#1 2015-07-09 13:20:12

alpinistbg
Member
Registered: 2014-11-12
Posts: 124

Autoincrementing IDs and the DB backends

Since I would like to generate sequence of natural numbers using the database itself, It occured to me that I can use the ID field of some side table for the purpose. My question is: Is the atomicity guaranteed when using different DB backends?

MSSQL for example usually gives such a guarantee on single statements (when outside of transaction) and for Firebird - there is always a pending transaction, so my concern is that in the MSSQL case, between the 'SELECT MAX(ID)+1 FROM' unitil actual 'INSERT INTO' there is a slight window where things can get messy and for the Firebird - that the insert can conflict with another one.

Regards,

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#2 2015-07-09 20:15:06

ab
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From: France
Registered: 2010-06-21
Posts: 13,192
Website

Re: Autoincrementing IDs and the DB backends

All this works as long as the ORM is the only one to access the database.

This is how it is expected to be.

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#3 2015-07-09 23:07:48

alpinistbg
Member
Registered: 2014-11-12
Posts: 124

Re: Autoincrementing IDs and the DB backends

Of course, but AFAIK it is not single threaded ...

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#4 2015-07-10 10:52:39

ab
Administrator
From: France
Registered: 2010-06-21
Posts: 13,192
Website

Re: Autoincrementing IDs and the DB backends

ID generation is protected by a critical section, so is thread safe within the ORM.

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