CPI4326 - &12 &13 processed in join position &10

CPI4326
Message Text:	&12 &13 processed in join position &10.
Cause Text:	Access path for member &5 of file &3 in library &4 was used to access records in member &2 of file &13 in library &1 for reason code &9. The reason codes and their meanings follow: Perform specified record selection. Perform specified ordering/grouping criteria. Record selection and ordering/grouping criteria. Perform specified join criteria. If file &13 in library &1 is a logical file then member &8 of physical file &6 in library &7 is the actual file in join position &10. A file name starting with TEMPX for the access path indicates it is a temporary access path built over file &6. A file name starting with N or QUERY for the file indicates it is a temporary file. Index only access was used for this file within the query: &11. A value of YES for index only access processing indicates that all of the fields used from this file for this query can be found within the access path of file &3. A value of *NO indicates that index only access could not be performed for this access path. Index only access is generally a performance advantage since all of the data can be extracted from the access path and the data space does not have to be paged into active memory.
Recovery Text:	Generally, to force a file to be processed in join position 1, specify an order by field from that file only. If ordering is desired, specifying ORDER BY fields over more than one file forces the creation of a temporary file and allows the optimizer to optimize the join order of all the files. No file is forced to be first. An access path can only be considered for index only access if all of the fields used within the query for this file are also key fields for that access path. Refer to Data access on DB2 UDB for iSeries: data access paths and methods for additional tips on optimizing a query's join order and index only access.

CPI4326

Message Text:

&12 &13 processed in join position &10.

Cause Text:

Access path for member &5 of file &3 in library &4 was used to access records in member &2 of file &13 in library &1 for reason code &9. The reason codes and their meanings follow:

Perform specified record selection.
Perform specified ordering/grouping criteria.
Record selection and ordering/grouping criteria.
Perform specified join criteria.

If file &13 in library &1 is a logical file then member &8 of physical file &6 in library &7 is the actual file in join position &10.

A file name starting with *TEMPX for the access path indicates it is a temporary access path built over file &6.

A file name starting with *N or *QUERY for the file indicates it is a temporary file.

Index only access was used for this file within the query: &11.

A value of *YES for index only access processing indicates that all of the fields used from this file for this query can be found within the access path of file &3. A value of *NO indicates that index only access could not be performed for this access path.

Index only access is generally a performance advantage since all of the data can be extracted from the access path and the data space does not have to be paged into active memory.

Recovery Text:

Generally, to force a file to be processed in join position 1, specify an order by field from that file only.

If ordering is desired, specifying ORDER BY fields over more than one file forces the creation of a temporary file and allows the optimizer to optimize the join order of all the files. No file is forced to be first.

An access path can only be considered for index only access if all of the fields used within the query for this file are also key fields for that access path.

Refer to Data access on DB2 UDB for iSeries: data access paths and methods for additional tips on optimizing a query's join order and index only access.

This message provides the join position of the specified table when an index is used to access the table's data. Join position pertains to the order in which the tables are joined.