customer analyzing sap cds on db2 - ibmsap optimizer profiles for db2 hint specification detached...

Analyzing SAP CDS on DB2Jörg Maier, SAP

April 14, 2016

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Agenda

Introduction

Core Data Services – chances and challenges

Recent development

Motivation

Increasing use of CDS with recent SAP shipments


Agenda

Working on example queries – how to dismantle complex CDS queries

ZCL_ANYDB_CDSTEST_TORQUAN_Q

ZCP_PERF_POSREP_EOD

CDS – DB2 Administration

CATMAINT (e.g. after System Copies) -> How to DROP and re-CREATE CDS objects

SAP Optimizer profiles for DB2


Introduction – Core Data Services

• CDS from SAP point of view: CDS view as re-usable building blocks to get an SAP object out of the DBMS

o Encourage app developers to build views over view over views over …

o Speed up app development

o Enable app developer with no DB know-how to write efficient code

Improved elapse time by exploiting more DBMS functionality (UDF, table function, scalar function)

Improved elapse time by running generic app functionality within the DBMS

• CDS from DB2 point of view: Cope with a lot more DB2 objects (other than tables and indexes)

o The objects often depend of each other (maintenance challenge/dependency graph)

o UDFs called often (performance challenge, debugging capability missing, monitoring challenge)

o Need to map ABAP semantics to DB2 semantics, for example RTRIM, CASE

o Lots of DECFLOAT usage because of DECIMAL limitations


Motivation

• OLAP and OLTP move closer together

• SELECTs get complex

Increasing use of CDS in recent SAP shipment

SAP ERP EHP8 is shipped with 2300+ CDS views

CDS is used as well in other products

– SOLMAN 7.2

– Plain Netweaver 7.4 and 7.5 use CDS for ABAP development


CDS in NetWeaver 7.50 and beyond

• New NW 7.50 SQL and CDS Features

• Built-in data type INT8

• Global Temporary Tables (GTTs)

• SELECT with UNION

• INSERT FROM SELECT

• SQL expressions on left hand sides of comparisons, e.g., ROUND, CONCAT, LPAD, RTRIM

• New scalar UDFs like

• DATS_IS_VALID(date), DATS_DAYS_BETWEEN(d1,

d2),TSTMP_CURRENT_UTCTIMESTAMP()

• ABAP runtime automatically maintains global session variables

• CLIENT, APPLICATIONUSER, LOCALE_SAP


Sample Query I - ZCL_ANYDB_CDSTEST_TORQUAN_Q

SELECT *…. Typical CDS SQL. Simple query,

here on a table UDF



• 38 tables

• 3 table UDFs

• 41 views

• 2 scalar

functions


Sample Query II - ZCP_PERF_POSREP_EOD



• Simple dependency line

• Fetch rows from underlying

object, usually only one

dependant object

• Only one join

(ICOEX110EODL)

• Two affected tables



• original query with markers

substituted by literals

• >20 seconds,

• CCOEXRP110POEODQ

• >20 seconds



• ICOEX110EODL

• >20 seconds

• PCOEX110IL

• < 1 millisecond



• Query comparable to ICOEX110EODL

• TUDF replaced by table

• Predicates of lower level functions added

• < 1.7 seconds



Toplevel query on DB2 12 ESP

< 1 sec


Dependency Browser

Possibility to browse the dependencies of

Views

Table Functions

Scalar Functions

Tables

Procedures

Global Variables

Triggers

Two detail views

Get detail information on the selected object

Display the create statement of the selected object

Structured display of the dependencies

of all the dependent object

Possibility to look for dependencies

up and downwards


Dependency BrowserTrigger Monitoring


CATMAINT SCHEMA SWITCHDEPENDENCY HANDLING

Issue

• Some objects need to be removed before calling SCHEMA

SWITCH

• Old method of re-activation via R3ldctl does not work for

CDS objects

Suggested solution

• DROP objects in dependency order. Plan is to write a tool

to generate the DROP DDL, or execute the DROP

immediately

• Re-activate scalar UDFs with RUTCNVFUNCCRE1 (from 7.4

SP8) and SAP CDS views with RUTDDLSACT


SAP Optimizer profiles for DB2Hint specification detached from ABAP sources

Issue

• CDS queries benefit from specific settings (DEGREE, QUERY OPTIMIZATION,

SUBSTITUTE_VALUES)

• Current hint mechanisms do not apply:

• BIND QUERY fails when stmt changes (different order, select list, …)

• DSN_PROFILE_TABLE no match possible for specific VIEW/table UDF object

• ABAP hints can not be used for generated stmts (e.g. SADL)

Suggested solution

• Specify a hint/guideline as a row in an SAP table (DB2_OPTIM_PROFIL).

• Supported Guidelines for now: QUERY_ACCELERATION and DEGREE

• This feature is the our development release lib_dbsl; it will be available in 7.51.We plan to do a

down port to 745 kernels (SAP NetWeaver 7.50).

• See Note 2270401 - DB2 z/OS: SAP Optimizer profiles for DB2

Thank youContact information:

Jörg Maier

IBM System z – SAP SE

[email protected]

customer analyzing sap cds on db2 - ibmsap optimizer profiles for db2 hint specification detached...

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