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Create index_drops.sql
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‎index_drops.sql

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/* index_drops.sql
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Copyright (C) 2013 Sean Scott
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License along
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with this program; if not, write to the Free Software Foundation, Inc.,
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51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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These scripts provide a variety of different methods for looking at indexes that
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are candidates to be dropped. */
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/* Indexes that don't have statistics */
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select index_name
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from dba_indexes
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where index_name not in (
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select index_name
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from v$segment_statistics);
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/* Indexes that are candidates for being dropped (not part of a constraint, not in
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an execution plan). */
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select owner
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, index_name
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from dba_indexes
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where (owner, index_name) not in (
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select owner, object_name
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from dba_hist_sql_plan
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where object_type = 'INDEX') --Exclude indexes that have been used in an execution plan.
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and (owner, index_name) not in (
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select owner, index_name
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from dba_constraints
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where constraint_type in ('P','R')) --Exclude indexes that are part of a referential integrity constraint.
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order by 1;
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column cardinality format 999,999,999.90
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column sample_pct format 999,999,999.90
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/* Indexes that may be empty/droppable because they have 0 distinct keys, 0 rows,
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and aren't part of a PK/FK constraint. */
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select owner
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, index_name
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, uniqueness
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, index_type
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, num_rows
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, decode(distinct_keys, NULL, 0, 0, 0, distinct_keys/num_rows) as cardinality
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, status
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, last_analyzed
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from dba_indexes
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where distinct_keys = 0
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and num_rows = 0
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and (owner, index_name) not in (
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select owner, index_name
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from dba_constraints
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where constraint_type in ('P','R'));
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/* Small indexes that may be droppable because they're small and not used in a
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FK/PK constraint. Sometimes, a FTS may be as good or better than doing an index
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lookup against a tiny index/table. */
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select owner
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, index_name
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, pct_free
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, logging
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, index_type
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, distinct_keys
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, num_rows
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, decode(distinct_keys, NULL, 0, 0, 0, distinct_keys/num_rows) as cardinality
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, status
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, last_analyzed
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, decode(distinct_keys, NULL, 0, 0, 0, distinct_keys/sample_size) * 100 as sample_pct
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from dba_indexes
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where (distinct_keys < 20
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or num_rows < 20)
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and distinct_keys != 0
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and num_rows != 0
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and (owner, index_name) not in (
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select owner, index_name
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from dba_constraints
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where constraint_type in ('P','R'))
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order by 8 desc, 1, 2;
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select owner
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, index_name
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, pct_free
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, logging
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, index_type
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, distinct_keys
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, num_rows
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, decode(distinct_keys, NULL, 0, 0, 0, distinct_keys/num_rows) as cardinality
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, status
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, last_analyzed
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, decode(distinct_keys, NULL, 0, 0, 0, distinct_keys/sample_size) * 100 as sample_pct
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from dba_indexes
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where uniqueness != 'UNIQUE'
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and distinct_keys != 0
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and num_rows != 0
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order by 8 desc, 1, 2;
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/* Identify potentially redundant indexes based on predicates */
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column column_name_list format a50
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column column_name_list_dup format a50
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select /*+ rule */
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a.table_owner
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, a.table_name
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, a.index_owner
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, a.index_name
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, column_name_list
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, column_name_list_dup
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, dup duplicate_indexes
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, i.uniqueness
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, i.partitioned
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, i.leaf_blocks
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, i.distinct_keys
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, i.num_rows
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, i.clustering_factor
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from (
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select table_owner
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, table_name
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, index_owner
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, index_name
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, column_name_list_dup
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, dup
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, max(dup) OVER (partition by table_owner, table_name, index_name) dup_mx
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from (
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select table_owner
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, table_name
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, index_owner
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, index_name
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, substr(SYS_CONNECT_BY_PATH(column_name, ','), 2) column_name_list_dup
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, dup
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from (
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select index_owner
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, index_name
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, table_owner
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, table_name
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, column_name
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, count(1) OVER (partition by index_owner, index_name) cnt
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, ROW_NUMBER () OVER (partition by index_owner, index_name order by column_position) as seq
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, count(1) OVER (partition by table_owner, table_name, column_name, column_position) as dup
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from dba_ind_columns
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where index_owner in ('&OWNER'))
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where dup != 1
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start with seq = 1
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connect by prior seq + 1 = seq
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and prior index_owner = index_owner
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and prior index_name = index_name)) a
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, (
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select table_owner
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, table_name
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, index_owner
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, index_name
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, substr(SYS_CONNECT_BY_PATH(column_name, ','), 2) column_name_list
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from (
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select index_owner
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, index_name
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, table_owner
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, table_name
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, column_name
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, count(1) OVER (partition by index_owner, index_name) cnt
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, ROW_NUMBER () OVER (partition by index_owner, index_name order by column_position) as seq
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from dba_ind_columns
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where index_owner in ('&OWNER'))
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where seq = cnt
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start with seq = 1
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connect by prior seq + 1 = seq
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and prior index_owner = index_owner
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and prior index_name = index_name) b
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, dba_indexes i
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where a.dup = a.dup_mx
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and a.index_owner = b.index_owner
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and a.index_name = b.index_name
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and a.index_owner = i.owner
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and a.index_name = i.index_name
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order by a.table_owner
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, a.table_name
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, column_name_list_dup;

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