"DA Morgan" <damorgan@x.washington.edu> wrote in message
news:1115160207.398912@yasure...
> RogBaker@gmail.com wrote:
>> 1. If you select * from a table, shouldn't that load the whole table
>> into the database buffer cache, provided it fits. I have a script that
>> I found that shows me what's in the cache ....
>
> Please post the script ... I have my doubts too.
> --

The point that's been missed is that if the table being selected is large
(greater than 2% of buffer cache), a full table scan will load blocks
directly into the cold or least recently used end of the buffer cache LRU
list resulting in it's blocks being subsequently overwritten during the
scan. Therefore, *no*, the whole table wouldn't be expected to be found in
the buffer cache, even if it's size is less than the buffer cache.

Thankfully it's expected and desirable behaviour else FTS of large tables
will have the undesirable effect of potentially forcing more useful blocks
out of cache. This mechanism is somewhat version dependent.

Of course, if the FTS is performed in parallel, then direct reads into the
PGA are performed, bypassing the buffer cache entirely.

Cheers

Richard