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- What is the leftmost prefix rule for composite indexes?
- Theleftmostprefixruleincompositeindexesmeansqueriesmustreferencetheleftmostcolumnstousetheindexeffectively.Forexample,anindexon(last_name,first_name,email)helpsqueriesfilteringonlast_name,last_nameandfirst_name,orallthreecolumns.However,queriesfilter
- Mysql Tutorial . Database 557 2025-06-12 10:36:12
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- What is the purpose of the InnoDB Buffer Pool?
- The function of InnoDBBufferPool is to improve MySQL read and write performance. It reduces disk I/O operations by cacheing frequently accessed data and indexes into memory, thereby speeding up query speed and optimizing write operations; 1. The larger the BufferPool, the more data is cached, and the higher the hit rate, which directly affects database performance; 2. It not only caches data pages, but also caches index structures such as B-tree nodes to speed up searches; 3. Supports cache "dirty pages", delays writing to disk, reduces I/O and improves write performance; 4. It is recommended to set it to 50%~80% of physical memory during configuration to avoid triggering swap; 5. It can be dynamically resized through innodb_buffer_pool_size, without restarting the instance.
- Mysql Tutorial . Database 757 2025-06-12 10:28:20
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- What is the MySQL binary log (binlog) and what is it used for?
- MySQL's binary log (binlog) is a binary log that records database change operations, and is used in scenarios such as data recovery, master-slave replication and auditing. 1. Binlog is a logical log file that records all operation events that modify data, such as INSERT, UPDATE, DELETE, etc., but does not include SELECT or SHOW query statements; 2. Its main uses include: data recovery through replay logs, supporting master-slave copying to achieve data synchronization, and used to analyze operation records to meet audit requirements; 3. Enable binlog requires setting log-bin, server-id, binlog_format and expire_logs_day in the configuration file.
- Mysql Tutorial . Database 974 2025-06-11 15:41:11
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- What is the purpose of SELECT ... FOR UPDATE?
- ThemainpurposeofSELECT...FORUPDATEistolockselectedrowsduringatransactiontopreventothersessionsfrommodifyingthemuntilthetransactioncompleteswhichensuresdataconsistencyinconcurrentenvironmentssuchasbankingandinventorysystems1Itplacesrow-levellocksallow
- Mysql Tutorial . Database 836 2025-06-11 15:37:11
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- What problems can a long-running transaction cause?
- Long transactions can cause multiple problems in the database environment. 1. Locking and blocking: Long transactions hold locks for a long time, preventing other transactions from accessing data, resulting in delay or timeout; 2. Increased risk of deadlock: Cross-waiting of multiple transactions is prone to cause deadlocks, and the database needs to interrupt transaction processing, which may lead to data inconsistency; 3. High resource consumption: Transaction logs and rollback segments occupy more memory and disk space, affecting backup and recovery and system performance; 4. Data consistency and recovery challenges: Uncommitted transactions extend the failure recovery time, and data delay or inconsistency may be caused in the replication environment; therefore transactions should be submitted or rolled back as soon as possible to avoid the above problems.
- Mysql Tutorial . Database 713 2025-06-11 15:33:10
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- How to enable SSL/TLS encryption for MySQL connections?
- Enable MySQL's SSL/TLS encryption connection can effectively prevent data leakage. The specific steps are as follows: 1. Confirm that the MySQL version supports SSL, and check whether the return value is YES through SHOWVARIABLESLIKE'have_ssl'; 2. Prepare a PEM format certificate file (ca.pem, server-cert.pem, server-key.pem), which can be generated through OpenSSL or obtained from CA; 3. Modify the MySQL configuration file, add ssl-ca, ssl-cert and ssl-key paths in the [mysqld] section and restart the service; 4. Force the client to use SSL, and use CREATEUSER
- Mysql Tutorial . Database 536 2025-06-11 15:29:10
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- How to install MySQL 8.0 on Windows/Linux?
