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Problems with JPA/Hibernate

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Re: Problems with JPA/Hibernate

#191

Post by cratermoon »

hodgesrm wrote: post #190
cratermoon wrote: post #186

Earlier quoted context omitted.

Can you clarify how autogenerated keys are different from an autoincrement id column? In my experience, the autogenerated keys are built on top of auto-increment columns. Of course, if you use a stored procedure or something to generate a value, then you're just using a unique ID, same as anything else, but making your system dependent on the DB, which isn't awesome if you have a distributed system with replication a…

I might have missed something upthread but autogenerated keys to me just mean that the key is somehow generated automatically for you rather than using a natural key like social security number (SSAN) when inserting rows. Autoincrement IDs are one way of autogenerating a key that delegates generation to the DBMS server. To expand on this, there are three common approaches to create automatic keys in SQL applications.…

How is SEQUENCE different from AUTO_INCREMENT if you have only a single writeable db instance? If you dump & restore a table with SEQUENCE values as IDs, does the restored DB have the same IDs, or are they generated anew on restore?

Also, SSN is a terrible key [1] and getting uniqueness without central coordination can be done with UUIDv4 or ksuid [2], as long as you have a reasonably trustworthy source of randomness

[1] https://news.ycombinator.com/item?id=26776092

[2] https://github.com/segmentio/ksuid/blob/master/README.md

Re: Problems with JPA/Hibernate

#192

Post by igouy »

AaronFriel wrote: post #49
jacques_chester wrote: post #33

Earlier quoted context omitted.

> Which of the TechEmpower benchmarks uses an ORM? There are two: single query and multiple query.

Sorry, I should have been more precise. I am very, very familiar with the TechEmpower benchmarks and I first learned Java around SE 5, right after they switched from 1.x numbering. Please don't mistake me for someone who just learned about Go or Rust and is evangelizing them because I think they're the cool new thing. Which of the Java implementations for the TechEmpower benchmarks use an ORM? Are they representative…

> Are there any other languages in the TechEmpower benchmark or the Debian benchmark game (formerly went by another name) that requires setting an "IntegerCache" to optimize... allocating integers?

afaict Java programs shown on the benchmarks game website do not.

Re: Problems with JPA/Hibernate

#193

Post by simonw »

orf wrote: post #131
simonw wrote: post #51

Earlier quoted context omitted.

I like IDs I can read out over a call, or recognize when I spot them in a log file. The few times I've used UUIDs for IDs I've later regretted it.

> or recognize when I spot them in a log file “14632” in a log file could be anything, whereas a UUID is way more explicit and searchable.

I have frequently memorized IDs of things in systems I interact with often:

"Oh, it's user 14632 - yeah I've seen that ID crop up against this issue a bunch of times in the past"

I can't do that with UUIDs.

Re: Problems with JPA/Hibernate

#194

Post by orf »

simonw wrote: post #193
orf wrote: post #131

Earlier quoted context omitted.

> or recognize when I spot them in a log file “14632” in a log file could be anything, whereas a UUID is way more explicit and searchable.

I have frequently memorized IDs of things in systems I interact with often: "Oh, it's user 14632 - yeah I've seen that ID crop up against this issue a bunch of times in the past" I can't do that with UUIDs.

Sure, but I think you would usually optimize for the inverse - actively finding a needle in a haystack rather than passively hoping a needle falls in your lap. I get 1k hits for "14632" in our Splunk for the last 60 minutes, all of it rubbish. Durations, image sizes, worker IDs, primary keys, port numbers.

Search for a UUID and the results are guaranteed to always be relevant. Can't do that with integers.

Re: Problems with JPA/Hibernate

#195

Post by hodgesrm »

cratermoon wrote: post #191
hodgesrm wrote: post #190

Earlier quoted context omitted.

I might have missed something upthread but autogenerated keys to me just mean that the key is somehow generated automatically for you rather than using a natural key like social security number (SSAN) when inserting rows. Autoincrement IDs are one way of autogenerating a key that delegates generation to the DBMS server. To expand on this, there are three common approaches to create automatic keys in SQL applications.…

How is SEQUENCE different from AUTO_INCREMENT if you have only a single writeable db instance? If you dump & restore a table with SEQUENCE values as IDs, does the restored DB have the same IDs, or are they generated anew on restore? Also, SSN is a terrible key [1] and getting uniqueness without central coordination can be done with UUIDv4 or ksuid [2], as long as you have a reasonably trustworthy source of randomness…

With SEQUENCE it's up to you to select the ID and insert it as a column value in your code. With AUTO_INCREMENT the DBMS does it for you. They both depend on a central DBMS to generate values. In both cases you can restore data. The IDs are just normal column values after generation.

As far as SSAN I'm not asserting it's a good key, just a natural key, which is to say a key inherent in the record.

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