The latest from the MySQL community

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 …

Welcome back. This issue covers five weeks rather than the usual one — the gap since the August issue took in Percona Live Amsterdam, the launch of the OurSQL Foundation, and the run-up to the MySQL Galera Cluster end of life on 30 September.

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Enjoy!

MySQL News

Note: Aggregated MySQL news can be found at Planet for MySQL Community and Planet MySQL (Oracle curated)

DISTANCE() and VECTOR_DISTANCE(): Vector Similarity in Percona Server for MySQL …

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() …

For this quick verification of the 0.0.7 development branch of VillageSQL with the new vsql-vector plugin. Recreate the VillageSQL Percona Live presentation using MySQL version 8.4 and SVECTOR. Demonstrate a more detailed example using SVECTOR(1024) string embedded data.

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 […]

We are pleased to announce a new extension for VillageSQL Server that enables running DuckDB queries from within MySQL and joining those results with MySQL query results. DuckDB has emerged as the analytical engine of choice for fast querying of data formats such as Parquet. It excels with analytics queries because of its columnar storage, vectorized execution, and embedded architecture. Applications often need to combine the results of analytical queries with operational results, though. There are multiple ways to do this, but many are suboptimal when the query's results need to be returned to an application that is connected to an operational database such as MySQL.

The new vsql-duckdb extension from VillageSQL solves this by embedding DuckDB inside MySQL, keeping your existing database …

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
... …