InnoDB depends on operating system threads to process the requests from user transactions, These transactions include requests to InnoDB before commit or rollback. The modern operating systems and servers with multi-core processors, where context switching is efficient, most workloads run well without any limit on the number of concurrent threads. InnoDB can efficiently control the number of concurrently executing operating system threads (and thus the number of requests that are processed at any one time) to minimize context switching between threads. if the number of threads concurrently executing is at a pre-defined limit, the new request sleeps for a short time before it tries again. The requests which cannot be rescheduled after the sleep is put in a first-in/first-out queue and eventually is processed. Threads waiting for locks are not counted in the number of concurrently executing threads.To limit the number of …

As a spin-off from the previous post, https://mysqlmed.wordpress.com/2018/08/23/get-the-auditors-in/, I thought that it would be good to see how well the Audit plugin upgrades to MySQL 8. The big change in auditing is that the tables change from MyISAM to InnoDB, so keep your eyes open.

I’m using the previously used instance in version 5.7.18.

Preparation

Before we do anything, let’s make sure auditing will be in place when we restart the instance with 8.0.12:

Uncomment the plugin-load & audit-log params we had originally commented out. After all, this is something we should have done in the last post (apologies!):

vi my_audit.cnf:
  ..
  [mysqld]
  plugin-load =audit_log.so
  audit-log =FORCE_PLUS_PERMANENT
  ..

Restart the 5.7 instance so we upgrade from a rebooted / ‘as real as can be …

Here I have been looking into using the MySQL Enterprise Edition Audit Log plugin for 5.7. We have many options to audit (filters, encryption, compression, Workbench, rotation & purging, viewing the log, etc.) and it’s quite clear cut on what we’re auditing and not when active.

If you’re looking to go deep into the Audit Plugin, as part of the Enterprise Edition, you’ll want to look at the following Support note:

Master Note for MySQL Enterprise Audit Log Plugin (Doc ID 2299419.1)

And if you’re looking for other Audit Plugin examples, I’d recommend Tony Darnell’s blog post:

…

I was recently asked a question by mail about MySQL Lossless Semi-Synchronous Replication. As I think the answer could benefit many people, I am answering it in a blog post. The answer brings us to the internals of transaction committing, of semi-synchronous replication, of MySQL (server) crash recovery, and of storage engine (InnoDB) crash recovery. I am also debunking some misconceptions that I have often seen and heard repeated by many. Let’s start by stating one of those misconceptions.

One of those misconceptions is the following (this is NOT true): semi-synchronous enabled slaves are always the most up-to-date slaves (again, this is NOT true). If you hear it yourself, then please call people out on it to avoid this spreading more. Even if some slaves have semi-synchronous replication disabled (I will use semi-sync for …

ProxySQL is the most preferred and is widely used for load-balancing MySQL workload, thanks to Rene Cannon & Team for the great tool, and kudos on the recent release of ProxySQL 1.4.10, with a lot of bug fixes. ProxySQL is simple in design, lightweight, highly efficient and feature rich, We have been working with ProxySQL in production for our client quite a sometime, we have also shared some of our encounters/experience and use cases in the below blogs.

• ProxySQL for replication – Read Write split
• ProxySQL for handling bad queries
• …

This article is inspired by Percona blog post comparing MySQL 8.0 and Percona Server 5.7 on IO-bound workload with Intel Optane storage. There are several claims made by Vadim based on a single test case, which is simply unfair. So, I'll try to clarify this all based on more test results and more tech details..
But before we start, some intro :
InnoDB Parallel Flushing -- was introduced with MySQL 5.7 (as a single-thread flushing could no more follow), and implemented as dedicated parallel threads (cleaners) which are involved in background once per second to do LRU-driven flushing first (in case there is no more or too low amount of free pages) and then REDO-driven flushing (to flush …

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MySQL has since version 5.7 had support for progress information for some queries. As promised in my previous post, I will here discuss how you can use that to get progress information for ALTER TABLE on InnoDB tables.

Background and Setup

Progress information is implemented through the Performance Schema using the stage events. In version 8.0.12 there are currently seven stages that can provide this information for  ALTER TABLE statements on InnoDB tables. In MySQL 8, it is easy to list the stages capable of reporting progress information by using the …

Recently one of our customers wanted us to benchmark InnoDB, TokuDB and RocksDB on Intel(R) Xeon(R) Gold 6140 CPU (with 72 CPUs),  nvme SSD (7 TB) and  530 GB RAM for performance. We have used Ubuntu xenial 16.04.4, Percona Server 5.7 (included storage engines- InnoDB/XtraDB, TokuDB and RocksDB) and  Sysbench 1.0.15 with custom Lua scripts for this exercise, This benchmarking exercise included bulk INSERTS, WRITES, READS and READS-WRITES. We have tried our best to capture maximum information about the hardware infrastructure and copied / shared scripts we have used for benchmarking. This is not a paid / sponsored benchmarking effort by any of the software or hardware vendors, We will remain forever an vendor neutral and independent web-scale database infrastructure operations company with core expertise in performance, scalability, high availability and database reliability engineering. This benchmarking is …

The main focus of a previous blog post was the performance of MyRocks when using fast SSD devices. However, I figured that MyRocks would be beneficial for use in cloud workloads, where storage is either slow or expensive.

In that earlier post, we demonstrated the benefits of MyRocks, especially for heavy IO workloads. Meanwhile, Mark wrote in his blog that the CPU overhead in MyRocks might be significant for CPU-bound workloads, but this should not be the issue for IO-bound workloads.

In the cloud the cost of resources is a major consideration. Let’s review the annual cost for the processing and storage …

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There are many nice changes included in the MySQL 8.0.12 release that were published a couple of days ago. One of the most exciting is the ability to make instant schema changes to tables. This blog will look into why I think that that is a stand-out change.

I will not go into details with the implementation other than noting that the new data dictionary in MySQL 8.0 has allowed for a nice implementation of the patch that was contributed by the Tencent Games DBA Team. If you are interested in learning more about the implementation, I will recommend you to read the blog by Bin Su ( …