Hi,

With the MVStore storage engine, which is the default in version 1.4.x, the
file size is typically a few times larger than the "real data". This is
expected. If you run "shutdown defrag", the file size should decrease. Does
it do that?

Reason for the larger file size: to speed up writes without risking to lose
data, old data (younger than a few minutes old) is not overwritten, but
kept. Disk space is eventually released and re-used, but that algorithm is
not yet optimized with the current version. I know this should be improved
in the future.

Regards,
Thomas



On Monday, July 18, 2016, ck <[email protected]> wrote:

> This is my first post on this group,
> Hello to everyone! :)
>
> I have a problem with my H2 DATABASE.
> I am seriously worried by the size it is getting, it is now about 350mb
> (Yeah I know it's not the largest one), but my worries go all to the future
> and how it will scale in the long run.
>
> Issues:
> - Trying to Export data as CSV using DataGrip (or any other Database
> Explorer) I get less than 50mb of real 'data'
> - Database seems filled with tons of 'unknown' data - I know the database
> stores indexes and such, but I tried DROPPING ALL OBJECTS, or DELETING
> TABLES , DELETING INFORMATION_SCHEMA just for test purpose and after all
> was cleaned it was around 250mb anyway.
> - After cleaning the whole DB which is now totally empty but still weights
> 250mb, the size changes after connect/disconnect, lowering abour 4mb each
> time
> - Deleting tables o creating tables and adding 1000 rows does not change
> file size (?) - and many times dropping tables/rows does not lower the DB
> Size (why?)
> - After cleaning the whole DB which is now totally empty, still weights
> 250mb, what is happening?
>
>
> Details:
> - I have INCREMENTAL IDS (with some jumping sequences, eg. from 10->40)
> - I store BLOBs
> - I store VARCHARs, many fixed to 125 chars, some with 250/500 or 2000 in
> a unique case
> - I use a JVM Web App that starts connection at program start and closes
> it at program closing (I used this approach because I thought it could be
> very slow and could waste tons of resources to 'reopen, commit, close'
> connection every single time, considering multiple people send multiple
> requests simultaneously. I am free too critics and I totally encourage
> opinions/advices about this.
> - Every query is immediately turned to a Map of results and the ResultSet
> is closed as soon as possible
>
>
> What is happening? I am mostly concerned about the fact it may get such a
> large db in production to cause slowdowns or crashes of the machine
>
> Might my question have some mistakes, feel free to correct me and
> apologize for my first post
>
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