Reduce db size of archive-blob-tables

[rr-it]

Description:

This uses ZLIB compression-level 9 instead of default 6 for archive-blob-tables. Thereby the needed storage size is reduced by 5%.

This implements #23186

Review

• Functional review done
• Potential edge cases thought about (behavior of the code with strange input, with strange internal state or possible interactions with other Matomo subsystems)
• Usability review done (is anything maybe unclear or think about anything that would cause people to reach out to support)
• Security review done
• Wording review done
• Code review done
• Tests were added if useful/possible
• Reviewed for breaking changes
• Developer changelog updated if needed
• Documentation added if needed
• Existing documentation updated if needed

[github-actions]

This issue is in "needs review" but there has been no activity for 7 days. ping @matomo-org/core-reviewers

[mneudert]

Hi @rr-it,

thank you for the patch, and sorry for the delay on this one.

Do you have, by chance, any in-depth resources on the CPU time it takes for the compression? Any good benchmark of different data sizes that also shows CPU times?

I only did a really quick check on a local dataset to see how that changes, and it was somewhere in the range of a threefold to fourfold increase in the compression time. For CLI archiving, it looked like an increase of 0.5% in total runtime. But when requesting a custom date range in the browser (that often has to compress a new range archive), the times were varying on a level of 2% to 3% in increased request time.

Those checks were far from scientific, or even being a well-taken average, just one-off requests to get some first numbers.

If there is a way to get a good estimate on the expected increase in compression time, it would help tremendously to decide if the compression level should change to the value you suggest, or maybe get a configuration if someone wants to do the CPU/storage tradeoff in the other direction.

[michalkleiner]

Replaced by #23257, thanks for your contribution regardless!