Creates a database file, specifies its name, and determines its
physical characteristics. This statement also creates a directory
in the data dictionary where definitions of other database
elements can be stored.
Example (single-file database):
RDO> DEFINE DATABASE 'PERSONNEL'.
1 – More
By using the RDBVMS$CREATE_DB logical name and the RDBVMS$CREATE_
DB identifier, you can restrict the ability of users to
create databases on your system. For more information on the
RDBVMS$CREATE_DB logical name and identifier, see the chapter
on defining database protection in the Oracle Rdb Guide to Database
Design and Definition manual.
If your system does not use the RDBVMS$CREATE_DB logical name and
identifier, all users on the system have the ability to create
databases.
When the DEFINE DATABASE statement executes, Oracle Rdb:
o Creates a database file, a snapshot file, and, if the database
is multifile, storage area files.
o Creates a data dictionary entity for the database, including
all the system fields and relations, if the dictionary is
installed.
o Assigns database parameters, and, if the database is
multifile, storage area parameters.
o Creates a default access control list.
o Invokes the newly created database, using the database file
name as the database handle.
You cannot issue the DEFINE DATABASE statement when a transaction
is active. Do not issue an INVOKE DATABASE statement after you
use DEFINE DATABASE. Oracle Rdb automatically invokes the database
after creating the database file.
Other users are not allowed to be attached to the database when
you issue the DEFINE DATABASE statement.
For Oracle Rdb for OpenVMS Alpha, RDO generates an error if you define
the CDDSHR logical name as NL: as shown in the following example:
$ DEFINE CDDSHR NL:
$ RDO
RDO> DEFINE DATABASE RENTALS.
-RDO-F-CDDERR, error occurred during CDD signin, CDD will not be used
-LIB-E-READERR, error reading !AS
If CDDSHR is defined as NL:, use the DCL command SHOW LOGICAL CDDSHR_TV
to check that the CDDSHR_TV logical name is also defined as NL:. Oracle
Rdb recommends that you do not define CDDSHR as NL:. If you want to
avoid using the dictionary, specify the DICTIONARY IS NOT USED clause on
the RDO IMPORT or DEFINE DATABASE commands.
2 – Format
(B)0[m[4mDEFINE[m [4mDATABASE[m qq> file-spec qqwqqqqqqqqqqq>qqqqqqqqwqk
mq> invoke-options qqj x
lqqqqqqqqqqqqqqqqqqqqqqqqqqq<qqqqqqqqqqqqqqqqqqqqqqqqqqj
mqwqwqqqqqqqqqqq>qqqqqqqqqqqqwqwqwqqqqqqqqqqqq>qqqqqqqqqqqqwqqk
x tqq> db-wide-options-1 qu x mq> storage-area-options qj x
x mqq> db-wide-options-2 qqj x x
mqqqqqqqqqqq<qqqqqqqqqqqqqqqqj x
lqqqqqqqqqqqqqqqqqqqqqqqqqqqqq<qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqj
mwwqqqqqqqqqqqqqq>qqqqqqqqqqqqqqqqqqqqqqqqqqqqqq>qqqqqqqqqqqwqwq> .
xtq> define-storage-area-clause qqqqqqqqqqqqqqqq>qqqqqqqqqqu x
xmq> [4mSEGMENTED[m [4mSTRING[m [4mSTORAGE[m [4mAREA[m IS q> storage-area-name j x
mqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqq<qqqqqqqqqqqqqqqqqqqqqqqqqqqqj
2.1 – file-spec
A file specification that names the database file. You should use
either a full file specification, including device, directory,
and file name without the file type, or a simple file name. In
the second case, Oracle Rdb creates the database in the current
default directory. In a single-file database, the file name
specified becomes the file name for two files:
o The database file. The default file type is RDB.
o The snapshot file. This file is used as a temporary file for
read-only transactions. The default file type is SNP.
Type the name of the file-spec in uppercase letters when you
define your database if you use the data dictionary or may
use it in the future. If you type the name of the file-spec in
lowercase letters and try to use the DEFINE GENERIC command of
the dictionary's CDO utility to create a directory name for the
database in the dictionary, the command will fail.
In a multifile database, the file name specified becomes the file
name for three files:
o The database root file. The default file type is RDB.
o The default storage area file. The default file type is RDA.
o A snapshot file. The default file type is SNP.
