Introducing the Analytic Keep Clause for Effective-Dated/Sequence Queries in PeopleSoft

Those of us who work with PeopleSoft, and especially the HCM product, are all too familiar with the concept of effect-dated data, and the need to find data that was effective at a particular date.  PeopleSoft products have always made extensive use of correlated sub-queries to determine the required rows from an effective-dated record.
The JOB record is the heart of HCM. It is both effective-dated and effective sequenced. I will use it for the demonstrations in this article. I am going to suggest an alternative, although Oracle-specific, SQL construction.
 Let's start by looking at the job data for an employee in the demo database. Employee KF0018 has 17 rows of data two concurrent jobs.  The question I am going to ask is "What was the annual salary for this employee on 11 February 1995?".  Therefore, I am interested in the rows marked below with the asterisks. 

column annual_rt format 999,999
SELECT  emplid, empl_rcd, effdt, effseq, action, deptid, currency_cd, annual_rt
FROM	ps_job j
WHERE	j.emplid = 'KF0018'
ORDER BY 1,2,3,4
/ 

EMPLID        EMPL_RCD EFFDT         EFFSEQ ACT DEPTID     CUR ANNUAL_RT
----------- ---------- --------- ---------- --- ---------- --- ---------
KF0018               0 12-JUN-83          0 HIR 13000      FRF   120,000
KF0018               0 01-JAN-84          0 PAY 13000      FRF   123,600
KF0018               0 01-JAN-85          0 PAY 13000      FRF   127,308
KF0018               0 01-JAN-86          0 PAY 13000      FRF   131,764
KF0018               0 01-JAN-87          0 PAY 13000      FRF   136,376
KF0018               0 01-JAN-88          0 PAY 13000      FRF   140,467
KF0018               0 01-JAN-89          0 PAY 13000      FRF   147,490
KF0018               0 22-JAN-95          0 PRO 13000      FRF   147,490
KF0018               0 22-JAN-95          1 PAY 13000      FRF   294,239 *
KF0018               0 22-JAN-96          0 PAY 13000      FRF   318,575
KF0018               0 01-JAN-98          0 PAY 13000      FRF   346,156
KF0018               0 01-JAN-00          0 DTA 13000      FRF   346,156
KF0018               0 01-JAN-02          0 PAY 13000      EUR    52,771
KF0018               1 01-NOV-89          0 ASG 21300      GBP    22,440
KF0018               1 31-DEC-93          0 ASC 21300      GBP    22,440
KF0018               1 01-JAN-94          0 ASG 12000      GBP    22,440 *
KF0018               1 31-DEC-95          0 ASC 10000      GBP    22,440

I will set the statistics level to ALL so I can obtain detailed information about how the SQL statements execute:

ALTER SESSION SET statistics_level = ALL;

I extracted the execution plans and execution statistics with the following command

select * from table(dbms_xplan.display_cursor(null,null,'IOSTATS')) 

Typical PeopleSoft Platform Agnostic Construction

This is the usual way to construct the query in PeopleSoft. It is also valid on all databases platforms supported by PeopleSoft, not just Oracle. 

SELECT  emplid, empl_rcd, effdt, effseq, action, deptid, currency_cd, annual_rt
FROM	ps_job j
WHERE	j.effdt = ( 
        SELECT MAX (j1.effdt) FROM ps_job j1 
        WHERE j1.emplid = j.emplid 
        AND j1.empl_rcd = j.empl_rcd 
        AND j1.effdt <= TO_DATE('19950211','YYYYMMDD')) 
AND j.effseq = ( 
        SELECT MAX (j2.effseq) FROM ps_job j2 
        WHERE j2.emplid = j.emplid 
        AND j2.empl_rcd = j.empl_rcd 
        AND j2.effdt = j.effdt)
AND j.emplid = 'KF0018'
ORDER BY 1,2,3,4
/

EMPLID        EMPL_RCD EFFDT         EFFSEQ ACT DEPTID     CUR ANNUAL_RT
----------- ---------- --------- ---------- --- ---------- --- ---------
KF0018               0 22-JAN-95          1 PAY 13000      FRF   294,239
KF0018               1 01-JAN-94          0 ASG 12000      GBP    22,440

This required three access of indexes on the PS_JOB table, and two accesses of the table, using 26 consistent reads.

