Multiple databases slower than one?

[sethseth]

I run about 6 different databases because I like to do housekeeping in smaller chunks, rather than have a cache update that takes most of a day. Can this cause a significant performance decrease over running just 2? What if I ran 15 databases, should this matter at all?

[kraada]

The more databases you have the more data that must be amalgamated and the more connection processes that must be kept open. If you have a sufficiently powerful computer you will probably not notice a difference, but we have never done internal testing on as many databases as you propose so I cannot say the extent of the performance decrease that you would experience.