2.2 – invoke-options
(B)0[minvoke-options =
qqwqqqqqqqqqqqqqqqqqqqqqqqqqqq>qqqqqqqqqqqqqqqqqqwqqqqqqqqqqqqqqqqq>
tqqqqq> [4mDB_HANDLE[m IS qqqqqqq> db-handle qqqqqqqu
mqqqqq> [4mDBKEY[m [4mSCOPE[m IS qqwqq> [4mCOMMIT[m qqqwqqqqqqj
mqq> [4mFINISH[m qqqj
2.2.1 – db-handle
The name of the variable you will use to refer to the database.
Do not use a file name for the db-handle.
2.2.2 – COMMIT
When the DBKEY SCOPE IS COMMIT clause is specified with a
DEFINE DATABASE statement, this means that the database key
(dbkey) of each record used is guaranteed not to change during
each transaction. That is, if a record is erased, its dbkey is
guaranteed not to be reused by another database user until after
a COMMIT statement is executed.
2.2.3 – FINISH
When the DBKEY SCOPE IS FINISH clause is specified with a DEFINE
DATABASE statement, this means that the database key (dbkey)
of each record used is guaranteed not to change until the
user detaches from the database (usually, by using the FINISH
statement).
2.3 – db-wide-options-1
(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
2.3.1 – 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.
2.3.2 – 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).
2.3.3 – 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.
2.3.4 – text
Provides a comment for a collating sequence or database being
defined.
2.3.5 – library-name
Specifies the name of an NCS library other than the default. The
default NCS library is SYS$LIBRARY:NCS$LIBRARY.
2.3.6 – 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.
2.3.7 – 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.
2.3.8 – 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.
2.3.9 – 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.
2.3.10 – 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
2.3.10.1 – 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.
2.3.10.2 – 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$BIND_
BUFFERS.
Although you can change the NUMBER IS parameter online, the
change will only take effect the next time that the database is
opened. By default, a database can be opened automatically (that
is, by any user who invokes the database and executes a data
manipulation language statement). If the database was modified
so that it must be manually opened, the RMU/OPEN command must be
used to open it.
2.3.10.3 – USER_LIMIT
The USER LIMIT clause specifies the maximum number of global
buffers each user allocates. Because global buffer pools are
shared by all users, you must define an upper limit on how many
global buffers a single user can allocate. This limit prevents a
user from defining the RDM$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.
2.4 – db-wide-options-2
(B)0[mdb-wide-options-2 = qwq> [4mBUFFER[m [4mSIZE[m IS qqqqq> buffer-blocks qq> [4mBLOCKS[m qqqqqqwq> tq> [4mADJUSTABLE[m [4mLOCK[m [4mGRANULARITY[m IS qwqqq> [4mENABLED[m qqqwqqqu x mqqq> [4mDISABLED[m qqj x tq> [4mSNAPSHOT[m IS qqqqwqqqqq> [4mENABLED[m qwqq> [4mIMMEDIATE[m qwqwqu x x mqq> [4mDEFERRED[m qqj x x x mqqqqq> [4mDISABLED[m qqqqqqqqqqq>qqqqqqj x tq> [4mDICTIONARY[m IS qqqwqqq> [4mREQUIRED[m qqqqqqqwqqqqqqqqqqqqqu x tqqq> [4mNOT[m [4mREQUIRED[m qqqu x x tqqq> [4mUSED[m qqqqqqqqqqqu x x mqqq> [4mNOT[m [4mUSED[m qqqqqqqj x tq> [4mCARRY[m [4mOVER[m [4mLOCKS[m ARE qqwq> [4mENABLED[m qwqqqqqqqqqqqqqqqqu x mq> [4mDISABLED[m j x mq> [4mLOCK[m [4mTIMEOUT[m [4mINTERVAL[m IS number-seconds SECONDS qqqqqj
2.4.1 – buffer-blocks
The number of blocks Oracle Rdb allocates per buffer. Specify an
unsigned integer greater than zero. If you do not specify this
parameter, Oracle Rdb uses a buffer size that is three times the
PAGE SIZE value.
Buffer size is a global parameter and the number of blocks per
page (or buffer) is constrained to less than 64 blocks per page.
The page size can vary by storage area for multifile databases,
so you should determine the page size of each storage area based
on the sizes of records that will be stored in each storage area.
