About "buffer" and row

   Hi,

   My db is 9.2.0.4

   From TKProf Interpretation (9i and above) [ID 760786.1] suddenly, I feel confused about word "buffer".

   Example:

update ...

where  ...

-----------------------------------------------------------------------

| call    | count | cpu | elapsed | disk |   query | current |   rows |

|---------|-------|-----|---------|------|---------|---------|--------|

| Parse   |     1 |   7 |     122 |    0 |       0 |       0 |      0 |

| Execute |     1 |  75 |     461 |    5 | [H] 297 |   [I] 3 | [J]  1 |

| Fetch   |     0 |   0 |       0 |    0 |       0 |       0 |      0 |

-----------------------------------------------------------------------

   [H] shows that this query is visiting 297 buffers to find the rows to update

  [I] shows that only 3 buffer are visited performing the update.

   Reading 297 buffers to update 1 rows is a lot of work ...

  I assume that I allocated db buffer cache is 100MB and 1 data block = 8K. ==> 100MB can contains about 12800 data block. So, how related between 297 buffers and 100MB. 1 buffer can contains how many data block ?