Sakila, Where Are You Going?

This article is in large part the same of what I have published in the Percona blog. However I am reproposing it here given it is the first some other benchmarking exercise that I am probably going to present here in an extended format, while it may be more concise in other platforms.

In any case why this tests.

I am curious, and I do not like (at all) what is happening around MySQL and MariaDB, never like it, but now is really think is time to end this negative trend, that is killing not only the community, but the products as well.

The tests

Assumptions

There are many ways to run tests, and we know that results may vary depending on how you play with many factors, like the environment or the MySQL server settings. However, if we compare several versions of the same product on the same platform, it is logical to assume that all the versions will have the same “chance” to behave well or badly unless we change the MySQL server settings.

Because of this, I ran the tests ON DEFAULTS, with the clear assumption that if you release your product based on the defaults, that implies you had tested with them and consider them the safest for generic use.

I also applied some modifications and ran the tests again to see how optimization would impact performance.

What tests do we run?

High level, we run two sets of tests:

Sysbench
TPC-C (https://www.tpc.org/tpcc/) like

The full methodology and test details can be found here, while actual commands are available:

Results

While I have executed the whole set of tests as indicated on the page, and all the results are visible here, for brevity and because I want to keep this article at a high level, I will report and cover only the Read-Write tests and the TPC-C.

This is because, in my opinion, they offer an immediate and global view of how the server behaves. They also represent the most used scenario, while the other tests are more interesting to dig into problems.

The sysbench read/write tests reported below have a lower percentage of writes ~36% and ~64% reads, where reads are point selects and range selects. TPC-C instead has an even distribution of 50/50 % between read and write operations.

Sysbench read and write tests

Test using default configurations only MySQL in different versions.

Small dataset:

Optimized configuration only MySQL:

Large dataset using defaults:

Using optimization:

The first two graphs are interesting for several reasons, but one that jumps out is that we cannot count on DEFAULTS as a starting point. Or, to be correct, we can use them as the base from which we must identify better defaults; this is also corroborated by Oracle's recent decision to modify many defaults in 8.4 (see article).

Given that I will focus on the results obtained with the optimized configs.

Now looking at the graphs above, we can see that:

MySQL 5.7 is performing better in both cases just using defaults.
Given bad defaults, MySQL 8.036 was not performing well in the first case; just making some adjustments allowed it to over-perform 8.4 and be closer to what 5.7 can do.

TPC-C tests

As indicated, TPC-C tests are supposed to be write-intensive, using transactions and more complex queries with join, grouping, and sorting.

I was testing the TPC-C using the most common isolation modes, Repeatable Reads, and Read Committed.

While we experienced several issues during the multiple runs, those were not consistent, mainly due to locking timeouts. Given that, while I am representing the issue presence with a blank in the graph, they are not to be considered to impact the execution trend but only represent a saturation limit.

Test using optimized configurations:

In this test we can observe that MySQL 5.7 is better performing in comparison with the other MySQL versions.

What if we compare it with Percona Server for MySQL and MariaDB?

I will present only the optimized tests here for brevity because, as I saw before, we know defaults are not serving us well.

When comparing the MYSQL versions against Percona Server for MySQL 8.0.36 and MariaDB 11.3, we see how MySQL 8.4 is doing better only in relation to MariaDB; after that, it remains behind also compared to MySQL 8.0.36.

TPC-C

As expected, MySQL 8.4 is not acting well here either, and only MariaDB is performing worse. Note how Percona Server for MySQL 8.0.36 is the only one able to handle the increased contention.

What are these tests saying to us?

Frankly speaking, what we get here is what most of our users get as well, but on their own skin. MySQL performances are degrading with the increase of versions.

For sure, MySQL 8.x comes with interesting additions; however, if you consider performance as the first and most important topic, then MySQL 8.x is not any better.

Having said this, we must say that probably most of the ones still using MySQL 5.7 (and we have thousands of them) are right. Why embark on a very risky migration and then discover that you have lost a considerable percentage in performance?

