Re: Isolation levels in Informix vs Oracle ~ Answered: amber (hollow confidence) — Mark Townsend's original questions about Informix isolation levels, batch-DML practice and savepoints are only quoted, not separately archived; the visible thread partially answers them (uncommitted data visible within-session; savepoints have no effect on concurrency) but drifts into a side debate about whether savepoints matter at all.

Advisory only.

Mark Townsend said: > > From within the same session (connection to the database), you can see > uncommitted data. Outside the session, no. That's handy. > Is it actually good practice to do a lot of seperate DMLs (100 ?) > affecting 100K rows in Informix without issuing a commit ? It depends. > Does Informix > have the concept of a save point (named point within a transaction you > can later rollback to if required) ? Red herring. > If you wanted to you could actually instrument your batch using a call > to DBMS_APPLICATION_INFO at the beginning and end of your 100 DMLs, and > get an overall estimate that was the sum off all the individual DMLs. Or > alternatively feed the package the % complete figures yourself using the > same package call during the logical operations (based, maybe, on a > count of rows within a table, which you can of course query from the > uncommitted data because you are now within the same session) Kerrist. Well, that's sounds a LOT simpler than doing it in your application code. -- Bye now, Obnoxio "C'est pas parce qu'on n'a rien ' dire qu'il faut fermer sa gueule" - Coluche "I'm trying to see things your way, but I can't get my head up my ass" - JCH "Ogni uomo mi guarda come se fossi una testa di cazzo" - Marco I went to the airport to check in and they asked what I did because I looked like a terrorist. I said I was a comedian. They said, "Say something funny then." I told them I had just graduated from flying school. -- Ahmed Ahmed sending to informix-list

Obnoxio The Chav wrote: >>Does Informix >>have the concept of a save point (named point within a transaction you >>can later rollback to if required) ? > > > Red herring. Why so? It is part of the ANSI standard is it not? -- Daniel A. Morgan University of Washington damorgan@x.washington.edu (replace 'x' with 'u' to respond)

"DA Morgan" <damorgan@x.washington.edu> wrote in message news:41d31d31$1_4@127.0.0.1... > Obnoxio The Chav wrote: > > >>Does Informix > >>have the concept of a save point (named point within a transaction you > >>can later rollback to if required) ? > > > > > > Red herring. > > Why so? It is part of the ANSI standard is it not? since when commitment to ANSI standard a point to debate. AFAIK Oracle does not provide all ANSI standard READ_UNCOMMITTED, READ_COMMITTED, REPEATABLE_READ, SERIALIZABLE isolation level. You won't hold that against Oracle,right :-) If ROLLBACK overrides save point, what is the use of save point, from an application point of view. rk-

DA Morgan wrote: > Obnoxio The Chav wrote: > >>> Does Informix >>> have the concept of a save point (named point within a transaction you >>> can later rollback to if required) ? >> >> >> >> Red herring. > > > Why so? It is part of the ANSI standard is it not? .. but irrelevant

rkusenet wrote: > "DA Morgan" <damorgan@x.washington.edu> wrote in message news:41d31d31$1_4@127.0.0.1... > >>Obnoxio The Chav wrote: >> >> >>>>Does Informix >>>>have the concept of a save point (named point within a transaction you >>>>can later rollback to if required) ? >>> >>> >>>Red herring. >> >>Why so? It is part of the ANSI standard is it not? > > > since when commitment to ANSI standard a point to debate. AFAIK Oracle > does not provide all ANSI standard READ_UNCOMMITTED, READ_COMMITTED, > REPEATABLE_READ, SERIALIZABLE isolation level. You won't hold that > against Oracle,right :-) > > If ROLLBACK overrides save point, what is the use of save point, from > an application point of view. > > rk- Please don't go sideways here. I was merely pointing out that SAVEPOINTS are not exactly a red herring. You can be a bit less defensive methinks as no database vendor is 100% ANSI compliant. -- Daniel A. Morgan University of Washington damorgan@x.washington.edu (replace 'x' with 'u' to respond)

Serge Rielau wrote: > DA Morgan wrote: > >> Obnoxio The Chav wrote: >> >>>> Does Informix >>>> have the concept of a save point (named point within a transaction you >>>> can later rollback to if required) ? >>> >>> >>> >>> >>> Red herring. >> >> >> >> Why so? It is part of the ANSI standard is it not? > > .. but irrelevant That is your opinion not mine as I find them quite useful. But that said ... they are as meaningful as identity column vs. sequence and hardly a herring of any shade. -- Daniel A. Morgan University of Washington damorgan@x.washington.edu (replace 'x' with 'u' to respond)

DA Morgan wrote: > Serge Rielau wrote: > >> DA Morgan wrote: >> >>> Obnoxio The Chav wrote: >>> >>>>> Does Informix >>>>> have the concept of a save point (named point within a transaction you >>>>> can later rollback to if required) ? >>>> >>>> >>>> >>>> >>>> >>>> Red herring. >>> >>> >>> >>> >>> Why so? It is part of the ANSI standard is it not? >> >> >> .. but irrelevant > > > That is your opinion not mine as I find them quite useful. But > that said ... they are as meaningful as identity column vs. > sequence and hardly a herring of any shade. Irrelevant to the discussion that is! Save points have no impact on concurrency. Cheers Serge