database
OLAP data warehouse to the main type of operation, which is different from OLTP type of operation.
OLTP reflect the real-time transaction processing, OLAP can be seen as OLTP historical data "warehouse"
OLAP operation mainly reflected in:
1) select query summary based on transactional require less
2) rapid replication of data, the demand for mobile
3) demand for distributed queries.
Mobile data
concept
1) to move data from a data warehouse, it is logical object level data replication, data movement, there are two engines:
①ORACLE_LOADER (Sqlload engine)
②ORACLE_DATAPUMP (data pump engine)
The difference between the two engines is: ORACLE_DATAPUMP only read files exported by it, and ORACLE_LOADER can read any third-party file formats it can parse.
## main engines for general ORACLE_LOADER txt file, ORACLE_DATAPUMP mainly for dmp file
2) data movement comprises two main aspects
Methods ⑴ create an external table of the two engines can generate external table data. However, uses and methods are different.
①Sqlload engine generates external table is a text format, cross-platform data between different databases movement.
②Data pump external table generated by the engine is in binary format. Fast moving data between the database for Oracle platforms.
Data ⑵ pump technology (expdp / impdp)
As an alternative to the traditional logic of import and export backup, replication and rapid recovery of data in the logical level
Directory (directory)
① create an external table must use the Directory to specify a destination outside table directory is a database object, the equivalent of the physical directory mapped into a logical directory name
② benefits introduced directory is described in simplified format the various OS directory path of the physical
You must use the specified directory ③ When creating an external table by Sqlload and Data pump two ways