Which one is more performance-consuming, mysql deletion operation or query operation
1. Analysis
MySQL delete operations consume more performance than query operations. Deletion operations are usually slower than query and insert operations because it can lead to reorganization and reconstruction of data inside the database.
When performing a delete operation, MySQL locks the rows to be deleted to ensure consistency of the data.
If the number of deleted rows is large, it may result in a long lock time, which will affect the system's concurrency performance.
2. The specific impact of deletion operation on performance
- Table-level locking:Deletion operations usually involve table-level locking, which means that other queries and operations may be affected during the deletion operation, degrading the concurrency performance of the database. In high concurrency environments, frequent deletion operations can lead to lock-up competition and performance bottlenecks.
- Waste of disk space and performance degradation:When deleting data using DELETE statements, MySQL does not immediately release the disk space occupied by the deleted records, which will cause table files to bloat and storage space to not be released. Especially in large databases, frequent DELETE operations will lead to fragmentation of disk space and degradation of performance.
- Index sparseness:After deleting data, the index will not decrease, which will lead to higher sparsity of the index and lower search efficiency. Index sparseness means that the index contains more null pointers or invalid records, thus increasing the search cost.
- Transaction log inflation:When performing DELETE operation, MySQL will write deleted data records to the transaction log for data recovery. For large databases and scenarios where DELETE operations are performed frequently, this can lead to a rapid growth in transaction logs, occupy a large amount of disk space, and may affect database performance.
3. Strategies to reduce the performance impact of deletion operations
- Make sure there is a proper index on the table:Indexing can speed up deletion operations.
- Delete in batches:Avoid performing a large number of deletion operations in production environments, and the impact on performance can be reduced by batch deletion.
- Use appropriate WHERE conditions:Limit the scope of deletion and avoid deleting too many lines.
Summarize
The above is personal experience. I hope you can give you a reference and I hope you can support me more.