The manual is not clear about this:
https://www.h2database.com/javadoc/org/h2/engine/DbSettings.html#autoCompactFillRate
 


Having a look into the source code I guess it should compact while the 
database is open.

I have a 2nd project where compacting works fine. But this project only has 
rare database changes.


[email protected] schrieb am Dienstag, 14. Juni 2022 um 
06:02:08 UTC+2:

> Greetings.
>
> My understanding is, there is no "auto compact" while the database is 
> running.
> Instead it will be compacted only during shutdown and only  within the 
> defined shutdown time period (longer will give more time to compact).
>
> And yes, H2 database consumes a lot of file space, especially when data 
> are constantly written and deleted. I made exactly the same observation.
>
> Best regards
> Andreas
>
> On Mon, 2022-06-13 at 02:48 -0700, Ulrich wrote:
>
> Hi all,
>
> I am running a H2 2.1.212 and I wonder why the automatic compact feature 
> does not shrink the database size.
>
> My application is continuously collecting data (around 100 inserts per 
> second). Most of the data is removed once a day. The data is kept in 4300 
> tables.
>
> The database file size is around 5 GB. When running a manual SHUTDOWN 
> COMPACT it is compacted to 40 MB. 
>
> I expected that the automatic compact algorithm of the MV_STORE is able to 
> keep the database smaller than it is. Are there any known circumstances why 
> the compact algorithm does not run or does not give good results?
>
> I already tried to use the latest git code but the results are the same.
>
> Here are some infos from the information_schema.settings table with the 
> relevant parameters:
>
> AUTO_COMPACT_FILL_RATE  90 
> info.FILL_RATE  19 
> info.CHUNKS_FILL_RATE  27 
> info.CHUNKS_FILL_RATE_RW  27 
> info.FILE_SIZE  4916121600  
> info.CHUNK_COUNT 490 
> info.PAGE_COUNT  1594967 
> info.PAGE_COUNT_LIVE 440730 
> info.PAGE_SIZE  4096 
> info.CACHE_MAX_SIZE 16 
> info.CACHE_SIZE 15 
> info.CACHE_HIT_RATIO 85 
> info.TOC_CACHE_HIT_RATIO 99 
> info.LEAF_RATIO 44
>
> Thanks!
> Ulrich
>
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