Tamino XML Server Version 9.7
 —  XQuery 4 Reference Guide  —

TaminoQPIExplain

Retrieve query execution plan.


Syntax

TaminoQPIExplain

graphics/TaminoQPIExplain.png

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Description

A TaminoQPIExplain is a query pragma that has the form of a QPI (query processing instruction), i.e., it is enclosed by "{?" and "?}". If you use this pragma, the query will not be executed. Instead, an XML representation of the execution plan for the query expression is returned in the result document. You can use this information to determine which access paths will be used for Tamino data during query execution.

The following operator elements are of interest:

XqcUnnestCollectionScan retrieve all documents of the current collection
XqcUnnestDoctypeScan retrieve all documents of a doctype
XqcUnnestStdIdxScan index-based retrieval of documents

The doctype scan operator contains information on which doctype it refers to. The index scan operator additionally contains information on the actual index, the index comparison operator and the comparison value.

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Example

{?explain?} input()/entry[@name="Hoch Franz"]

The result document contains this XqcUnnestStdIdxScan operator:

graphics/xqr-explain-ex.png

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Related Syntax Constructs

The following construct(s) refer to this construct:

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