FOSDEM 2026 - Notizen

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preFOSDEM MySQL Belgian Days 2026

Agenda

The PlanetScale Binlog Server

Shlomi Noach, PlanetScale/Vitesse

• Inventor Jean-François Gagné
• Duplicate Binary Log (possible to store to “slow” hdd?, S3)
• Works semi-sync
• Serve binary logs
• Only one singe replication tree
• See also Percona binlog server

Binary Log Server - the missing MySQL infrastructure component

Yura Sorokin, Percona, Source

• mysqlbinlog --from-remote-server is very limited
• Blackhole SE: Overhead in Level 0 slaves → opportunity:
• Percona Binlog Server
  • Much less overhead compared to mysqld
  • Works in 2 modes:
    • Fetch: until last or error
    • Pull: continues + reconnect

InnoDB: Deep dive into Dynamic Redo logging and Instant DDL

Dimitri Kravtchuk

• Dynamic REDO configuration
  • Tail: Checkpoint-age
  • InnoDB log streaming
  • *_tmp: not in user
  • 32 log files
  • See also here and here
  • Details you will find in P_S
  • 
• Instant ADD/DROP COLUMN
  • → Version → check in P_S
  • Best practice: ALGORITH = INSTANT
  • See also I_S.innodb_tables
  • Page fragmentation hints
  • 

Beyond Linear Read-Ahead: Logical Prefetching using Primary and Secondary Indexes in InnoDB

Vitor Oliveira (Huawei)

Innovating in MySQL with Extensions

Tomas Ulin and Dominic Preuss

• Tomas Ulin → own company: VillageSQL
• A branch of MySQL

Starting a New Era for the MySQL Community, Part II

Heather VanCura, Oracle

Bringing Flamegraphs to MySQL Query Optimization

Vinicius Grippa, Percona

• EXPLAIN ANALYZE with: explain_json_format_version = 2
• myflames on Github

FOSDEM, Saturday

Agenda

PostgreSQL and MySQL, Two Databases, Three Perspectives

Rohit Nayak, Shlomi Noach, Ben Dicken, Pep Pla

• PostgreSQL
  • License and Community (+)
  • Extensions (+)
  • Vibes (+)
• Architecture
  • Clustered table vs. heap table
  • Processes vs. threads → Pooling necessary if > 100 connections, pg_bouncer, ProxySQL (- PostgreSQL)
  • Index flexibility (+ PostgreSQL)
  • Storage Engine → pg_repack, pq_squeeze, OriolDB
  • Extensibility (+ PostgreSQL)
  • Replication (- PostgreSQL)
• MVCC
  • PostgreSQL: in table
  • InnoDB: in undo
• In PostgreSQL reads can provoke writes (visibility bit)!
• InnoDB: No bloat
• Clean-up:
  • InnoDB page cleaner process
  • PostgreSQL: VACUUM
• Logical replication:
  • MySQL logical binlog application
  • PostgreSQL → WAL, physical copy
  • MySQL: all changes
  • PostgreSQL: only row changes + relation info

“Drop-in Replacement”: Defining Compatibility for Postgres and MySQL Derivatives

Jimmy Angelakos, Daniël van Eeden (pgEdge)

Jack of all trades: query federation in modern OLAP databases

Nicoleta Lazar

• Trino → Global Query layer
• StarRocks → Extension of OLAP Engine (OSS)

                           +--------------+
                           | ...          |
+--------+    +-------+    +--------------+
| Client | -> | Trino | -> | Data Sources |
+--------+    +-------+    +--------------+
                           | ...          |
                           +--------------+

                                               +--------------+
              +---------------------------+    | ...          |
+--------+    |+-----------+ +-----------+|    +--------------+
| Client | -> || StarRocks | | DataCache || -> | Data Sources |
+--------+    |+-----------+ +-----------+|    +--------------+
              +---------------------------+    | ...          |
                                               +--------------+

• Apache IceBerg
  • Open Table Format

Cracking Down the Code: What Really Happens When You Run a SELECT?

