About the Author

Hi, I'm James.

// Director of Engineering · Database Infrastructure & Reliability

I've been working with data for almost 20 years and spent over a decade keeping databases alive at scale, under pressure, across most major platforms. I'm a DBA who doesn't believe in silos: I work with SQL Server, PostgreSQL, MongoDB, MySQL, Redis, and whatever else the architecture calls for.

There's no substitute for experience, but sharing it is the next best thing. This blog is where I write up what I've learned across nearly 20 years of database work: the patterns, the pitfalls, and the fixes that actually hold up in production.

Based in Ireland with my wife, two kids, and a dog named Daisy. When I'm not at a keyboard I'm on a pitch, playing or coaching sport, which turns out to be pretty good training for staying calm under pressure.

James Gallagher - The Polyglot DBA
James Gallagher
The Polyglot DBA
20yr+
Professional Data Experience
10
Different Database Types
Articles Published
∞
Query Plans Read
Databases

What I Work With

I cover all of these in production, not just toy examples. Each one has its own quirks, and I've hit most of them.

sql-server
SQL Server
My primary platform. Extended events, query store, AG clusters, TDE, replication - all of it.
Depth
postgresql
PostgreSQL
Vacuuming, logical replication, partitioning, EXPLAIN ANALYZE and an appreciation for its planner.
Depth
aws
AWS
RDS, Aurora, ElastiCache, DMS - managing database infrastructure across the AWS stack.
Depth
snowflake
Snowflake
Cloud data warehousing, virtual warehouses, time travel, and query optimisation for analytics workloads.
Depth
azure-sql
Azure SQL
Managed SQL on Azure - elastic pools, serverless compute, hyperscale, and hybrid connectivity with SQL Server.
Depth
mongodb
MongoDB
Aggregation pipelines, Atlas, replica sets, index strategy, and schema design for document stores.
Depth
elasticache
ElastiCache
Memcached, Redis, and Valkey on AWS - engine selection, cluster sizing, eviction tuning, and failover.
Depth
qdrant
Qdrant Cloud
Vector similarity search, embedding storage, and building semantic retrieval pipelines at scale.
Depth
dynamodb
DynamoDB
NoSQL key-value and document store - partition keys, GSIs, streams, DAX caching, and serverless scale.
Depth
elasticsearch
Elasticsearch
Index management, shard sizing, mapping strategy, and when to use it vs. native DB search.
Depth
Expertise

What I Write About

The topics I keep coming back to - because they keep coming up in production.

🔥

Performance Tuning

Index strategy, query plan analysis, wait stats, execution plan regression - finding where time is actually going and fixing it.

🛡️

High Availability & DR

Availability groups, replica sets, replication topologies, failover testing, RTO/RPO trade-offs across platforms.

🔒

Security & Compliance

TDE, encryption at rest, permission auditing, row-level security, and keeping auditors happy without killing performance.

🏗️

Infrastructure at Scale

Managing fleets of database instances, automation, monitoring, capacity planning, and keeping ops sane.

🔄

Replication & Sync

Transactional replication, logical replication, change data capture, and the joys of resolving conflicts at 2am.

🗺️

Polyglot Architecture

When to use which database, how to manage them together, and why "just use Postgres for everything" isn't always right.

Background

The Journey

How I got here.

2026

Started The Polyglot DBA

Writing up 20 years of patterns so others don't have to learn them the hard way.

2025 – Present

Director of Engineering, GLG

Engineering leadership, still close to the data problems that got me here.

2011 – 2025

Senior Engineer → Principal Engineer, GLG

Fourteen years building and running data infrastructure for one of the world's leading professional learning platforms.

2006 – 2011

Ergo & Early Career

Software and BI development across financial services clients in Ireland. Where it all started.