It's time to continue my new series that I've started 2 weeks ago. I'd like to start with a reminder that it's time to send your talks for "MySQL and Friends Devroom" at FOSDEM 2017 - the only MySQL-related event next year that I plan to attend in any case. It seems we have one more week to submit, but I've already filled in all the details for the "main" talk, "Understanding MyRocks locks and deadlocks". I'd like to apply my usual source code reading and gdb breakpoints approach in case if by the end of January, 2017 official documentation still misses important details. Official MySQL …[Read more]
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PS_history is a tool which collects historical snapshots of the
PERFORMANCE_SCHEMA (P_S). This allows you to trend P_S values
over time, for example, it is possible to look at the 95 th
percentile response time for a query over time.
PS_history is stored procedure and event based, and thus it resides entirely inside of the database with no external dependencies. It uses a clever technique to capture all of the P_S data in one consistent snapshot. This ensures that all of the sys_history views (bundled now with PS_history) have a consistent set of data.
By default, as long as the event_schedule is enabled, PS_history will collect data every 30 seconds. If a snapshot takes 30 seconds, there will be a 30 second delay before the next snapshot starts. This value can be changed by calling the `ps_history`.`set_collection_interval`(N) where N is the number of seconds between samples.
The `sys_history` schema is …
MySQL 5.7.14 was officially released yesterday. So, it's time
to check what bugs reported by MySQL Community in public were
fixed in this release. Some of these bugs are presented
As usual, let me start with InnoDB. The following bugs were fixed there:
- Bug #80296 - "FTS query exceeds result cache limit". It was reported (for 5.6, but I do not see new 5.6 release notes yet) by Monty Solomon and verified by Umesh.
- Bug #80304 - "generated columns don't work with foreign key actions". It was reported by Guilhem Bichot based on test case by Peter Gulutzan presented …
Last week during the Oracle Users Group Leaders Summit in Bucharest I had the pleasure the meet the leaders for the MySQL Users Group from Azerbaijan, Finland, Madrid and the Netherlands.
During some discussions, it appeared that some users are not aware of the Performance_Schema integration in MySQL Workbench. Indeed with WB you can enable PFS, add sys table if not present by default (<5.7).
You can use a default configuration or customize it and enable all the instruments and consumers you need.
When enabled, you can generate some useful reports
In case you are also not yet aware of it, the following dashboard is also available in MySQL Workbench
The latest version of MySQL Workbench has been released yesterday, June 13th : 6.3.7 GA
MySQL 5.7.12 was released more than 2 weeks ago. New features
introduced there in a form of "rapid plugins" are widely
discussed, but I am more interested in bugs reported by MySQL
Community users that are fixed there. Unfortunately I do not see
MySQL Community Release Notes by Morgan (like this) for quite a some time, so I have to
continue describing key bug fixes and name people who reported
and verified bugs in my "Fun with Bugs" series.
As usual, let's start with InnoDB bugs fixed:
- Bug #80070 - "allocated_size and file_size differ if create general tablespace outside datadir". It was reported by my former colleague from Percona …
A while back, I wrote a blog post explaining how
PERFORMANCE_SCHEMA improvements in MySQL Server 5.7
provides new visibility into the SSL/TLS status of each
running client configuration. An excellent
recent post from Frederic Descamps at Percona covers
similar territory. Both of us use
PERFORMANCE_SCHEMA tables directly – a powerful
interface, but one that requires a query joining multiple tables.
Thanks to the excellent work of Mark Leith, and a contribution from Daniël van Eeden, access to this
same information is made far easier via the
I overlooked the
When trying out new software there are many other questions you may ask and one of those is going to be the one above. The answer requires you to have built your software to capture and record low level database metrics and often the focus of application developers is slightly different: they focus on how … Continue reading Is MySQL X faster than MySQL Y? – Ask queryprofiler
In many types of database workloads, using a multi-threaded slave from 5.6+ helps improve replication performance. I’ve had a number of users enable this feature, but have not seen anyone ask how each thread is performing. Here’s a quick way with Performance_Schema to measure the amount of multi-threaded slave activity on each thread (after you have already configured MTS on your slave of course ).
First, we need to enable the
slave1> UPDATE setup_consumers SET ENABLED = 'YES' WHERE NAME LIKE 'events_statements_%'; Query OK, 2 rows affected (0.00 sec) Rows matched: 3 Changed: 2 Warnings: 0
Next, let’s find the
for our slave workers:
slave1> SELECT …[Read more]
MySQL Connector/Java supports connection attributes since version 5.1.25. This projects useful metadata about the client environment into the database, where MySQL administrators can query PERFORMANCE_SCHEMA tables to remotely survey application deployment environments. One useful piece of information exposed is the version and vendor of the JVM in use by the client. This very short blog demonstrates how to get this information from PERFORMANCE_SCHEMA.
The metadata including the Java runtime environment version and vendor can be found in PERFORMANCE_SCHEMA.SESSION_CONNECT_ATTRS table. Here’s the full contents of that table for a single connection from Connector/Java:
mysql> SELECT * -> FROM PERFORMANCE_SCHEMA.SESSION_CONNECT_ATTRS -> WHERE processlist_id = 31\G *************************** 1. row *************************** PROCESSLIST_ID: 31 ATTR_NAME: _runtime_version ATTR_VALUE: …[Read more]
These days everybody is excited with recent announcement of
MySQL 5.7.9 GA release. If you are not aware
of this event yet (I've noted it from numerous posts even during
my short vacation), wait for the Oracle Open World 2015 to begin tomorrow to
announce it even wider and louder!
I already have 5.7.9 built from source, up and running, so it's time to check what else we can expect from this new GA release besides new great features (this is a topic for a separate post or two) and usual excitement. Yes, I mean known, verified bugs in MySQL 5.7.9.
Let me start with a quick summary and then present the details. So, even though MySQL Community tried hard to check 5.7.x at early stages and report bugs to Oracle, MySQL 5.7.9 GA has a number of known …
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