Re: From 8.1 to 8.3

On Wed, 2009-04-22 at 12:49 -0400, Alvaro Herrera wrote:
> S Arvind escribió:
> > Our company wants to move from 8,1 to 8.3 latest. In irc they told me to
> > check realse notes for issues while upgrading. But there are lots of release
> > notesss. Can anyone tell some most noticable change or place-of-error while
> > upgrading?
>
> If you're too lazy to read them, we're too lazy to summarise them for
> you ...
>

And to actually be helpful, the number one issue people see to run into
is this one:

Non-character data types are no longer automatically cast to
TEXT (Peter, Tom)

Previously, if a non-character value was supplied to an operator
or function that requires text input, it was automatically cast
to text, for most (though not all) built-in data types. This no
longer happens: an explicit cast to text is now required for all
non-character-string types. For example, these expressions
formerly worked:

substr(current_date, 1, 4)
23 LIKE '2%'

but will now draw "function does not exist" and "operator does
not exist" errors respectively. Use an explicit cast instead:

substr(current_date::text, 1, 4)
23::text LIKE '2%'

(Of course, you can use the more verbose CAST() syntax too.) The
reason for the change is that these automatic casts too often
caused surprising behavior. An example is that in previous
releases, this expression was accepted but did not do what was
expected:

current_date < 2017-11-17

This is actually comparing a date to an integer, which should be
(and now is) rejected — but in the presence of automatic casts
both sides were cast to text and a textual comparison was done,
because the text < text operator was able to match the
expression when no other < operator could.

Types char(n) and varchar(n) still cast to text automatically.
Also, automatic casting to text still works for inputs to the
concatenation (||) operator, so long as least one input is a
character-string type.

However Alvaro is right. You should read the entire incompatibilities
section, and of course test.

Sincerely,

Joshua D. Drake

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