Plan hash value: 2299825310
----------------------------------------------------------------------------------------------------------------
| Id  | Operation                         | Name    | Starts | E-Rows | A-Rows |   A-Time   | Buffers | Reads  |
----------------------------------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT                  |         |      1 |        |      2 |00:00:00.01 |      26 |      2 |
|   1 |  SORT ORDER BY                    |         |      1 |      1 |      2 |00:00:00.01 |      26 |      2 |
|   2 |   NESTED LOOPS                    |         |      1 |      1 |      2 |00:00:00.01 |      26 |      2 |
|   3 |    NESTED LOOPS                   |         |      1 |      1 |      3 |00:00:00.01 |      21 |      2 |
|   4 |     VIEW                          | VW_SQ_1 |      1 |      1 |      2 |00:00:00.01 |      14 |      2 |
|*  5 |      FILTER                       |         |      1 |        |      2 |00:00:00.01 |      14 |      2 |
|   6 |       HASH GROUP BY               |         |      1 |      1 |      2 |00:00:00.01 |      14 |      2 |
|   7 |        TABLE ACCESS BY INDEX ROWID| PS_JOB  |      1 |      1 |     12 |00:00:00.01 |      14 |      2 |
|*  8 |         INDEX RANGE SCAN          | PS_JOB  |      1 |      1 |     12 |00:00:00.01 |       2 |      2 |
|   9 |     TABLE ACCESS BY INDEX ROWID   | PS_JOB  |      2 |      1 |      3 |00:00:00.01 |       7 |      0 |
|* 10 |      INDEX RANGE SCAN             | PSAJOB  |      2 |      1 |      3 |00:00:00.01 |       4 |      0 |
|* 11 |    VIEW PUSHED PREDICATE          | VW_SQ_2 |      3 |      1 |      2 |00:00:00.01 |       5 |      0 |
|* 12 |     FILTER                        |         |      3 |        |      3 |00:00:00.01 |       5 |      0 |
|  13 |      SORT AGGREGATE               |         |      3 |      1 |      3 |00:00:00.01 |       5 |      0 |
|* 14 |       FILTER                      |         |      3 |        |      5 |00:00:00.01 |       5 |      0 |
|* 15 |        INDEX RANGE SCAN           | PSAJOB  |      3 |      1 |      5 |00:00:00.01 |       5 |      0 |
----------------------------------------------------------------------------------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------

   5 - filter("J1"."EMPLID"='KF0018')
   8 - access("J1"."EMPLID"='KF0018' AND "J1"."SYS_NC00164$">=HEXTORAW('883CFDF4FEF8FEFAFF') )
       filter(SYS_OP_UNDESCEND("J1"."SYS_NC00164$")<=TO_DATE(' 1995-02-11 00:00:00', 'syyyy-mm-dd
              hh24:mi:ss'))
  10 - access("J"."EMPLID"='KF0018' AND "ITEM_2"="J"."EMPL_RCD" AND
              "J"."SYS_NC00164$"=SYS_OP_DESCEND("MAX(J1.EFFDT)"))
       filter(SYS_OP_UNDESCEND("J"."SYS_NC00164$")="MAX(J1.EFFDT)")
  11 - filter(SYS_OP_UNDESCEND("J"."SYS_NC00165$")="MAX(J2.EFFSEQ)")
  12 - filter(COUNT(*)>0)
  14 - filter('KF0018'="J"."EMPLID")
  15 - access("J2"."EMPLID"='KF0018' AND "J2"."EMPL_RCD"="J"."EMPL_RCD" AND
              "J2"."SYS_NC00164$"=SYS_OP_DESCEND(SYS_OP_UNDESCEND("J"."SYS_NC00164$")))
       filter(SYS_OP_UNDESCEND("J2"."SYS_NC00164$")=SYS_OP_UNDESCEND("J"."SYS_NC00164$"))

This construction is also the reason you are required to set

_UNNEST_SUBQUERY=FALSE

on all PeopleSoft systems

Analytic Function and In-Line View/Sub-query Factor

I have seen people use a combination of analytic functions and in-line views to avoid having to use the correlated sub-query construction. This has been possible since Oracle 9i.

WITH X AS (
SELECT  emplid, empl_rcd, effdt, effseq, action, deptid, currency_cd, annual_rt
,	ROW_NUMBER() OVER (PARTITION BY emplid, empl_rcd 
                           ORDER BY effdt DESC, effseq DESC) myrowseq
FROM	ps_job j
WHERE	j.effdt <= TO_DATE('19950211','YYYYMMDD')
AND	j.emplid = 'KF0018'
)
SELECT 	emplid, empl_rcd, effdt, effseq, action, deptid, currency_cd, annual_rt
FROM 	x
WHERE	myrowseq = 1
ORDER BY 1,2,3,4
/

EMPLID        EMPL_RCD EFFDT         EFFSEQ ACT DEPTID     CUR ANNUAL_RT
----------- ---------- --------- ---------- --- ---------- --- ---------
KF0018               0 22-JAN-95          1 PAY 13000      FRF   294,239
KF0018               1 01-JAN-94          0 ASG 12000      GBP    22,440

We get the same result, but now the index is scanned just once and we only need 14 consistent reads, so it produces a significant improvement. However, it still includes a sort operation in addition to the window function. We have to create a sequence number field in the in-line view and filter by that in the final query.

