I have lost commands in the Bash history as well and I don't know why. Fortunately, I store all commands executed (+ time, return value etc.) in an sqlite database so I run a program from time to time to import that into the Bash history. The Bash history is useful for Ctrl+R
Exactly. That is what we have today at Belfort; not enough for making all AI work privacy preserving, but fast enough for many applications, where otherwise unencrypted compute is not acceptable.
It's not unique to postgres, as others have said; the same thing can happen with e.g. MySQL poolers/proxies/etc., since the behavior of the connection can be changed dynamically and it persists for the lifetime of the connection.
Example: legacy client A connects to MySQL via the bouncer and says 'I want all of our conversations to use latin-1, not utf-8'. This changes the character set that MySQL parses queries with and returns responses in. The legacy client does some queries and then disconnects.
Now a new client connects to MySQL, and the bouncer just assigns it to the still-open connection from before. The new client is fully UTF-8 compatible and since this is the default for our database it doesn't explicitly say so; it just assumes that UTF-8 is the way to go. Unfortunately, the database server is still thinking in latin-1, meaning that if this new client sends UTF-8 data it will be parsed as latin-1; latin-1 is a subset of UTF-8, meaning that queries will actually work fine unless they need to use a character outside of latin-1, in which case they will get an error, or corrupted data, from the server.
The only solutions around this are:
1. Ensure that every client is using the same settings; if your database is for a single app that uses the same ORM, then this is automatic.
2. Ensure that every client is always explicit about everything it might need to change e4very time, so that every UTF-8 client explicitly sets UTF-8 connections even when that's the default; clients that need utf8mb4 ask for it explicitly and clients that can't handle it ask for something else. One way of ensuring this happens is to configure the server (or the bouncer) to use defaults which are not valid for anyone, or which are going to cause errors frequently and not rarely (e.g. setting the default character set to 7-bit swedish, which would cause frequent errors).
3. Use a bouncer which can either disallow these changes or detect and revert them after the original client has disconnected. I'm not sure if this exists for MySQL at least.
4. Use separate bouncers for each application that might be different (extension of #1); in other words, instead of having a bouncer or set of bouncers for each pool of database servers, you have them for each application; your web app gets one, your legacy reporting tool gets one, your ODBC connector gets one, and so on.
It's kind of a huge mess in theory; in practice, a lot of installations fall into the #1 case so it never matters, but that makes the occasional instance where it does matter extremely difficult to debug.
Recently ran into a related bug in duckdb. They implemented a basic http connection pooler (described as a parking lot) but there are edge cases where broken connections get returned to the pool then the next thing tries to use a busted connection and fails.
> 3. Use a bouncer which can either disallow these changes or detect and revert them after the original client has disconnected. I'm not sure if this exists for MySQL at least.
I was thinking of something that only exists at the pool level.
Every new version of your app has the potential to change behavior in a way that would affect the previous version if the connection was recycled during a progressive rollout.
But I don’t think I would want to create a real database user for every version of the app.
I suppose the connection pooler could map versioned users to the same real user, and use separate pools, but a dedicated UA field is probably better.
You'll see this kind of fun in other databases that support "persistent connections." When you start up, you have absolutely no idea what the state of the database is. If a previous process errored out, you might find yourself in the middle of a broken transaction for example. Did the last session do some weird SET magic to make things work? Did it create temporary tables? Well guess what, it's all still there!
Yes, as a consequence of how aggressively transparent to the postgres wire protocol pgbouncer wants to be. This article does a good job explaining it: https://www.augusteo.com/blog/how-pgbouncer-works
But doesn't that make situation even worse? They likely would be 100B+ market cap/total asset value if spun off into independent company, but not able to generate even 1B in annual profit? Activision Blizzard managed 1.5B income/20% margin by themselves before being bought by Xbox -- and somehow whole of Xbox now earns less?
It didn't destroy itself, it was intentionally harvested and the husk was sold to the highest bidder. The original leadership is long gone, the shareholders got their money back long ago, and the staff has turned over significantly. The Blizzard of yore is long gone, and that's ok.
