Actually, I've got another test system with only few sensors (thus few tables)
and it's working well (<10ms insert) with all the indexes.
I know it's slowing down my performance but I need them to interogate the big
tables (each one can reach millions rows with time) really fast.
> Each INDEX crea
On this smaller test, the indexes are over the allowed memory size (I've got
over 400.000 readings per sensor) so they are mostly written in disk. And on the
big test, I had small indexes (< page_size) because I only had about 5-10 rows
per table, thus it was 3000*8kb = 24mb which is lower than the