Regarding this, if we analyze the data and convert the trends into transactions/sec, we can identify the following scenarios if we compare the tests done using TPC:

As we can see, the performance degradation can be significant in both tests, while the benefits (when present) are irrelevant.

In absolute numbers:

In this scenario, we need to ask ourselves, can my business deal with such a performance drop?

Considerations

When MySQL was sold to SUN Microsystems, I was in MySQL AB. I was not happy about that move at all, and when Oracle took over SUN, I was really concerned about Oracle's possible decision to kill MySQL. I also decided to move on and join another company.

In the years after, I changed my mind, and I was supporting and promoting the Oracle/MySQL work. In many ways, I still am.

They did a great job rationalizing the development, and the code clean-up was significant. However, something did not progress with the rest of the code. The performance decrease we are seeing is the cost of this lack of progress; see also Peter's article Is Oracle Finally Killing MySQL?.

On the other hand, we need to recognize that Oracle is investing a lot in performance and functionalities when we talk of the OCI/MySQL/Heatwave offer. Only those improvements are not reflected in the MySQL code, no matter if it is Community or Enterprise.

Once more, while I consider this extremely sad, I can also understand why.

Why should Oracle continue to optimize the MySQL code for free when cloud providers such as Google or AWS use that code, optimize it for their use, make billions, and not even share the code back?

We know this has been happening for many years now, and we know this is causing a significant and negative impact on the open source ecosystem.

MySQL is just another Lego block in a larger scenario in which cloud companies are cannibalizing the work of others for their own economic return.

What can be done? I can only hope we will see a different behavior soon. Opening the code and investing in projects that will help communities such as MySQL to quickly recover the lost ground.

Let me add that while is perfectly normal in our economy to look for profit, at the end this is what capitalism is for, it is not normal, or for better say it is negative, to look for profit without keeping in mind you are burning out the resources. that gives you that profit.

This last is consumerism, using and abusing, without keeping in mind you MUST give the resources you use the time/energy/opportunity to renew and florish is stupid, short sight and suicidal.

Perfectly in line with our times isen't it?

So let say that many big names in the cloud, should seriously rethink what they are doing, not because they need to be nice. But because they will get better outcome and income helping the many opensource community instead as they are doing today, abusing them.

In the meantime, we must acknowledge that many customers/users are on 5.7 for a good reason and that until we are able to fix that, they may decide not to migrate forever or, if they must, to migrate to something else, such as Postgres.

Then Sakila will slowly and painfully die as usual for the greed of the human being, nothing new in a way, yes, but not good.

Happy MySQL to all.

Is MySQL Router 8.2 Any Better?

In my previous article, Comparisons of Proxies for MySQL, I showed how MySQL Router was the lesser performing Proxy in the comparison. From that time to now, we had several MySQL releases and, of course, also some new MySQL Router ones.

Most importantly, we also had MySQL Router going back to being a level 7 proxy capable of redirecting traffic in case of R/W operations (see this).

All these bring me hope that we will also have some good improvements in what is a basic functionality in a router: routing.

So with these great expectations, I had to repeat the exact same tests I did in my previous tests, plus I tested for MySQL Router only the cost of encapsulating the select inside a transaction.

Just keep in mind that for all the tests, MySQL Router was configured to use the read/write split option.

The results

Given this is the continuation of the previous blog, all the explanations about the tests and commands used are in the first article. If you did not read that, do it now, or it will be difficult for you to follow what is explained later.

As indicated, I was looking to identify when the first proxy would reach a dimension that would not be manageable. The load is all in creating and serving the connections, while the number of operations is capped at 100.

As you can see, MySQL Router was reaching the saturation level and was unable to serve traffic at exactly the same time as the previous test.

Test two

When the going gets tough, the tough get going reprise ;)

Let’s remove the –rate limitation and see what will happen. First, let us compare MySQL router versions only:

As we can see the MySQL Router version 8.2 is doing better up to 64 concurrent threads.

Latency follows the same trend in old and new cases, and we can see that the new version is acting better, up to 1024 threads.

Is this enough to cover the gap with the other proxies? Which, in the end, is what we would like to see.