When you choose the number of blocks per buffer, choose a number
that is wholly divisible by all page sizes for all storage
areas in your multifile database. For example, if your database
has three storage areas with page sizes of 2, 3, and 4 blocks
respectively, choosing a buffer size of 12 blocks will ensure
optimal buffer utilization. If you choose a buffer size of 8, the
storage area with a page size of 3 blocks will waste 2 blocks per
buffer. Oracle Rdb reads as many pages as will fit into the buffer.
In this case, Oracle Rdb reads two pages of 3 blocks apiece into the
buffer, wasting 2 blocks.
2.4.2 – ADJUSTABLE_LOCK
Enables or disables whether or not the database system will
automatically maintain as few locks as possible on database
resources. The default is ENABLED, and results in fewer locks
against the database. However, if contention for database
resources is high, the automatic adjustment of locks can become a
CPU drain. Such databases can trade more restrictive locking for
less CPU usage by disabling adjustable lock granularity.
Disabling adjustable locking granularity may require that the
LOCKIDTBL, LOCKIDTBL_MAX, PQL_DENQLM, PQL_MENQLM OpenVMS SYSGEN
parameters for locks be increased.
2.4.3 – ENABLED-IMMEDIATE
The default, ENABLED IMMEDIATE causes read/write transactions
to write copies of records to the the snapshot file before
those records are modified, regardless of whether a read-only
transaction is active.
If you use the SNAPSHOT IS ENABLED clause to enable snapshots
on a multifile database, writing to all snapshot files for all
storage areas is enabled.
2.4.4 – ENABLED-DEFERRED
Specifies that read/write transactions not write copies of
records they modify to the snapshot file unless a read-only
transaction is active. Read-only transactions that attempt to
start after an active read/write transaction begins must wait for
all active read/write users to complete their transactions.
If you use the SNAPSHOT IS ENABLED clause to enable snapshots
on a multifile database, writing to all snapshot files for all
storage areas is enabled.
2.4.5 – DISABLED
Disables snapshot transactions. If you use the SNAPSHOT IS
DISABLED clause to disable snapshots on a multifile database,
writing to all snapshot files for all storage areas is disabled.
2.4.6 – DICTIONARY
The DICTIONARY IS [NOT] REQUIRED clause determines whether the
database must be invoked by path name for data definition changes
to occur. If you specify the DICTIONARY IS REQUIRED option,
the database must be invoked by path name to change metadata
and the data dictionary will be maintained. If you specify the
DICTIONARY IS NOT REQUIRED option, the database can be invoked by
either file name or path name to change metadata. The default is
DICTIONARY IS NOT REQUIRED.
The DICTIONARY IS [NOT] USED clause determines whether the
definition of the database and definitions of database elements
will be stored in the data dictionary. If you specify the
DICTIONARY IS USED option, the definition of the database and
definitions of database elements will be stored in the data
dictionary. If you specify the DICTIONARY IS NOT USED option,
no definitions will be stored in the data dictionary. The default
is DICTIONARY IS USED.
You receive an error message if you specify incompatible options,
such as the DICTIONARY IS REQUIRED option and the DICTIONARY IS
NOT USED option.
2.4.7 – CARRY_OVER_LOCKS
The carry-over locks option is a database-wide parameter
that allows you to disable carry-over lock optimization. This
optimization is enabled by default. Although this is an advantage
in more environments, it can result in false lock conflicts in
some applications.
The carry-over locks optimization holds area and record locks
across transactions and depends on NOWAIT transactions asking for
and acquiring the NOWAIT lock. This can result in long delays if
concurrent users are executing long verbs. You should consider
disabling the carry-over locks optimization if transactions
experience noticeable delays in acquiring the NOWAIT lock (as
seen in the output of the RMU/SHOW STATISTICS command). Note that
if you do disable the carry-over locks option, there may be some
performance degradation because transactions will acquire and
release area and top level ALG locks for every transaction.
2.4.8 – LOCK_TIMEOUT
Specifies the number of seconds for processes to wait during a
lock conflict before timing out. The number of seconds can be
between one and 65,000.
Sets the default database lock timeout interval. This is the
database wide timeout interval. It is used as the default as well
as the upper limit in determining the timeout interval to use.
For example, if LOCK TIMEOUT INTERVAL IS 25 SECONDS is specified
with the CHANGE DATABASE or DEFINE DATABASE statement, and a
user specifies 30 seconds with the SQL SET TRANSACTION WAIT 30
statement or sets the logical name RDM$BIND_LOCK_TIMEOUT_INTERVAL
to 30, RDO would still use the interval of 25 specified with the
LOCK TIMEOUT INTERVAL clause.
