SQL Loader

Hi guys, in this blog I am going to explain you about SQL Loader.

 

SQL Loader-

Oracle has a powerful application called SQL Loader, which is often referred to as SQL*Loader, that makes it easy to load data from external files into Oracle database tables. When dealing with enormous volumes of data that must be loaded precisely and fast, this is especially helpful.

 

Export In 0racle-

Here's a brief explanation of SQL Loader in Oracle 19c:

 

Overview-

Using a command-line program called SQL Loader, you can load data into Oracle tables from external files, such flat files. The format of the data file and the mapping between the data file and the database table are specified using a control file.

 

Key Components:

 

Control File:

This file specifies the data format, source file details, and how the data should be loaded into the database. It contains information such as table name, field names, data types, and data file location.

Data File:

The external file containing the actual data that needs to be loaded into the Oracle table.

 

Bad File:

A file that contains records that were rejected during the load process due to errors.

 

Discard File:

A file that contains records that were intentionally discarded during the load process.

 

Syntax:

The basic syntax for using SQL Loader is as follows:

sqlldr username/password@database control=your_control_file.ctl

 

Example Control File:

An example of a control file might look like this:

LOAD DATA

INFILE 'data_file.csv'

INTO TABLE employees

FIELDS TERMINATED BY ',' OPTIONALLY ENCLOSED BY '"'

(employee_id, first_name, last_name, hire_date DATE 'YYYY-MM-DD')

 

This example specifies that data in the 'data_file.csv' file is to be loaded into the 'employees' table. The data is comma-separated, and certain fields are enclosed by double quotes. The 'hire_date' field is explicitly defined with a date format.

 

Explanation:

LOAD DATA:

This is the keyword that signals the beginning of the SQLLoader control file. It indicates that you are instructing SQLLoader to load data.

 

INFILE 'data_file.csv':

Specifies the name of the input data file, in this case, 'data_file.csv'. This is the external file from which SQL*Loader will read the data.

 

INTO TABLE employees:

Specifies the target database table where the data will be loaded. In this example, the data will be loaded into the 'employees' table.

 

FIELDS TERMINATED BY ',':

Indicates that the fields in the data file are separated by commas. This is essential information for SQL*Loader to correctly parse the data.

 

OPTIONALLY ENCLOSED BY '"':

Specifies that fields may be optionally enclosed by double quotes ("). This is common in CSV (Comma-Separated Values) files, where data fields can be enclosed to handle cases where the field itself contains the delimiter.

 

(employee_id, first_name, last_name, hire_date DATE 'YYYY-MM-DD'):

Describes the mapping between the fields in the data file and the columns in the 'employees' table. Each field in the data file corresponds to a column in the table. The columns are listed within parentheses.

 

employee_id:

This is assumed to be a numeric column in the 'employees' table.

 

first_name:

This is assumed to be a text column.

 

last_name:

Another text column.

 

hire_date DATE 'YYYY-MM-DD':

This specifies that the 'hire_date' field in the data file should be interpreted as a date in the 'YYYY-MM-DD' format.

 

 

Modes of Operation:

SQL Loader supports various modes of operation, including direct path and conventional path. Direct path loading is generally faster, as it bypasses much of the Oracle database processing and writes data directly to the data files.

 

Enhancements in Oracle 19c:

Oracle Database 19c may introduce new features or enhancements to existing features. Be sure to consult the official Oracle documentation for the latest information on SQL Loader features and improvements specific to Oracle 19c.

 

Best Practices:

Optimize the control file for better performance.

Use direct path loading for large datasets.

Monitor and review the log files for any errors or warnings.