CPI432F - Access path suggestion for file &1

CPI432F
Message Text:	Access path suggestion for file &1.
Cause Text:	To improve performance the query optimizer is suggesting a permanent access path be built with the key fields it is recommending. The access path will access records from member &3 of file &1 in library &2. In the list of key fields that follow, the query optimizer is recommending the first &10 key fields as primary key fields. The remaining key fields are considered secondary key fields and are listed in order of expected selectivity based on this query. Primary key fields are fields that significantly reduce the number of keys selected based on the corresponding selection predicate. Secondary key fields are fields that may or may not significantly reduce the number of keys selected. It is up to the user to determine the true selectivity of secondary key fields and to determine whether those key fields should be used when creating the access path. The query optimizer is able to perform key positioning over any combination of the primary key fields, plus one additional secondary key field. Therefore it is important that the first secondary key field be the most selective secondary key field. The query optimizer will use key selection with any remaining secondary key fields. While key selection is not as fast as key positioning it can still reduce the number of keys selected. Hence, secondary key fields that are fairly selective should be included. When building the access path all primary key fields should be specified first followed by the secondary key fields which are prioritized by selectivity. The following list contains the suggested primary and secondary key fields: &11. If file &1 in library &2 is a logical file then the access path should be built over member &9 of physical file &7 in library &8.
Recovery Text:	If this query is run frequently, you may want to create the suggested access path for performance reasons. It is possible that the query optimizer will choose not to use the access path just created. For more information, refer to Data access on DB2 UDB for iSeries: data access paths and methods.

CPI432F

Message Text:

Access path suggestion for file &1.

Cause Text:

To improve performance the query optimizer is suggesting a permanent access path be built with the key fields it is recommending. The access path will access records from member &3 of file &1 in library &2.

In the list of key fields that follow, the query optimizer is recommending the first &10 key fields as primary key fields. The remaining key fields are considered secondary key fields and are listed in order of expected selectivity based on this query. Primary key fields are fields that significantly reduce the number of keys selected based on the corresponding selection predicate. Secondary key fields are fields that may or may not significantly reduce the number of keys selected. It is up to the user to determine the true selectivity of secondary key fields and to determine whether those key fields should be used when creating the access path.

The query optimizer is able to perform key positioning over any combination of the primary key fields, plus one additional secondary key field. Therefore it is important that the first secondary key field be the most selective secondary key field. The query optimizer will use key selection with any remaining secondary key fields. While key selection is not as fast as key positioning it can still reduce the number of keys selected. Hence, secondary key fields that are fairly selective should be included. When building the access path all primary key fields should be specified first followed by the secondary key fields which are prioritized by selectivity. The following list contains the suggested primary and secondary key fields:

&11.

If file &1 in library &2 is a logical file then the access path should be built over member &9 of physical file &7 in library &8.

Recovery Text:

If this query is run frequently, you may want to create the suggested access path for performance reasons. It is possible that the query optimizer will choose not to use the access path just created.

For more information, refer to Data access on DB2 UDB for iSeries: data access paths and methods.