Etymology

"Collation" is probably best defined on etymology.com,

late 14c., "act of bringing together and comparing,"

It hasn't changed at all in the past 600 years. "collate" means "to bring together" and whether it's the ordering of a book, chronologically or otherwise in a database, it's all the same.

Computer Science

As it applies to Computer Science, what we're doing is separating the storage mechanism from the ordering. You may have heard of ASCII-betical. That refers to a comparison based on the binary encoding of ASCII characters. In that system, storage and collation are two in the same. If the ASCII-standardized "encoding" ever changed the "collation" (order) would change too.

POSIX started to break that with LC_COLLATE. But as we move into Unicode a consortium emerged to standardize collations as well: ICU.

SQL

In the SQL spec there are two extensions to provide collations,

• F690: “Collation support:

  Includes collation name, collation clause, collation definition and drop collation.

• F692: Extended collation support,

  Includes attaching a different default collation to a column in the schema.

Essentially these provide the ability to CREATE and DROP collations, to specify them for operators and sorts, and to define a default for columns.

For more information on what SQL has to offer check out,

• PostgreSQL documentation on collations
• Oracle Linguistic Sorting and Matching
• MS SQL Server, Collation and Unicode Support, and Collations
• Character Sets and Collations in MySQL

Examples

Rather than pasting a limited example, here is the PostgreSQL test suite it's pretty extensive. Check out at least the first link and look for 'Türkiye' COLLATE "tr-x-icu" ILIKE '%KI%' AS "false"

• collate.icu.utf8.out
• collate.linux.utf8.out
• collate.out Probably not worth checking out, but I placed it here for completeness, boring POSIX checks.

Do not know if this will be useful to you because it requires quite a few changes, but the problem is interesting, so I'll try.

These would be the major changes

• Using the tree closure instead of the adjacency list for the reference hierarchy. The closure table contains paths form each parent to all of it descendants, so all possible parent-child combinations are exposed.

Note that with the tree closure, each ancestor node points to itself as a descendant, meaning that in CaseProperty recursion stops on ID = ParentID instead on ParentID is NULL

It is not clear to me is a parent allowed to be any ancestor or just the one first step up. The closure table exposes ancestor and all descendants, so Level Difference is added to the TreeClosure, which is sub-typed as AllowedCombos for LevelDifference in (0,1).

• Propagating AK {PropertyID, PropertyTypeID} instead of just PropertyID

• Using composite key in CaseProperty

Here are main constraints from the model to clarify relationships (you may need to modify syntax)

ALTER TABLE Property ADD
  CONSTRAINT PK_PR  PRIMARY KEY (PropertyID)

, CONSTRAINT AK1_PR UNIQUE (PropertyID ,PropertyTypeID)

, CONSTRAINT FK1_PR FOREIGN KEY (PropertyTypeID)
         REFERENCES PropertyType(PropertyTypeID)
;



ALTER TABLE TreeClosure ADD
  CONSTRAINT PK_TC PRIMARY KEY (AncestorID ,DescendantID ,AncestorTypeID ,DescendantTypeID)

, CONSTRAINT FK1_TC FOREIGN KEY (AncestorID ,AncestorTypeID) 
             REFERENCES Property(PropertyID ,PropertyTypeID)

, CONSTRAINT FK2_TC FOREIGN KEY (DescendantID ,DescendantTypeID)
             REFERENCES Property(PropertyID   ,PropertyTypeID)
;



ALTER TABLE CaseProperty ADD
  CONSTRAINT PK_CP PRIMARY KEY (CaseID, PropertyID, PropertyTypeID)

, CONSTRAINT FK1_CP FOREIGN KEY (CaseID)
                 REFERENCES Case(CaseID)

, CONSTRAINT FK2_CP FOREIGN KEY (PropertyID ,PropertyTypeID)
             REFERENCES Property(PropertyID ,PropertyTypeID)

, CONSTRAINT FK4_CP FOREIGN KEY (ParentCaseID ,ParentPropertyID ,ParentPropertyTypeID)
         REFERENCES CaseProperty(CaseID       ,PropertyID       ,PropertyTypeID)

, CONSTRAINT FK5_CP FOREIGN KEY (ParentPropertyID ,PropertyID   , ParentPropertyTypeID ,PropertyTypeID) 
        REFERENCES AllowedCombos(AncestorID       ,DescendantID , AncestorTypeID       ,DescendantTypeID)

;