Identifying the Implementation Attributes

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Identifying the Implementation Attributes

The following table shows the i OS implementation attributes for each of the access paths:


Access Path Type	(1) (2) Unique or Dup Key Sequence (DDS only)	(3) Access Path Maint.	(4) Alt Col (DDS only)	(5) Selection	SQL Implementation	DDS Implementation
PHY Physical UPD Update (default) UPD Update RTV Retrieval (default) RTV Retrieval RSQ Resequence QRY Query SPN Span	Generating and Compiling	- I I/D/R I I/D/R I,D,R I/D/R (6) I,D,R	- - - - - Yes - Yes	- - - S,D S,D S,D D S,D	Table View and Index View and Index View and Index View and Index View and Index View and Index Two indexes and two views	Physical File Logical File Logical File Logical File Logical File Logical File Physical File Logical File CL Program Logical File
The following legend applies for the access path types: (1) Unique key status (DDS unique keyword or SQL unique keyword with create index statement). U indicates unique; if not unique, see Note (2). The default UPD and RTV access paths must be unique. (2) Duplicate key sequence for DDS only (L=LIFO, F=FIFO,' '=undefined, C=FCFO). (3) i OS access path maintenance (I=IMMED,R=REBLD, D=DLY). For QRY access paths, see item (6). (4) Alternative collating sequence table for DDS only (DDS ALTCOL keyword). (5) Selection type (S=static, D=dynamic) (DDS DYNSLT keyword). (6) Causes the i OS OPNQRYF command to be called with the OPTIMIZE option equal to FIRSTIO, MINWAIT, or ALLIO, respectively.

Access Path Type

(1) (2)

Unique or Dup Key Sequence (DDS only)

(3)

Access Path

Maint.

(4)

Alt Col (DDS only)

(5)

Selection

SQL
Implementation

DDS
Implementation

PHY Physical

UPD Update (default)

UPD Update

RTV Retrieval (default)

RTV Retrieval

RSQ Resequence

QRY Query

SPN Span

Generating and Compiling

I/D/R

I,D,R

I/D/R (6)

I,D,R

Yes

S,D

Table

View and Index

Two indexes and two views

Physical File

Logical File

Physical File

Logical File

CL Program

Logical File

The following legend applies for the access path types:

(1) Unique key status (DDS unique keyword or SQL unique keyword with create index statement). U indicates unique; if not unique, see Note (2). The default UPD and RTV access paths must be unique.

(2) Duplicate key sequence for DDS only (L=LIFO, F=FIFO,' '=undefined, C=FCFO).

(3) i OS access path maintenance (I=*IMMED,R=*REBLD, D=*DLY). For QRY access paths, see item (6).

(4) Alternative collating sequence table for DDS only (DDS ALTCOL keyword).

(5) Selection type (S=static, D=dynamic) (DDS DYNSLT keyword).

(6) Causes the i OS OPNQRYF command to be called with the OPTIMIZE option equal to *FIRSTIO, *MINWAIT, or *ALLIO, respectively.

For SQL, static selection is implemented through SQL Data Definition Language (DDL) statements. Dynamic selection is implemented by Data Manipulation Language (DML) statements.

Note: If an SQL-generated RSQ access path has select/omit criteria and is defined as Unique with Static maintenance, the key defined as unique must be unique over the entire file and not just with a subset of that file (as defined by the select/omit criteria).

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