2.5 – storage-area-options
(B)0[mstorage-area-options = qwwqqqqqqqqqqqqqqqqqqqqqqqqqqq>qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqwwq> xtqq> [4mALLOCATION[m IS qqq> number-pages qqqq>qqqqqqqqq PAGES qqqqux xtqq> [4mPAGE[m [4mSIZE[m IS qqqq> page-blocks qqqqq>qqqqqqqqq BLOCKS qqqux xtqq> [4mPAGE[m [4mFORMAT[m IS qqwqqqq> [4mUNIFORM[m qqqqwqqqqqqqqqqqqqqqqqqqqux xx mqqqq> [4mMIXED[m qqqqqqj xx xtqq> [4mTHRESHOLDS[m ARE q> ( q> val1 wqqqqqqqqqqqqqqqqqqqqwq> ) qqux xx m> ,val2 wqqqqqqqqqwqj xx xx m> ,val3 qj xx xtqq> [4mINTERVAL[m IS qqqqqqq> number-data-pages qqqqqqqqqqqqqqqqqqux xtqq> [4mSNAPSHOT_FILENAME[m [4mIS[m qqqq> file-spec qqqqqqqqqqqqqqqqqqqqux xtqq> [4mSNAPSHOT[m [4mALLOCATION[m IS qqq> snp-pages qqq> PAGES qqqqqqqqux xtwq> [4mSNAPSHOT[m [4mEXTENT[m IS qwqqwq> extent-pages qqqq> PAGES qwqqqux xxmq> [4mEXTENT[m IS qqqqqqqqqqj mq> extension-options qqqqqqqqj xx xmqq> [4mWRITE_ONCE[m qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqjx mqqqqqqqqqqqqqqqqqqqqqqqqqqqq<qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqj
2.5.1 – number-pages
The number of database pages allocated to the database initially.
Oracle Rdb automatically extends the allocation to handle the
loading of data and subsequent expansion. The default is 400
pages.
2.5.2 – page-blocks
The size in blocks of each database page. Page size is allocated
in 512-byte blocks. The default is two blocks (1024 bytes). If
your largest record is larger than approximately 950 bytes,
allocate more blocks per page to prevent records from being
fragmented.
2.5.3 – PAGE_FORMAT
Specifies whether a storage area contains uniform or mixed pages.
You can use the PAGE FORMAT option with multifile databases
only. In storage areas with uniform page format, all pages in
a specific logical area contain records from the same relation.
In storage areas with mixed page format, pages can hold records
from different relations. The default is UNIFORM.
2.5.4 – THRESHOLDS
Specifies one, two, or three threshold values. The threshold
values represent a fullness percentage on a data page and
establish four possible ranges of guaranteed free space on the
data pages. When a data page reaches the percentage defined by
a given threshold value, the SPAM entry for the data page is
updated to reflect the new fullness percentage and its remaining
free space.
The default thresholds are 70, 85, and 95 percent. When
THRESHOLDS ARE is used, the first threshold value is required.
If you specify only one or two values, unspecified values default
to 100 percent. You can specify the THRESHOLDS option only on a
storage area for a multifile database. Threshold values can be
set for storage areas with MIXED or UNIFORM storage area page
formats.
2.5.5 – number-data-pages
Specifies the number of data pages between SPAM pages in the
physical storage area file, and thus the maximum of data pages
each SPAM page will manage. The default, and also the minimum
interval, is 256 data pages. The first page of each storage
area is a SPAM page. The interval you specify determines where
subsequent SPAM pages are to be inserted, provided there are
enough data pages in the storage file to require more SPAM pages.
You can specify the INTERVAL option only on a storage area for a
multifile database. The storage area page format must be MIXED.
2.5.6 – file-spec
Provides a separate file specification for the snapshot file.
Do not specify a file extension other than SNP to the file
specification. You cannot specify a global default for the
SNAPSHOT_FILENAME. Thus, in a multifile database, the SNAPSHOT_
FILENAME option must be within a DEFINE STORAGE AREA definition.
The SNAPSHOT_FILENAME option cannot be specified for a single-
file database.
2.5.7 – snp-pages
Specifies the number of pages allocated for the snapshot file.
The default is 100 pages.
2.5.8 – extent-pages
Specifies the number of pages of each extent. The default is 100
pages.
