SQL*Loader
SQL*Loader loads data from external files, called data files (not to be confused with the internal database data files), into database tables. It has a powerful data parsing engine that puts little limitation on the format of the data in the data file.
You can use SQL*Loader to do the following:
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Load data from multiple data files into multiple tables
You store the data to be loaded in SQL*Loader data files. The SQL*Loader control file is a text file that contains DDL instructions that SQL*Loader uses to determine where to find the data, how to parse and interpret it, where to insert it, and more.
Note:
The SQL*Loader data files and control file are unrelated to the Oracle Database data files and control file.
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Control various aspects of the load operation
For example, you can selectively load data, specify the data character set, manipulate the data with SQL functions, generate unique sequential key values in specified columns, and so on. You can also generate sophisticated error reports.
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Use conventional path, direct path, or external table loads
A conventional path load executes SQL
INSERTstatements to populate tables. In contrast, a direct path INSERT eliminates much of the database overhead by formatting data blocks and writing them directly to the data files. Direct writes operate on blocks above the high water mark (HWM) and write directly to disk, bypassing the database buffer cache. Direct reads read directly from disk into the PGA, again bypassing the buffer cache.An external table load creates an external table for data that is contained in a data file. The load executes
INSERTstatements to insert the data from the data file into the target table.扫描二维码关注公众号，回复： 11157569 查看本文章
A typical SQL*Loader session takes as input a SQL*Loader control file and one or more data files. The output is an Oracle database, a log file, a bad file, and potentially, a discard file. The following figure illustrates the flow of a typical SQL*Loader session.
You can also use SQL*Loader express mode, which is activated when you specify the table parameter in the SQL*Loader command, as in the following example:
% sqlldr hr table=employees
No control file is permitted, which makes SQL*Loader easier to use. Instead of parsing a control file, SQL*Loader uses the table column definitions to determine the input data types. SQL*Loader makes several default assumptions, including the character set, field delimiters, and the names of data, log, and bad files. You can override many of the defaults with command-line parameters.