I asked this on general, but got no answer on this particular
point, maybe someone here knows. Are blobs are stored in the
shared memory cache upon retrieval?
I ask because we're trying to decide whether to store an enormous
number of images in PostgreSQL, and I'd be concerned that
frequent retrieval of those images would effectively empty the
cache of the rest of the non-image data.
I watched the pg_statio* numbers during some test retrievals, and
it appears the reads and cache hits on the binary image data are
not being counted. I'm wondering if that is the truth of what's
going on, or just an accounting oversight.
Thanks.