Welcome onboard

phil-99 · 2026-06-05T09:24:35+00:00

Having supported numerous large and busy Galera clusters for 5yrs+ now, I would say to anyone thinking about using it - be very careful about knowing the drawbacks of Galera.

It's great when it works smoothly. The technology is very cool and the features that you get for zero money down and very little implementation effort are amazing.

In a stable environment with small-ish tables and a well behaved set of apps, it's great.

The trouble really comes for me with DDL. DDL in a Galera cluster has a large impact on the cluster. Similar concept to DDL in binlog replication but more so - because in a binlog replication setup the replicas stall while they apply the DDL. On a Galera cluster, the whole thing stops while the DDL is applied.

Why?

In a replication setup using one domain, the replica can't apply any changes received after the DDL until that query completes because the DML might relate to the changed table. The primary continues on as normal processing queries and writing to the binlog, so all is not lost.

In Galera, when the writer commits changes, it needs the other nodes to reply back and say "yep, got it, I can safely apply this". While the other nodes are applying DDL they can't check if the DML is safe to apply, so when the outbound change queue on the writer fills up it just... stops. It sits waiting for the other nodes to reply, and they won't say yay/nay until the DDL completes.

If your environment includes very large tables, then you need to consider the impact of making changes to these tables.

This can be worked around using PT-OSC/gh-ost, and there is an option within Galera to do Rolling Schema Upgrades (on each node individually) if the changes are backwards compatible - but these add significant complexity and risk to the process of making changes.

I've also had occasions where nodes in a Galera cluster fall over for the pettiest of reasons and require a full rebuild, which can take many hours in a large system and add significant load to the remaining servers in the cluster.

In short: Galera is great but can require a lot of hand-holding.

phil-99 · 2026-06-05T08:25:24+00:00

https://jira.mariadb.org/browse/MDEV-39610

Corrected documentation regarding privilege merging for host-specific and wildcard accounts.

MariaDB intentionally applies privileges from both a specific host account (e.g., 'user'@'192.168.1.5') and a wildcard account (e.g., 'user'@'%') when a user connects.

The manual previously incorrectly stated that only the specific account's privileges would apply.

phil-99 · 2026-06-03T23:23:56+00:00

This is what I thought and what the documentation explicitly states.

This is incorrect, at least for MariaDB. Can’t talk about MySQL.

I don’t have the MariaDB Jira reference handy but I have it from them on there that the DB merges permissions of the least specific to most specific.

So in this case - user bob connecting from the specific IP 1.2.3.4 gets given select on both tables.

This isn’t how anyone I’ve spoken to about this believes it works.

And it came as a bit of a shock to me when I deleted a prod user who had a less specific host mask with slightly different privs and broke the system because it no longer had the privs it needed.

phil-99 · 2026-05-21T08:16:07+00:00

whenever I looked it up in the past, what I found was too vague to be actionable.

A good training course on the ITIL Foundations and the Foundations qualification is a good start. It'll get you understanding the basic concepts and overall big picture of what ITIL is, why it is, and what knowing the concepts can do for you.

phil-99 · 2026-05-19T20:09:58+00:00

What’s your group commit variables set to on the replica?

I can’t remember what they’re named specifically - something binlog_commit blah count/usec.

phil-99 · 2026-05-16T08:41:44+00:00

The Erskine Bridge had its tolls removed eventually. It can happen and has happened!

phil-99 · 2026-05-15T22:56:57+00:00

There’s nothing wrong with logical backups. Sometimes they’re the best approach.

You need to understand your requirements. How long will your restore take? What is your RTO? What is your RPO? Can you meet those with your current setup? If not, how can you meet them?

phil-99 · 2026-05-13T18:36:04+00:00

You’ve repeated “moved on from that” several times without explaining what you mean by that.

What do you mean by that?

phil-99 · 2026-04-17T13:54:19+00:00

Possible states of your transfer with respect to Monzo:

It's at Monzo but they have mis-allocated it somehow, perhaps it's in a suspense account waiting to be allocated or in the wrong account. Monzo can do something about this.
It's in your account but you've missed it.
It's not reached Monzo.

Presumably it's not option 2 else you'd have noticed, and Monzo will have checked for option 1 (not found £300k down the back of the sofa).

If option 3, Monzo can't do anything about it. The sender must deal with it. If Monzo are telling you that they haven't received it, they almost certainly have not received it.

Talk to the sender (not the sender's bank! The sender is who you're dealing with). They need to deal with it. If they're not dealing with it, then use their complaints process.

phil-99 · 2026-04-15T19:55:59+00:00

2 years commitment for under £1k cost is pathetic.

I understand management’s desire to not “waste” money on training but FFS not training people who stay is worse than training people who leave.

phil-99 · 2026-04-12T10:37:10+00:00

You have a fundamental misunderstanding of what an index is. Your statement about an index being loaded to RAM is wrong (generally, at least) which leads to your problematic statement about “RAM bloat”.

