The region labeled as Index Value in the graphic of the row format is the column_1 value set for the row, an abbreviation for the data type orderings and offsets shown in detail in the row format diagrams for non-row compressed join index rows.
For example, consider the following example CREATE JOIN INDEX text:
CREATE JOIN INDEX test AS SELECT (a,b), (x,y) FROM table1, table2;
The system packs columns a and b in the last subfield of Field1 of a row compressed join index row the same way that index keys (an index key is the set of values stored as "the index" in a secondary index) are packed in the Field1 of a secondary index row (columns a and b are stored in the area labeled as Index Value in the row format graphic).
The system also stores the uncompressed index values (each instance of those (x,y) values that has the same (a,b) values as a minirow in Field2) in the area labeled as Index Minirow List in the row format graphic.
Each minirow consists of a BYTE length field, an optional presence bits array field, and a column_2_name value set as described in Packed64 Row Structure for an Uncompressed Join Index With an Nonpartioned Primary Index.
