One thing we were guessing at with Massimo yesterday is, if you
large blobs as disk data, how much will they consume DataMemory and
IndexMemory (primary key, each "chunk" has a hidden primary key, first 25x bytes
of blob stored in memory...)?
My empirical test showed that about 2% of the total size
of blobs is needed for RAM
(25% of that is IndexMemory).
IMHO this is close to negligible, but in many situations not
at all (may have close to TB of disk data -> 20GB of RAM needed for
Also note that this is a minimum figure. If you actually have
else than the blob (like other indexes) you of course use much more RAM.
The test was:
CREATE TABLE `jpgtest` (
`id` int(11) NOT NULL,
PRIMARY KEY (`id`)
) TABLESPACE ts_1 STORAGE DISK ENGINE=ndbcluster;