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Displaying posts with tag: Community Love (reset)
The weird messages Anthology of MySQL – Episode 1

Hi dear community.
Today I want to share with you some funny and weird error messages which can be extremely annoying

So let’s begin:

CREATE temporary TABLE `sbtest1_temp` (
  `k` int(11) NOT NULL DEFAULT '0',
  `c` char(120) NOT NULL DEFAULT '',
  `pad` char(60) NOT NULL DEFAULT '',
  `json_test_v` json GENERATED ALWAYS AS (json_array(`k`,`c`,`pad`)) VIRTUAL,
  `json_test_s` json GENERATED ALWAYS AS (json_array(`k`,`c`,`pad`)) STORED,
  `json_test_index` varchar(255) GENERATED ALWAYS AS (json_array(`k`,`c`,`pad`)) STORED,
  PRIMARY KEY (`id`),
  KEY `k_1` (`k`),
  KEY `json_test_index` (`json_test_index`)

ERROR 1478 (HY000): InnoDB: Unsupported encryption option for temporary tables.

Okay, let’s disable it:

CREATE temporary TABLE `sbtest1_temp` (
  `id` int(11) NOT NULL AUTO_INCREMENT, …
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Doc BUGs – an easy way to contribute Open Source project(part-1)

In this topic I would like to make some notes about questions, how we can contribute or help on Open Source project.
The first thing is, to learn the product itself, how to install, how to remove, how to use etc.
Of course, the first place for this information is an official documentation.
How you can use the DOC? I am taking following approach:
* Read the doc to learn the needed thing.
* Test the info provided in the DOC –
if the info is valid(i.e you have different results)
if it is not valid:
Report a bug – then continue reading.

The issue can be in DOC itself or in the product.
Did you find small typo in DOC? Did you think some info about topic is wrong? Or maybe you found wrong code samples?
Report it immediately and you will be the part of community.

Let’s take some DOC bug reports and examine them to get the idea.
The first is -> …

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Running simultaneous queries with Python, for killing them

This topic is about, simple approach to run multiple sql statements for testing XtraBackup behaviour – if it is going to kill them due to blocked FTWRL(FLUSH TABLES WITH READ LOCK).

According to the DOC -> Backup Locks

Percona Server has implemented this feature to be a lightweight alternative to FLUSH TABLES WITH READ LOCK for both physical and logical backups. Three new statements are now available: LOCK TABLES FOR BACKUP, LOCK BINLOG FOR BACKUP and UNLOCK BINLOG.

So by default, if you are using PS it is going to use LOCK TABLES FOR BACKUP prior copying non-InnoDB tables.

Well, how to force to use FTWRL instead of Backup Locks?
Congratulations – we have --no-backup-locks option, if you specify it, the FTWRL will be used.

Okay, again reading the DOC …

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XtraBackup vs. OOM killer(usage of mprof)

This small article is about nicely depicting memory usage prior to OOM killers show.

I have started MySQL with:

/home/shahriyar.rzaev/XB_TEST/server_dir/PS131117-percona-server-5.7.19-17-linux-x86_64/bin/mysqld --no-defaults \
--innodb_buffer_pool_size=1G --innodb_log_file_size=1G --innodb_page_size=64K \ --keyring_file_data=/home/shahriyar.rzaev/XB_TEST/server_dir/PS131117-percona-server-5.7.19-17-linux-x86_64/mysql-keyring/keyring \
--log-bin=mysql-bin --log-slave-updates --server-id=1 --gtid-mode=ON --enforce-gtid-consistency --binlog-format=row --core-file --basedir=/home/shahriyar.rzaev/XB_TEST/server_dir/PS131117-percona-server-5.7.19-17-linux-x86_64 \
--tmpdir=/home/shahriyar.rzaev/XB_TEST/server_dir/PS131117-percona-server-5.7.19-17-linux-x86_64/data \
--datadir=/home/shahriyar.rzaev/XB_TEST/server_dir/PS131117-percona-server-5.7.19-17-linux-x86_64/data \ …
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How to combine BATS, PyTest and MySQL X Plugin for tests

In this post I am going to show some tricks on using BATS framework + PyTest + Python X Plugin things, to have combined, simple test solutions.

