytes) of the SQLPool. The SQLPool memory area grows dynamically, but the size will never exceed this parameter. Use this parameter to control the maximum virtual size (maximum page file usage) for the database server process.
 MemLock
A number which specifies whether the bufferpool and communication buffers should be locked in memory (1) or not locked in memory (0).
 Minidump
Small bufferpool dump (no page content).
0 = No
1 = Yes (default)
 AutoStart
UNIX: By default, this parameter is set to 1 which indicates that the database should be started automatically when the operating system goes into multi-user mode. If the parameter is set to 0 the database will not be started automatically.
 DumpScript
UNIX: If the database server goes into an erroneous and unrecoverable state, it will produce dumps of the current internal database structures before it goes down. If this situation occurs, it is of great importance for the error detection process to get a UNIX kernel stack trace from the location where the error was located.
By defining this parameter to a command that can produce a kernel trace, such as pstack, stack information will be automatically generated to mimer.log. The %p option, used in the example above, is used to get the current process ID as a parameter to the command given.
 DECPort
VMS: Specifies the DECNET network object that the database server listens to. Each database server must use a unique network object. The default value is the database name.
If you set this parameter to - (a single dash), the DECNET capability will be disabled for the database server.
 ProcName
VMS: This parameter specifies the process name prefix for the database server. (The last part of the process name is always Srv).
Specify a maximum of 11 characters. The default value is to use the first 11 characters of the database name.
 NetUsers
VMS: This parameter specifies the number of users who can access the database through a network connection.
The value used by the system will be the minimum of this parameter and the Users parameter. The default value is 5000.
Since the Users parameter can not be larger than 5000, this means that all users may be network users.
 ServPrio
VMS: This parameter specifies the OpenVMS priority for the database server process.
 BackgroundPriority
UNIX: Specifies if the background threads should run at a higher priority than other server threads. During certain circumstances like in situations where the background threads cannot manage to shorten a transaction queue this can be an alternative.
 Cleanup
VMS: Specifies the time (in seconds) between the cleanup sweeps that check for terminated database clients.
 IOThreads
UNIX: The number of threads in the database server that can serve I/O requests. This parameter is only present and used for some Unix implementations (if it is not present in a default generated multidefs file, the most common reason is that the native Asynchronous I/O is used.)
 BPResident
VMS: If the BPResident parameter is blank (default) the bufferpool will be allocated in normal process memory and is backed by the paging file. The paging file process quota for the database server will be increased accordingly.
If the BPResident parameter specifies a name, a memory resident global section with this name will be created to hold the buffer pool. Since physical memory is used, the buffer pool will not be backed by the paging file. Also, the working set quota of the process does not have to include the buffer pool. This is recommended for larger buffer pools.
To use the BPResident parameter, the user that starts the database server must hold the VMS$MEM_RESIDENT_USER process right.
Please see the VMS Guide for more information.


Mimer
Mimer Information Technology AB
Voice: +46 18 780 92 00
Fax: +46 18 780 92 40
info@mimer.se
Mimer SQL Documentation TOC PREV NEXT INDEX