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Re: RSTOBJ then CPYF CPF5090



fixed

My attempt to respond to the prior post got too messy. So I will respond here to suggest that for the /no active data/ case, I think there may be a defect. Why thinking defect? Well, and sorry about the flow being somewhat /thinking out loud/...

That conclusion suggests an oddity, probably worth review by the development team. What is described is a case of /no active rows/ versus /no data/ versus /active rows/. In the /no data/ case I would expect that the access paths would be rebuilt inline to the restore. I would expect that for the case of /no active rows/ the outcome would be identical to the /active rows/ case, such that the access path would both save and restore. It is possible the development team is not aware of this outcome, and your scenario points out at least how the async rebuild can be a problem for a scenario with a UNIQUE keyed logical. Or perhaps if known, a missing PTF for QDBSVPRE and/or QDBSVPST.

For the /no data/ case, I believe the rebuilds are done inline to the restore, rather than asynchronous in the QDBSRV## runpty-52 jobs. As I recall, they were rebuilt inline [synchronous and serially] in the past [just as RGZPFM does by default], and would be indicated as such by status messages flashing by during a restore in an interactive job suggesting that "Access path for file &1 was rebuilt". In fact I recall there were complaints about those messages. Perhaps the conclusion that they are neither built nor restored is for lack of visual notice of the flashing messages? They would appear in a trace.

If not done synchronous for all files, it should probably be done at least for any UNIQUE defined access paths, specifically to prevent that type of problem. Defect or not, the RGZPFM before save should serve as resolution [even if the restore feature were changed].

Hmmm... memory blurry, having thoughts about inline rebuilds. Perhaps it was after one of the problems that was exposed by the changes, that the no-load with rebuild for /no data/ case was replaced by either a fixup-proc or a create-as-valid-and-empty feature. If so, then I wonder if save sees the /no active rows/ member as /no data/, but the restore recognizes that in fact it is not actually a legitimate /no data/ case but is instead a /no active rows/ case, and thus such a new feature would not be functional for that case. If prior to a new feature it was inline rebuild after load, then this problem would not exist even if there was confusion between save & restore on the definition of /empty/. I think that might be the problem.

Really the ACCPTH(*YES) never should have had its definition vitiated by a change to an effective ACCPTH(*MAYBE). That is, the code change to enable deferral of access path activity to restore versus save for /empty/ members, should have been a new\separate option like ACCPTH(*DATA). With separate options any problems would be more obvious from the choice on the parameter, and the other choices might serve as a circumvention. If I had had my way, the change would have been done only in a new\next release with a new keyword; or not done at all. I had predicted that it was going to prove a very problematic change, and I was proven a good prognosticator of outcomes for the [bad] decision. My first concern, I recall clearly, was that the number of events [on a restore of many thousand keyed but empty members] would flood the system with access path rebuild events and due to a known issue could [compounded by the ¿runpty-9? qdbsrv01] cause the system to effectively hang due to thrashing. That is why I recall the code was changed to synchronous rebuilds during restore. Anyhow if that since changed to something other than inline builds, development probably needs to review your scenario for consideration as alluded above.

Regards, Chuck

craigs@xxxxxxxxx wrote:
Just a clarification on my previous post after doing some detail tests: SAVOBJ an empty physical file with deleted records and any logicals over that physical. Then, later, RSTOBJ to an empty library
like QTEMP triggers the rebuilding of access paths. RGZPFM with MONMSG(CPF2981) before the SAVOBJ ensures the access paths are "cleaned". This ensures that those QDBSRVxx jobs running to rebuild access paths don't cause CPYF to those files to blow up. If the file has data, the access path will be saved and therefore restored. So, that would not cause rebuilding the access path. If the file is empty
(no current or deleted records) it neither restores an access path nor submits an access path rebuild.

So, to effectively stop CPYF from blowing up with CPF5090 then CPF2972 after a RSTOBJ, make sure the access paths aren't triggered to rebuild by making sure deleted records are removed BEFORE the files are restored. RGZPFM with MONMSG(CPF2981) before SAVOBJ and the
access paths will be cleaned inline with the RGZPFM (no QDBSRVxx
jobs used). Note that this doesn't stop all RSTOBJ access path
rebuild submissions such as restoring a physical without the logical.





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