Structured Query Language (SQL) is a programming language used to manage data stored in relational database management systems (RDBMS). SQL Loader, which is a tool provided by Oracle Database, is used to load data from external files into Oracle Database tables. Oracle Corporation designed SQL Loader to optimize data loading into Oracle Database and to minimize the impact of loading data on database performance.
How SQL Loader Works
SQL Loader reads data from a source file and then loads it into a target table in an Oracle Database. A control file specifies the format of both the source file and the target table. SQL Loader reads the control file to determine how to map the source data to the target table. The control file also defines field specifications, data types, and data formats for the source data and target table. SQL Loader then applies these specifications to each field in the source file and inserts the corresponding values into the target table.
SQL Loader Modes
SQL Loader has two operating modes: conventional path mode and direct path mode. The conventional path mode reads the source file, converts data to the target table's format, and inserts the data into the table. Conventional path mode can execute different load operations simultaneously with other database operations but can be slower than direct path mode. Direct path mode is a faster way to load data because it doesn't log every row inserted into the database. Direct path mode writes directly into data files bypassing the buffer cache. However, it is only available for some types of database tables.
The Benefits of Using SQL Loader
SQL Loader provides several benefits, including:
- Efficient Loading: SQL Loader can load data from external files into Oracle Database more quickly and efficiently than other methods such as insert statements or database triggers.
- Improved Performance: SQL Loader optimizes data loading by using parallel processing, sorting data in the correct order, and manipulating field values according to the specified format. The result is faster and more efficient loading of data into the database.
- Reduced Impact on Database Performance: SQL Loader is designed to minimize the impact of loading data on the database during the loading process. For example, it can allocate a dedicated temporary space in memory for loading data, thus avoiding tablespace fragmentation.
Conclusion
SQL Loader is a powerful Oracle Database tool that can dramatically reduce the time and effort required to load data into Oracle Database. It is an essential tool for database administrators and developers who need to efficiently load external data into their databases. By using SQL Loader, organizations can improve database performance, reduce data loading time, and minimize the impact on database operations.
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