Tips for migrating from MySQL to Cloud SpannerTips for migrating from MySQL to Cloud SpannerSoftware Engineering Manager, Cloud Spanner

Since its initial release in 1995, MySQL has not only been the de-facto database for many data storage needs, but has gathered much attention over the years as one of the most well-recognized databases around when it comes to Relational Database Management Systems and transactional data processing.

Any application in retail, e-commerce, or banking has likely had its fair share of business depending on a relational database for its transactional needs. Many of these applications are built on MySQL due to its flexibility, open source nature, and strong community support.

Whether in the context of a migration from a relational database (like MySQL or PostgreSQL) , migration from a NoSQL database (like Cassandra), or a green grass workload, many companies turn to Cloud Spanner seeking a high availability SLA (99.99% for regional instances and 99.999% for multi region instances),  unlimited scale,  and low operational overhead – no patching required, no maintenance or other planned downtimes, just to name a few benefits.

The tooling and open source ecosystem around Spanner has evolved and grown ever since the service was introduced. HarbourBridge is a part of this ecosystem, and it’s meant to help customers port their existing MySQL or PostgreSQL schema to a Cloud Spanner schema. 

Application Migration Tips

Despite helpful tools like HarbourBridge, database migrations are never trivial. Here are a few things to pay attention to when migrating from MySQL to Spanner, and how to update your application logic to address them.

Note – The following snippets use the PHP client for Cloud Spanner. A couple of the snippets reference a partial Magento port that our friends over at Searce have been working on. Once you understand the operations, you should be able to implement the same in any of the other languages that Cloud Spanner supports.

Cloud spanner enforces strict data types  

In a MySQL query, the value of an attribute can be referenced as either a string or an integer. Example:

Both are valid and equivalent. 

In Cloud Spanner, the query will return an error if you try to reference an integer type by using a string representation.

Here is an example of a working query from Cloud Spanner:

  • select * from catalog_eav_attribute where attribute_id = 46; — this will work

  • Select * from catalog_eav_attribute where attribute_id = “46” — will fail, since we are supplying a string with “46” 

You may use a function like the following to assist you with such transformations.

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