[TYPO3-english] Database cleaning advice

[Jigal van Hemert]

Hi,

On 28/05/2016 18:33, Chad Manookin wrote:
> The database of our Typo3 installation (version 4.5.45 -- trust me, I'm
> working to get upgraded) has become huge, making backups a pain and
> possibly slowing the site.
>
> While I've been working with it for just under a year, from what I
> understand the site has been running for ~8 years, which leads me to
> believe that a lot of unnecessary 'tracking' data has accumulated. The
> problem is, I don't know what I can clear safely, or how exactly I
> should go about it.
>
> The biggest table, by far, is tx_realurl_chashcache that clocks in at
> 822 MiB. Since it would drop the total size of the database by nearly
> 1/3, does anyone know if there is a safe way to clear out old data in
> this table?
>
> Same question regarding sys_log and cache_hash since they are ~500 MiB
> each.

cache_* tables are the "old" cache tables. They can all be emptied, 
except for cache_extensions. This one contains the list of available TER 
extensions. It can be emptied, but the you'd have to download the list 
again and you end up with exactly the same table size.

cf_* tables are cache tables from the (newer) caching framework; they 
can be emptied

sys_history contains the changes editors made. This helps you to roll 
back any changes that must be undone. You can empty it, but you'll lose 
the ability to undo modifications in content.

sys_log contains all logged information. Who logged in, pages that were 
added/removed/modified, record changes, extension changes, etcetera. If 
you don't mind losing that (the information you see in the Log module) 
it can be emptied too.

tx_realurl_chashcache contains calculated hashes for links. It's a 
cache, it can be emptied.
tx_realurl_errorlog contains requests that didn't have a correct 
realurl. Can be emptied if you don't want to preserve the information
tx_realurl_pathcache can be emptied if necessary
tx_realurl_redirects : keep it!
tx_realurl_uniquealias : better keep it. It keeps track of record IDs 
and titles. If there are multiple records from the same table with the 
same title the title with numeric suffix is stored here. For this reason 
the information should be kept.
tx_realurl_urldecodecache, tx_realurl_urlencodecache can be emptied



-- 
Jigal van Hemert
TYPO3 CMS Active Contributor

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