Why is MySQL no longer supported?

[Koki Okubo]

Hi there,
We are using Maria DB 10.6.8 with HAPI FHIR 5.6, and have some questions about MySQL that is no longer supported by HAPI FHIR.
As My SQL and Maria DB are actually the same, we are wondering what problems would be expected in the future.
Also, we would like to know why MySQL-support was ended.
If anybody knows above information, please let us know!
Thanks.

[Joel Schneider]

I'm also interested in the MySQL question.

We have a hapi-fhir version 5.6 system using MySQL 5.7.  When executing the hapi-fhir-cli migrate-database command for hapi-fhir version 5.7, it command returned an error saying, "FlywayException: Unsupported Database: MySQL 5.7" (for additional details, see issue #3444).  The root cause of the error seems to be the discontinuation of MySQL 5.7 support in the Flyway Community edition (as indicated in the Flyway MySQL documentation).  It was possible to avoid the error by using the hapi-fhir-cli migrate-database --dont-use-flyway option, but this seemed like a less-than-ideal solution.

I haven't seen an announcement saying hapi-fhir no longer supports MySQL, so I'm hopeful that migrating the database to MySQL 8 will enable the hapi-fhir-cli migrate-database command to once again use Flyway.

[Kevin Dougan]

Smile CDR are the maintainers of hapi-fhir and they have provided some clarifications on their documentation site:

https://smilecdr.com/docs/database_administration/setting_up_mysql.html

"Note that as of 2021.11.R01, MySQL is discouraged for production use due to performance limitations of the database. SmileCDR will continue to support customers on this database, but if serious performance issues arise, we will suggest migrating to a more performant database."

https://smilecdr.com/docs/getting_started/platform_requirements.html#database-requirements

"Smile CDR can also run on the following database platforms, however these databases do not perform well at scale. Smile CDR recommends that these databases be used for testing purposes only.

• H2
• Derby
• MySQL 5.7
• MariaDB 10.1

"

I hope this helps clarify the situation!

Kevin

[Joel Schneider]

Thanks, that's very informative.

In our case, the database backend we're using is Amazon Aurora MySQL.  I think this system is intended to perform well at scale.  However, we do use a MySQL JDBC driver to connect with it.

It would be interesting to know if there is guidance or tooling available to support migrating from MySQL to one of the more recommended platforms such as PostgreSQL, Oracle, or MS SQL Server.

 

[James Agnew]

For what it's worth, our concern with MySQL is that it tends to perform poorly at scale for the specific way that HAPI FHIR uses it, when compared to PG (or Oracle/MSSQL/etc). Certainly I don't think it can't perform at scale (Uber uses it as a significant part of their backend, which must tell us something about its ability to work at scale) but in benchmarks we've done we tend to see 50-100% slower performance on MySQL than on any of the other supported databases.

I don't see us dropping support for MySQL completely, so if it's working for you with the performance you need it may well not be worth worrying about. But if you are planning a new deployment, I think it's worth considering using PG instead.

Cheers,

James

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[tomo yamano]

Thanks for the clarification James, 

I just wonder why MongoDB is not supported. All of them are RDBMS-based. 

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[Kevin Dougan]

MongoDB is actually supported, see the docs here:

https://smilecdr.com/docs/getting_started/platform_requirements.html#database-requirements

"Non-Relational Database

The following database platforms are supported:

• MongoDB 4.2

[Sajith Jamal]

Hi Kevin,

How much of Smile CDR's documentation is relevent to HAPI FHIR when it comes to the mongoDB setup?......I have not seen much related to mongo on HAPI's github.

Or is it only available if we buy Smile CDR?

regards,

Sajith

[tomo yamano]

I think this is only for  the commercial product and not for the open-source . 

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[Kevin Dougan]

Yes, that is correct.

In order to get MongoDB support you need to purchase Smile CDR.

Here is the list of databases supported on hapi-fhir:

https://hapifhir.io/hapi-fhir/docs/server_jpa/database_support.html

Kevin

[tomo yamano]

It is generous yet. Thanks, Kevin

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