The first one, yes.
The other 10k no, if they are called after in a loop in the user language
that runs over every row returned by the first query.
Like it is done in a lot of REST interfaces
That is the difference I was pointing out.
In fact I also said that in case of simple interfaces ORM does its work
well.
If I got you wrong, please show me some example that can optimize the other
queries after returning the first result set.
PSK
On Sat, Dec 21, 2024 at 2:06 PM Robert Engels <reng...@ix.netcom.com> wrote:
> This is incorrect. Most ORM will efficiently execute the first query with
> a single SQL statement. It’s called the N+1 Select problem and it is
> solvable.
>
> On Dec 21, 2024, at 3:43 AM, Luca Pascali <pascko...@gmail.com> wrote:
>
>
> In my experience, ORM has a structural flaw, and it cannot be otherwise
> (as well as a lot of automatic tools)
>
> Using ORM you are driven to write queries like (pseudo go code)
>
> objects := Table.filter(some rules)
> for o := range objects {
> if o.field == 5 {
> sub := Table2.filter(some other rules)
> }
> }
>
>
> this cannot be optimized a lot by compiler or ORM engine, because queries
> are separated.
> So having 10k elements on first query can bring up to 10k subqueries and
> the (almost) only optimization that the engine can operate is to cache
> queries result to choose if using an old result (can bring to other issues
> like memory usage or data retention) or ask to the db (lots, lots, lots of
> queries)
>
> If you manage to reduce 10k automatically generated queries to just 1
> handcraft query, you can save hundreds of seconds of execution time. Sorry
> for stating the obvious.
>
> Another aspect that magnifies the problem is that ORM engines creates SQL
> code that must be parsed by the db server, and this time is definetly not
> zero.
> And not all db servers have the possibility to precompile queries.
>
> Again the obvious: 1ms over 1 query is not a problem. 1ms over 10k queries
> takes 10 seconds (plus the execution time, plus the parsing time to build
> object representation, plus ... ).
>
> So ORM can be the wrong choice,but
> If you don't have a complex db structure (this means a few connected
> tables) and/or you can use some sort of advanced merges where you can
> specify the projection in the orm itlself (that's something like writing a
> raw query) ORM is a fantastic abstraction, because it allows you to write
> simpler code.
>
> In conclusion, it is not ORM that is slow.
> Sometimes it is just not the right tool.
>
> If you need some simple access proceed with ORM. If you need something
> more complex, optimize the code to reduce db access to the essential
> (prefetch as much as you can) and write your own queries. In that case sqlc
> is perfect
>
> My 2¢
>
> PSK
>
>
> On Fri, Dec 20, 2024 at 6:54 PM Kerem Üllenoğlu <kerem.ul...@gmail.com>
> wrote:
>
>> Hey,
>>
>> I keep hearing ORMs - especially GORM - is slow. But I have never felted
>> like it was slow and used in a couple of projects now. Is there a good
>> article you recommend reading about ORMs in Go - especially GORM - being
>> slow?
>>
>> Sorry, my reply is not actually an answer to the original question. But I
>> am really curious about it now. Is it really important, really slow?
>>
>> Thanks,
>> Kerem
>>
>> --
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