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Appendix
C. System Limitations
 C.1
Naming Limitations
C.2
Storage Limitations
C.3
Processing Limitations
C. System Limitations
C.1 Naming Limitations
The ANSI/ISO
standard for the SQL language specifies that database objects should
be identified by giving them unique names, and defines the database
objects that require names. These names are used in SQL statements to
identify which objects the statements act on. The database objects that
require names are:
tables
columns
users
In the
ANSI/ISO standard, SQL database object names have a maximum length of
18 characters, and may contain letters and numbers. They may not contain
spaces or punctuation characters. DBMaker conforms to the ANSI/ISO standard
with the exception of user names and passwords, which may only contain
1 to 8 characters.
However,
DBMaker also supports names for several additional database objects
and extends the range of characters that can be used in names. Additional
database objects that can be given names are:
indexes
cursors
tablespaces
primary/foreign keys
In DBMaker,
database names may contain 1 to 18 alpha-numeric characters, Chinese
double-byte characters, or the underscore character, in any position
including the first.
All other
names, with the exception of user names, may include 1 to 18 alpha-numeric
characters, Chinese double-byte characters, spaces, underscores, and
the symbols $ and #, in any position including the first. If spaces
are used, the name must be enclosed in double quotes (" "),
and any trailing spaces are ignored. User names also follow these rules,
but are limited to a maximum length of 8 characters.
The size
limitations on all of the named database objects supported by DBMaker
are shown in the table below.
|
Item
|
Minimum
|
Maximum
|
|
Database
Name
|
1
|
18
|
|
Tablespace
Name
|
1
|
18
|
|
Table
Name
|
1
|
18
|
|
Column
Name
|
1
|
18
|
|
Index
Name
|
1
|
18
|
|
Cursor
Name
|
1
|
18
|
|
User
Name
|
1
|
8
|
|
User
Password
|
1
(1)
|
8
|
|
Physical
File Name with file path
|
1
|
80
(2)
|
|
Logical
File Name
|
1
|
18
|
|
SQL
Statement
|
-
|
32767
|
Table
C-1: Minimum/maximum lengths of database object names (in characters).
C.2 Storage Limitations
The following
table shows the storage limitations placed on database objects by DBMaker.
While the maximum value is shown as a specific number for most of these
limitations, you should keep in mind that physical system limitations
(such as system memory or disk space) and operating system limitations
(such as system resources or other limitations) may impose a restriction
before the specified value is reached. Unless otherwise noted, all limitations
are the same for all platforms supported by DBMaker.
|
Item
|
Minimum
|
Maximum
|
|
size
of a database
|
-
|
70,000
GB
|
|
number
of files in a database
|
1
|
32767
|
|
number
of tablespaces in a database
|
1
|
32767
|
|
number
of files in a tablespace
|
1
|
32767
|
|
number
of tables in a tablespace
|
0
|
no
limit (3)
|
|
number
of pages in a data file
|
2
|
524287
|
|
number
of columns in a table
|
1
|
252
|
|
size
of a tuple (row) in a table
|
0
|
3996
(4)
|
|
number
of indices on a table
|
0
|
no
limit3
|
|
number
of columns in an index
|
1
|
16
|
|
length
of the key in an index
|
0
|
10241
|
|
column
ID which can be used in an index
|
1
|
127
(5)
|
|
number
of journal files
|
1
|
8
|
|
number
of pages in the journal file
|
23
|
524287
|
|
number
of projection columns
|
1
|
252
|
|
number
of GROUP BY columns
|
1
|
128
|
|
number
of ORDER BY columns
|
1
|
128
|
|
number
of ODBC binding parameters
|
0
|
255
|
|
number
of SQL sources
|
1
|
31
(6)
|
|
number
of bytes in a BLOB file
|
0
|
231-1
|
|
number
of pages in a data buffer
|
15
|
depends
on OS
|
|
number
of pages in a journal buffer
|
16
|
depends
on OS
|
|
number
of operators in predicate for a scan
|
1
|
100
|
Table
C-2: Minimum and maximum size of database objects (in bytes)
C.3 Processing Limitations
The following
table shows the processing limitations placed on a database by DBMaker.
|
Item
|
Minimum
|
Maximum
|
|
number
of concurrent transactions (connections) in a running database
|
0
|
240
|
|
length
of CHAR or BINARY data items
|
0
|
3992
bytes
|
|
length
of VARCHAR data items
|
0
|
3992
bytes
|
|
length
of LONG VARCHAR or LONG VARBINARY data items
|
0
|
231
- 1 bytes
|
|
number
of items in the projection list of a selected command
|
1
|
252
|
Table
C-3: Processing Limitations of DBMaker.
Footnotes
1. If a user does not set the password, then the length of the
password is NULL.
2. Including null terminator.
3. The number of tables and indexes
is currently restricted only by operating system limitations.
4. Including header. See Section 6.9
for more information.
5. Must be one of the first 127 columns.
6. A source is defined as a database
object which physically contains the data. If an SQL statement lists
an object (such as a view) that is a combination of data from other
objects that actually contain the data, it should be counted as the
number of objects combined to create it when calculating the number
of sources.
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