Hi All,
When select statement run, full table scan or index scan happen. Data block address is hashed and search for the hash bucket. if it is in the buffer cache, it will be in the hash chain. I have several questions regarding this process.
First of all what buffer cache buffer store? Does it store single data block or multiple data blocks?
Also, regarding to hash chain, buffer headers are linked to the hash chain. Does the specific hash chain only hold buffer headers that belong to single database object?
During full scan, what if several data blocks are in buffer cache but the others are not? I mean, are the intended buffers in the buffer cache and some of them are wiped out? What will happen for this kind of situations?
Thanks