2.5.9 – extension-options
Specifies the MIN, MAX, and percent growth of each database file
extent. Enclose the parameter list in parentheses.
(B)0[mextension-options =
qqq> ( qqq> [4mMINIMUM[m OF qq> min-pages qqq> PAGES, qk
lqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqj
mqq> [4mMAXIMUM[m OF qq> max-pages qq> PAGES,qk
lqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqj
mqq> [4mPERCENT[m [4mGROWTH[m IS qqq> growth qqqq> ) qqq>
2.5.9.1 – min-pages
Specifies the minimum number of pages of each extent. The default
is 99 pages.
2.5.9.2 – max-pages
Specifies the maximum number of pages of each extent. The default
is 9,999 pages.
2.5.9.3 – growth
Specifies the percent growth of each extent. The default is 20
percent growth.
2.5.10 – WRITE_ONCE
You can use the WRITE_ONCE option to change a storage area
containing stable segmented string data to a format that can
be stored on a write-once, read-many (WORM) optical disk. A WORM
optical disk offers a relatively inexpensive way of storing large
amounts of data for read-only access compared to other storage
media.
The following restrictions apply to the WRITE_ONCE option:
o Note that you cannot write data other than segmented strings
to a write-once storage area. Oracle Rdb issues an error message
if you try to create a storage map that stores data other than
segmented strings in a write-once storage area. Storage maps
for non-segmented-string data must be removed before you can
alter a storage area to WRITE_ONCE.
o When you create a storage area on WORM media, you must specify
that the snapshot area remains on read/write media: do not
give a snapshot file the WRITE_ONCE attribute.
o If you specify the WRITE_ONCE option when storing a segmented
string, database keys are not compressed. For more information
on database key compression, see the Oracle Rdb Guide to Database
Maintenance.
o Write-once storage areas do not use SPAM pages to look for
storage space, but to assist moving data back to non-WORM
media in which SPAM pages must be built again, space is still
allocated for them. Since SPAM pages are essential in uniform
areas, Write-once storage areas cannot be of uniform format
and therefore are required to be of mixed format.
o You can use the PAGE SIZE IS clause of CREATE STORAGE AREA to
change the default page size for a storage area. You should
specify an even number of blocks per page. The smallest amount
of space used in a write operation to WORM media is 1024 bytes
(2 blocks). Therefore, by specifying an even number of blocks
per page, you minimize the space wasted when writing segmented
strings to WORM media.
o Rdb does not support magnetic media for storing write-once
storage areas.
o After you move a storage area to or from a WORM device,
Do a full and complete backup of your database with the
RMU/BACKUP command and start a new after-image journaling
file. For more information on backup and recovery procedures
with write-once storage areas, see the Oracle Rdb Guide to
Database Maintenance.
2.6 – define-storage-area-clause
(B)0[mdefine-storage-area-clause =
qqqq> [4mDEFINE[m [4mSTORAGE[m [4mAREA[m qqwqqqq> storage-area-name qqqqwqqqqqqk
mqqqq> RDB$SYSTEM qqqqqqqqqqqj x
lqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqq<qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqj
mqqqqq> [4mFILENAME[m qqqqq> file-spec qqwqqqqqqqqqqqq>qqqqqqqqqqqqqwqqqk
mq> storage-area-options qqj x
lqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqq<qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqj
mqqqqq> [4mEND[m qqqqqqqwqqqqqqqqqq>qqqqqqqqqqqwq> STORAGE AREA qqqq>
tq> storage-area-name qu
mq> RDB$SYSTEM qqqqqqqqj
2.6.1 – storage-area-name
The name of the storage area you want to create.
2.6.2 – file-spec
The storage area file that is associated with the named storage
area. If you use a simple file name, Oracle Rdb creates the storage
area file in the current default directory. Use a name that is
unique among all storage area files defined for the database.
2.6.3 – RDB$SYSTEM
The default storage area. If you directly specify RDB$SYSTEM
in the DEFINE STORAGE AREA clause, you can override the default
characteristics for the main storage area.
2.6.4 – storage-area-options
Ask for HELP on "DEFINE_DATABASE Format storage-area-options" for
information on storage area options.
2.7 – SEGMENTED_STRING
The name of the storage area that will hold all segmented
strings. For a single file database or multifile database, if you
do not explicitly define a storage area for segmented strings,
segmented strings will be stored in the default storage area,
RDB$SYSTEM. If your database is a single-file database and you
specify a storage area other than RDB$SYSTEM, you receive an
error message because RDB$SYSTEM is the only storage area in a
single-file database.
