maria-developers team mailing list archive

[Sergei Golubchik <serg@xxxxxxxxxxxx>]

Hi, md!

On Sep 08, md@xxxxxxxxxxxxx wrote:
> Does anybody have any thoughts on what would be involved with getting
> Aria Tables to have an option to be memory only (Fully cached with no
> disk writing, power off means data loss)

It should be quite easy, I suppose. One would just need to add some
option that would prevent flushing pages of these tables from the page
cache down to disk.

> ARIA support row locking instead of Memory Tables which only have
> Table locking.  Table locking sucks for anything that is heavy
> read/write.

Aria does not support row locking.

> Right now I am using RAM DISKs to store my memory based ARIA tables so
> I can get decent speed for heavy read/write sections of the DB.
> 
> But there is a bit of a operations headache where I have to allocate
> the RAM disks on system boot and the storage strategy of Aria does not
> release disk blocks when records are deleted, those spaces are left
> for future records by setting the deleted flag back to undeleted.  So
> the memory pool is not used very effectively.
> 
> So deleting records from a RAM disk ARIA table means that I have to
> vaccuum the tables using ALTER table every so often or I could run out
> of memory. (Very bad for ramdisks)
> 
> If the ARIA cache routines could allocate memory dynamically from the
> global heap and return the memory upon delete operations, that would
> be a better options.  And of course, no data is written to disk, just
> kept in cache.

Allocating memory dynamically would be more difficult that simply not
flushing pages. But anyway, the point is moot, because Aria uses
table-level locking.

Regards,
Sergei