Figure 6-29 is a simple dba_segments-based query. Each row in dba_segments contains information about a single Oracle segment. It also contains columns for the header block's file number and block number. So a simple query like the one shown in Figure 6-29 will reveal if the busy buffer is in fact a header block. In our example, block 4,54 is not a header block. Therefore, because the segment type is table, we know the busy buffer contains rows. In addition to this, when I repeatedly queried the v$sesson_wait-based script shown in Figure 6-25, I noticed that different orders table blocks were being waited upon. This means sessions are waiting to access rows within multiple blocks of the orders table.

Figure 6-29. This simple dba_segments-based query clearly shows that block 4,54 is not a header block.

Now that we have identified the buffer busy pattern, the object type, and whether the block is a header block, we have enough information to proceed directly to a list of possible solutions.