The page format for the segmented string storage area can
be UNIFORM or MIXED. However, Rdb recommends that if you
store segmented strings in a MIXED storage area, that area
contain only segmented strings.
3 – Examples
Example 1
Use the default DEFINE DATABASE statement. If you specify the
DICTIONARY IS NOT USED clause, the data dictionary will not be
used to store the database definition and definitions of database
elements.
RDO> DEFINE DATABASE 'PERSONNEL'
cont> DICTIONARY IS NOT USED.
Example 2
Use DEFINE DATABASE with qualifiers:
RDO> DEFINE DATABASE 'PERSONNEL'
cont> NUMBER OF BUFFERS IS 10
cont> BUFFER SIZE IS 10 BLOCKS
cont> DICTIONARY IS NOT USED.
This statement performs the following actions:
o Names the database.
o Specifies a number of buffers, and the length of each buffer.
o Commits the database definition implicitly.
o Specifies that the data dictionary will not be used to store
the database definition and definitions of database elements.
o Invokes the database, using the file name as the database
handle.
Example 3
The scope of each record's database key is set to FINISH during
the RDO session of the user who entered DEFINE DATABASE:
RDO> DEFINE DATABASE DISK2:[USER.DBS]PERS2
cont> DBKEY SCOPE IS FINISH.
Note that this command does NOT set a "default" DBKEY SCOPE
characteristic for the database. For each user, the default is
COMMIT unless that user specifies INVOKE DATABASE...DBKEY SCOPE
FINISH.
Example 4
The upper limit on the number of nodes from which users can
access the common, cluster-wide database is set to 8:
RDO> DEFINE DATABASE ACCTING NUMBER CLUSTER NODES IS 8
cont> DICTIONARY IS NOT USED.
If you attempt to access the shared database from a node and,
in doing so, exceed the maximum nodes parameter, an error is
signaled to your RDO session or program.
The DICTIONARY IS NOT USED clause specifies that the data
dictionary will not be used to store the database definition
and definitions of database elements.
Example 5
The following RDO command procedure defines a multifile database
called MULTI_PERS. The example:
o Defines database wide characteristics
o Defines global storage area defaults
o Specifies local attributes for RDB$SYSTEM, the default storage
area
o Defines a storage area for segmented strings
o Defines other storage areas
DEFINE DATABASE 'DB_DISK:MULTI_PERS'
! Define database-wide characteristics
DESCRIPTION IS /* Sample multifile definition */
NUMBER OF USERS IS 60
NUMBER OF CLUSTER NODES IS 22
NUMBER OF RECOVERY BUFFERS IS 200
DICTIONARY IS NOT USED
! Define global storage area characteristics
ALLOCATION IS 500 PAGES
PAGE FORMAT IS MIXED
! Specify local attributes for the default storage area
! Override the global default of MIXED page format
DEFINE STORAGE AREA RDB$SYSTEM
FILENAME 'DISK1:PERS_DEFAULT'
PAGE FORMAT IS UNIFORM
ALLOCATION IS 300 PAGES
SNAPSHOT_FILENAME IS 'DISK2:PERS_DEFAULT'
END RDB$SYSTEM STORAGE AREA
! Define storage area for segmented strings
DEFINE STORAGE AREA PERS_SEGSTR
FILENAME 'DISK1:PERS_SEGSTR'
PAGE FORMAT IS UNIFORM
END PERS_SEGSTR STORAGE AREA
SEGMENTED STRING STORAGE AREA IS PERS_SEGSTR
! Definition of some sample storage areas
DEFINE STORAGE AREA CANDIDATES
FILENAME 'DISK3:CANDIDATES'
PAGE FORMAT IS UNIFORM
SNAPSHOT_FILENAME IS 'DISK4:CANDIDATES'
END CANDIDATES STORAGE AREA
DEFINE STORAGE AREA EMPIDS_LOW
FILENAME 'DISK5:EMPIDS_LOW'
SNAPSHOT_FILENAME IS 'DISK6:EMPIDS_LOW'
END EMPIDS_LOW STORAGE AREA
DEFINE STORAGE AREA EMPIDS_MID
FILENAME 'DISK7:EMPIDS_MID'
SNAPSHOT_FILENAME IS 'DISK8:EMPIDS_MID'
END EMPIDS_MID STORAGE AREA.