Combining index types

If a column is going to be used in more than one type of query, more than one column index type might be appropriate. Table 6-6 shows which index types make good combinations.

Table 6-6: Mix of valid index

Add Index

Existing Index

HG

HNG

LF

CMPa

WD

DATE, TIME, or DTTM

HG

-

1

2

1

1

1

HNG

1

-

1

1

2

2

LF

2

1

-

1

2

1

1 = A reasonable combination

2 = An unlikely combination

a. A CMP index applies to a pair of columns. Each of those columns always has at least one other index.

NoteThe High_Group index in Sybase IQ Version 12 differs from earlier versions. For some columns you may want both High_Group and High_Non_Group; previously, it did not make sense to have both.A CMP index applies to a pair of columns. Each of those columns always has at least one other index.