2026-03-12 20:23:15
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vdh/index_efficiency_3.sql
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147
vdh/index_efficiency_3.sql
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rem
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rem Script: index_efficiency_3.sql
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rem Author: Jonathan Lewis
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rem Dated: Sept 2003
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rem Purpose: Example of how to check leaf block packing
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rem
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rem Last tested
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rem 11.1.0.7
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rem 10.2.0.3
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rem 9.2.0.8
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rem Not tested
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rem 11.2.0.1
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rem 10.2.0.4
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rem Not applicable
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rem 8.1.7.4 -- no sys_op_lbid()
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rem
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rem Notes
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rem Example of analyzing index entries per leaf block.
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rem
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rem Set up the schema, table name, and index name before
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rem running the query.
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rem
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rem The code assumes you have no more than 10 columns in
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rem the index for the purposes of generating "is not null"
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rem clauses to force the necessary index-only execution path.
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rem This limit can easily be extended by cloning and editing
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rem the lines of the "setup" statement.
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rem
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rem For a simple b-tree index, the first parameter to the
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rem sys_op_lbid() function has to be the object_id of the
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rem index.
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rem
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rem The query will work with a sample clause if you are
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rem worried that the index you want to investigate is too
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rem large to analyze in a reasonable time. (I take 100 blocks
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rem per second as a conservative estimate for the I/O rate
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rem when running this script on very large indexes but have
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rem seen it running three or four times faster that.)
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rem
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rem This version of the code is suitable only for simple
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rem B-tree indexes - although that index may be reversed,
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rem have descending columns or virtual (function-based)
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rem columns, or be a global index on a partitioned table.
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rem
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define m_owner = &m_schema
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define m_table_name = &m_table
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define m_index_name = &m_index
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column ind_id new_value m_ind_id
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select
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object_id ind_id
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from
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dba_objects
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where
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owner = upper('&m_owner')
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and object_name = upper('&m_index_name')
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and object_type = 'INDEX'
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;
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column col01 new_value m_col01
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column col02 new_value m_col02
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column col03 new_value m_col03
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column col04 new_value m_col04
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column col05 new_value m_col05
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column col06 new_value m_col06
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column col07 new_value m_col07
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column col08 new_value m_col08
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column col09 new_value m_col09
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select
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nvl(max(decode(column_position, 1,column_name)),'null') col01,
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nvl(max(decode(column_position, 2,column_name)),'null') col02,
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nvl(max(decode(column_position, 3,column_name)),'null') col03,
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nvl(max(decode(column_position, 4,column_name)),'null') col04,
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nvl(max(decode(column_position, 5,column_name)),'null') col05,
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nvl(max(decode(column_position, 6,column_name)),'null') col06,
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nvl(max(decode(column_position, 7,column_name)),'null') col07,
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nvl(max(decode(column_position, 8,column_name)),'null') col08,
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nvl(max(decode(column_position, 9,column_name)),'null') col09
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from
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dba_ind_columns
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where table_owner = upper('&m_owner')
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and table_name = upper('&m_table_name')
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and index_name = upper('&m_index_name')
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order by
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column_position
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;
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break on report skip 1
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compute sum of blocks on report
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compute sum of row_ct on report
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spool index_efficiency_3
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prompt Owner &m_owner
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prompt Table &m_table_name
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prompt Index &m_index_name
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set verify off
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select
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rows_per_block,
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blocks,
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rows_per_block * blocks row_ct,
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sum(blocks) over (order by rows_per_block) cumulative_blocks
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from (
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select
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rows_per_block,
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count(*) blocks
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from (
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select
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/*+
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cursor_sharing_exact
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dynamic_sampling(0)
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no_monitoring
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no_expand
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index_ffs(t1, &m_index_name)
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noparallel_index(t1, &m_index_name)
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*/
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sys_op_lbid( &m_ind_id ,'L',t1.rowid) as block_id,
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count(*) as rows_per_block
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from
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&m_owner..&m_table_name t1
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-- &m_owner..&m_table_name sample block (5) t1
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where
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&m_col01 is not null
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or &m_col02 is not null
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or &m_col03 is not null
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or &m_col04 is not null
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or &m_col05 is not null
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or &m_col06 is not null
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or &m_col07 is not null
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or &m_col08 is not null
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or &m_col09 is not null
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group by
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sys_op_lbid( &m_ind_id ,'L',t1.rowid)
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)
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group by
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rows_per_block
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)
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order by
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rows_per_block
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;
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spool off
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