| Oracle® XML DB Developer's Guide 11g Release 2 (11.2) Part Number E23094-02 |
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PDF · Mobi · ePub |
| Oracle® XML DB Developer's Guide 11g Release 2 (11.2) Part Number E23094-02 |
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|
PDF · Mobi · ePub |
This chapter describes how to load XML data into Oracle XML DB with a focus on SQL*Loader.
This chapter contains these topics:
Starting with Oracle9i release 1 (9.0.1), the Export-Import utility and SQL*Loader support XMLType as a column type. Starting with Oracle Database 10g, SQL*Loader also supports loading XMLType tables. You can load XMLType data with SQL*Loader using either the conventional method or the direct-path method, regardless of how it is stored (structured, unstructured, or binary XML storage).
Note:
For structured storage of XML data, if the data involves inheritance (extension or restriction) of XML Schema types, then SQL*Loader does not support direct-path loading.That is, if an XML schema contains a complexType element that extends or restricts another complexType element (the base type), then this results in some SQL types being defined in terms of other SQL types. In this case, direct-path loading is not supported for object-relational storage.
Oracle XML DB Repository information is not exported when user data is exported. Neither the resources nor any information are exported.
XML columns are columns declared to be of type XMLType.
SQL*Loader treats XMLType columns and tables like object-relational columns and tables. All methods described in the following sections for loading LOB data from the primary datafile or from a LOBFILE value apply also to loading XMLType columns and tables when the XMLType data is stored as a LOB.
See Also:
Oracle Database UtilitiesNote:
You cannot specify a SQL string for LOB fields. This is true even if you specify
LOBFILE_spec.XMLType data can be present in a control file or in a LOB file. In the former case, the LOB file name is present in the control file.
Because XMLType data can be quite large, SQL*Loader can load LOB data from either a primary datafile (in line with the rest of the data) or from LOB files, independent of how the data is stored (the underlying storage can, for example, still be object-relational).
To load internal LOBs, Binary Large Objects (BLOBs), Character Large Objects (CLOBs), and National Character Large Object (NCLOBs), or XMLType columns and tables from a primary datafile, use the following standard SQL*Loader formats:
Predetermined size fields
Delimited fields
Length-value pair fields
These formats are described in the following sections and in more detail in Oracle Database Utilities.
This is a very fast and conceptually simple format to load LOBs.
Note:
Because the LOBs you are loading might not be of equal size, you can use whitespace to pad the LOB data to make the LOBs all of equal length within a particular data field.This format handles LOBs of different sizes within the same column (datafile field) without problem. However, this added flexibility can affect performance, because SQL*Loader must scan through the data, looking for the delimiter string.
As with single-character delimiters, when you specify string delimiters, you should consider the character set of the datafile. When the character set of the datafile is different than that of the control file, you can specify the delimiters in hexadecimal (that is, hexadecimal string). If the delimiters are specified in hexadecimal notation, then the specification must consist of characters that are valid in the character set of the input datafile. In contrast, if hexadecimal specification is not used, then the delimiter specification is considered to be in the client (that is, the control file) character set. In this case, the delimiter is converted into the datafile character set before SQL*Loader searches for the delimiter in the datafile.
LOB data can be lengthy enough so that it makes sense to load it from a LOBFILE instead of from a primary datafile. In LOBFILEs, LOB data instances are still considered to be in fields (predetermined size, delimited, length-value), but these fields are not organized into records (the concept of a record does not exist within LOBFILEs). Therefore, the processing overhead of dealing with records is avoided. This type of organization of data is ideal for LOB loading.
There is no requirement that a LOB from a LOBFILE fit in memory. SQL*Loader reads LOBFILEs in 64 KB chunks.
In LOBFILEs the data can be in any of the following types of fields, any of which can be used to load XML columns:
A single LOB field into which the entire contents of a file can be read
Predetermined size fields (fixed-length fields)
Delimited fields (that is, TERMINATED BY or ENCLOSED BY)
The clause PRESERVE BLANKS is not applicable to fields read from a LOBFILE.
Length-value pair fields (variable-length fields) .
To load data from this type of field, use the VARRAY, VARCHAR, or VARCHAR2 SQL*Loader data types.
You can specify LOBFILEs either statically (you specify the name of the file) or dynamically (you use a FILLER field as the source of the filename). In either case, when the EOF of a LOBFILE is reached, the file is closed and additional attempts to read data from that file produce results equivalent to reading data from an empty field.
You should not specify the same LOBFILE as the source of two different fields. If you do so, then typically, the two fields read the data independently.
XMLType data can be loaded directly from a control file. SQL*Loader treats XMLType data like any scalar type. For example, consider a table containing a NUMBER column followed by an XMLType column that is stored object-relationally. The control file used for this table can contain the value of the NUMBER column followed by the value of the XMLType instance.
SQL*Loader accommodates XMLType instances that are very large. You also have the option to load such data from a LOB file.
You can use SQL*Loader to load large amounts of XML data into Oracle Database. Follow these steps:
List in a data file, say filelist.dat, the locations of the XML documents to be loaded.
Create a control file, say load_data.ctl, with commands that process the files listed in the data file.
Invoke the SQL*Loader shell command, sqlldr, passing it the name of the control file.
This is illustrated in Example 35-2, Example 35-1, and Example 35-3. File filelist.dat lists XML files that contain purchase orders for the year 2002.
Example 35-1 Data File filelist.dat: List of XML Files to Load
2002/Jan/AMCEWEN-20021009123335370PDT.xm 2002/Jan/AWALSH-2002100912333570PDT.xml 2002/Jan/CJOHNSON-20021009123335170PDT.xml 2002/Jan/LSMITH-20021009123335500PDT.xml 2002/Jan/PTUCKER-20021009123335430PDT.xml 2002/Jan/SBELL-20021009123335280PDT.xml 2002/Jan/SKING-20021009123335560PDT.xml 2002/Jan/SMCCAIN-20021009123335470PDT.xml 2002/Jan/TFOX-20021009123335520PDT.xml 2002/Jan/VJONES-20021009123335350PDT.xml 2002/Jan/WSMITH-20021009123335450PDT.xml 2002/Feb/AMCEWEN-20021009123335600PDT.xml 2002/Feb/AMCEWEN-20021009123335701PDT.xml 2002/Feb/DAUSTIN-20021009123335811PDT.xml 2002/Feb/EABEL-20021009123335791PDT.xml 2002/Feb/PTUCKER-20021009123335721PDT.xml 2002/Feb/PTUCKER-20021009123335821PDT.xml 2002/Feb/SBELL-20021009123335771PDT.xml 2002/Feb/SMCCAIN-20021009123335681PDT.xml 2002/Feb/WSMITH-20021009123335650PDT.xml 2002/Feb/WSMITH-20021009123335741PDT.xml 2002/Feb/WSMITH-20021009123335751PDT.xml ...
Example 35-2 Control File load_datra.ctl, for Loading Purchase-Order XML Documents
load data infile 'filelist.dat' append into table PURCHASEORDER xmltype(XMLDATA) ( filename filler char(120), XMLDATA lobfile(filename) terminated by eof )
Example 35-3 Loading XML Data Using Shell Command sqlldr
sqlldr load_data.ctl
For direct-path loading, use this instead:
sqlldr load_data.ctl direct=y
See Also:
Chapter 3, "Using Oracle XML DB", "Loading Large XML Files using SQL*Loader"
Oracle Database Utilities for information about shell command sqlldr
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