Charly Batista

• SQL - The wish
• Planer - The bet
• Executor - The bill
• Parser → Tree profile
• Analyzer → Query tree
• Rewriter
• Planer + Statistics
• Executor - Measure shared buffer usage

Server, Storage Engine, Protocol, Client: Suspects of a MySQL Performance Mystery

Vitor Oliveira (Huawei)

• GaussDB
• BenchmarkSQL or BenchmarkSQL
• Important tuning parameter for the benchmark: JDBC fetch_size

Delegating SQL Parsing to PostgreSQL

Greg Potter

• *.sql → empty DB → query DB → system catalog + pg_class, pg_depend, pg_attribute
• Stores the graph

Replicating Transactional Databases to ClickHouse: Transaction Log Analysis and Time Travel

Arnaud Adant

• Replication (logical)
• CDC (Debezium)
• Antlr → PeerDB

MariaDB Day – Brussels

Agenda

Meet 12.3 LTS

Nikita Malyavin, MariaDB Corp.

New features in MariaDB 12.3 LTS

• SET SESSION AUTHORIZATION user@host
• File key management
• SQL: IS JSON
• SET PATH
• Storage Engine: VIDEX (hypothetic indexes) → EXPLAIN
• Performance
  • aria_page_cache segments, for temporary tables
  • MDL lock sharding
• Replication
  • wsrep_applier_retry_count
  • slave_parallel_threads
• Storing binary log in InnoDB!!! → Slides
• Oracle compatibility

How MariaDB Achieved 2.5× OLTP Throughput in Enterprise Server 11.8

Steve Shaw, HammerDB (“leads” the MariaDB Plc. performance/bencharking team!!!)

• Amdahls law
• Universal Scalability Law (USL)
• TPC-Council
• TPC-C is a trademark
• TPS vs. CPU load (mysqld + app) → 5 min test

MariaDB is the Future of MySQL

Michael “Monty” Widenius, MariaDB Corp

• OSS vs. commercial
• PostgreSQL
  • Connections/threading
  • Logical replication

MySQL 8.0 Galera Cluster to MariaDB Galera Cluster migration: Theory and Practice

Jan Lindström, MariaDB Corp

What MariaDB Community Can Learn From PostgreSQL

Peter Zaitsev, Percona

Seamless Schema Changes: Mastering Non-Blocking ALTER TABLE in MariaDB

Nikita Malyavin, MariaDB Corp

Rebuildilng Code with CodeWolf and Mariadb Galera Cluster with Vector Databases

Paul Clevett, Wolf Software Systems Ltd

• Rewrites old legacy code (Cobol, etc.) into modern languages (like Rust)
• Wolf Software Systems Ltd
• Github

Optimising Ingres Data Migration

Nick Deninng, Diegesis

• Slides

Deploying RAG Without the Plumbing: MariaDB’s Unified Approach

Alejandro Duarte, MariaDB Corp.

• RAG: Context is all you need
• MariaDB AI RAG → Enterprise
• Model LLM für Laptop für RAG
• See video on YouTube

The blissful boredom of choosing MariaDB

Dirk Hillbrecht, Cantamen

(Almost) No Downtime MariaDB Upgrades

Andrija Vučinić, Automattic

Building the European Cloud with MariaDB

Carl Schwan, Nextcloud

Running MariaDB When Nobody Wants to Be the DBA: From Manual Guesswork to Safe Automation

Roman Agabekov, Releem

HyperDB

• On Github
• Query Response time plug-in

Summit for MySQL Community – Europe – 2026

Announcement

Some statements noted at the Summit organized by Percona:

• MySQL is becoming a DB2.
• PostgreSQL is still a bitch to operate.
• There are significant differences between user behaviour in Europa/North America and Asia.
• 50% of MySQL staff was RIFfed (Reduction in Force = fired) recently at Oracle. But after significant growth in the last years. We are talking about 50 Developers now.
• MySQL is at risk at #Oracle.
• MySQL is not dead but in “maintenance mode”.
• #Alibaba has more developers working on MySQL than Oracle.
• Why PostgreSQL is winning: Extensions!

Companies seen at this Summit: Percona, MariaDB, Oracle, AWS, Ubuntu/Canonical, WordPress, booking.com, ProxySQL, and many other huge players of the ecosystem.

Summary by Kaj Arnö, MariaDB Foundation? having stakes in the MariaDB Corp, 2026-02-03 : Reading the Room: What Europe’s MySQL Community Is Really Saying

Why PostgreSQL is winning? → Extentsions! I am not so sure if this technical explanation is the only one…