Erik is certainly right on this. All queries are point in time and in databases with large numbers of inserts per second, getting the true last two inserts will be relative to when the query starts. On Jun 18, 2014 9:33 AM, "Erik Cederstrand" <erik+li...@cederstrand.dk> wrote:
> Den 18/06/2014 kl. 14.31 skrev Glen Jungels <glenjung...@gmail.com>: > > > It will be different depending on the database (assuming you are asking > about the query only). You will need to do an order by on either your auto > incremented field or dat field plus something like a limit 2 (Postgres and > I believe MySQL) or top 2 for something like SQL Server. > > Interestingly, the question is very simple, but the answer is very > complicated if you simply *must* get the exact answer. > > Databases don't make any promises on the order of the rows returned unless > a specific order clause is provided. auto_increment sequences can be reset > and primary keys can be reused, so you can't necessarily order by primary > key. Result limits are implemented very differently depending on the > database vendor since LIMIT is not part of the SQL standard (see > http://en.wikipedia.org/wiki/Select_(SQL)#Result_limits), and your > database backend might not even support it. > > Finally, using an 'insert_date' field only works if the precision of the > column type is significantly lower than the rate of insertion. E.g. MySQL > <= 5.5 only has second precision for the DATETIME type and wouldn't be > useful if you have 10 inserts per second. > > Erik > > -- > You received this message because you are subscribed to the Google Groups > "Django users" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to django-users+unsubscr...@googlegroups.com. > To post to this group, send email to django-users@googlegroups.com. > Visit this group at http://groups.google.com/group/django-users. > To view this discussion on the web visit > https://groups.google.com/d/msgid/django-users/A9576EA4-D3D5-4E5E-836E-0B5CE450FBE2%40cederstrand.dk > . > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "Django users" group. To unsubscribe from this group and stop receiving emails from it, send an email to django-users+unsubscr...@googlegroups.com. To post to this group, send email to django-users@googlegroups.com. Visit this group at http://groups.google.com/group/django-users. To view this discussion on the web visit https://groups.google.com/d/msgid/django-users/CAA_%3DsbQqoSAM4_g9hZfrqBWxsaMwz4fH_ia1ycFRnktq94Tgmg%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