Well, I would say not really; we see a bit of better performance with low concurrent threads, but still not scaling and definitely lower than the other two.

Now let us take a look at the CPU saturation:

Here, we can see how MySQL Router hits the top as soon as the rate option is lifted and gets worse with the increase of the running threads.

Test three

This simple test was meant to identify the cost of a transaction, or better, what it will cost to include selects inside a transaction.

As we can clearly see, MySQL Router, when handling selects inside a transaction, will drop its performance drastically going back to version 8.0 performance.

Conclusions

To the initial question — Is MySQL Router 8.2 any better? — we can answer a small (very small) yes.

However, it is still far, far away from being competitive with ProxySQL (same proxy level) or with HAProxy. The fact it is not able to serve efficiently the requests also inside the lower set of concurrent threads, is disappointing.

Even more disappointing because MySQL Router is presented as a critical component in the MySQL InnoDB Cluster solution. How can we use it in the architectures if the product has such limitations?

I know that Oracle suggests to scale out, and I agree with them. When in need to scale with MySQL Router, the only option is to build a forest. However, we must keep in mind that each MySQL Router connects and queries the data nodes constantly and intensively. Given that it requires adding a forest of router nodes to scale, it is not without performance impact, given the increasing noise generated on the data nodes.

Anyhow also, if there is a theoretical option to scale, that is not a good reason to use a poor performing component.

I would prefer to use ProxySQL with Group Replication and add whatever script is needed in mysqlshell to manage it as Oracle is doing for the MySQL InnoDB cluster solution.

What also left me very unhappy is that MySQL InnoDB Cluster is one of the important components of the OCI offer for MySQL. Is Oracle using MySQL Router there as well? I assume so. Can we trust it? I am not feeling like I can.

Finally, what has been done for MySQL Router so far leads me to think that there is no real interest in making it the more robust and performing product that MySQL InnoDB Cluster deserves.

I hope I am wrong and that we will soon see a fully refactored version of MySQL Router. I really hope Oracle will prove me wrong.

Great MySQL to everyone.

Export and import of MySQL passwords using caching_sha2

Some fun is coming

While I was writing the internal guidelines on how to migrate from MariaDB to Percona Server, I had to export the users accounts in a portable way. This given MariaDB uses some non standard syntax brings me to first test some external tools such as Fred https://github.com/lefred/mysqlshell-plugins/wiki/user#getusersgrants and our PT-SHOW-GRANTS tool.

Useless to say this had open a can worms, given first I had to fix/convert the specifics for MariaDB (not in the scope of this blog), then while testing I discover another nasty issue, that currently prevent us to easily export the new Passwords in MySQL 8 (and PS 8) when caching_sha2 is used.

So what is the problem I am referring to?

Well the point is that when you generate passwords with caching_sha2 (default in mysql 8) the password generated can (will) contain characters that are not portable, not even between mysql 8.

Let's see a practical example to understand.

If I use old mysql_native_password and I create a user such as:

create user dba@'192.168.1.%' identified with mysql_native_password by 'dba';

My authentication_string will be:

root@localhost) [(none)]>select user,host,authentication_string,plugin from mysql.user where user ='dba' order by 1,2;
+------+-------------+-------------------------------------------+-----------------------+
| user | host        | authentication_string                     | plugin                |
+------+-------------+-------------------------------------------+-----------------------+
| dba  | 192.168.1.% | *381AD08BBFA647B14C82AC1094A29AD4D7E4F51D | mysql_native_password |
+------+-------------+-------------------------------------------+-----------------------+

At this point if you want to export the user:

(root@localhost) [(none)]>show create user dba@'192.168.1.%'G
*************************** 1. row ***************************
CREATE USER for This email address is being protected from spambots. You need JavaScript enabled to view it..1.%: CREATE USER `dba`@`192.168.1.%` IDENTIFIED WITH 'mysql_native_password' AS '*381AD08BBFA647B14C82AC1094A29AD4D7E4F51D' REQUIRE NONE PASSWORD EXPIRE DEFAULT ACCOUNT UNLOCK PASSWORD HISTORY DEFAULT PASSWORD REUSE INTERVAL DEFAULT PASSWORD REQUIRE CURRENT DEFAULT
1 row in set (0.01 sec)

You just need to use the text after the semicolon and all will work fine. Remember that when you want to preserve the already converted password you need to use the IDENTIFIED … AS <PW> not the BY or you will re-convert the password ;).

