(B)0[mdb-wide-options-1 =
qqwq> [4mIN[m qqqqqq> path-name qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqwq
tq> [4mCOLLATING_SEQUENCE[m IS sequence-name qqk x
x lqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqj x
x mqwqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqwqq> ncs-name qqk x
x mq> [4mDESCRIPTION[m IS qq> /* text */ qqj x x
x lqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqj x
x mqwqqqqqqqqqqqqqqqqqqqqqqqwqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqu
x mq> [4mFROM[m library-name qqj x
tq> [4mDESCRIPTION[m IS qqqqqqq> /* text */ qqqqqqqqqqqqqqqqqqqqqqqqqqu
tq> [4mNUMBER[m OF [4mUSERS[m IS qq> number-users qqqqqqqqqqqqqqqqqqqqqqqqqu
tq> [4mNUMBER[m OF [4mBUFFERS[m IS qqqqq> number-buffers qqqqqqqqqqqqqqqqqqu
tq> [4mNUMBER[m OF qqwqq> [4mCLUSTER[m qqqqwq> [4mNODES[m IS qq> number-nodes qqu
x mqq> [4mVAXCLUSTER[m qj x
tq> [4mNUMBER[m OF [4mRECOVERY[m [4mBUFFERS[m IS qqq> recovery-buffers qqqqqqqqqu
mq> global-buffer-params qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqj
1 – path-name
The data dictionary path name for the dictionary path name
where the database definition is stored. Use this qualifier to
store the data dictionary definitions for the database in a data
dictionary entity other than the default path, which is defined
by the name of the database file.
2 – COLLATING_SEQUENCE
Specifies a collating sequence to be used for all fields in the
database. Sequence-name is a name of your choosing; use this
sequence-name in any subsequent statements that refer to this
collating sequence.
The OpenVMS National Character Set (NCS) Utility provides
a set of pre-defined collating sequences and also lets you
define collating sequences of your own. The COLLATING_SEQUENCE
clause accepts both pre-defined and user-defined NCS collating
sequences.
If you do not specify a collating sequence, the default is ASCII
(shown as "no collating sequence" in some displays).
3 – ncs-name
Specifies the name of a collating sequence in the default NCS
library, SYS$LIBRARY:NCS$LIBRARY, or in the NCS library specified
by the argument library-name. (In most cases, it is probably
simplest to make the sequence-name the same as the ncs-name: for
example, COLLATING_SEQUENCE IS FRENCH FRENCH.) You can view the
collating sequence names by using the command NCS/LIST at DCL
level.
The collating sequence can be either one of the pre-defined NCS
collating sequences or one that you have defined yourself using
NCS.
4 – text
Provides a comment for a collating sequence or database being
defined.
5 – library-name
Specifies the name of an NCS library other than the default. The
default NCS library is SYS$LIBRARY:NCS$LIBRARY.
6 – number-users
The maximum number of users allowed to access the database at one
time. The default is 50 users. The largest number of users you
can specify is 2032, and the fewest number of users is 1.
7 – number-buffers
The number of buffers Oracle Rdb allocates per process using this
database. Specify an unsigned integer between 2 and 32768. The
default is 20 buffers.
8 – number-nodes
The NUMBER OF CLUSTER NODES is clause and the NUMBER OF
VAXCLUSTER NODES is clause have exactly the same effect. The
option of using NUMBER OF CLUSTER NODES has been added to reflect
the fact that Oracle Rdb can run on different hardware platforms (in
addition to VAXclusters).
Sets the upper limit on the maximum number of nodes in the
cluster from which users can access the shared database. The
default is 16 nodes. The range is 1 node to 96 nodes. The actual
maximum limit is the current cluster limit.
In some cases, after you have specified a particular number of
users and nodes, doing a dump of the database root file will
display a different number of nodes than the value you set. The
following paragraphs explain why this occurs.
The relationship between the number of users and the number of
nodes supported on a database can be seen when you specify 2032
users and 4 nodes in a SQL CREATE/ALTER DATABASE or RDO DEFINE
/CHANGE DATABASE statement and then dump the database root file.
The dump displays values of 2032 users and 41 nodes.