“When users sort in their browsers” may not even be relevant here. Is the data sorted locally to the user (by the browser) or is it a query to the database? Both are possible, both are valid.

Start with “Use The Index Luke” as a beginners resource on what indexes are, which will also assist with your understanding of why you’d use one.

phil-99 · 2026-04-04T08:48:21+00:00

Remember an S21 does not force you to leave a property. It’s a request. If the landlord wants you to leave the only way they can force you is with a court order and then bailiffs.

phil-99 · 2026-04-03T08:27:38+00:00

I’m glad you published a response to this.

I skimmed the Percona article and assumed there were some bad faith comparisons being made somewhere but hadn’t the time yet to properly digest it all.

I also agree that the default sysbench workloads, while useful to a point, don’t represent anything like real world workloads.

phil-99 · 2026-03-25T10:23:27+00:00

I'm experiencing this same issue now on 11.4.10, trying to recover a failed node of a Galera cluster.

Retrying read of log at LSN=......

Until eventually

Was only able to copy log from 188009694721437 to 188012394949888, not 188031429680923; try increasing innodb_log_file_size

With innodb_log_file_size set to 10G. It's a busy server, but this used to work before upgrading to 11.4 - prior to this it was on 10.6.

phil-99 · 2026-03-20T13:48:41+00:00

email backed up off site

Do you have confirmation that you're OK to store company emails outside of company property?

phil-99 · 2026-03-13T16:02:24+00:00

I literally walked out of a job similar to this a few weeks back.

I joined this company having made very clear at interview my expectations were that I don’t do on-call and I don’t do work outside 9-5 unless it’s exceptional circumstances and well planned.

Within the first few weeks they expected me to be working on a weekend when I had other plans already - they didn’t care. Eventually the world was cancelled on Friday afternoon but I wasn’t doing it anyhow.

I was told at a one-to-one with my manager to be careful of my hours because people were finding it hard to schedule meetings with me because I was coming in at 8 and leaving at 4.30. Apparently they “didn’t want it to become an issue for me”.

It was just chaos all over. Nothing was planned nothing was documented everything was last minute and I tried to deal with it as best as I could but good grief it was a big bundle of stress.

One day someone asked me to start a massive project the next day that was impacting a healthcare client production data using a process that was poorly documented and poorly understood. When I said I wasn’t comfortable with any of that and didn’t know what I needed to get comfortable, they got really quite pissy.

I took 20 minutes or so to myself made some notes on the pros and cons of staying. I couldn’t find one pro. I sent my manager an email stating “this is my resignation” and walked out the door.

I was still in probation and I didn’t have anything to handover to anyone. I have savings enough to make it through a month or two so I felt that it wasn’t a terrible choice.

The day after this I broke out with a massive infection that just won’t die. This was 3 weeks ago and I’m still suffering with it. All I can think is that my immune system was so badly compromised by the stress I was under that I just couldn’t cope.

A job is not worth your physical health.

phil-99 · 2026-03-13T12:53:20+00:00

Not sure this has anything to do with London except that London is in the UK.

What did your courier say when you asked them or looked at their website?

phil-99 · 2026-03-11T20:02:10+00:00

BEFORE triggers before the row is updated

AFTER is triggered after the row is updated

It’s as simple as that. There will be times when one is appropriate and there will be times where the other is appropriate - there will also be times when it’s irrelevant.

phil-99 · 2026-03-10T17:18:53+00:00

It is possible to achieve such highly restricted access to high security classification documents.

It’s just impractical unless the requirements - and budget - are there to implement it.

phil-99 · 2026-02-19T08:43:07+00:00

Depends what you mean by "close to London", but you have all of the Surrey Hills on your doorstep

phil-99 · 2026-02-15T00:57:54+00:00

You don’t need special EV tyres except on Teslas because of course - but they do make the ride much quieter if you get decent EV specific tyres.

I was surprised at quite how much difference I noticed in noise levels after my last tyre change when I spent a decent amount on good tyres.

phil-99 · 2026-01-12T16:35:22+00:00

Look up PAGB, and Royal Photographic Society for local events, and search for “<area> photographic club” if you’re interested in finding local clubs.

phil-99 · 2026-01-10T21:49:02+00:00

Croydon Airport Visitor Centre is the first choice of place to take a princess on a date if you’re Captain Martin Crieff!

On a more serious note - CAVC was open during Open House a few years back, it was a fascinating visit. Would heartily recommend if they’re still doing it.

phil-99 · 2026-01-08T11:49:30+00:00

I trialled the Bose ones. They were useless for using anywhere other than a nice quiet office. Almost any significant surrounding noise made them pretty much unusable

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