- The key to installing MySQL 8.0 is to follow the steps and pay attention to common problems. It is recommended to use the MSI installation package on Windows. The steps include downloading the installation package, running the installer, selecting the installation type, setting the root password, enabling service startup, and paying attention to port conflicts or manually configuring the ZIP version; Linux (such as Ubuntu) is installed through apt, and the steps are to update the source, installing the server, running security scripts, checking service status, and modifying the root authentication method; no matter which platform, you should modify the default password, create ordinary users, set up firewalls, adjust configuration files to optimize character sets and other parameters to ensure security and normal use.
- Mysql Tutorial . Database 1146 2025-06-11 15:25:11
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- MySQL Triggers: Trigger naming conventions?
- MySQLtriggersshouldbenamedusingastructuredconvention:1)Prefixwith'trg_'or'trigger_',2)Includethetablename,3)Specifytheeventtype(insert,update,delete),4)Indicatetiming(beforeorafter);forexample,'trg_tbl_user_before_insert'enhancesreadability,organizat
- Mysql Tutorial . Database 921 2025-06-06 00:14:31
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- MySQL Triggers: Can I disable triggers in some cases?
- Yes,youcandisabletriggersinMySQLusingtwomethods.1)Setauser-definedvariabletocontroltriggerexecution:useSET@disable_triggers:=TRUE;beforeoperationsandSET@disable_triggers:=FALSE;tore-enable.2)Renametriggerstemporarily:useRENAMETRIGGERmy_triggerTOmy_tr
- Mysql Tutorial . Database 412 2025-06-06 00:14:10
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- MySQL BLOB: How to store GIF images?
- GIF images can be stored in MySQL using the BLOB field. 1) Create a table structure and use LONGBLOB to store GIF data. 2) Read and insert GIF files through Python. 3) Considering performance and scalability, it is recommended to store file paths instead of the file itself. 4) Use Python to retrieve and display GIFs from the database. 5) Ensure verification of file type and size for security.
- Mysql Tutorial . Database 551 2025-06-06 00:13:50
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- MySQL Triggers: What if I have complex triggers?
- ComplextriggersinMySQLarepowerfulforautomatingdatabaseoperationsandmaintainingdataintegrity,buttheyrequirecarefulmanagement.1)Theycanimpactperformancebyslowingdownoperations,soprofilingandbatchingarecrucial.2)Debuggingischallenging,necessitatingloggi
- Mysql Tutorial . Database 527 2025-06-06 00:13:30
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- MySQL: how to use string datatypes for a professional database?
- In MySQL, professional databases should use CHAR, VARCHAR, TEXT, and BLOB to handle string data types. 1.CHAR is suitable for fixed-length data, such as country code. 2.VARCHAR is suitable for variable length data, such as email. 3.TEXT and BLOB are used for big data, such as blog content and images. 4. When choosing, you need to consider performance, storage and data integrity, and use index and character set settings reasonably.
- Mysql Tutorial . Database 1101 2025-06-06 00:11:40
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- MySQL Triggers: Can I use triggers for everything?
- No,youcannotusetriggersforeverythinginMySQL.Triggersareidealformaintainingdataintegrityandautomatingtaskslikeloggingstockupdates,buttheycanleadtoperformanceissuesandcomplexityifusedforheavyoperationsornestedlogic.Usethemforsimple,focusedtasksandalway
- Mysql Tutorial . Database 337 2025-06-05 00:14:40
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- MySQL Triggers: Can triggers call other triggers?
- Yes,MySQLtriggerscancallothertriggers,butcarefulmanagementisneededtoavoidissueslikeinfiniteloopsandperformanceimpacts.1)BeawareofcascadingtriggersanduseMySQL'srecursiondepthlimit.2)Considertheperformanceoverheadofmultipletriggerexecutions.3)Planforin
- Mysql Tutorial . Database 266 2025-06-05 00:09:10
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