Wednesday, August 11, 2021

Reporting View Hierarchies

It is a feature of PeopleSoft that it uses lots of views to present data within the application, and frequently views reference other views.  There are examples of this design going 5 levels deep in HR and deeper in Financials.  When faced with a SQL execution plan for such a view you often wonder which view referenced which table.

However, the Oracle database describes "dependencies between procedures, packages, functions, package bodies, and triggers accessible to the current user, including dependencies on views created without any database links" in the view ALL_DEPENDENCIES.

This hierarchical query (depend_heir.sql) on this view will report the structure of views within views. 

REM depend_hier.sql
undefine view_name
set pages 999 lines 176 long 50000
break on name skip 1 on owner 
ttitle 'Dependency Hierarchy'
column my_level format a5 heading 'Level'
column owner format a12
column name format a18
column type format a7
column referenced_type format a7 heading 'Refd|Type'
column referenced_owner format a6 heading 'Refd|Owner'
column referenced_name format a18 heading 'Refd|Name'
column referenced_link_name format a10 heading 'Refd|Link'
column dependency_type heading 'Dep|Type'
column text heading 'View Text' format a80 wrap on
spool depend_hier.&&view_name..lst
with d as (
  select * from all_dependencies
  union all
  select null, null, null, owner, view_name, 'VIEW', null, null
  from all_views 
  where owner = 'SYSADM' and view_name = UPPER('&&view_name')
select LPAD(TO_CHAR(level),level,'.') my_level
, d.type, d.owner,
, d.referenced_type, d.referenced_owner, d.referenced_name, d.referenced_link_name
, d.dependency_type
, v.text
from d
  left outer join all_views v 
    on  v.owner = d.referenced_owner
    and v.view_name = d.referenced_name
  connect by nocycle = prior d.referenced_name
  and   d.owner = prior d.referenced_owner
start with d.owner IS NULL and IS NULL
spool off
ttitle off
For example, this is the report for PS_POSN_HISTORY3 from a demo HCM database. It is only three levels deep. "POSN_HISTORY3 is the third of three nested views which retrieve position incumbent history.  It selects job records with effective dates before position exits to obtain exit salaries."
Wed Aug 11                                                                                                                                                             page    1
                                                                              Dependency Hierarchy

                                              Refd    Refd   Refd               Refd       Dep
Level TYPE    OWNER        NAME               Type    Owner  Name               Link       Type View Text
----- ------- ------------ ------------------ ------- ------ ------------------ ---------- ---- --------------------------------------------------------------------------------
1                                             VIEW    SYSADM PS_POSN_HISTORY3                   SELECT A.Position_Nbr ,A.Position_Entry_Dt ,A.Emplid ,A.EMPL_RCD ,B.EFFDT ,B.EFF
                                                                                                SEQ ,B.Sal_Admin_Plan ,B.Grade ,B.Step ,B.Comprate ,B.Comp_Frequency ,B.Currency
                                                                                                _Cd ,' ' ,' ' ,' ' ,' ' FROM PS_POSN_HISTORY2 A ,PS_JOB B WHERE B.EmplID = A.Emp
                                                                                                lID AND B.EMPL_RCD = A.EMPL_RCD AND B.Position_Nbr = A.Position_Nbr AND B.EffDt
                                                                                                = ( SELECT MAX(C.EffDt) FROM PS_JOB C WHERE C.EmplID = B.EmplID AND C.EMPL_RCD =
                                                                                                 B.EMPL_RCD AND (C.EffDt < A.Position_End_Dt OR (C.EffDt = A.Position_End_Dt AND
                                                                                                 C.EffSeq = A.EffSeq - 1))) AND B.Effseq = ( SELECT MAX(C.Effseq) FROM PS_JOB C
                                                                                                WHERE C.EmplID = B.EmplID AND C.EMPL_RCD = B.EMPL_RCD AND (C.EffDt < A.Position_
                                                                                                End_Dt OR (C.EffDt = A.Position_End_Dt AND C.EffSeq = A.EffSeq - 1)))

.2    VIEW    SYSADM       PS_POSN_HISTORY3   TABLE   SYSADM PS_JOB                        HARD
.2    VIEW                                    VIEW    SYSADM PS_POSN_HISTORY2              HARD SELECT A.Position_Nbr , A.Position_Entry_Dt , A.Emplid , A.EMPL_RCD , B.EffDt ,
                                                                                                B.EffSeq , B.Action FROM PS_POSN_HISTORY A , PS_JOB B WHERE A.EmplID = B.EmplID
                                                                                                AND A.Empl_Rcd = B.Empl_Rcd AND B.EffDt = ( SELECT MIN(C.EffDt) FROM PS_JOB C WH
                                                                                                ERE C.EmplID = B.EmplID AND C.Empl_Rcd = B.Empl_Rcd AND (C.EffDt > A.Position_En
                                                                                                try_Dt OR (C.EffDt = A.Position_Entry_Dt AND C.EffSeq > A.EffSeq)) AND ((C.Posit
                                                                                                ion_Nbr <> A.Position_Nbr) OR (C.HR_STATUS <> 'A'))) AND B.EffDt<=TO_DATE(TO_CHA
                                                                                                R(SYSDATE,'YYYY-MM-DD'),'YYYY-MM-DD') AND B.EffSeq = ( SELECT MIN(D.EffSeq) FROM
                                                                                                 PS_JOB D WHERE D.EmplID = B.EmplID AND D.Empl_Rcd = B.Empl_Rcd AND D.EffDt = B.
                                                                                                EffDt AND ((D.Position_Nbr <> A.Position_Nbr) OR (D.HR_STATUS <> 'A')))

..3   VIEW    SYSADM       PS_POSN_HISTORY2   TABLE   SYSADM PS_JOB                        HARD
..3   VIEW                                    VIEW    SYSADM PS_POSN_HISTORY               HARD SELECT A.Position_Nbr ,A.Position_Entry_Dt ,A.Emplid ,A.EMPL_RCD ,A.EFFSEQ ,A.EF
                                                                                                FDT ,A.Sal_Admin_Plan ,A.Grade ,A.Step ,A.CompRate ,A.Comp_Frequency ,A.Currency
                                                                                                _Cd ,' ' ,' ' ,' ' ,' ' FROM PS_Job A WHERE A.Position_Entry_Dt = A.Effdt AND A.
                                                                                                Effseq = ( SELECT MIN(B.Effseq) FROM PS_Job B WHERE B.Emplid = A.Emplid AND B.EM
                                                                                                PL_RCD = A.EMPL_RCD AND B.Effdt = A.Effdt AND B.Position_Nbr = A.Position_Nbr)

...4  VIEW    SYSADM       PS_POSN_HISTORY    TABLE   SYSADM PS_JOB                        HARD
We can see from the report that view PS_POSN_HISTORY3 calls view PS_POSN_HISTORY2 that in turn calls view PS_POSN_HISTORY
Each of the views also contains multiple references to PS_JOB that perform various effective date/sequence sub-queries. Where there are multiple references to the same object, there is still only one dependency.
The script is available on Github as a part of my psscripts repository.

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