Let’s describe MySQL X Plugin side, here is the full class:

# Connecting to MySQL and working with a Session
import mysqlx

class MyXPlugin:

    def __init__(self, schema_name, collection_name):
        # Connect to a dedicated MySQL server
        self.session = mysqlx.get_session({
            'host': 'localhost',
            'port': 33060,
            'user': 'bakux',
            'password': 'Baku12345',
            'ssl-mode': mysqlx.SSLMode.DISABLED

        self.schema_name = schema_name
        self.collection_name = collection_name

        # Getting schema object
        self.schema = self.session.get_schema(self.schema_name)
        # Creating collection
        self.schema.create_collection(self.collection_name, reuse=True)
        # Getting collection object …
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Using MySQL Connector/Python X (mysqlx module) MyRocks episode

This post is about, how I have tried to make simple Python script using mysqlx module work with MyRocks.
This is also related to pytest, as I have implemented simple pytest tests to call them from bash file.

So let’s discuss problem description:
The base problem is, by default when you create collection using Python X Plugin, the collection will have, 1 json type column called `doc` and 1 generated column from this `doc` column called `_id`.
So basically, you can not alter table engine to MyRocks because it will give an error something like:

ERROR 3106 (HY000): 'Specified storage engine' is not supported for generated columns.

The result:

Well, it can be solved by dropping generated `_id` column. Here we are encountering another issue that, if you have table with json data, please do NOT alter it to MyRocks, otherwise, you will get some weird results as described here:

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Using MySQL Connector/Python X (mysqlx module)

This post is about simple usage of mysqlx module i.e X Plugin with latest Connector/Python DMR.
The version of Python Connector is 8.0.4.


sudo yum install mysql-connector-python-8.0.4-0.1.dmr.el7.x86_64.rpm

Sample Python code:

# Connecting to MySQL and working with a Session
import mysqlx

# Connect to a dedicated MySQL server
session = mysqlx.get_session({
    'host': 'localhost',
    'port': 33060,
    'user': 'bakux',
    'password': 'Baku12345',
    'ssl-mode': mysqlx.SSLMode.DISABLED

schema = session.get_schema('generated_columns_test')

# Create 'my_collection' in schema

# Get 'my_collection' from schema
collection = schema.get_collection('my_collection')

assert(True == collection.exists_in_database())

# You can also add multiple documents at once …
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Testing MySQL 8.0 – let me create a ton of undo files

This is the late blog post about 2 recent bug reports

The basic idea came after reading ->

So the result of test ->
After each restart of MySQL the new undo log files are going to be created + keeping old files.

shahriyar.rzaev@qaserver-06:~/sandboxes/msb_8_0_1/data$ du -hs
# The count of undo files
shahriyar.rzaev@qaserver-06:~/sandboxes/msb_8_0_1/data$ ls | grep undo | wc -l

After new restart:

# New count
shahriyar.rzaev@qaserver-06:~/sandboxes/msb_8_0_1/data$ ls | grep undo | wc -l

So how to …

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Experimental MySQL UDF code partially written in Python

Hi dear all,
I would like to share our experimental tests about, writing UDF with Python.
So the basic idea was writing a UDF for factorial calculation. The interesting part was to move factorial calculation logic to Python code and then calling this Python file inside UDF code.

Here is the repo link -> UDFs-written-in-Python

The factorial calculation is here ->
UDF code is here ->

Basic idea with UDF code quite simple as it has 3 parts:
1. initialization part -> factorial_init() -> all necessary checks reside here
2. main logic -> …

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My first patch for MySQL world; fixing BUG #76852

Hi dear MySQL Community.
I have reported a bunch of bugs and wrote some articles, but today is a special for me
Because today I send my first PR for MySQL source code.

So I have logged a bug -> #76852 and now fixed it after year.
Okey, I know I am lazy.

Let’s reproduce the bug.
Simulating full disk condition is easy as:

mkdir /filesystems
dd if=/dev/zero of=/filesystems/tmp_fs bs=1024 count=0 seek=$[1024*10]
mkfs.ext4 /filesystems/tmp_fs
mkdir small_mounted_dir
mount -o loop /filesystems/tmp_fs /home/sh/small_mounted_dir/

Then obtain MySQL source and compile it with DEBUG. If you don’t know how to do it just refer to -> installing-mysql-from-source-cmake-issues

From now you can use MySQL Sandbox to …

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