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Handling large object (LOB) data during loading in SQL Loader.

When dealing with large volumes of data in a database, it is common to encounter Large Object (LOB) data types, such as BLOB (Binary Large Object) and CLOB (Character Large Object). LOB data can present challenges during loading using SQL Loader, as they require special handling due to their size.

In this blog post, we will explore how to efficiently handle LOB data during the loading process using SQL Loader.

Table of Contents

Introduction to SQL Loader

SQL Loader is a powerful tool provided by Oracle for loading data from external files into Oracle databases. It offers high performance and flexibility for handling large volumes of data.

Handling LOB Data in SQL Loader

When dealing with LOB data in SQL Loader, it is important to consider the following points:

  1. Control File Definition: The control file used by SQL Loader must specify the correct data format and field length for LOB columns. The LOB segments are not stored inline with the rest of the row, so it is essential to correctly define the LOB column’s position and format.

  2. Data File Format: The input data file being loaded should be in a compatible format. LOB data should be properly formatted in the input data file to match the LOB column’s datatype in the control file.

  3. LOBFILE and LOBFILE (CONTINUEIF) Options: SQL Loader provides the LOBFILE and LOBFILE (CONTINUEIF) options to handle LOB data. The LOBFILE option allows you to specify the file containing the LOB data, while the LOBFILE (CONTINUEIF) option is used when the LOB data spans multiple lines in the input file.

Loading BLOB Data

Loading BLOB data in SQL Loader requires the following steps:

  1. Specify the column as a BLOB datatype in the control file, with the correct length (in bytes) for the BLOB data.

  2. Create a separate file containing the BLOB data. This file should be referenced in the control file using the LOBFILE option.

  3. In the control file, use the BLOBFILE directive to specify the location of the file containing the BLOB data.

Here’s an example control file snippet for loading BLOB data:

LOAD DATA
INFILE 'input_data.dat'
INTO TABLE my_table
FIELDS TERMINATED BY ','
(
  id,
  blob_data BLOB EXTERNAL LOBFILE(blob_file) TERMINATED BY EOF
)

Loading CLOB Data

Loading CLOB data in SQL Loader follows a similar approach to loading BLOB data. The steps involved are:

  1. Define the column as a CLOB datatype in the control file, with the appropriate length (in characters) for the CLOB data.

  2. Create a separate file containing the CLOB data. This file is referenced in the control file using the LOBFILE option.

  3. Use the CLOBFILE directive in the control file to specify the location of the file containing the CLOB data.

Here’s an example control file snippet for loading CLOB data:

LOAD DATA
INFILE 'input_data.dat'
INTO TABLE my_table
FIELDS TERMINATED BY ','
(
  id,
  clob_data CLOB EXTERNAL LOBFILE(clob_file) TERMINATED BY EOF
)

Conclusion

Handling LOB data during loading in SQL Loader requires attention to detail and proper control file configuration. By understanding the specific requirements for BLOB and CLOB data types, you can ensure a smooth and efficient loading process of LOB data into your database.

SQL Loader offers various options, such as LOBFILE and LOBFILE (CONTINUEIF), to handle LOB data effectively. With the correct configuration and setup, you can successfully load large object data into your Oracle database.

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