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Displaying posts with tag: MySQL 5.7 (reset)
pt-online-schema-change resulted in missing MySQL triggers ?

Recently, while doing a test process to examine resource usage and the time required to alter the table using pt-osc, it leads to a loss of triggers even though the –preserve-triggers option is specified. I made the decision to recreate the identical circumstance so that everyone could see it.

Test environment : 

OS: Amazon Linux 2

MySQL version: 5.7.40

pt-online-schema-change version: 3.1.0

Before digging deeper, we must first obtain the whole picture. Here is an illustration of the table’s structure.

Table structure:

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How to Estimate time for Rollback in a cancelled transaction MySQL ?

Rollback is an operation, which changes the current state of the transaction to the previous state. Undo logs are generally required if we want to roll back any of the uncommitted transactions and it plays a major role in Isolation.

For any changes made during a transaction, it must be stored priorly, because they are required if we choose to roll back the transaction.

Entries are made in undo logs when data modifications are done. If a transaction modifies data with SQL commands, It will create discrete undo logs for each operation. Once a transaction is committed MySQL is free to purge the undo logs created in that transaction. 

To know more about undo logs, you can check our previous blogs on overview to undo logs.

Usually, the Rollback process will take more time than the original operation. Because …

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Crashing MySQL with Malicious Intent and a lot of Determination

A year ago, I blogged about An Unprivileged User can crash your MySQL Server.  At the time, I explained how to protect yourself against this problem.  A few weeks ago, I revisited this vulnerability in a follow-up post in which I explained the fix, claimed that the MySQL 5.7 default configuration for Group Replication is still problematic, and explained a tuning to avoid the vulnerability.  In

Follow-up on an Unprivileged User can Crash your MySQL Server

A year ago, I blogged about An Unprivileged User can Crash your MySQL Server.  At the time, I presented how to protect yourself against this problem without explaining how to generate a crash.  In this post, I am revisiting this vulnerability, not giving the exploit yet, but presenting the fix.  Also, because the default configuration of Group Replication in 5.7 is still vulnerable (it is not in

Introduction to MySQL Parallel query in AWS Aurora

Aurora has a salient feature “Parallel query“, Which will be more beneficial for analytical workload environments.

Before going to deep dive on this particular feature, let us understand the basis of Aurora.

Aurora Archiecture

Key feature

  • The key feature of Aurora is simple data synchronisation among the nodes. The sync latency will be too low when compared to RDS because the synchronisation is happening on storage volumes among the nodes. Also all the server will available in different zone, even when a zone goes down we can able to maintain will other server present in other zone with auto failure.
  • Auto healing volume, Each …
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Fastest Parallel replication method in MySQL 8.

From MySQL 5.7, we had a Multi-threaded Slave (MTS) Applier mechanism called LOGICAL_CLOCK to overcome the problems of parallel replication within a database.

To further improve the parallelisation mechanism, from MySQL 8 (5.7.22) we have write-set replication, so before going further , lets look at the difference between Logical clock (LC) and Writeset.

LOGICAL_CLOCK

Transactions that are part of the same binary log group commit on a master are applied in parallel on a slave. The dependencies between transactions are tracked based on their timestamps to provide additional parallelisation where possible.

WRITESET

Write-set is a mechanism to track independent transactions that can be executed in parallel in the slave. Parallelising on write sets has potentially much more parallelism than logical_clock ,since it does not depend …

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Setting MySQL Configuration Variables – MySQL 5.7 vs MySQL 8.0

MySQL configuration variables are a set of server system variables used to configure the operation and behavior of the server. In this blog post, we will explain the differences in managing the configuration variables between MySQL 5.7 and MySQL 8.0. We will explain three different ways for setting the configuration variables based on your use-case. […]

An Unprivileged User can crash your MySQL Server

Yes, your read the title correctly: an unprivileged user can crash your MySQL Server.  This applies for the default configuration of MySQL 8.0.21 (and it is probably the case for all MySQL 8 GA versions).  Depending on your configuration, it might also be the case for MySQL 5.7.  This needs malicious intent and a lot of determination, so no need to panic as this will not happen by accident.  I am

MySQL File Privilege

While preparing a set of student instructions to create a MySQL 8 (8.0.21) Windows 10 instance I found an error with LOAD command and the --secure-file_priv variable set in the my.ini file. After granting the global FILE permission to the previously provisioned student user:

GRANT FILE ON *.* TO 'student'@'localhost';

Any attempt to run the following command failed:

LOAD DATA INFILE 'C:\ProgramData\MySQL\MySQL Server 8.0\Uploads\avenger.csv'
INTO TABLE avenger
FIELDS TERMINATED BY ','
ENCLOSED BY '"'
ESCAPED BY '\\'
LINES TERMINATED BY '\r\n';

and, raise this error message:

ERROR: 1290: The MySQL server is running with the --secure-file-priv option so it cannot execute this statement

The following covers my exploration to try and fix this error without removing a designated directory for secure file uploads. While MySQL 5.7 …

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InnoDB Cluster with MySQL Server 5.7 & MySQL-Shell & Router 8.0

MySQL Server 8.0 has introduced numerous advancements in an ongoing, release by release basis. This includes features such as Multi-Value Indexes, Provisioning InnoDB Cluster 8.0 members using CLONE, among other things in 8.0.17 …. as well other MySQL enhancements such as the addition of InnoDB ReplicaSets, bootstrapping mysql-router using --account to re-use a current MySQL User for Router… Read More »

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