Ideas, releases, practical guides, and perspectives from the people building with MySQL.
I’ve once again published a massive issue of the OpenLampTech newsletter, the newsletter for PHP/MySQL developers. If you’re looking to learn more about PHP and MySQL, you’ve come to the right place…
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The Newsletter for PHP and MySQL Developers
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[Read more]Anyone familiar with Oracle performance tuning knows about ASH , aka active session history. ASH saves a history of every session that is active every collection, which by default is once per second. Once per second is fast enough to give a clear view of database load.
The ASH data comes from v$session which is a structure that contains information on every connection and shows which connections are active, what SQL they are running (SQL_ID) and if they are runnable on CPU or waiting on a wait_event for some resource like an I/O to complete or a lock or latch. It’s a pretty simple select query on v$session to select who is active, their wait_event and SQL_ID.
On Oracle that gives us a query like:
select sid||':'||serial# session_id,
username,
s.sql_id||':'||sql_child_number sqlid,
decode(state, 'WAITING', wait_class||':'||event, 'CPU') event
from v$session s
where (( s.wait_time != 0 /* on CPU */ …[Read more]
On 22nd March 2022 08:43 UTC, we became aware of the issue affecting Okta, a third-party identity provider that Percona uses for https://id.percona.com. Initially, there was no statement from Okta, so our Security Operations team reviewed the information available from LAPSUS$ and other public sources.
Based on the public information available about the issue, we evaluated the potential exposure to Percona and determined that the impact was minimal. Percona uses Okta integrations so https://id.percona.com can be used to authenticate against Percona’s deployments of:
Integrations of …
[Read more]How does one use NESTING_EVENT_ID?
Below I’ve selected from events_waits_history_long for a single thread, but none of the NESTING_EVENT_ID values show up in EVENT_ID or END_EVENT_ID.
To simplify things , I’m just showing the data for one THREAD_ID listed in order of TIMER_START.
mysql> select
THREAD_ID,
EVENT_ID,
END_EVENT_ID,
NESTING_EVENT_ID,
NESTING_EVENT_TYPE,
EVENT_NAME,
SOURCE,
TIMER_WAIT,
SPINS,
OBJECT_SCHEMA,
OBJECT_NAME,
INDEX_NAME,
OBJECT_TYPE,
OBJECT_TYPE,
OBJECT_INSTANCE_BEGIN,
OPERATION,
NUMBER_OF_BYTES,
FLAGS
from
performance_schema.events_waits_history_long
where
THREAD_ID in ( select max(thread_id) from performance_schema.events_waits_history_long where …[Read more]
MySQL Shell for VS Code is a brand new extension for MS Visual Studio Code. We have taken the full power of MySQL Shell – our advanced MySQL Client for Developers and DBAs – and made it available directly inside Visual Studio Code. Together with support for the MySQL Database Service on Oracle Cloud, our […]
A short introduction to the new MySQL Shell for VS Code extension.
PlanetScale Rewind is the world’s first data migration time machine. Revert changes to your database after a migration with no downtime and zero data loss.
Learn how we used VReplication to allow for migration reverts with data retention.
For a very long part of its history, MySQL replication has been limited in terms of performance. Because there was no way of knowing if transactions or updates were independent, the updates had to be executed on a replica following the exact same sequence of operations as on the primary server. The only way to guarantee the same sequence of operations on the replica was to use a single thread. In this post, we’ll do a dive into the MySQL multi-threaded replication (MTR) implementation and explore the available tuning options.
MTR is the culmination of the evolution in the development of parallel replication which followed the path:
We’ll leave aside, for now, the recent dependency tracking feature.
Context
Before we discuss the multi-threaded implementation, let’s review in …
[Read more]I record this for posteriority without much comment.
The error message “Truncated incorrect DOUBLE value” when issued by MySQL can be a confused parser, and masks unintended barely legal syntax:
kris@localhost [kris]> select * from testtable;
+----+------+
| id | d |
+----+------+
| 1 | eins |
| 2 | zwei |
| 3 | drei |
+----+------+
3 rows in set (0.00 sec)
kris@localhost [kris]> update testtable set d="vier" and id = 4 where id = 3;
ERROR 1292 (22007): Truncated incorrect DOUBLE value: 'vier'
The actual problem here is the incorrect use of and
in the set-clause of the update
statement when a comma was intended.
kris@localhost [kris]> update testtable set d="vier", id = 4 where id = 3;
Query OK, 1 row affected (0.02 sec)
Rows matched: 1 Changed: 1 Warnings: 0
Technically, an and is possible and legal, if you …