Anyhow .. this is simple and what we are all used to.

Now if you instead try to use caching_sha2 things will go differently:

root@localhost) [(none)]>create user dba@'192.168.4.%' identified with caching_sha2_password by 'dba';
Query OK, 0 rows affected (0.02 sec)

(root@localhost) [(none)]>select user,host,authentication_string,plugin from mysql.user where user ='dba' order by 1,2;
+------+-------------+------------------------------------------------------------------------+-----------------------+
| user | host        | authentication_string                                                  | plugin                |
+------+-------------+------------------------------------------------------------------------+-----------------------+
| dba  | 192.168.1.% | *381AD08BBFA647B14C82AC1094A29AD4D7E4F51D                              | mysql_native_password |
| dba  | 192.168.4.% | $A$005$@&%1H5iNQx|.l{N7T/GosA.Lp4EiO0bxLVQp8Zi0WY2nXLr8TkleQPYjaqVxI7 | caching_sha2_password |
+------+-------------+------------------------------------------------------------------------+-----------------------+
2 rows in set (0.00 sec)

Probably you will not see it here given that while converted on your screen the special characters will be replaced, but the password contains invalid characters.

If I try to extract the Create USER text I will get:

 (root@localhost) [(none)]>show create user dba@'192.168.4.%'G
*************************** 1. row ***************************
CREATE USER for This email address is being protected from spambots. You need JavaScript enabled to view it..4.%: CREATE USER `dba`@`192.168.4.%` IDENTIFIED WITH 'caching_sha2_password' AS '$A$005$@&%1H5iNQx|.l{N7T/GosA.Lp4EiO0bxLVQp8Zi0WY2nXLr8TkleQPYjaqVxI7' REQUIRE NONE PASSWORD EXPIRE DEFAULT ACCOUNT UNLOCK PASSWORD HISTORY DEFAULT PASSWORD REUSE INTERVAL DEFAULT PASSWORD REQUIRE CURRENT DEFAULT
1 row in set (0.00 sec)

However if I try to use this text to generate the user after I drop it:

(root@localhost) [(none)]>drop user dba@'192.168.4.%';
Query OK, 0 rows affected (0.02 sec)
(root@localhost) [(none)]>create user dba@'192.168.4.%' IDENTIFIED AS 'NQx|.l{N7T/GosA.Lp4EiO0bxLVQp8Zi0WY2nXLr8TkleQPYjaqVxI7';
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'AS 'NQx|.l{N7T/GosA.Lp4EiO0bxLVQp8Zi0WY2nXLr8TkleQPYjaqVxI7'' at line 1

Don’t waste time, there is nothing wrong in the query, except the simple fact that you CANNOT use the text coming from the authentication_string when you have caching_sha2.

So? What should we do?

The answer is easy, we need to convert the password into binary and use/store that.

Let us try.

First create the user again:

(root@localhost) [(none)]>select user,host,authentication_string,plugin from mysql.user where user ='dba' order by 1,2;
+------+-------------+------------------------------------------------------------------------+-----------------------+
| user | host        | authentication_string                                                  | plugin                |
+------+-------------+------------------------------------------------------------------------+-----------------------+
| dba  | 192.168.1.% | *381AD08BBFA647B14C82AC1094A29AD4D7E4F51D                              | mysql_native_password |
| dba  | 192.168.4.% | $A$005$X>ztS}WfR"k~aH3Hs0hBbF3WmM2FXubKumr/CId182pl2Lj/gEtxLvV0 | caching_sha2_password |
+------+-------------+------------------------------------------------------------------------+-----------------------+
2 rows in set (0.00 sec)

(root@localhost) [(none)]>exit
Bye
[root@master3 ps80]# ./mysql-3307 -udba -pdba -h192.168.4.57 -P3307
...
(This email address is being protected from spambots. You need JavaScript enabled to view it.) [(none)]>

OK as you can see I create the user and can connect, but as we know the PW is not portable.