Plan hash value: 1316906785
---------------------------------------------------------------------------------------------------
| Id  | Operation                      | Name   | Starts | E-Rows | A-Rows |   A-Time   | Buffers |
---------------------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT               |        |      1 |        |      2 |00:00:00.01 |      14 |
|   1 |  SORT ORDER BY                 |        |      1 |      1 |      2 |00:00:00.01 |      14 |
|*  2 |   VIEW                         |        |      1 |      1 |      2 |00:00:00.01 |      14 |
|*  3 |    WINDOW NOSORT               |        |      1 |      1 |     12 |00:00:00.01 |      14 |
|   4 |     TABLE ACCESS BY INDEX ROWID| PS_JOB |      1 |      1 |     12 |00:00:00.01 |      14 |
|*  5 |      INDEX RANGE SCAN          | PSAJOB |      1 |      1 |     12 |00:00:00.01 |       2 |
---------------------------------------------------------------------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------

   2 - filter("MYROWSEQ"=1)
   3 - filter(ROW_NUMBER() OVER ( PARTITION BY "EMPLID","EMPL_RCD" ORDER BY
              "J"."SYS_NC00164$","J"."SYS_NC00165$")<=1)
   5 - access("J"."EMPLID"='KF0018' AND "J"."SYS_NC00164$">=HEXTORAW('883CFDF4FEF8FEFAFF')
              )
       filter(SYS_OP_UNDESCEND("J"."SYS_NC00164$")<=TO_DATE(' 1995-02-11 00:00:00',
              'syyyy-mm-dd hh24:mi:ss'))

Analytic Function Keep Clause

This form of the analytic functions is documented for the first time in 12c, but is available in 10g (my thanks to Tony Hasler for introducing me to it). It works by effectively keeping a running maximum value of the columns in the order by clause within in group.

SELECT emplid, empl_rcd
, MAX(effdt) KEEP (DENSE_RANK LAST ORDER BY effdt, effseq) AS effdt
, MAX(effseq) KEEP (DENSE_RANK LAST ORDER BY effdt, effseq) AS effseq
, MAX(action) KEEP (DENSE_RANK LAST ORDER BY effdt, effseq) AS action
, MAX(deptid) KEEP (DENSE_RANK LAST ORDER BY effdt, effseq) AS deptid
, MAX(currency_cd) KEEP (DENSE_RANK LAST ORDER BY effdt, effseq) AS currency_cd
, MAX(annual_rt) KEEP (DENSE_RANK LAST ORDER BY effdt, effseq) AS annual_rt
FROM ps_job j
WHERE	j.effdt <= TO_DATE('19950211','YYYYMMDD')
AND	j.emplid = 'KF0018'
GROUP BY emplid, empl_rcd
/

EMPLID        EMPL_RCD EFFDT         EFFSEQ ACT DEPTID     CUR ANNUAL_RT
----------- ---------- --------- ---------- --- ---------- --- ---------
KF0018               0 22-JAN-95          1 PAY 13000      FRF   294,239
KF0018               1 01-JAN-94          0 ASG 12000      GBP    22,440

Although this construction uses an additional consistent read, it has the advantage of not using either an inline view or a window function and does not sort the data.

Plan hash value: 1550496807
-------------------------------------------------------------------------------------------------
| Id  | Operation                    | Name   | Starts | E-Rows | A-Rows |   A-Time   | Buffers |
-------------------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT             |        |      1 |        |      2 |00:00:00.01 |      15 |
|   1 |  SORT GROUP BY NOSORT        |        |      1 |      1 |      2 |00:00:00.01 |      15 |
|   2 |   TABLE ACCESS BY INDEX ROWID| PS_JOB |      1 |      1 |     12 |00:00:00.01 |      15 |
|*  3 |    INDEX RANGE SCAN          | PS_JOB |      1 |      1 |     12 |00:00:00.01 |       3 |
-------------------------------------------------------------------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------

   3 - access("J"."EMPLID"='KF0018' AND "J"."SYS_NC00164$">=HEXTORAW('883CFDF3FEF8FEFAFF'
              ) )
       filter(SYS_OP_UNDESCEND("J"."SYS_NC00164$")<=TO_DATE(' 1995-02-12 00:00:00',
              'syyyy-mm-dd hh24:mi:ss'))

I think this construction could be useful in PeopleSoft.  At first glance, the SQL appears more complicated, but in this example, it removed two correlated sub-queries. 

Using Analytic Functions in PS/Query

Of course, you can code it anywhere where you can simply enter SQL as text.  However, it also has the advantage over the other analytic function construction that it can be coded in the PS/Query tool.  The analytic functions in the select clause should be created in PS/Query expressions with the aggregate expression checkbox ticked.

