Oracle外部表ORACLE_DATAPUMP部类的创建语法详解
日期：2014-05-16 浏览次数：20579 次
This chapter describes the ORACLE_DATAPUMP
access driver. The following topics are discussed:
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access_parameters Clause
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Unloading and Loading Data with the ORACLE_DATAPUMP Access Driver
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Supported Datatypes
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Unsupported Datatypes
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Reserved Words for the ORACLE_DATAPUMP Access Driver
To use the information in this chapter, you must know enough about SQL to be able to create an external table and perform queries against it.
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Notes:
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access_parameters Clause
When you create the external table, you can specify certain parameters in an access_parameters
clause. This clause is optional, as are its individual parameters. For example, you could specify LOGFILE
, but not VERSION
, or vice versa. The syntax for the access_parameters
clause is as follows:
Description of the illustration et_oracle_datapump.gif
comments
Comments are lines that begin with two hyphens followed by text. Comments must be placed before any access parameters, for example:
--This is a comment. --This is another comment. NOLOG
All text to the right of the double hyphen is ignored, until the end of the line.
LOGFILE | NOLOGFILE
LOGFILE
specifies the name of the log file that contains any messages generated while the dump file was being accessed. NOLOGFILE
prevents the creation of a log file. If a directory object is not
specified as part of the log file name, then the directory object
specified by the DEFAULT
DIRECTORY
attribute is used. If a directory object is not specified and no default directory was specified, an error is returned.
If LOGFILE
is not specified, a log file is created in
the default directory and the name of the log file is generated from the
table name and the process ID with an extension of .log
.
If a log file already exists by the same name, the access driver reopens
that log file and appends the new log information to the end. See Filenames for LOGFILE
for information about using wildcards to create unique filenames during parallel loads or unloads.
See Example of LOGFILE Usage for ORACLE_DATAPUMP .
Filenames for LOGFILE
The access driver does some symbol substitution to help make filenames unique in the case of parallel loads. The symbol substitutions supported are as follows:
-
%pis replaced by the process ID of the current process. For example, if the process ID of the access driver is 12345, thenexttab_%p.logb
