What does a value of 5 in "SYSIDX.unique" mean?

[VolkerBarth]

The SYSIDX system view has a column "unique" that classifies the logical index as follows:

Indicates whether the index is a unique index (1), a non-unique index (4), or a unique constraint (2). A unique index prevents two rows in the indexed table from having the same values in the index columns

What does a value of 5 mean? An unique index with the new "CREATE INDEX ... WITH NULLS NOT DISTINCT" clause?

(At least that seems to be the case in my tests...)

[Former Member · Accepted solution]

You are correct. The values are:

• 1 - index is a unique index
• 2 - index is for a UNIQUE constraint
• 3 - reserved
• 4 - index is not unique
• 5 - index is WITH NULLS NOT DISTINCT

I will make sure that the documentation is modified appropriately. Thanks for reporting the oversight.

[VolkerBarth · Accepted solution]

I may be hairsplitting but for the docs, I guess the description for values 1 and 5 should be worded differently as both are for unique indizes, such as:

• 1 - index is a unique index (not declared WITH NULLS NOT DISTINCT)
• 5 - index is a unique index WITH NULLS NOT DISTINCT

(Apparently, that would only make sense for v12 and above...)