Re: Rollback on include error in psql
| От | David Johnston |
|---|---|
| Тема | Re: Rollback on include error in psql |
| Дата | |
| Msg-id | CAKFQuwYkfuxRrpKSe1n3wAgN+QTfXL3F7UCHmdvtm9KUX7gwkw@mail.gmail.com обсуждение исходный текст |
| Ответ на | Re: Rollback on include error in psql (Adrian Klaver <adrian.klaver@aklaver.com>) |
| Ответы |
Re: Rollback on include error in psql
|
| Список | pgsql-general |
On 12/29/2014 02:28 PM, David Johnston wrote:On Mon, Dec 29, 2014 at 3:07 PM, Adrian Klaver
<adrian.klaver@aklaver.com <mailto:adrian.klaver@aklaver.com>>wrote:
On 12/29/2014 09:38 AM, David Johnston wrote:
This is one of those glass half full/empty situations,
where it is
down to the eye of the beholder. I would also say this a
perfect
example of why tests are written, to see what actually happens
versus what you think happens.
If a user of our product needs to run a test to determine
behavior then
our documentation is flawed - which is the point I am making.
Still not seeing the flaw in the documentation....
psql does not see any error due to meta-commands or SQL as fatal -
which is why the ON_ERROR_STOP option exists.
And ON_ERROR_STOP does not change that. All it does is toggle
whether psql continues on after an error or stops processing commands.
If it walks and talks like a duck...the fact that ON_ERROR_STOP makes
psql halt processing means that it now treats them like it does any
other fatal error.
But it does not:
ON_ERROR_STOP
By default, command processing continues after an error. When this variable is set, it will instead stop immediately. In interactive mode, psql will return to the command prompt; otherwise,
<HIGHLIGHT> psql will exit, returning error code 3 to distinguish this case from fatal error conditions, which are reported using error code 1.<HIGHLIGHT>
In either case, any currently running scripts (the top-level script, if any, and any other scripts which it may have in invoked) will be terminated immediately. If the top-level command string contained multiple SQL commands, processing will stop with the current command.
I am not seeing what point you are trying to make here. psql exits - my contention is that it should do so before issuing "COMMIT;" if --single-transaction was specified. I really don't care what made psql exit - a fatal error or a non-fatal one while running under ON_ERROR_STOP.
I can find out the root cause by checking for either a 3 or a 1 but what am I supposed to do with that information? More specifically, what should I do if I see a 3 that I wouldn't do if I see a 1; and vice-versa. As a user I really don't care I just want to know that any changes my script may have performed prior to the error have been rolled back if psql exits with a non-zero status.
I believe that if ON_ERROR_STOP causes an abort that the COMMIT from
--single-transaction should not run. That is a behavior
change. But
not documenting the known and deterministic interaction between
the two
options is a bug.
I am not seeing anything in the below that says an ABORT is issued:
I was using term in its non-SQL sense: to stop processing and return
control to the user.
So if is non-SQL why should the transaction care about it?
The transaction doesn't - but psql allows me to do non-SQL stuff along side of SQL stuff and I want the entire thing to fail if either the SQL or the non-SQL stuff has a problem. It is incumbent upon psql to make the boundary between the two as invisible as possible and right now it does not do as good a job as it could.
From the standpoint of psql \include should be just as much a part of the transaction as SELECT * FROM tbl - at least when operating in file/script mode. My issue is with psql - how it manages the underlying session/transaction to make that works is its problem and should be an implementation detail I do not have to worry about.
Note: This all likely extends to "\!" as well but I haven't gone and explored that dynamic.
2) the implications of \include being a client-side mechanic and
thus,
invisible to the server, is not well explained. Specifically that a
failure to include is the equivalent of simply omitting the
statement
altogether (aside from the psql warning). i.e., if in an actual
transaction the server will not issue the standard "error has
occurred,
you must ROLLBACK." message for any subsequent statements in the
script. This is probably not to the level of a bug but it is
related to
the ON_ERROR_STOP bug.
I could see improving the wording on this, to let the user know that
includes are on them as Viktor already determined and took action on.
I think you have a typo somewhere here 'cause that sentence fragment
(...includes and on them as) makes no sense to me.
Should have been clearer. I am saying that it would be good to tell users that using \i(nclude) puts the burden on them to verify the included scripts actually can be found.
Why? Most script languages will report an error to the user if a specified file is missing and provide them a means to respond to that error. psql lacks formal error handling capabilities (e.g., try/catch) but it does offer ON_ERROR_STOP and users should be able to rely on that to behave in a sane manner - i.e., STOPping - without explicitly committing - since something went wrong.
David J.
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