3.分析方法

    存储参数基本上属于oracle internal的东西，因此oralce并没有提供很好的手段来分析。但是对于DBA来说，还是可以通过block dump和DBMS_SPACE等手段来获取部分信息。

    3.1 提取block和free list信息

    创建dbms_space使用的存储过程show_space

  SQL>
    create or replace procedure show_space
    ( p_segname in varchar2,
    p_owner in varchar2 default user,
    p_type in varchar2 default 'TABLE',
    p_partition in varchar2 default NULL )
    as
    l_free_blks number;
    l_total_blocks number;
    l_total_bytes number;
    l_unused_blocks number;
    l_unused_bytes number;
    l_LastUsedExtFileId number;
    l_LastUsedExtBlockId number;
    l_last_used_block number;
    procedure p( p_label in varchar2, p_num in number )
    is
    begin
    dbms_output.put_line( rpad(p_label,40,'.') || p_num );
    end;
    begin
    dbms_space.free_blocks
    ( segment_owner => p_owner,
    segment_name => p_segname,
    segment_type => p_type,
    partition_name => p_partition,
    freelist_group_id => 0,
    free_blks => l_free_blks );
    dbms_space.unused_space
    ( segment_owner => p_owner,
    segment_name => p_segname,
    segment_type => p_type,
    partition_name => p_partition,
    total_blocks => l_total_blocks,
    total_bytes => l_total_bytes,
    unused_blocks => l_unused_blocks,
    unused_bytes => l_unused_bytes,
    last_used_extent_file_id => l_LastUsedExtFileId,
    last_used_extent_block_id => l_LastUsedExtBlockId,
    last_used_block => l_last_used_block );
    p( 'Free Blocks', l_free_blks );
    p( 'Total Blocks', l_total_blocks );
    p( 'Total Bytes', l_total_bytes );
    p( 'Unused Blocks', l_unused_blocks );
    p( 'Unused Bytes', l_unused_bytes );
    p( 'Last Used Ext FileId', l_LastUsedExtFileId );
    p( 'Last Used Ext BlockId', l_LastUsedExtBlockId );
    p( 'Last Used Block', l_last_used_block );
    end;
    过程已创建。

    对非segment header的data block的dump方法和上述类似。data block的结构和segment header block不一样，如果需要了解，可查阅参考文献和资料。