apt update changing sources

[jlittle]

I am puzzled after seeing two different runs of apt update, with no changes of anything by myself

$ sudo apt update
[sudo] password for john: 
Hit:1 http://archive.canonical.com/ubuntu bionic InRelease
Hit:2 http://archive.ubuntu.com/ubuntu bionic InRelease
Get:3 http://archive.ubuntu.com/ubuntu bionic-updates InRelease [74.2 kB]
Hit:4 http://archive.ubuntu.com/ubuntu bionic-backports InRelease
Get:5 http://archive.ubuntu.com/ubuntu bionic-security InRelease [78.6 kB]
Get:6 http://archive.ubuntu.com/ubuntu bionic-updates/universe Sources [3,176 B]
Get:7 http://archive.ubuntu.com/ubuntu bionic-updates/main i386 Packages [35.6 kB]
Get:8 http://archive.ubuntu.com/ubuntu bionic-updates/main amd64 Packages [36.2 kB]
Get:9 http://archive.ubuntu.com/ubuntu bionic-updates/universe i386 Packages [10.5 kB]
Get:10 http://archive.ubuntu.com/ubuntu bionic-updates/universe amd64 Packages [10.5 kB]
Get:11 http://archive.ubuntu.com/ubuntu bionic-updates/universe Translation-en [4,740 B]
Get:12 http://archive.ubuntu.com/ubuntu bionic-security/universe Sources [2,532 B]
Get:13 http://archive.ubuntu.com/ubuntu bionic-security/main amd64 DEP-11 Metadata [204 B]
Get:14 http://archive.ubuntu.com/ubuntu bionic-security/main DEP-11 64x64 Icons [29 B]
Get:15 http://archive.ubuntu.com/ubuntu bionic-security/main DEP-11 128x128 Icons [29 B]
Get:16 http://archive.ubuntu.com/ubuntu bionic-security/universe i386 Packages [9,012 B]
Get:17 http://archive.ubuntu.com/ubuntu bionic-security/universe amd64 Packages [8,996 B]
Get:18 http://archive.ubuntu.com/ubuntu bionic-security/universe Translation-en [4,096 B]
Fetched 278 kB in 3s (90.8 kB/s)                                     
Reading package lists... Done
Building dependency tree       
Reading state information... Done
2 packages can be upgraded. Run 'apt list --upgradable' to see them.

Sometime later, maybe a half hour,

$ sudo apt update
[sudo] password for john: 
Hit:1 http://archive.canonical.com/ubuntu bionic InRelease                 
Hit:2 http://archive.ubuntu.com/ubuntu bionic InRelease                    
Get:3 http://archive.ubuntu.com/ubuntu bionic-updates InRelease [74.2 kB]
Hit:4 http://archive.ubuntu.com/ubuntu bionic-backports InRelease
Get:5 http://archive.ubuntu.com/ubuntu bionic-security InRelease [78.6 kB]
Fetched 153 kB in 3s (59.3 kB/s)   
Reading package lists... Done
Building dependency tree       
Reading state information... Done
2 packages can be upgraded. Run 'apt list --upgradable' to see them.

Why the difference? What does "Hit" and "Get" mean?

[chimak111]

What does "Hit" and "Get" mean?

https://www.bleepingcomputer.com/for...s-hit-get-ign/
https://askubuntu.com/questions/2945...apt-get-update

[claydoh]

perhaps the InRelease file is used to see if there have been any changes? The first time, it does the longer version, but a short time later, the checksums from the InRelease match what you had previously, and doesn't have to go diving into the rest of the archive.

[GreyGeek]

https://blog.packagecloud.io/eng/201...ory-internals/

"... it’s a version of Release with a clearsign signature, used by newer versions of APT."

[claydoh]

...which is a list of files, dirs, and the checksums for each, so if there are no changes (ie the checksums match what you already have downloaded previously) it does not have to dive deeper to get the full, updated set of package data. Or it is also time-based perhaps? I am surmising this, but have not seem the actual steps/process used when checking for updates. I didn't dig very much, though. The day job is distracting

[jlittle]

Thanks all, for your responses.
I was investigating because it seemed that updates for Bionic had dried up, after a month or so of many and often. I realised that I didn't understand much about the update process. The links given by the responders have shed some light, but mostly have assured me that I'm not alone in a lack of understanding.

Regards, John Little

[claydoh]

Bionic was only released two weeks ago. The many updates must have been from running a pre-release, where there are constant changes, right up to nearly the release date, perhaps?