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I hope those are interview questions for dbas because it's way outside common knowledge for backend developers.

tatersolid 9y ago
Why are back-end developers not supposed to have a deep understanding of their tools? I hear this sort of statement all the time, it’s infuriating. I once even had a dev team lead claim that it was not a dev’s responsibility at all if the app generates bad SQL; the DBA is supposed to make the queries fast (this person no longer works for me, but I consistently hear similar claims from consultants and others in the dev community). DBAs are expected to understand the crappy inefficient row-at-a-time ORM in use by the devs, which implies understanding a particular programming language, but not the other way around? There’s nothing magical about SQL databases that a decent developer can’t understand.
- marcosdumay 9y ago
  > Why are back-end developers not supposed to have a deep understanding of their tools? You mean all their tools? Like how does modern processors handle branch predictions in the face of out of order operations, or what differences in server cooling will affect throughput or peak performance? Do you have a deep understanding of all the tools you use? Because I honestly doubt so.
- BOBOTWINSTON 9y ago
  I think there is a very large gap between being able to answer that interview question effectively and having decent understanding of how to not misuse your ORM. Specifically with ORMs, It does seem that a lot of devs don't understand or care about the generated SQL... but that question was way above the knowledge level I would expect/want out of someone IMO.
brlewis 9y ago
Not for DBAs, but I also don't expect candidates to get all the answers in that comment. It's a decent data structure question to ask why databases generally use binary trees for indexes when hash lookups are faster. Non-DBAs usually have to think a little bit.
- jeltz 9y ago
  Databases do not use binary trees for indexes and tables, they use B-trees. B-trees are a family of self balancing tree data structures which usually are not binary because in a database you want the tree to have few levels.
  - virmundi 9y ago
    Thank you. I remembe having to balance a B-Tree in my DB final. 5 nodes deep. Had to show all of the work. I think it ended up with 20 some revisions based on all the insert and delete statements.

Why are back-end developers not supposed to have a deep understanding of their tools? I hear this sort of statement all the time, it’s infuriating. I once even had a dev team lead claim that it was not a dev’s responsibility at all if the app generates bad SQL; the DBA is supposed to make the queries fast (this person no longer works for me, but I consistently hear similar claims from consultants and others in the dev community). DBAs are expected to understand the crappy inefficient row-at-a-time ORM in use by the devs, which implies understanding a particular programming language, but not the other way around? There’s nothing magical about SQL databases that a decent developer can’t understand.

marcosdumay 9y ago
> Why are back-end developers not supposed to have a deep understanding of their tools? You mean all their tools? Like how does modern processors handle branch predictions in the face of out of order operations, or what differences in server cooling will affect throughput or peak performance? Do you have a deep understanding of all the tools you use? Because I honestly doubt so.
BOBOTWINSTON 9y ago
I think there is a very large gap between being able to answer that interview question effectively and having decent understanding of how to not misuse your ORM. Specifically with ORMs, It does seem that a lot of devs don't understand or care about the generated SQL... but that question was way above the knowledge level I would expect/want out of someone IMO.

brlewis 9y ago

Not for DBAs, but I also don't expect candidates to get all the answers in that comment. It's a decent data structure question to ask why databases generally use binary trees for indexes when hash lookups are faster. Non-DBAs usually have to think a little bit.

jeltz 9y ago
Databases do not use binary trees for indexes and tables, they use B-trees. B-trees are a family of self balancing tree data structures which usually are not binary because in a database you want the tree to have few levels.
- virmundi 9y ago
  Thank you. I remembe having to balance a B-Tree in my DB final. 5 nodes deep. Had to show all of the work. I think it ended up with 20 some revisions based on all the insert and delete statements.