To understand this relationship, Oracle Rdb uses a data structure
called a TSN Block (TSNBLK). A TSN Block keeps track of
transaction activity on a node and transaction information for
each user on a particular node. Each TSN Block is owned by a
particular node and can handle up to 50 users. For each group of
50 users one TSNBLK is allocated per node to cover the maximum
number of users and nodes the database is expected to support,
which is determined as either one TSNBLK per node, or one TSNBLK
per 50 users, whichever is larger. The maximum number of TSN
blocks is equal to the value of the current maximum number of
nodes that are supported for a database.
For example, if the DBA specifies 2032 users and 4 nodes, this
is calculated as 2032/50 for a total of 41 TSNBLKs and this
equates to 41 nodes. The algorithm selects the maximum value
of (number of nodes specified, number of nodes calculated). So in
this example, 41 is the maximum calculated value (calculated 41 >
specified 4).
Had the DBA specified 2032 users and 50 nodes, 50 would be the
maximum value for the number of nodes (specified 50 > calculated
41) and 50 TSNBLKs would be allocated, one for each node.
As another example, if the DBA specifies 50 users and 10 nodes,
the maximum value is 10 nodes (specified 10 > calculated 1), so
ten TSNBLKs would be allocated, one for each node.
9 – recovery-buffers
The number of database buffers used during the automatic recovery
process that is initiated after a system or process failure. This
recovery process uses the recovery-unit journal file. Specify an
unsigned integer between 2 and 32768. The default is 20 buffers.
10 – global-buffer-params
(B)0[mglobal-buffer-params=
q> [4mGLOBAL[m [4mBUFFERS[m ARE qwq> [4mENABLED[m qqwqk
mq> [4mDISABLED[m qj x
lqqqqqqqqqqqqqqqqqqqqq<qqqqqqqqqqqqqqqqj
mqwqqqqqqqqqqqqqqqqqqqqqqqq>qqqqqqqqqqqqqqqqqqqqqqqwqq>
mq> ( qq> [4mNUMBER[m IS number-glo-buffers qq> , qk x
lqqqqqqqqqqqqqqq<qqqqqqqqqqqqqqqqqqqqqqqqqj x
mq> [4mUSER[m [4mLIMIT[m IS max-glo-buffers qq> ) qqqqqj
10.1 – GLOBAL_BUFFERS
The GLOBAL BUFFERS ARE ENABLED clause specifies that Oracle Rdb
maintain one global buffer pool per node in the cluster for each
database. By default, Oracle Rdb maintains a local buffer pool for
each user. For more than one user to use the same page, each
must read it from disk into their local buffer pool. When the
GLOBAL BUFFERS ARE ENABLED clause has been specified, a page
in the global buffer pool may be read by more than one user at
the same time, although only one user reads the page from disk
into the global buffer pool. Global buffering provides improved
performance because I/O is reduced and memory is better utilized.
The default is GLOBAL BUFFERS ARE DISABLED, in which Oracle Rdb
maintains a local buffer pool for each user, and global buffers
are not enabled.
10.2 – NUMBER
When global buffers are enabled, the NUMBER IS clause is used to
specify the default number of global buffers per node.
In database parameter syntax, a user designates an attach to the
database, not a person who uses the database.
The default number of global buffers is the maximum number
of users multiplied by 5. (In the RDO syntax for database
parameters, a user is the same as an attach.) You can override
the default by defining a value for the logical name RDM$BIND_
BUFFERS.
Although you can change the NUMBER IS parameter online, the
change will only take effect the next time that the database is
opened. By default, a database can be opened automatically (that
is, by any user who invokes the database and executes a data
manipulation language statement). If the database was modified
so that it must be manually opened, the RMU/OPEN command must be
used to open it.
10.3 – USER_LIMIT
The USER LIMIT clause specifies the maximum number of global
buffers each user allocates. Because global buffer pools are
shared by all users, you must define an upper limit on how many
global buffers a single user can allocate. This limit prevents a
user from defining the RDM$BIND_BUFFERS to use all the buffers in
the global buffer pool. The user limit cannot be greater then the
total number of global buffers. The default is 5.
See the Oracle Rdb Guide to Database Performance and Tuning for
information on determining the maximum number of global buffers a
user can allocate.
Although you can change the USER LIMIT IS parameter online, the
change will only take effect the next time that the database is
opened. By default, a database can be opened automatically (that
is, by any user who invokes the database and executes a data
manipulation language statement). If the database was modified
so that it must be manually opened, the RMU/OPEN command must be
used to open it.