Thursday, January 12, 2017

Identifying Redundant Indexes in PeopleSoft

This is the first of a two-part series that discusses how to identify and remove redundant indexes from a PeopleSoft system.
I recently wrote a series of articles on my Oracle blog about identifying redundant indexes on an Oracle database. The same approach can be taken with PeopleSoft, but using the metadata in the PeopleTools tables rather than the database catalogue.
(This means you could take a similar approach for PeopleSoft on databases other than Oracle, but I can't say anything about the behaviour of other optimizers) 
The following query returns a report of superset and redundant subset indexes in a PeopleSoft system. It can be downloaded as a script from my website (psredundant.sql).
The generic Oracle version of this script will identify subset indexes that are unique as redundant because the primary key and unique constraints can be altered to use the superset index.  However, this query does not make subset unique indexes as redundant because PeopleSoft does not explicitly create unique constraints, only unique indexes.  If I disabled a unique index, I would not be able to maintain the unique constraint via Application Designer.
Subquery IC returns a list of columns for each index. Subqueries UNI, AS2 and USI retrieve columns for unique/duplicate key, alternate search and user defined indexes respectively. The absolute value of key position is not important for this exercise, it is merely used to sort the column list in the listagg() function in subquery I.
REM psredundant.sql
set lines 160 pages 50 trimspool on
column recname format a15
column superset_index format a60
column redundant_index format a60
break on recname skip 1 on indexid skip 1
spool psredundant

WITH uni AS (/*unique indexes*/
SELECT /*+MATERIALIZE*/ f.recname, i.indexid
,      MIN(i.uniqueflag) OVER (PARTITION BY f.recname) uniqueflag
,      CASE WHEN MAX(CASE WHEN f.recname != f.recname_parent THEN 1 ELSE 0 END) OVER (PARTITION BY f.recname)=1 
        THEN f.fieldnum ELSE k.keyposn END keyposn
,      k.fieldname
FROM   psrecfielddb f
,      psindexdefn i
,      pskeydefn k
WHERE  i.recname IN(f.recname,f.recname_parent)
AND    i.recname = k.recname
AND    k.fieldname = f.fieldname
AND    i.indexid = '_' /*unique index*/
AND    k.indexid = i.indexid
AND    bitand(f.useedit,3) > 0 /*unique or dup key*/
), as0 AS (/*leading column on alternate search indexes*/
SELECT f0.recname, k0.indexid, i0.uniqueflag, 0 keyposn, f0.fieldname
FROM   psrecfielddb f0
,      psindexdefn i0
,      pskeydefn k0
WHERE  bitand(f0.useedit,16) = 16 /*alternate search key*/
AND    k0.recname = f0.recname_parent
AND    k0.fieldname = f0.fieldname
AND    i0.recname = k0.recname
AND    i0.indexid = k0.indexid
AND    i0.indexid BETWEEN '0' AND '9' /*alternate search index*/
), as1 AS ( /*now add unique columns*/
SELECT as0.recname, as0.indexid, as0.uniqueflag, as0.keyposn, as0.fieldname
FROM   as0
UNION ALL /*append unique key index columns*/
SELECT as0.recname, as0.indexid, as0.uniqueflag, uni.keyposn, uni.fieldname
FROM   as0, uni
WHERE  as0.recname = uni.recname
), as2 AS (
SELECT as1.recname, as1.indexid, as1.uniqueflag, NVL(k.keyposn,as1.keyposn), as1.fieldname
FROM   as1
       LEFT OUTER JOIN pskeydefn k /*to handle custom key order*/
       ON  k.recname = as1.recname
       AND k.indexid = as1.indexid
       AND k.fieldname = as1.fieldname
), usi AS (/*user indexes*/
SELECT i.recname, i.indexid, i.uniqueflag, k.keyposn, k.fieldname
FROM   psindexdefn i
,      pskeydefn k
WHERE  k.recname = i.recname
AND    k.indexid = i.indexid
AND    k.indexid BETWEEN 'A' AND 'Z'
AND    i.platform_ora = 1
), m AS (/*merge three kinds of index here*/
SELECT uni.recname, uni.indexid, uni.uniqueflag, uni.keyposn, uni.fieldname
FROM   uni
SELECT as1.recname, as1.indexid, as1.uniqueflag, as1.keyposn, as1.fieldname
FROM   as1
SELECT usi.recname, usi.indexid, usi.uniqueflag, usi.keyposn, usi.fieldname
FROM   usi
), ic AS ( /*list of columns, restrict to tables*/
SELECT r.recname, m.indexid, m.uniqueflag, m.keyposn, m.fieldname
FROM   m
,      psrecdefn r
WHERE  r.rectype IN(0,7)
And    r.recname = m.recname
), i AS ( --construct column list
       ic.recname, ic.indexid, ic.uniqueflag
,      count(*) num_columns
,      listagg(ic.fieldname,',') within group (order by ic.keyposn) AS fieldlist
FROM   ic
GROUP BY ic.recname, ic.indexid, ic.uniqueflag
SELECT r.recname
,      i.indexid||' ('||i.fieldlist||')' superset_index
,      r.indexid||' ('||r.fieldlist||')' redundant_index
FROM   i
,      i r
WHERE  i.recname = r.recname
AND    i.indexid != r.indexid
AND    r.uniqueflag = 0 /*non-unique redundant*/
AND    i.fieldlist LIKE r.fieldlist||',%'
AND    i.num_columns > r.num_columns
order by r.recname, r.indexid

spool off
This is part of the output for a HR 9.2 demo database. In all it identified 58 indexes on 41 records. However, some of those records are temporary records with several physical instances, so the number of database objects that will be removed is higher.
RECNAME         SUPERSET_INDEX                                               REDUNDANT_INDEX
--------------- ------------------------------------------------------------ -----------------------------------------------------------
HRS_APP_PROFILE C (HRS_AL_LOG_ID,HRS_PERSON_ID)                              B (HRS_AL_LOG_ID)


HR_PROMOTE_XREF C (EMPLID,EMPL_RCD)                                          A (EMPLID)
                B (EMPLID,EMPL_RCD,ACTION_DT_SS,EFFSEQ)                      A (EMPLID)
                B (EMPLID,EMPL_RCD,ACTION_DT_SS,EFFSEQ)                      C (EMPLID,EMPL_RCD)


HR_TRANSFR_XREF C (EMPLID,EMPL_RCD)                                          A (EMPLID)
                B (EMPLID,EMPL_RCD,ACTION_DT_SS,EFFSEQ)                      A (EMPLID)
                B (EMPLID,EMPL_RCD,ACTION_DT_SS,EFFSEQ)                      C (EMPLID,EMPL_RCD)

PA_ALIAS_USE    0 (ALIAS_TYPE,ALIAS_NAME)                                    A (ALIAS_TYPE)

The articles on my Oracle blog discuss how to identify redundant indexes on an Oracle database, and then how to go about removing them.  Of course, in PeopleSoft, you should only remove indexes by making the change within Application Designer, and that is what the next posting discusses.

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