Analytic Function in Aggregated Expression in Windows Client version of PS/Query 

The analytic functions can be selected in the PS/Query, and their lengths and titles can be tidied up.

PS/Query with Analytic 'Keep' Functions

This is the resulting SQL which is the same as before (with row-level security added by PS/Query) and produces the same results.

SELECT A.EMPLID, A.EMPL_RCD, MAX(effdt) KEEP (DENSE_RANK LAST ORDER BY effdt, effseq)
, MAX(effseq) KEEP (DENSE_RANK LAST ORDER BY effdt, effseq), MAX(action) KEEP (DENSE_RANK LAST ORDER BY effdt, effseq), MAX(deptid) KEEP (DENSE_RANK LAST ORDER BY effdt, effseq), MAX(currency_cd) KEEP (DENSE_RANK LAST ORDER BY effdt, effseq), MAX(annual_rt) KEEP (DENSE_RANK LAST ORDER BY effdt, effseq)					
  FROM PS_JOB A, PS_EMPLMT_SRCH_QRY A1
  WHERE ( A.EMPLID = A1.EMPLID
    AND A.EMPL_RCD = A1.EMPL_RCD
    AND A1.OPRID = 'PS'
    AND ( A.EFFDT <= TO_DATE('1995-02-11','YYYY-MM-DD')
     AND A.EMPLID = 'KF0018' ) )
  GROUP BY  A.EMPLID,  A.EMPL_RCD

Implementing Deferred Segment Creation After an Upgrade

I have written previously about Deferred Segment Creation. Each empty table and its indexes use only 64Kb (assuming an 8Kb block size and locally managed tablespaces), but in a PeopleSoft there can be be tens of thousands of such tables and that adds up to a saving worth making.

If you are upgrading your database to 11gR2 , you might want to make sure that you are using it.  Deferred segment creation was introduced in Oracle 11.2.0.2 and it became the default in 11.2.0.3.  However, any table created in a previous version will have a physical segment.

This problem could affect any system, but it also manifests itself in PeopleSoft in a particular way.

When you run the alter scripts in PeopleTools a table may be recreated.  If it is a regular table (record type 0) then the CREATE TABLE command will not specify a segment creation clause and so the segment creation will be deferred until rows are inserted.

CREATE TABLE PS_TL_IPT1 (PROCESS_INSTANCE DECIMAL(10) NOT NULL,
   EMPLID VARCHAR2(11) NOT NULL,
...
   INITIAL_SEQ_NBR DECIMAL(15) NOT NULL) TABLESPACE TLWORK STORAGE
 (INITIAL 40000 NEXT 100000 MAXEXTENTS UNLIMITED PCTINCREASE 0)
 PCTFREE 10 PCTUSED 80
/

However, from PeopleTools 8.51, Application Designer uses the Oracle delivered DBMS_METADATA package to extract the DDL to recreate the object from the actual object.  However, this behaviour only occurs for Temporary working storage tables (record type 7).  Yes, these are exactly the tables that would benefit most from deferred segment creation because in many systems there are many unused temporary table instances.  If table was created under a version of the database prior to 11.2.0.2 then the segment will exist and DBMS_METADATA will generate the DDL with the SEGMENT CREATION IMMEDIATE clause. 

-- Create temporary table 
CREATE TABLE PSYPERSON (EMPLID VARCHAR2(11) NOT NULL,
...
   LAST_CHILD_UPDDTM tIMESTAMP) SEGMENT CREATION IMMEDIATE
  PCTFREE 10 PCTUSED 80 INITRANS 1 MAXTRANS 255
 NOCOMPRESS LOGGING
  STORAGE(INITIAL 40960 NEXT 106496 MINEXTENTS 1 MAXEXTENTS 2147483645
  PCTINCREASE 0 FREELISTS 1 FREELIST GROUPS 1
  BUFFER_POOL DEFAULT FLASH_CACHE DEFAULT CELL_FLASH_CACHE DEFAULT)
  TABLESPACE "HRLARGE"
/

You can use DBMS_SPACE_ADMIN.DROP_EMPTY_SEGMENTS to remove the segments for any empty tables (and their indexes) for which the segment has been previously created.  There would be no harm in simply running this program for every table in the system.  If there are rows then DBMS_SPACE_ADMIN will take no action.

