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Technical Articles

Database

Mysql Tutorial

Understanding Different Storage Engines in MySQL Like InnoDB and MyISAM

InnoDBisgenerallypreferredoverMyISAMduetokeydifferences.1.InnoDBsupportstransactions(COMMIT/ROLLBACK)andACIDcompliance,crucialfordataintegrityinsystemslikebanking;MyISAMlackstransactionsupport.2.InnoDBusesrow-levellocking,allowingbetterconcurrencyand

Jul 04, 2025 am 01:36 AM

mysql storage engine

Techniques for Constructing Advanced MySQL Queries

1. The rational use of subqueries and temporary tables can improve the readability and efficiency of query, such as calculating the average score through subqueries and filtering the results; 2. Flexible use of JOIN types such as LEFTJOIN to ensure that all records in the left table are retained; 3. Window functions such as RANK() are used to achieve salary ranking within the department; 4. Clearly specify the return field and use LIMIT to control the number of rows to save resources. To construct advanced MySQL queries, you need to understand the data structure and optimization logic, and combine subqueries, JOIN selection, window functions and field control to ensure accuracy and performance.

Jul 04, 2025 am 01:18 AM

database mysql query

Managing MySQL users and permissions securely

MySQL users and permission management must follow the principle of minimum permissions, restrict access sources, regularly clean users and use strong password policies. 1. Assign permissions as needed, only grant users the minimum permissions required to complete tasks, avoid using GRANTALL; 2. Restrict access sources, set the local account to 'user'@'localhost', remote account specifies specific IP or intranet segments, and prohibits unnecessary external access; 3. Regularly check and clean up accounts that are no longer used, and use DROPUSER to delete discarded accounts; 4. Enable strong password policy, configure validate_password.policy=STRONG, and regularly change key account passwords to improve security.

Jul 04, 2025 am 01:10 AM

authority management MySQL Users

Key Metrics for Monitoring MySQL Performance

Key metrics for monitoring MySQL performance include system resources, query efficiency, connection status, and replication status. 1. The high CPU and memory usage may be due to complex queries or missing indexes. It is recommended to use top, htop, free-m and Prometheus Grafana to monitor and optimize slow queries; 2. The number of slow queries and execution time reflect SQL efficiency problems. You need to enable slow query logs and analyze them with tools, regularly view the execution plan and optimize them; 3. Too many connections may lead to resource competition, so you should set reasonable max_connections, enable threadcache, use connection pools, and pay attention to the Aborted_connects indicator; 4. Master-slave replication delay can be passed through Seco

Jul 04, 2025 am 01:05 AM

mysql performance Monitoring indicators

Setting up read replicas for scaling MySQL read operations

ReadreplicasscaleMySQLreadsbyoffloadingqueriestosecondaryservers.Tosetupabasicreadreplica,enablebinaryloggingontheprimaryserver,createareplicationuser,takeasnapshotwithmysqldump,restoreitonthereplica,andstartreplicationwhileensuringuniqueserver-idsan

Jul 04, 2025 am 12:52 AM

mysql

Indexing Strategies for Improving Query Performance in MySQL

To improve MySQL query performance, the key is to use indexes reasonably. First, select the appropriate column to establish an index, and give priority to the commonly used columns in WHERE, JOIN, ORDERBY and GROUPBY to avoid blindly gathering columns with small value ranges; second, use composite indexes instead of multiple single-column indexes, and note that the query needs to use prefix columns to hit the index; third, avoid full table scanning and unnecessary sorting, ensure that the sorted fields have a suitable index, and avoid SELECT* and LIKE'%xxx'; finally, regularly analyze and maintain the index, check the index usage and optimize through EXPLAIN, information_schema.STATISTICS, performance mode and other tools.

Jul 04, 2025 am 12:51 AM

mysql Query optimization

Troubleshooting 'Access denied for user' error 1045 in MySQL

"Accessdeniedforuser" (Error1045) errors are usually caused by problems with login credentials, user permissions, or authentication methods. 1. First, confirm that the user name and password are correct, check whether there are spelling errors, case mismatches or extra spaces, and verify that the values ??in the script or configuration file are accurate. 2. Then check the user permissions and host access settings, use SELECTUser, HostFROMmysql.user to confirm the host that the user allows to connect, and create or update the user permissions through the CREATEUSER and GRANT commands if necessary to match the connection source. 3. Finally, verify whether the MySQL authentication plug-in is compatible. If the client does not support it

Jul 04, 2025 am 12:37 AM

Creating a New Database and User Account in MySQL

To create a new database and user in MySQL and assign permissions, you need to follow the following steps: 1. After logging in to MySQL, use CREATEDATABASE to create a database, which can specify the character set and sorting rules; 2. Use CREATEUSER to create a user and set a password to specify the host that is allowed to connect; 3. Assign corresponding permissions through GRANT, such as ALLPRIVILEGES or SELECT, INSERT, etc., and refresh the permissions with FLUSHPRIVILEGES. The entire process requires attention to correct syntax, reasonable permission control and password security to avoid failure due to misspelling or improper configuration.

