## A.1 MySQL 8.0 FAQ: General

[]()A.1.1. [ Which version of MySQL is production-ready (GA)? ](faqs-general.html#faq-mysql-version-ga)A.1.2. [ Why did MySQL version numbering skip versions 6 and 7 and go straight to 8.0? ](faqs-general.html#faq-mysql-why-8.0)A.1.3. [ Can MySQL 8.0 do subqueries? ](faqs-general.html#faq-mysql-do-subqueries)A.1.4. [ Can MySQL 8.0 perform multiple-table inserts, updates, and deletes? ](faqs-general.html#faq-mysql-do-multiple-iud)A.1.5. [ Does MySQL 8.0 have Sequences? ](faqs-general.html#faq-mysql-have-sequences)A.1.6. [ Does MySQL 8.0 have a NOW() function with fractions of seconds? ](faqs-general.html#faq-mysql-have-now-fractions)A.1.7. [ Does MySQL 8.0 work with multi-core processors? ](faqs-general.html#faq-mysql-support-multi-core)A.1.8. [ Why do I see multiple processes for mysqld? ](faqs-general.html#faq-mysql-why-multiple-processes)A.1.9. [ Can MySQL 8.0 perform ACID transactions? ](faqs-general.html#faq-mysql-have-acid-transactions)

|[]()[]()<br/><br/>**A.1.1.**|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          Which version of MySQL is production-ready (GA)?                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
|:---------------------------|: |
|                            | MySQL 8.0, 5.7, and MySQL 5.6 are supported for production use.<br/><br/> MySQL 8.0 achieved General Availability (GA) status with MySQL 8.0.11, which was released for production use on 19 April 2018.<br/><br/> MySQL 5.7 achieved General Availability (GA) status with MySQL 5.7.9, which was released for production use on 21 October 2015.<br/><br/> MySQL 5.6 achieved General Availability (GA) status with MySQL 5.6.10, which was released for production use on 5 February 2013.<br/><br/> MySQL 5.5 achieved General Availability (GA) status with MySQL 5.5.8, which was released for production use on 3 December 2010. Active development for MySQL 5.5 has ended.<br/><br/> MySQL 5.1 achieved General Availability (GA) status with MySQL 5.1.30, which was released for production use on 14 November 2008. Active development for MySQL 5.1 has ended.<br/><br/> MySQL 5.0 achieved General Availability (GA) status with MySQL 5.0.15, which was released for production use on 19 October 2005. Active development for MySQL 5.0 has ended.|
|[]()[]()<br/><br/>**A.1.2.**|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           Why did MySQL version numbering skip versions 6 and 7 and go straight to 8.0?                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |
|                            |                                                                                                                                                                                                                                                                                                                                                                                                                        Due to the many new and important features we were introducing in this MySQL version, we decided to start a fresh new series. As the series numbers 6 and 7 had actually been used before by MySQL, we went to 8.0.                                                                                                                                                                                                                                                                                                                                                                                                                        |
|[]()[]()<br/><br/>**A.1.3.**|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    Can MySQL 8.0 do subqueries?                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |
|                            |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     Yes. See [Section 13.2.11, “Subqueries”](subqueries.html).                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
|[]()[]()<br/><br/>**A.1.4.**|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                Can MySQL 8.0 perform multiple-table inserts, updates, and deletes?                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |
|                            |                                                                                                                                                                                                                                                                                          Yes. For the syntax required to perform multiple-table updates, see [Section 13.2.13, “UPDATE Statement”](update.html); for that required to perform multiple-table deletes, see [Section 13.2.2, “DELETE Statement”](delete.html).<br/><br/> A multiple-table insert can be accomplished using a trigger whose `FOR EACH ROW` clause contains multiple [`INSERT`](insert.html) statements within a `BEGIN ... END` block. See [Section 25.3, “Using Triggers”](triggers.html).                                                                                                                                                                                                                                                                                          |
|[]()[]()<br/><br/>**A.1.5.**|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   Does MySQL 8.0 have Sequences?                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |
|                            |                                                                                                                                                                                                    No. However, MySQL has an `AUTO_INCREMENT` system, which in MySQL 8.0 can also handle inserts in a multi-source replication setup. With the [`auto_increment_increment`](replication-options-source.html#sysvar_auto_increment_increment) and [`auto_increment_offset`](replication-options-source.html#sysvar_auto_increment_offset) system variables, you can set each server to generate auto-increment values that don't conflict with other servers. The [`auto_increment_increment`](replication-options-source.html#sysvar_auto_increment_increment) value should be greater than the number of servers, and each server should have a unique offset.                                                                                                                                                                                                   |
|[]()[]()<br/><br/>**A.1.6.**|                                                                                                                                                                                                                                                                                                                                                                                                                                                                           Does MySQL 8.0 have a [`NOW()`](date-and-time-functions.html#function_now) function with fractions of seconds?                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
|                            |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      Yes, see [Section 11.2.6, “Fractional Seconds in Time Values”](fractional-seconds.html).                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |
|[]()[]()<br/><br/>**A.1.7.**|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          Does MySQL 8.0 work with multi-core processors?                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
|                            |                            Yes. MySQL is fully multithreaded, and makes use of all CPUs made available to it. Not all CPUs may be available; modern operating systems should be able to utilize all underlying CPUs, but also make it possible to restrict a process to a specific CPU or sets of CPUs.<br/><br/> On Windows, there is currently a limit to the number of (logical) processors that [**mysqld**](mysqld.html) can use: a single processor group, which is limited to a maximum of 64 logical processors.<br/><br/> Use of multiple cores may be seen in these ways:<br/><br/>* A single core is usually used to service the commands issued from one session.<br/><br/>* A few background threads make limited use of extra cores; for example, to keep background I/O tasks moving.<br/><br/>* If the database is I/O-bound (indicated by CPU consumption less than capacity), adding more CPUs is futile. If the database is partitioned into an I/O-bound part and a CPU-bond part, adding CPUs may still be useful.                           |
|[]()[]()<br/><br/>**A.1.8.**|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   Why do I see multiple processes for [**mysqld**](mysqld.html)?                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |
|                            |                                                                                                                                                                                                                                                                                                                      [**mysqld**](mysqld.html) is a single-process program, not a multi-process program, and does not fork or launch other processes. However, [**mysqld**](mysqld.html) is multithreaded and some process-reporting system utilities display separate entries for each thread of multithreaded processes, which may lead to the appearance of multiple [**mysqld**](mysqld.html) processes when in fact there is only one.                                                                                                                                                                                                                                                                                                                       |
|[]()[]()<br/><br/>**A.1.9.**|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              Can MySQL 8.0 perform ACID transactions?                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |
|                            |                                                                                                                                                                                                                                                                                                                  Yes. All current MySQL versions support transactions. The `InnoDB` storage engine offers full ACID transactions with row-level locking, multi-versioning, nonlocking repeatable reads, and all four SQL standard isolation levels.<br/><br/> The [`NDB`](mysql-cluster.html) storage engine supports the [`READ COMMITTED`](innodb-transaction-isolation-levels.html#isolevel_read-committed) transaction isolation level only.                                                                                                                                                                                                                                                                                                                  |

