The latest from the MySQL community

The Model Context Protocol (MCP) has become a standard way for AI agents to discover the tools an application, database, or service offers. Claude Code, Codex, Cursor, Antigravity, et al. can connect to an MCP server, ask it what tools are available, and call these tools instead of figuring out what they can or can't do on the fly or piecing together API calls. Setting up an MCP server for a database usually means running a separate process that holds a database credential and turns tool calls into queries. Then you have another process to deploy, another place a credential lives, and a set of guardrails that sit outside the database.

The vsql-mcp extension from VillageSQL takes a different approach. It puts the MCP server inside the database. Install it, set a handful of global variables, and your MySQL server itself serves MCP over Streamable HTTP from a background …

The MySQL Community conversation continues this fall with two opportunities to connect, share feedback, and help shape the future of MySQL.  Following the recent Contributor Summits and Public Discussions, we are continuing to expand practical ways for users, developers, DBAs, partners, and contributors to participate in technical discussions, share ideas, and collaborate more openly across the MySQL […]

EmergencyReparentShard operations are being hardened in upcoming release v25. In this blog, we cover how ERS works and the upcoming changes that make recovery safer, faster and less brittle What is EmergencyReparentShard? # EmergencyReparentShard (ERS) is the Vitess failover process used when a shard's current primary is dead or unreachable. While PlannedReparentShard gets a clean handoff from a healthy primary, ERS has to pick a replacement using only surviving tablets. It compares their transaction histories, promotes an eligible replacement, updates the topology and points the other tablets at the new primary.

Before MySQL 8.0, DDL was not crash-safe. There were three main problems:

1. The metadata in the server layer and the metadata/data in InnoDB could become inconsistent.

   The server-layer metadata was stored in files — for example, table definitions were kept in .frm files — while InnoDB kept its own copy of the metadata in its tables. A crash could leave the server-layer metadata inconsistent with InnoDB’s metadata or even with the table data. For example, the server layer still had the table’s .frm file and believed the table existed, but InnoDB’s .ibd data file was gone, so InnoDB believed the table did not exist.

2. InnoDB’s metadata and data could become inconsistent.

3. The binlog and the data could become inconsistent.

   For example, after a crash and …

TL;DR

Percona Server for MySQL 9.7.2-2 now supports DISTANCE() for vector similarity scoring directly in SQL (COSINE, EUCLIDEAN, MANHATTAN, DOT metrics). This is the compute primitive you need to rank or filter embeddings by similarity directly in SQL. ANN indexing (e.g. HNSW, IVF) is the next milestone for fast large-scale similarity search; and this function provides the scoring layer that indexing strategies will further accelerate.

Why we’re adding this

MySQL’s native DISTANCE() and VECTOR_DISTANCE() functions are only available in HeatWave MySQL on OCI, not included in Community or Commercial MySQL, and limited to three metrics (COSINE, DOT, EUCLIDEAN). Percona is bringing the same capability to anyone running Percona Server for MySQL on any supported platform.

MySQL 9.7 already supports the VECTOR data type (TO_VECTOR() and FROM_VECTOR() functions) for storing embeddings. DISTANCE() …

This September and October, Heather VanCura will meet with MySQL users, contributors, developers, DBAs, customers, and community leaders across Brazil and Europe. With more than 30 years of innovation behind it, the MySQL community is entering an important new phase. The focus is on expanding engagement, collaboration, and contributions while increasing and driving innovation and unification of the ecosystem. The tour will […]

A while ago, we discussed the cross-site replication feature of the Percona PXC operator. Recently, a similar cross-site replication feature was introduced in the Percona (PS MySQL) operator v1.2.0, a topology based on Group Replication/InnoDB Cluster.

In this blog post, we will explore how to add a DR Cluster to an existing DC Cluster to form a ClusterSet environment, which provides a seamless switchover between DC/DR members. The good part is that all the complexity and configuration will be managed by the Percona operator, with very few setup steps required.

Group Replication …

A few thousand gcache.page.* files in a Percona XtraDB Cluster (PXC) data directory is not something you see every day. We came across a case where these files had been accumulating over time and slowly consuming disk space. So, let’s dig into what happened.

At first glance, it looked like GCache had simply stopped cleaning itself up. The investigation started by answering two simple questions: when did the files start appearing, and what changed in the cluster at that time?

Finding the starting point

The oldest files showed the issue started on July 9.

[hostx] percona@hostx: ~ $ ls -lh /var/lib/mysql/mysql-data/gcache.page.*
-rw-r----- 1 mysql mysql 128M Jul 9 21:42 /var/lib/mysql/mysql-data/gcache.page.000000
-rw-r----- 1 mysql mysql 128M Jul 9 21:42 /var/lib/mysql/mysql-data/gcache.page.000001
-rw-r----- 1 mysql mysql 128M Jul 9 21:42 /var/lib/mysql/mysql-data/gcache.page.000002
... …

“Would making this capability available help a meaningful part of the MySQL community build better applications or run better systems?”

Q1. MySQL has recently made available several features from the enterprise tier to the MySQL Community Edition. What is driving this direction?

The simple answer is that Community Edition needs to stay strong for the people who build, run, and depend on MySQL every day. That includes developers, DBAs, startups, large enterprises, and software vendors.

When we bring broadly useful capabilities into Community Edition, particularly in areas like observability, high availability, performance, and developer experience, the whole MySQL ecosystem benefits. Users get a better platform, and we get better feedback from real workloads at scale.

Recent examples include replication observability and Group Replication capabilities, …

Percona gives us room to work on our own AI-assisted projects, and I used mine to fix a problem I kept running into. Every time I wanted to try a new database feature, debug something tricky, or reproduce a customer issue, I ended up rebuilding much of the same infrastructure: DNS, TLS, Docker networking, database topologies, users and test data. Over the years, I wrote scripts to automate this but I still found myself copying and pasting post-installation steps from one lab to the next.

That repetition is what turned into DBCanvas, a self-hosted lab for designing, deploying, operating, and stress-testing multi-node database stacks on my own machine. Just design a topology on a canvas, click Deploy, and get real running nodes connected to the services and supporting infrastructure your test requires. Then, use the tools built into it or third party tools to load those …