[Bug 1214482] Re: Not-grouping dependent packages in Phased Updates changes propability distribution for entire group of dependent packages.

[Marek Wrzosek]

After some consideration - maybe real life scenario will be better. Regard Linux, Nvidia, ATI and some DVB-T dongle without driver in current kernel. There will be 6 groups of users:
a) only Linux, (i=1)
b) Linux and Nvidia, (i=2)
c) Linux and ATI, (i=2)
d) Linux and DVB-T dongle, (i=2)
e) Linux, Nvidia and DVB-T dongle, (i=3)
f) Linux, ATI and DVB-T dongle. (i=3)
These are all kernel or kernel modules so they could share the same threshold value. You can calculate percentage of users for Linux-only using normal distribution and use it directly for group a), for other groups will be easy to calculate parameters of their distribution using the i value (number of random variables) and recalculate pristine threshold for all packages from b) to f) groups accordingly, then compare it with maximum value of random generated numbers for Linux, graphics and DVB-T. That way will be possible to determine percentage of users that installed newer versions of packages and this percentage can be equal for all groups (from a) to f)). The value of i can be estimated using list of installed packages for every user reporting bug.
For other software packages it should be similar as for Linux example.

I can be wrong, so correct me if you find any mistake.

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https://bugs.launchpad.net/bugs/1214482

Title:
  Not-grouping dependent packages in Phased Updates changes propability
  distribution for entire group of dependent packages.

Status in “update-manager” package in Ubuntu:
  New

Bug description:
  I assume that you decided for uniform distribution in the random
  number generator. If group of dependent packages is installed only
  when all phased-update-percentage values (for each package) are
  smaller than the present percentage on server - it will change
  probability distribution for the whole group of packages.

  Just run this:

  figure(1)
  hist(rand(1,100000))
  for i = 2:10
  	figure(i)
  	hist(max(rand(i,100000)))
  endfor

  in octave and look at histograms for i>1 (i is the number of dependent
  packages).

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