Shulou(Shulou.com)05/31 Report--

This article introduces the relevant knowledge of "what is the background process of Oracle". In the operation of actual cases, many people will encounter such a dilemma, so let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!

1 SMON: general tasks: regularly merge free space in the tablespace managed by the dictionary; apply entries in the online redo log file to the data file in the event of a system crash or instance failure, perform crash recovery, and clear temporary segments in all tablespaces during restart.

2 PMON: clear user connections or processes that have been deleted or otherwise failed. Roll back to what you were working on when the power was turned off. Mark the fifteen blocks available in the buffer buffer. Removes locks on affected rows in the table. Removes the process ID of an unconnected process from the list of active processes. Interact with the listener to provide information about the status of the instance to the incoming connection request.

3 DBWn: write new or changed data blocks (dirty blocks) in the buffer to the data file. LRU algorithm gives priority to writing the earliest and smallest dirty blocks. The blocks with more requests are placed in memory. Up to 20 processes, controlled by the DB_WRITER_PROCESS parameter. The process name is DBW0-DBW9,DBWa-DBWj.

4 LGWR: manage the redo log buffer, write the redo information to the redo log file, this thing can be considered completed, and the dirty blocks in the buffer can be written to the data file through DBWn. If the redo log file is corrupted, LGWR writes the log to the uncorrupted file and logs errors in the alter file. If all members are unavailable, the process fails and suspends the instance until the problem is corrected.

5 ARCn: when the database is in ARCHIVELOG mode (using archive log list to view database logs), the full redo logs are copied to one or more destination directories (called archive redo log directories). Ideally, the archiving process completes the copy operation the next time the redo log file is filled with money, otherwise it will affect performance and prevent the redo log file from receiving new redo records. You can increase the number of redo log groups and the number of ARCn processes by setting larger redo log files. Up to 30 ARCn processes (LOG_ARCHIVE_MAX_PROCESSES).

6 CKPT:CKPT updates the title of the control file and data file, writing to the recently successful SCN. The redo log file switch automatically generates a checkpoint.

7 RECO: handles distributed transactions (including transactions that make changes to tables in multiple databases)

This is the end of the content of "what is the background process of Oracle". Thank you for reading. If you want to know more about the industry, you can follow the website, the editor will output more high-quality practical articles for you!

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.