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

--

-- File name: indexes_2b_shrunk.sql

--

-- Purpose: List of candidate indexes to be shrunk (rebuild online), if:

-- 1. they are larger than a certain MB threshold; and

-- 2. space savings is larger than a certain % threshold

--

-- Author: Carlos Sierra

--

-- Version: 2017/09/27

--

-- Usage: Execute on PDB

--

-- Example: @indexes_2b_shrunk.sql

--

-- Notes: Execute connected into a PDB.

-- Consider then:

-- ALTER INDEX [schema.]index REBUILD ONLINE;

--

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

-- select only those indexes with current size (as per cbo stats) greater than 10MB

VAR b_minimum_size_mb NUMBER;

EXEC :b_minimum_size_mb := 10;

-- select only those indexes with an estimated space saving percent greater than 25%

VAR b_savings_percent NUMBER;

EXEC :b_savings_percent := 25;

-- select only those indexes if recently referenced by an INDEX FULL SCAN operation (Y: only full scans, N: all)

VAR b_only_if_ref_by_full_scans CHAR(1);

EXEC :b_only_if_ref_by_full_scans := 'N';

-- have Oracle Diagnostics Pack License

VAR b_diagnostics_pack_license CHAR(1);

EXEC :b_diagnostics_pack_license := 'Y';

SET SERVEROUT ON ECHO OFF FEED OFF VER OFF TAB OFF LINES 300;

COL report_date NEW_V report_date;

SELECT TO_CHAR(SYSDATE, 'YYYY-MM-DD"T"HH24-MI-SS') report_date FROM DUAL;

PRO please wait...

SPO /tmp/indexes_2b_shrunk_fast_full_scan_&&report_date..txt;

DECLARE

l_used_bytes NUMBER;

l_alloc_bytes NUMBER;

l_percent NUMBER;

BEGIN

DBMS_OUTPUT.PUT_LINE('PDB: '||SYS_CONTEXT('USERENV', 'CON_NAME'));

DBMS_OUTPUT.PUT_LINE('---');

DBMS_OUTPUT.PUT_LINE(

RPAD('TABLE_NAME', 30)||' '||

RPAD('OWNER.INDEX_NAME', 55)||' '||

LPAD('SAVING %', 10)||' '||

LPAD('CURRENT SIZE', 20)||' '||

LPAD('ESTIMATED SIZE', 20)||' '||

RPAD('COMMAND', 75));

DBMS_OUTPUT.PUT_LINE(

RPAD('-', 30, '-')||' '||

RPAD('-', 55, '-')||' '||

LPAD('-', 10, '-')||' '||

LPAD('-', 20, '-')||' '||

LPAD('-', 20, '-')||' '||

RPAD('-', 75, '-'));

FOR i IN (

WITH

candidates_as_per_stats AS (

SELECT /*+ MATERIALIZE NO_MERGE */

x.table_name, x.owner, x.index_name,

SUM(s.leaf_blocks) * TO_NUMBER(p.value) index_size_before

FROM dba_users u, dba_indexes x, dba_ind_statistics s, v$parameter p

WHERE u.oracle_maintained = 'N'

AND x.owner = u.username

AND x.table_name <> 'KIEVTRANSACTIONS' -- KIEV application does LOCK TABLE IN EXCLUSIVE MODE, then exclude

AND x.tablespace_name NOT IN ('SYSTEM','SYSAUX')

AND x.index_type LIKE CHR(37)||'NORMAL'||CHR(37)

AND x.table_type = 'TABLE'

AND x.status = 'VALID'

AND x.temporary = 'N'

AND x.dropped = 'NO'

AND x.visibility = 'VISIBLE'

AND x.segment_created = 'YES'

AND x.orphaned_entries = 'NO'

AND s.owner = x.owner

AND s.index_name = x.index_name

AND s.table_owner = x.table_owner

AND s.table_name = x.table_name

AND p.name = 'db_block_size'

