I would say not. For example, I have been doing oracle database administration work for many years. Even though I'm also good with a lot of other technologies, like Linux, programming in many languages, other databases. But no one will consider me for jobs other than oracle DBA/developer for the salary I know have. So it is kind of a trap. And it is super hard to accept a junior job offer when you are approaching forties.
Hey. I am 37 and a week ago started to learn to touch type the proper way. It's not a problem for me to touch type, but I did it with like 4-5 fingers and Never could get past 80 wpm. Now I started to learn the 10 fingers method and I feel like I miss almost every stroke. So frustrating
I am talking about INDEX FAST FULL SCAN (Oracle) for example. If you do 'select distinct last_name from users;' and you have an index on users (last_name) you do not need to read the table at all. It is enough to read the index.
Otherwise it does not matter how many columns you select, because you will have to read all the columns for every row anyway.
It's not about choosing the right index. The point here is that the database can only read the index (without going into the table) if all the columns you need and use in where clause are in the index. Usually index segments are smaller, so it could be faster. I am talking from the Oracle perspective, but I believe PostgreSQL would work in a similar way.
Hey, guys, thanks for answers. Didn't think anyone would even notice my comment! I really like the idea of helping the community even for free. The problem here is I have no idea how to start. For me to dig deeper (and I am working with Oracle on a daily basis) the problem has to occure and be repetable, so how can I get into fixing problems if I am not even using PG? I could, probably, install it on my PC/notebook, but it won't be a production use, so I probably won't face any problems.. It's always been a puzzle for me: how do people start with open source projects.
I am 35 and I am lonely and it's not getting any better + my job is getting boring (DBA), since I am pretty familiar with everything, and there's no chance for me to switch to programming, even though I know JS and many other languages, but my resume says: 10+ years DBA.
Can't talk about MySQL or PostgreSQL, but with Oracle I am pretty sure you can get very much close to this result with cached data. And this is without using the in-memory option. However, talking about it withouth any experiments to prove a point is just speculation. Memory vs Disks changes a lot performance-wise.