This month I wish to do a quick run through, and review, of the effects of REBIND with active packages and how phases, both in and out, have given us some interesting problems to deal with!
As I mentioned in an earlier blog, the phase-in/phase-out was a very good idea indeed! It finally meant that we could do REBINDs whenever we wanted and no-one had to shut down servers to simply action a REBIND. This was always especially galling when it was an “empty” package or just to get an FL upgrade.
Remember, Phase-in is only allowed with PLANMGMT(EXTENDED) style packages and if the package is not a generated package for a trigger or SQL routine, such as a procedure or user-defined function.
The problems began soon after it was introduced in June 2019 with PH09191 and FL505. Now, it looked really good, and indeed it was, but it had one little flaw… it still required a SIX lock to do the business.
This was solved in January 2021 with APAR PH28693 which changed the lock from a SIX to a much better U lock. With this APAR all of our problems were fixed and life would be good!
Sadly, we then found out that the inactive/phased-out packages were actually causing rapid space growth in the SYSPACKCOPY (Not in SYSPACKAGE!) Remember that the phased-out packages all get copied across with a new number to the “back-up” SYSPACKCOPY for use until the active thread finally disconnects.
The Problem Gets Worse
Now these backed-up, old packages are sitting around in SYSPACKCOPY waiting until the next REBIND comes along whereupon Db2 will attempt a FREE. Various customers noticed that, for their intensely used packages, this free never really happened and so they “hit the buffers” of 14 copy_ids for packages… very nasty!
Another APAR to the Rescue!
IBM then created a new APAR, PH33295, that enhanced the FREE PACKAGE command to have a new PLANMGMTSCOPE sub-clause PHASEOUT. All this does is delete all of those old, no longer used packages. However, I can testify that doing a:
FREE PACKAGE(*.*.(*)) PLANMGMTSCOPE(PHASEOUT)
in production is one of the scariest commands I have ever issued!!! Personally, I would have preferred a brand new command like FREE PHASEDOUT PACKAGES or so…
Invalid as Well
While you are ridding yourself of 100’s of packages you could also issue the PLANMGMTSCOPE(INVALID) command which removes the phased-out and also gets rid of the dead, invalid packages which cannot ever be used anyway.
Do not Forget to Tidy up!
Once all these commands have been done, a REORG of the tablespace DSNDB06.SYSTSPKC is very highly recommended!
How have you experienced phase-in and phase-out? Do you think it’s a great feature or not?
Whatever you think, I would love to hear from you!