Description

 

 

Adaptive Server IQ 12.4.0

Description

For joins within a query, the IQ optimizer has a choice of several algorithms

 

for processing the join. This option allows you to override the optimizer’s

 

cost—based decision when choosing the algorithm to use. It does not override

 

internal rules that determine whether an algorithm is legal within the query

 

engine. If you set it to any non-zero value, it affects every join in a query; it

 

cannot be used to selectively modify one join out of several in a query.

 

This option is normally used for internal testing, and only experienced DBA's

 

should use it. The following table describes the valid values for this option and

 

their action.

 

 

 

 

Value

 

Action

 

 

 

 

 

 

 

 

0

 

Let the optimizer choose

 

 

 

 

 

 

1

 

Prefer sort/merge

 

 

 

 

 

 

2

 

Prefer nested loop

 

 

 

 

 

 

3

 

Prefer nested loop push-down

 

 

 

 

 

 

4

 

Prefer hash

 

 

 

 

 

 

5

 

Prefer hash push-down

 

 

 

 

 

 

6

 

Prefer join index

 

 

 

 

 

 

-1

 

Avoid sort/merge

 

 

 

 

 

 

-2

 

Avoid nested loop

 

 

 

 

 

 

-3

 

Avoid nested loop push-down

 

 

 

 

 

 

-4

 

Avoid hash

 

 

 

 

 

 

-5

 

Avoid hash push-down

 

 

 

 

 

 

–6

 

Avoid join index

 

 

 

 

 

9.4.7 Corrections to INSERT LOCATION

These corrections apply to the Adaptive Server IQ Reference Manual and the

Adaptive Server IQ Administration and Performance Guide.

If you plan to use the INSERT LOCATION command (syntax 3 of the INSERT command), the Adaptive Server Enterprise server you are connecting to must exist in the interfaces file on the local machine.

Also, the syntax in the Adaptive Server IQ Reference Manual is incorrect. The servername.dbname must be enclosed in single quotes, and the SELECT statement must be in braces. An example of correct syntax is:

INSERT CUSTOMERS LOCATION ’BOSTON.PUBS2’

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Release Bulletin for Digital UNIX

Page 32
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Sybase IQ 12.4.0 installation instructions Corrections to Insert Location, Description Adaptive Server IQ