The following script identifies candidate tables where the statistics suggest that there are no rowa or where there are no statistics.  I am indebted to Tim Hall for the idea for this tip.

set serveroutput on 
BEGIN
 FOR i IN (
  SELECT owner, table_name
  FROM   all_tables
  WHERE  owner = 'SYSADM'
  AND    segment_created = 'YES'
  AND    temporary = 'N'
  AND   (num_rows = 0 OR num_rows IS NULL)
 ) LOOP
  dbms_output.put_line(i.owner||'.'||i.table_name);
  dbms_space_admin.drop_empty_segments (
    schema_name    => i.owner,
    table_name     => i.table_name);
 END LOOP;
END;
/

As this package drops the empty segments, the SEGMENT_CREATED column on USER_TABLES changes to NO and if you were to extract the DDL with DBMS_METADATA the SEGMENT CREATION clause would have changed to DEFERRED.

As soon as any data is inserted, the segment is created, SEGMENT_CREATED changes to YES and the DDL generated by DBMS_METADATA would have SEGMENT CREATION IMMEDIATE.

The result is that 64Kb of space (assuming a block size of 8Kb) will be freed up for each empty table and index segment that is dropped. Your mileage may vary, but in my demo HR database that is over 20000 tables and 25000 indexes. 2.7Gb isn't a vast amount these days, but it is an easy win.

Added 1.2.2014:

To answer Noons' question below.  So long as the table or partition doesn't have any rows, the segment will be dropped it will as if the segment creation had been deferred.  You don't have to do anything special to the table.  There is no problem applying this to any empty tables create with their segments.  Here is a simple test with my results on 11.2.0.3:

I will create a table and I have explicitly created the segment immediately, then I insert a row, commit the insert and delete the row.  I haven't even bothered to commit the delete.

SQL> create table t(a number) segment creation immediate;
SQL> insert into t values(42);
SQL> commit;
SQL> delete from t;
SQL> select segment_type, segment_name, tablespace_name from user_Segments where segment_name = 'T';

SEGMENT_TYPE       SEGMENT_NAME    TABLESPACE_NAME
------------------ --------------- ------------------------------
TABLE              T               PSDEFAULT

SQL> select table_name, segment_created from user_tables where table_name = 'T';

TABLE_NAME                     SEG
------------------------------ ---
T                              YES

SQL> select dbms_metadata.get_ddl('TABLE','T') from dual;

DBMS_METADATA.GET_DDL('TABLE','T')
--------------------------------------------------------------------------------
  CREATE TABLE "SYSADM"."T"
   ( "A" NUMBER
   ) SEGMENT CREATION IMMEDIATE

So, at the moment the segment exists, it has had rows in it, but they have been deleted and the table is empty. If I run DBMS_SPACE_ADMIN.DROP_EMPTY_SEGMENTS the segment is dropped.

SQL> execute dbms_space_admin.drop_empty_segments (user,'T');
SQL> select segment_type, segment_name, tablespace_name from user_Segments where segment_name = 'T';

no rows selected

SQL> select table_name, segment_created from user_tables where table_name = 'T';

TABLE_NAME                     SEG
------------------------------ ---
T                              NO

SQL> select dbms_metadata.get_ddl('TABLE','T') from dual;

DBMS_METADATA.GET_DDL('TABLE','T')
--------------------------------------------------------------------------------
  CREATE TABLE "SYSADM"."T"
   ( "A" NUMBER
   ) SEGMENT CREATION DEFERRED

Date to Timestamp Conversion during PeopleTools Upgrade

This blog posting describes a script to convert Oracle date columns to Timestamps as used from PeopleTools 8.50 but only rebuilding those indexes that reference those columns, rather than drop and recreate every index in the system, thus producing a significant saving of time during the upgrade.

(A longer version of this article is available on my website)

I am working on a PeopleSoft upgrade project.  We are going from PeopleTools 8.49 to 8.53.  One of the things that happens is that some date columns in the Oracle database become timestamps.

Timestamps were introduced by Oracle in version 10g of the database, and provide the ability to store times accurate to the nanosecond (although the default is microsecond). Dates are accurate to the whole second.

There are 3 types of temporal column in PeopleSoft as defined on PSDBFIELD.  Prior to PeopleTools 8.50 they all become Oracle date columns in the database.  However, from PeopleTools 8.50; Time and DateTime fields are built as TimeStamp columns.if bit 5 of PSSTATUS.DATABASE_OPTIONS (value 32) is set.

PeopleTools Field Type		Database Column Type
		PeopleTools <= 8.49	PeopleTools >= 8.50
4	Date	DATE	DATE
5	Time	DATE	TIMESTAMP
6	DateTime	DATE	TIMESTAMP

Timestamps must be handled differently to dates in SQL.  Some date arithmetic must be done differently, in particular the difference between two timestamps is a timestamp rather than a number of days.  Therefore this setting also controls how PeopleCode date macros expand on Oracle.

During the upgrade, PeopleSoft Change Assistant simply alters all the Time and DateTime columns from dates to timestamps.  This generally works well.  The data value doesn't appear to get longer, so the block doesn't run out of room leading to row migration, and so it isn't necessary to rebuild every table that is affected.

