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SAP HANA Extended SQL Executor (ESX) Interview Questions and Answers

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SAP HANA Extended SQL Executor (ESX) Interview Questions and Answers
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SAP HANA Extended SQL Executor (ESX) FAQs

1) Define SAP HANA Extended SQL Executor (ESX)?

SAP HANA Extended SQL Executor (ESX) is a front-end execution engine which replaced the row engine. it recovers the database request from session level and assign it to lower-level engines such HEX engine, join engine or calculation engine:

2) What are some important benefits of ESX?

The following are the benefits and components are provided by ESX:

  • It minimizes the runtimes and memory requirements by pipelining
  • It uses itabs as common format, therefore, making communication with other engines becomes easy.
  • It is light-weight and separate library which reduces dependencies from other components

3) How to control the usage of ESX?

Following parameter can be used on a global level in order to activate or deactivate ESX

  • indexserver.ini -> [sql] -> esx_level

The user can also USE_ESX_PLAN and NO_USE_ESX_PLAN hints on statement level in order to activate or deactivate ESX

4) How to trace ESX?

Please, following parameters exist to trace ESX:

Parameter Value Details
indexserver.ini -> [trace] -> esx_dump_plan debug Detailed ESX plan information including node operation tree and input itab type information (available with SAP HANA 2.0 >= SPS 03)

5) What are the various indications that ESX is used for processing database request?

The modules related ESX in the call stack of threads indicate the use of ESX such as:

  • ESX::EsxFieldExpression
  • ESX::ItabMaterialize::open
  • ESX::NestedLoopJoin::open
  • ESX::OperatorNode::fetchAll
  • ESX::ParallelItabBuildJob::runInternal
  • ESX::Plan::execute
  • ESX::Plan::generateItab
  • ESX::Plan::getOutputItab
  • ESX::Select::open
  • ESX::Utils::setValues
  • ESX::Window::fetch
  • ESX::Window::increaseFetchThreads
  • ESX::Window::prepareFetchInfo
  • ptime::Esx_search::do_open
  • ptime::PtimeEsxPlan::fetch

6) Mention some known issues related to ESX?

The following known issues listed below in the table exist in relation to ESX:

Problem Impacted Revisions
Termination with unable to update attribute store 2.00.020
Crash in ESX::ParallelItabBuildJob::runInternal 2.00.020
Termination with NOT NULL constraint violation <= 2.00.022
Crash in ESX::Window::prepareFetchInfo <= 2.00.022
Termination with unknown attribute error <= 2.00.023
Memory Leak in Pool/ESX When Using PlanViz <= 2.00.023
Crash in UnifiedTable::Alphanum::set <= 2.00.024.01
2.00.030

7) How can we configure ESX?

Please use these following SAP HANA parameters in order adjust the ESX behaviour:

Parameter Default Details
indexserver.ini -> [sql] -> esx_level
1

Activation (1) or deactivation (0) of ESX

indexserver.ini -> [sql] -> use_esx_project
true

If set to true, ESX can write search results directly into a stream without using an itab


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