Let us convert it and create the user:

(root@localhost) [(none)]>select user,host,convert(authentication_string using binary),plugin from mysql.user where user ='dba' and host='192.168.4.%' order by 1,2;
+------+-------------+------------------------------------------------------------------------------------------------------------------------------------------------+-----------------------+
| user | host        | convert(authentication_string using binary)                                                                                                    | plugin                |
+------+-------------+------------------------------------------------------------------------------------------------------------------------------------------------+-----------------------+
| dba  | 192.168.4.% | 0x2441243030352458193E107A74537D0157055C66527F226B7E5C6148334873306842624633576D4D32465875624B756D722F434964313832706C324C6A2F674574784C765630 | caching_sha2_password |
+------+-------------+------------------------------------------------------------------------------------------------------------------------------------------------+-----------------------+

So the password is:

0x2441243030352458193E107A74537D0157055C66527F226B7E5C6148334873306842624633576D4D32465875624B756D722F434964313832706C324C6A2F674574784C7656

Let us use it:

(root@localhost) [(none)]>drop user dba@'192.168.4.%';
Query OK, 0 rows affected (0.02 sec)

(root@localhost) [(none)]>create user dba@'192.168.4.%' IDENTIFIED with 'caching_sha2_password' AS 0x2441243030352458193E107A74537D0157055C66527F226B7E5C6148334873306842624633576D4D32465875624B756D722F434964313832706C324C6A2F674574784C765630;
Query OK, 0 rows affected (0.03 sec)

Let us check the user now:

(root@localhost) [(none)]>select user,host, authentication_string,plugin from mysql.user where user ='dba' and host= '192.168.4.%' order by 1,2;
+------+-------------+------------------------------------------------------------------------+-----------------------+
| user | host        | authentication_string                                                  | plugin                |
+------+-------------+------------------------------------------------------------------------+-----------------------+
| dba  | 192.168.4.% | $A$005$X>ztS}WfR"k~aH3Hs0hBbF3WmM2FXubKumr/CId182pl2Lj/gEtxLvV0 | caching_sha2_password |
+------+-------------+------------------------------------------------------------------------+-----------------------+
1 row in set (0.00 sec)

[root@master3 ps80]# ./mysql-3307 -udba -pdba -h192.168.4.57 -P3307

(This email address is being protected from spambots. You need JavaScript enabled to view it.) [(none)]>select current_user();
+-----------------+
| current_user()  |
+-----------------+
| This email address is being protected from spambots. You need JavaScript enabled to view it..4.% |
+-----------------+
1 row in set (0.00 sec)

As you can see the user has been created correctly and password is again in encrypted format.

In short what you need to do when in need to export users from MySQL/PS 8 is:

Read the user information
Convert Password to hex format when plugin is caching_sha2
Push the AS <password> converted to a file or any other way you were used to

Another possible solution is to use at session level the parameter print_identified_with_as_hex. If set causes SHOW CREATE USER to display such hash values as hexadecimal strings rather than as regular string literals. Hash values that do not contain unprintable characters still display as regular string literals, even with this variable enabled.

This at the end is exactly what Fred and I have done for our tools:

See:

Conclusions

MySQL 8 and Percona server comes with a more secure hashing mechanism caching_sha2_password which is also the default. However if you have the need to migrate users and you use your own tools to export and import the passwords, you must update them as indicated. Or use the Percona Toolkit tools that we keep up to date for you.

Have fun with MySQL!!

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Sakila, Where Are You Going?

The tests

Assumptions

What tests do we run?

Results

Sysbench read and write tests

TPC-C tests

What if we compare it with Percona Server for MySQL and MariaDB?

TPC-C

What are these tests saying to us?

Considerations

Is MySQL Router 8.2 Any Better?

The results

Test two

Test three

Conclusions

Export and import of MySQL passwords using caching_sha2

Conclusions

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