However, there are some limitations. If the column being converted to a timestamp falls into one of the following categories you will get an error.

• The column is a key column in a function-based index.
• The table or index is partitioned by the column.

The functional key index issue has not affected many customers because the upgrade template drops all the indexes before altering the tables and rebuilding them again.

However, dropping and recreating all these indexes can be very time consuming and increases the duration of the outage required to perform the upgrade.  This has been my incentive to find a better way.

Function-Based Indexes
PeopleSoft Application Designer defines some key and search fields as descending.  The rows in components and the results of search dialogue are sorted on the key fields in the order specified.  Application Designer then indexes these columns in descending order (prior to PeopleTools 8 and since PeopleTools 8.47).  If any column in an Oracle index is in descending order the index is created as a function-based index.  Consequently, there can be a lot of descending indexes in a PeopleSoft system!  HR systems are particularly affected because many tables are effective-dated, and the field EFFDT is usually a descending key field.

It is not possible to alter a column to a timestamp if it appears anywhere in a function-based index. You get the following error:

ORA-30556: functional index is defined on the column to be modified 

Partitioning
Partitioning is not something that you usually encounter in a vanilla PeopleSoft system, but it can be added by customisation.  You generate the necessary DDL yourself if you want to use it. However, from PeopleTools 8.51 Application Designer will preserve existing partitioning.

In the system on which I am working, when partitioned the audit tables by AUDIT_STAMP which is a DateTime field.

ORA-14060: data type or length of an table partitioning column may not be changed 

We have had no alternative but to rebuild these tables and repopulate the data. This has also dealt with all locally partitioned indexes.

We have also found that we have one global index partitioned on a timestamp.

ORA-14061: data type or length of an index partitioning column may not be changed 

We also have had to drop this index in order to alter the table.

My Approach
We have had no alternative but to rebuild and repopulate our partitioned audit tables which are partitioned by a DateTime field.  However, that is what we did when we first partitioned them.  The scripts are very similar to those generated by Application Designer.  The table is renamed, a new one is built, and the data is copied.  In our case these scripts are built with a PL/SQL utility.  This also addressed the need to rebuild the locally partitioned indexes..

To minimize the number of indexes which must be rebuilt I have written a PL/SQL script (http://www2.go-faster.co.uk/scripts/gfc_desc_timestamp_index.sql) that:

• identifies the indexes that need to be dropped.
• captures the DDL to recreate the indexes using DBMS_METADATA and stores it in a table,
• drops the indexes,
• alters the columns that cannot be altered with the index in place,
• recreates the index.

The script successfully handles partitioned function-based indexes.

On this particular HR system we only rebuilt about 400 indexes instead of over 10000. Now the standard PeopleSoft upgrade template can be run without dropping or recreating any further indexes.

Minimum Number of Recycling Server Processes

When I rebuilt my demo system (some while ago) with PeopleTools 8.52, I noticed a new message generated by ubbgen in PeopleTools 8.52 when the minimum number of recycling servers is set to 1.

WARNING: PSAPPSRV, PSSAMSRV, PSQRYSRV, PSQCKSRV, PSPPMSRV and PSANALYTICSRV are configured with Min instance set to 1. 
To avoid loss of service, configure Min instance to at least 2.

What Produces the Message?
ubbgen is the PeopleSoft utility that merges the template file (psappsrv.ubx) with the configuration file (psappsrv.cfg) file to produce the Tuxedo configuration file (psappsrv.ubb) and the environment file (psappsrv.env). It is invoked by psadmin during Tuxedo domain configuration.

ubbgen -t psappsrv.ubx -c psappsrv.cfg -o psappsrv.ubb -v psappsrv.val -q y -u PUBSUB=n/QUICKSRV=n/QUERYSRV=n/JOLT=y/JRAD=n/DBGSRV=n/RENSRV=n/MCF=n/PPM=n/ANALYTICSRV=n

The message is produced at this time.

Recycling Servers
Several servers in a PeopleSoft application Server domain recycle after they have handled a number of services. Recycling is a PeopleSoft behaviour and not a Tuxedo behaviour.  It is controlled by the Recycle Count parameter in the PeopleSoft configuration file (psappsrv.cfg).  This parameter is not referenced in the template file (psappsrv.ubx).

[PSAPPSRV]
;=========================================================================
; Settings for PSAPPSRV
;=========================================================================

;-------------------------------------------------------------------------
; UBBGEN settings
Min Instances=2
Max Instances=3
Service Timeout=0

;-------------------------------------------------------------------------
; Number of services after which PSAPPSRV will automatically restart.
; If the recycle count is set to zero, PSAPPSRV will never be recycled.
; The default value is zero.
; Dynamic change allowed for Recycle Count
Recycle Count=1000

PeopleSoft first started using BEA Tuxedo (as it was then) in PeopleTools 6 to remote call Cobol processes in the Financials product.  The Application Server was introduced in PeopleTools 7.  PSAPPSRV had recycling from the first release.  Legend has it that the engineers at Tuxedo where horrified when they heard that PeopleSoft had introduced recycling to resolve problems created by dynamic memory allocation and deallocation by the Panel Processor (now known as the component Processor).

