Why has Kubuntu installed apt-xapian-index on my system?

[chimak111]

Today, I updated my Kubuntu 16.04 to see this:

The following packages were automatically installed and are no longer required:
 linux-headers-4.10.0-32 linux-headers-4.10.0-32-generic linux-image-4.10.0-32-generic linux-image-extra-4.10.0-32-generic
 linux-signed-image-4.10.0-32-generic
Use 'sudo apt autoremove' to remove them.
The following NEW packages will be installed:
 [B]apt-xapian-index libxapian-1.3-5 python3-xapian1.3[/B]
The following packages will be upgraded:
 bind9-host dnsutils gstreamer-qapt libbind9-140 libdns-export162 libdns162 libgdk-pixbuf2.0-0 libgdk-pixbuf2.0-common libisc-export160 libisc160
 libisccc140 libisccfg140 liblwres141 libpython3.5 libpython3.5-minimal libpython3.5-stdlib libqapt3 libqapt3-runtime libxml2 libxml2-utils
 python3.5 python3.5-minimal qapt-batch qapt-deb-installer
24 upgraded, 3 newly installed, 0 to remove and 0 not upgraded.
Need to get 732 kB/10.4 MB of archives.
After this operation, 4,950 kB of additional disk space will be used.
Do you want to continue? [Y/n]

I don't know why this xapian stuff has made its appearance. All I ran was sudo apt-get update followed by sudo apt-get dist-upgrade!

AFAIK, baloo doesn't use it.

To look into this the only way I know,

$ apt rdepends apt-xapian-index
apt-xapian-index
Reverse Depends:
 Recommends: software-center (>= 0.38ubuntu1)
 Depends: muon
 Depends: libqapt3
 Suggests: packagekit-backend-aptcc
 Depends: ubuntu-kylin-software-center
 Suggests: synaptic
 Breaks: python-apt (<< 0.25)
 Depends: packagesearch
 Depends: muon
 Depends: goplay
 Suggests: aptitude
 Suggests: packagekit-backend-aptcc
$

But muon and libqapt3 were already on my system without needing any "xapian" stuff.

The reason I'm asking is that this "xapian" stuff is used for indexing (IIRC) and is not particularly resource-friendly.

[claydoh]

Muon package manager, among other non-kubuntu software, needs it for search, etc. It is just a simple index of apt packages/information. I do not know why it was not installed when you installed Muon package manager, but it always has been a dep of Muon, for quite a few years now. it doesn't run every time you update, but it does do so periodically.

Note that on *buntu systems, package deps listed as "recommends" are usually installed along with those listed as "depends" So here, the packages muon, libqapt3, ubuntu-kylin-software-center, packagesearch, goplay, and Ubuntu's software center all would pull in apt-xapian-index when they are installed.

[chimak111]

@claydoh, thank you for clarifying.

I did not install muon or take any steps to avoid its installation. Mine is a vanilla installation from the Kubuntu 16.04 iso and I just ran apt policy muon and it came up with

muon:
Installed: (none)
Candidate: 4:5.6.0-0ubuntu1.16.04.1
Version table:
   4:5.6.0-0ubuntu1.16.04.1 500
      500 http://archive.ubuntu.com/ubuntu xenial-updates/universe amd64 Packages
   4:5.6.0-0ubuntu1 500
      500 http://archive.ubuntu.com/ubuntu xenial/universe amd64 Packages
$

I remember this xapian stuff bumping up my CPU usage way back in Ubuntu 11.04 (which was my first Linux experience). After that, in 12.10, I switched to Lubuntu which didn't have it. Kubuntu 16.04 is my first look at Kubuntu and so I don't want to turn off anything default provided by the system.

[acheron]

This update to libqapt would be the cause

https://launchpad.net/ubuntu/+source...0.2-0ubuntu1.2

which has just been released to the main archive.

[chimak111]

@acheron, thanks for explaining