GROUP BY

x.table_name, x.owner, x.index_name, p.value

HAVING

SUM(s.leaf_blocks) * TO_NUMBER(p.value) > :b_minimum_size_mb * POWER(2,20)

),

snap AS (

SELECT /*+ MATERIALIZE NO_MERGE */

dbid, MIN(snap_id) min_snap_id

FROM dba_hist_snapshot

WHERE :b_diagnostics_pack_license = 'Y'

AND :b_only_if_ref_by_full_scans = 'Y'

AND dbid = (SELECT dbid FROM v$database)

AND end_interval_time > SYSDATE - 7 /* only last 7 days */

GROUP BY

dbid

),

awr_plans AS (

SELECT /*+ MATERIALIZE NO_MERGE */

UNIQUE hist.dbid, hist.sql_id, hist.plan_hash_value

FROM snap, dba_hist_sqlstat hist

WHERE :b_diagnostics_pack_license = 'Y'

AND :b_only_if_ref_by_full_scans = 'Y'

AND hist.dbid = snap.dbid

AND hist.snap_id >= snap.min_snap_id

),

referenced_by_fast_full_scan AS (

SELECT /*+ MATERIALIZE NO_MERGE */

object_owner, object_name

FROM v$sql_plan

WHERE :b_only_if_ref_by_full_scans = 'Y'

AND operation = 'INDEX'

AND options IN ('FULL SCAN', 'FAST FULL SCAN')

AND object_owner <> 'SYS'

GROUP BY

object_owner, object_name

UNION

SELECT /*+ MATERIALIZE NO_MERGE */

p.object_owner, p.object_name

FROM awr_plans h, dba_hist_sql_plan p

WHERE :b_diagnostics_pack_license = 'Y'

AND :b_only_if_ref_by_full_scans = 'Y'

AND p.dbid = h.dbid

AND p.sql_id = h.sql_id

AND p.plan_hash_value = h.plan_hash_value

AND p.operation = 'INDEX'

AND p.options IN ('FULL SCAN', 'FAST FULL SCAN')

AND p.object_owner <> 'SYS'

GROUP BY

p.object_owner, p.object_name

)

SELECT c.table_name, c.owner, c.index_name, c.index_size_before,

REPLACE(DBMS_METADATA.GET_DDL('INDEX',c.index_name,c.owner),CHR(10),CHR(32)) index_ddl

FROM candidates_as_per_stats c

WHERE :b_only_if_ref_by_full_scans <> 'Y'

OR (c.owner, c.index_name) IN (SELECT r.object_owner, r.object_name FROM referenced_by_fast_full_scan r)

OR c.table_name = 'KIEVTRANSACTIONKEYS' -- adding indexes for this table regardless if they are referenced on full scans, simply because of space and not because of performance concerns (they get very large)

ORDER BY

MOD(c.index_size_before, 1e4) -- randomize index selection

)

LOOP

DBMS_SPACE.CREATE_INDEX_COST(i.index_ddl,l_used_bytes,l_alloc_bytes);

IF i.index_size_before * (100 - :b_savings_percent) / 100 > l_alloc_bytes THEN

l_percent := 100 * (i.index_size_before - l_alloc_bytes) / i.index_size_before;

DBMS_OUTPUT.PUT_LINE(

RPAD(i.table_name, 30)||' '||

RPAD(i.owner||'.'||i.index_name, 55)||' '||

LPAD(TO_CHAR(ROUND(l_percent, 1), '990.0')||' % ', 10)||' '||

LPAD(TO_CHAR(ROUND(i.index_size_before / POWER(2,20), 1), '999,999,990.0')||' MB', 20)||' '||

LPAD(TO_CHAR(ROUND(l_alloc_bytes / POWER(2,20), 1), '999,999,990.0')||' MB', 20)||' '||

RPAD('ALTER INDEX '||LOWER(i.owner||'.'||i.index_name)||' REBUILD ONLINE;', 75));

END IF;

END LOOP;

END;

/

SPO OFF;