Oracle Database - Database Writer Process (DBWn)

The database writer process (DBWn) is a background process that writes buffers in the database buffer cache to data files.

Modified data and new data are not necessarily written to the data file immediately. In order to reduce disk access and improve performance, the data is stored in memory and written to the appropriate data file (in batch mode) at once, as determined by the background process's database writer process (DBWn).

After COMMIT, the database writes the redo buffer to the disk but does not immediately write the data block to the disk. Instead, the database writer (DBWn) performs deferred writes in the background.

The database writer (DBWn) process periodically writes cold, dirty buffers to disk. DBWn writes to the buffer under the following conditions.

When the buffer becomes dirty, the number of empty buffers decreases. If the number is below the internal threshold and a clean buffer is required, the server process sends a signal for writing to DBWn.

The database uses LRU to determine which dirty buffer to write to. When the dirty buffer reaches the cold end of the LRU, the database moves them from the LRU to the write queue. DBWn writes the buffer in the queue to disk. If possible, use multiple write blocks. This mechanism prevents the end of the LRU from being blocked by the dirty buffer and allows to find the clean buffer for reuse.

Database installation and configuration: The database administrator is responsible for installing the database software. He sets up the database software and upgrades as necessary. Because there are many database software such as Oracle, Microsoft SQL, MySQL, etc. in the industry, the DBA decides how to install and set up these database software. If a company owns a large database, the database may fail in any situation. The DBA needs to periodically back up the entire database. The DBA needs to determine the amount of data to be backed up and its frequency. When the DBA loses the database, the database is also recovered by the DBA.

The database administrator or DBA is important to the company. DBA's job is to design, maintain and support the database. In order to design the database infrastructure, the DBA needs to be familiar with the database platform such as Oracle. Therefore, getting good Oracle certification is very important for DBA. You can also use SQL authentication. In addition, the database administrator needs to understand exactly how the database platform is affected by the hardware specification. Database administrators need to evaluate process loads and other variables in order to design databases and create database solutions. As part of its maintenance work, the DBA needs to keep the database online and to be accessible to future end users. You also need to maintain database security and performance. The DBA monitors the size, accessibility, and speed of the database and ensures that the database has adequate backups and is safe.

Oracle Exadata Database raises the performance of the database to a whole new level, do you want to know the factors of speedup? Several components of the Oracle Exadata Database Machine (such as Oracle Database 11g Release 2), Oracle Exadata's Smart Flash Cache, Hybrid Columnar Compression, SmartScan features, InfiniBand interconnection are useful for achieving high performance. One of the key technologies to support this performance is storage indices that are not ordinary database indexes. In this article we save the storage index to the memory of the storage server (also called the storage unit) and exclude extraneous database blocks in the storage unit, greatly reducing unnecessary I / O. Please make sure they are used effectively