By: CJ

@CJ
Hi Tanel,

It’s been a while but this question has started bothering me again, so I thought I might ask again.

Suppose a block is in the buffer cache and server process needs to fetch a row from that block, after taking the latch etc etc. Will it:

A. Copy the block from the share memory into the process private memory (UGA/CGA/PGA) and then read the row needed?

or

B. Read the requisite row from the block while it resides in the shared memory itself?

or

C. Something totally different?

Now the difficult part – how to prove that the server process is indeed doing A or B or C? My hunch is option B, but I can’t think of how to prove it one way or another.

Many thanks.