Q130545: Description of New Integer Data Type
Article: Q130545
Product(s): Microsoft FoxPro
Version(s): WINDOWS:3.0
Operating System(s):
Keyword(s):
Last Modified: 11-FEB-2000
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The information in this article applies to:
- Microsoft Visual FoxPro for Windows, version 3.0
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SUMMARY
=======
Visual FoxPro version 3.0 has a new data type called Integer. This is a
four-byte binary type that is stored as such in memory and on disk. Its range
is:
-2,147,483,647 to 2,147,483,646 (-2**32 to 2**32 - 1).
If used, Integers can increase performance and reduce disk space for tables
compared to the other numeric data types.
You will find the new data type in the Table Designer as an "Integer" type. It
will also show up in CREATE/ALTER TABLE, DISPLAY STRUCTURE, AFIELDS(), and COPY
STRUCTURE EXTENDED.
MORE INFORMATION
================
Integers should be familiar to developers using third-generation languages like
C/C++ and Pascal. The integer in Visual FoxPro version 3.0 is the same as a
signed long in C/C++.
Field Type Description Size Range
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Integer Integer values 4 bytes -2147483647 to
2147483646
Numeric Integers or 8 bytes in -.9999999999E+19 to
fractions memory; .9999999999E+20
1 to 20 bytes
in table
Use integers for non-decimal numbers that are not exceeding the range. Serial
numbers, counters, customer ID numbers are examples. There are two major
advantages to using integers instead of numerics, size and performance.
Size
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Integers take up less disk space because they are saved on disk in their binary
representation. They use only four bytes per number as compared to 10 for
numerics. This can be significant savings for large tables. The following is an
example, having one CUST_ID field:
Numeric (10.0) Integer
# of Records (bytes) (bytes) Gain
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1,000 10,000 4,000 6 K
100,000 1,000,000 400,000 586 K
1,000,000 10,000,000 4,000,000 6 MB
Performance
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Using an integer has several performance advantages over a numeric. First of all,
it loads faster from disk. Only four bytes are read from disk compared to 10 for
each Numeric.
Integers are stored on disk in a binary format. They can be read directly into
memory. When numerics are read from disk, a conversion takes place because they
are stored as ASCII text strings.
Also, the SQL SELECT optimizer has improved performance during joins and queries
that use the ORDER BY or GROUP BY clauses. By using integers, Visual FoxPro can
generate smaller and more efficient intermediate temporary tables for these
queries.
Additional query words: VFoxWin kbfest
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Keywords :
Technology : kbVFPsearch kbAudDeveloper kbVFP300
Version : WINDOWS:3.0
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