I am wondering why longtext data has to be considered while the result set is just 0 rows? There are no rows satisfying the WHERE clause. What difference does it make that the selected column is longtext when the WHERE clause is not satisfied anyway?Ĭaching is disabled. Why is there a huge difference in timelines? If the WHERE clause is processed first, the time for these SELECTs should be the same but that is not the case here. Mysql> EXPLAIN select FILE_DATA from bb_table where UPDATE_STAMP > '0' and SID='M02147' limit 1 | 1 | SIMPLE | bb_version_mas | ALL | UPDATE_STAMP_SID | NULL | NULL | NULL | 2555 | Using where | | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | Mysql> EXPLAIN select VERSION_NO from bb_table where UPDATE_STAMP > '0' and SID='M02147' limit 1 Mysql> select FILE_DATA from bb_table where UPDATE_STAMP > '0' and SID='M02147' limit 1 Online editions are also available for most titles ().Server version: Amazon AWS: 5.6.19-log MySQL Community Server (GPL) mysql> select VERSION_NO from bb_table where UPDATE_STAMP > '0' and SID='M02147' limit 1 O’Reilly books may be purchased for educational, business, or sales promotional use. Published by O’Reilly Media, Inc., 1005 Gravenstein Highway North, Sebastopol, CA 95472. Grippa and Sergey Kuzmichev Copyright © 2021 Vinicius M. Walks the reader through all the important MySQL concepts, from the foundation of SQL and data modeling to advanced topics like high availability and cloud, using clear, concise, direct language. Simply an indispensable book to increase MySQL knowledge. With clear and objective communication, it covers topics from basic to advanced. Brett Holleman, software engineer This book is essential for anyone who wants to dive into the MySQL ecosystem. Alkin Tezuysal, senior technical manager at PlanetScale This book is a terrific resource, whether you’re installing MySQL for the first time, learning load balancing, or migrating your database to the cloud. I highly recommend this book to all readers, from developers to operations. It’s a smooth read with well-organized content befitting the quality of O’Reilly publishing. This book offers the most comprehensive details on MySQL, not only how to get started but also for complex topics like high availability and load balancing. Don’t miss the last chapter-it’s very interesting! -Frederic Descamps, MySQL evangelist at Oracle First of all, I want to thank Vinicius and Sergey for making possible my dream book for all beginners of MySQL while I work on the developer edition. Many third-party tools are also covered, like dbdeployer and ProxySQL, which are MySQL DBA’s very good friends but are often not covered in the literature. Many topics are clearly covered with examples, from installation and database design to maintenance and architecture for HA and cloud. It’s been a long time since a good book covering MySQL and its ecosystem has been published, and many changes have occurred since then. Praise for Learning MySQL, Second Edition Installing MySQL Shell on Ubuntu 20.04 Focal Fossaĭeploying a Sandbox InnoDB Cluster with MySQL Shellīuilding MySQL for Ubuntu Focal Fossa and ARM Processors Using pt-stalk to Collect MySQL and OS Metricsīasic Parameters to Set on the Source and the ReplicaĬreating a Replica Using PerconaXtraBackupĬreating a Replica Using the Clone PluginĬreating a Replica Using mydumper and myloaderĭeploying Percona XtraDB Cluster in Kubernetes Gathering System Status Variable Values Periodically Incident/Diagnostic and Manual Data Collection Point-in-Time-Recovery Example: mysqldumpĮxporting and Importing InnoDB TablespacesĬhapter 11. Point-in-Time-Recovery Example: XtraBackup Persistent System Variables Configuration File Performing Updates and Deletes with Multiple TablesĬhanging root’s Password and Insecure Startup MySQL Parameters Related to Isolation and Locks The ANY, SOME, ALL, IN, and NOT IN Clauses Renaming Tables and Altering Other Structures The SELECT Statement and Basic Querying TechniquesĮxploring Databases and Tables with SHOW and mysqlshowĬhapter 4. Mapping Entities and Relationships to Database TablesĬonverting the EER to a MySQL Database Using Workbench Third Normal Form: Eliminate Data Not Dependent on Key Second Normal Form: Eliminate Redundant Data Installing MySQL on Ubuntu 20.04 LTS (Focal Fossa)Ĭhapter 2. Perform Any Necessary Post-Installation Setup Download the Distribution that You Want to Installģ.
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