Informix database storage technical principle

Informix database is a powerful and reliable relational database management system (RDBMS) that uses a series of storage technology to effectively store and manage data.These storage technologies include original data files, logical logs, physical logs and log mirrors. 1. Original data file: Informix uses raw data files to store data from tables, indexes and other database objects.These files are stored in a binary form, and they are stored in different positions in the file system according to different database partitions.Each data file is divided into multiple blocks, usually in 4KB.When the data is written or read, Informix is operated in the block, which improves the throughput and access speed of the database. 2. Logic log: Informix uses a logical log to record the detailed information of the database operation, such as inserting, updating and deleting records.Each database has a logical log. It is a circular file that adds the latest log records to the end of the file.When the database executes the writing operation, the relevant logical log records will be written.The purpose of a logical log is to restore the status of the database so that it can be rolled or replaced during the system failure. 3. Physical log: Informix uses physical logs to record the low -level details of the database operation, such as changes in disk blocks.Physical log files are recorded in transactions, and each transaction writes relevant logs into physical log files before submitting.The purpose of a physical log is to ensure the consistency of the database so that the database can be restored to the nearest consistent state under the fault. 4. Log mirror: Informix provides log mirror function. By writing logical logs and physical logs into two different devices at the same time, it improves the reliability and redundancy of the database.If a device fails, the database can continue to run and read a log from another device for recovery.Log mirrors ensure that the integrity of the database can be protected even in the case of hardware failure. The above is the general principle of Informix database storage technology.In order to better understand, the following example provides programming code and configuration related to Informix: 1. Database table creation example: CREATE TABLE students ( id INT PRIMARY KEY, name VARCHAR(50), age INT ); 2. Data insertion example: INSERT INTO students (id, name, age) VALUES (1, 'Alice', 22); 3. Data query example: SELECT * FROM students WHERE age > 20; 4. Data update example: UPDATE students SET age = 23 WHERE id = 1; 5. Data deletion example: DELETE FROM students WHERE id = 1; 6. Database configuration example (informix.conf file): # Database server name DBSERVERNAME informix # Physical log file location PHYSFILE /opt/informix/logs/physlog1 # Logical log file location LOGFILE /opt/informix/logs/logicallog # Log mirror location MIRRORPATH /opt/informix/logs/mirrorlog # Buffer pool size BUFFERPOOL 80000 # Checkpoint interval CKPTINTVL 300 Through these examples and configurations, people can better understand the storage technical principles of the Informix database, and make relevant programming and settings when developing and configured databases.