Tuxedo servers are supposed to be robust, long lived and not require to be regularly restarted.  Hence the server restart functionality in Tuxedo is only designed to be invoked in the rare occasions when a server process crashes.  Server processes are started by the Restart Server (restartsrv), and only one process can be started concurrently.

The minimum of 2 applies to the following servers because they can both recycle and be configured to spawn additional instances on demand PSAPPSRV, PSANALYTICSRV, PSSAMSRV, PSQCKSRV, PSQRYSRV, PSPUBHND, PSSUBHND, PSBRKHND.  In the delivered configuration file for the developer domain, recycling is disabled for several servers by setting the recycle count to zero.  However, the message is produced by ubbgen irrespective of the value of recycle count.

The message handler servers can be set to have just a single instance, without producing any warning.  They only consume messages from the dispatcher processes so their temporary disappearance will not cause user errors.

What Happens When The Only Server Recycles?
Tuxedo server processes consume service requests placed on queues.  When a server starts up, it advertises its services on the Bulletin Board.  Tuxedo processes that submit requests (mostly the JSH processes, but also the message dispatcher processes, the Process Scheduler) look up on the Bulletin Board where a service is advertised and place it on the appropriate queue.

When a server process performs an orderly shutdown (as it does during a recycle) it removes the adverts for its services (the command is unadvertise).  If a process crashes the Bulletin Board Liaison process (BBL) detects the crash and cleans the Bullentin Board. When all services advertised on a queue have been unadvertised, the queue is also removed from the Bulletin Board.  If the process submitting the service request cannot find any server advertising a service it generates an error.  

074001.GO-FASTER-6!JSH.3124.5736.-2: JOLT_CAT:1043: "ERROR: tpacall() call failed, tperrno = 6"

This is why the minimum is 2.  If you recycled the only server process, it is possible for someone to produce this error (see also Minimum Number of Application Server Processes).

Should I set the minimum higher than 2?
The number of services handled by different server processes on the same queue is usually uneven because the service is handled by the first free server.  Therefore it is rare for the processes will reach the recycle count simultaneously, but it can still happen.  Even in a quiet system that doesn't have sufficient activity to justify 3 PSAPPSRVs, I prefer to set the minimum number of servers to at least 3. 

Debugger
NB: If the debugger process is enabled then PSADMIN will force the minimum and maximum number of PSAPPSRV processes to at least 2.  ubbgen will actually update psappsrv.cfg.

Warning:  PSAPPSRV Min Instances too small, setting to 2 for debugger.

No DBA is an Island

Introduction

I gave an OakTalk at the UKOUG2012 conference. This article is based upon the notes for that talk. It is not a technical article, just an opinion piece.
I have always described myself as a DBA, although it has been many years since I had day-to-day responsibility for a production database.  My day job is about performance, helping people to get the best possible performance from their PeopleSoft systems.  That can involve anything from tuning a specific SQL statement, to changing how the database, middleware, or application has been configured, through to standing back and looking at the way the architecture has been put together.  Lots of people have to work together on any system, and I frequently work with people for whom the database is not their home
The concept of the division of labour is nothing new.  Plato suggested the ‘minimum state would consist of four or five men’.  Adam Smith (possibly inspired by Henri-Louis Duhamel du Monceau) famously took the manufacture of pins as his example.  Businesses must break tasks down into manageable units, and as they do each person’s job becomes progressively more specific and specialised. 
IT is no exception.  The modern IT department is broken down into teams of administrators.  We have desktop teams, network teams, application administrators, middleware teams, DBA, operating system admins, storage area network teams.  In some places, I have seen DBA teams broken down into a core database team and separate application DBA teams for each major application.  Every tier and technology has its team, each with specialist knowledge and skills. Such are the tribes of IT.
I have heard these groupings described as verticals, or stove-pipes, or silos.  The clue is in the name.  The problem that I perceive is that these groups are not always good at communicating with each other, and when something goes wrong, they are not always above blaming one another.

What is IT for? 

A modern company simply couldn’t function without IT.  The business systems that we, as IT professionals design, build and manage are fundamental to the companies in which we work.  There will be lots of different systems that do stuff.  Different companies will do slightly different stuff.  Absolute minimum, you need a PC that can connect to things.  There will always be e-mail. There will be a Finance system to track the money.  There will be some form of HR system to track employees.  There will be a payroll system to pay the employees.  If a company sells widgets, there will be some form of stock control, and some form of logistics to manage its movement.  Those systems will communicate with each other. Lots of systems, and it doesn’t really matter what the system is.  The point is that every system will need the services provided by several of those IT silos. Each system is a chain of technology that is laid horizontally across those IT silos. At one end you have users, and at the other end, you probably have physical spinning disks (for now).  Over time, those chains have come to exist of every more links.