Jul 04, 2025 am 12:20 AM

mysql database

Understanding the role of foreign keys in MySQL data integrity

ForeignkeysinMySQLensuredataintegritybyenforcingrelationshipsbetweentables.Theypreventorphanedrecords,restrictinvaliddataentry,andcancascadechangesautomatically.BothtablesmustusetheInnoDBstorageengine,andforeignkeycolumnsmustmatchthedatatypeoftherefe

Jul 03, 2025 am 02:34 AM

Best ways to handle NULL values in MySQL queries

When handling NULL values ??in MySQL queries, you need to pay attention to their characteristics that represent "unknown" or "not exist", and cannot be judged by ordinary comparison characters. 1. Use ISNULL and ISNOTNULL to filter or exclude NULL values, such as WHEREemailISNULL or WHEREemailISNOTNULL. 2. Replace the NULL value with IFNULL() or COALESCE(). IFNULL(col,'default') is used in two-parameter scenarios. COALESCE(col1,col2,...,default) returns the first non-NULL value. 3. Handle NULL with caution in JOIN or WHERE clauses, LEFTJOI

Jul 03, 2025 am 02:33 AM

mysql null value

Resetting the root password for MySQL server

To reset the root password of MySQL, please follow the following steps: 1. Stop the MySQL server, use sudosystemctlstopmysql or sudosystemctlstopmysqld; 2. Start MySQL in --skip-grant-tables mode, execute sudomysqld-skip-grant-tables&; 3. Log in to MySQL and execute the corresponding SQL command to modify the password according to the version, such as FLUSHPRIVILEGES;ALTERUSER'root'@'localhost'IDENTIFIEDBY'your_new

Jul 03, 2025 am 02:32 AM

mysql reset Password

Monitoring MySQL server health and performance metrics

Monitoring MySQL health and performance requires attention to five core dimensions. 1. Check the number of connections and thread status, and use SHOWSTATUSLIKE'Threads%'; view Threads_connected and Threads_running. If Threads_running is higher than 10~20 for a long time, you need to combine the slow query log troubleshooting; 2. Enable and analyze the slow query log, configure slow_query_log, long_query_time, use mysqldumpslow or pt-query-digest analysis to optimize the SQL of the missed index; 3. Monitor the InnoDB status and pay attention to the buffer pool hit rate and log

Jul 03, 2025 am 02:31 AM

Performance mysql monitoring

Tuning MySQL memory usage for optimal performance

MySQL memory tuning needs to be reasonably configured based on load, data volume and hardware. Key parameters include: 1. Innodb_buffer_pool_size is recommended to set to 50%~80% of physical memory, but does not exceed the actual data requirements; 2. key_buffer_size is suitable for MyISAM engine, and InnoDB users can keep it small; 3. query_cache_type and query_cache_size are easily bottlenecks in scenarios that write more and read less, and MySQL8.0 has been removed; 4. max_connections and thread-level buffers need to control the total amount to avoid memory overflow. Before tuning, you should pass top, SHOWENGINEINNODBS

Jul 03, 2025 am 02:30 AM

mysql performance Memory optimization

Optimizing GROUP BY and ORDER BY clauses in MySQL

The key to optimizing GROUPBY and ORDERBY performance is to use matching indexes to speed up queries. 1. Create a composite index for the columns involved in GROUPBY, and the order must be consistent, so as to avoid using functions on the columns; 2. Ensure that the ORDERBY column is overwritten by the index and try to avoid sorting large result sets; 3. When GROUPBY and ORDERBY coexist, if the sorting is based on aggregate values, the index cannot be used. Consider limiting the number of rows or pre-calculating the aggregate value; 4. Check and remove unnecessary grouping or sorting, reduce data processing, and improve overall efficiency.

Jul 03, 2025 am 02:30 AM

mysql optimization