Re: Feature discussion: Should syntax errors abort a transaction?

On 20/06/12 01:35, Rafal Pietrak wrote:
> On Tue, 2012-06-19 at 19:06 +0800, Craig Ringer wrote:
>> On 06/19/2012 02:20 PM, Tom Lane wrote:
>>> So you're suggesting that "SELECT 1/0;" should terminate a transaction,
>>> but "SELECT 1//0;" should not? How about "ROLBACK;"? It gets pretty
>>> squishy pretty fast when you try to decide which sorts of errors are
>>> more important than others.
>>>
>> When put that way, it seems blindingly obvious. You have a talent for
>> making a devastating point very succinctly.
> I'd humbly disagree.
>
> Not to drag this discussiong any further, just to make a point that the
> other approach is also "blindingly obvious". Only the other way around.
>
> The point is, that SQL syntax errors are so obviusly different from
> execution errors, that noting this distinction should not raise any
> ambiguity. In Tom's example "ROLBACK":
> 1. should not break the transaction
> 2. should only raise NOTICE: "syntax error"
> 2.1. in case this was issued from command line - user can always
> ROL<TAB> to see what's next.
> 2.2. in case of a compiled program sending a "ROLBACK" to the
> backend .... hack, the programmer should know better.
> 3. and BTW: what about rolling back a tediously cooked sequence of
> statements finished by "COMINT"?
>
> Things are not so obvious. And frankly, if not for the "<TAB>" I'd have
> case (3) so often, that it would have driven me crasy.
>
>
> -R
>
>> --
>> Craig Ringer
>>
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>>
>
>
I would be be extremely concerned about any move to allow syntax errors
not to abort a transaction.

Even minor syntax errors may indicate that something much more serious
is wrong.

PL/1 was designed to tolerate various errors and guess what the
programmer intended, it would make assumptions and act on them – a good
way to hide serious programming errors.

A language that is too forgiving encourages sloppy thinking.

A bit like in chess, if you don't follow the dictum of 'touch a piece
move it' in social play (it is the rule in match and tournament play),
then your level of skill in Chess is unlikely to improve much. I coach
Chess at my son's school and I used to be Director-of-Play for Chess
tournaments.

I remember learning C many years ago, very unforgiving. However, the
discipline imposed was very beneficial to improving my programming skills.

I would far rather a compiler pull me up for minor violations, than an
obvious error not picked up until I came to test the program. The
compiler is not perfect and some errors will slip through. However, the
sooner errors are detected, the less likely an error will cause bad
problems in production.

The greater the size and complexity of code, the more important this all
becomes. Mind you, even very simple SQL SELECT's might have results used
to make critical business decisions - so even then, sloppy habits should
be discouraged.

I would be very reluctant to hire any developer who had the mind set of
seriously wanting something like psql to be forgiving of any kind of
error - as it suggests that they are more careless than normal, and lack
the attitude to be reliably rigorous.