The DBA’s view?

I described myself as a DBA, because that is the tribe I came from. However, I firmly believe, if I was still a day-to-day production DBA, that in order to do my job properly, I would occasionally need to look out from my silo and not just to look at the neighbouring silos along the chains of technology, but all the silos on the chains, and sometimes even outside IT department.
I believe that the DBA is well placed and appropriately skilled to asses most aspects of a system.  Let me illustrate this with 2 examples

Example 1: Two Temporary Tablespace

I have seen more than one HR system where the temporary tablespace has been allowed to grow hugely, sometimes hundreds of GB, in response to space errors. Each time, the root cause has been users running ad-hoc queries concurrently with critical batch processes. So, I have suggested that they use two temporary tablespaces.
•    One for regular processing – on-line transaction processing, regular and scheduled batch processes.
•    Another for ad-hoc queries whether submitted by ad-hoc database users or by the application’s ad-hoc query tool.
As a DBA, that seems like a straight forward technical decision.  It will protect the critical batches from out of space errors that occur when the temp space has been consumed by the ad-hoc queries.  It allows me to regulate bad queries by restricting their temporary tablespace consumption limiting their effect on the system while they run for hours on end while they copy data into the temporary tablespace (and before anybody asks, we are also thinking about Oracle resource manager).
But it isn’t as simple as that.  It requires a different relationship between the users and their application support team.  Now, when a query crashes with an out of space error we don’t just extend the temporary tablespace, we need to examine the query and consider how it can be improved. Meanwhile, the users have to understand that this approach is for the greater good of the system, and in time it will also improve their query performance.
It is no longer just a technical problem.  It has become political.  It needs to be sold to the users, and it needs a change in the business process.  So the DBA needs to talk to people outside their silo, and sometimes even outside IT.

Example 2: Archiving

I work on an Time & Labor and Payroll system that has run for 4 years without any archiving.  We have 4 years of schedule data.  4 years of reported time.  4 years of payroll data. 4 years of audit data.  We now have a 4TB OLTP database. Archiving was de-scoped from the initial implementation.
How have we survived this long?  Many of the tables that hold this data have been partitioned, mostly on a time basis – that is to say that different periods of time are different partitions.  In many cases, but by no means all, the long tail of history is hidden by partition elimination.  Partitioning was introduced to improve performance, but the design of the partitioning always had an eye to future archiving.
With or without partitioning, keeping all the data forever is not an option.  Quite apart from data security and performance, the size of the database is becoming a challenge.  Periodically, we have to copy the production database into various development and test environments.  We trim some history from some of those environments, but size is still a challenge.
So we had to look at archive and purge.  So the first step it to understand the application, and then work out with the business users at what point do they at least no longer need the data to operate their process, and at what point can we ultimately purge the data entirely from the database. 
We are about to deliver the first tranche of archiving into one functional area.  Conceptually our process is very simple.  Some data we can purge, often by dropping partitions.  Some data we have had to keep for ad-hoc query.  Where possible, we use partition exchange to exchange historical partitions into archive tables.  We have also been very successful in using table compression to further reduce the overall database size.
Archive and purge is going to be a regular, rolling process - at least monthly.  It is going to be done without any system outage, and it will as far as possible be automated.  Therefore, we have had to build some of these processes into the application not least so the application support team has visibility. The archive process is sensitive to the system date and some application data. So it has had to involve developers.
We have created a meta-data driven PL/SQL package, effectively an API, to do all the partition handling and compression. The developers call that from their processes.
It takes someone who is, if not a DBA, then very database aware to design the concept (and you’ve probably guessed correctly that in this case that DBA is me). That person also needs to have some understanding of the application and how the application data fits together. I think it is also essential, at least for the largest and most critical systems, that the DBA understands how the business uses the application.  The DBA can’t do this hiding in their silo.

Conclusion

I have heard it said that some production DBAs think their job is to make sure nothing happens; by making sure that nothing happens. Business is not about maintaining the status quo.  Businesses talk about bigger, better, cheaper, faster. You can track the pulse of a business by measuring its critical IT systems. A DBA’s job is not to hold the tide back, but to make sure that the systems we tend are fit for purpose, and continue so to be. We need to be proactive. Sometimes, we should go out and be consultants, look for improvements, initiate changes, and advise on developments.
Therefore, if you are a production DBA hiding in your silo, send not to know for whom the bell tolls, it tolls for thee.