Key parts, in index order. An expression key part (PostgreSQL lower(code), MySQL
functional key part) appears as AUTODOC_EXPRESSION_KEY_PART at its position, so the
order of the named columns, and therefore which column leads the index, is preserved.
OptionalFilterPartial-index predicate (PostgreSQL WHERE / SQL Server filter), when present.
True when some key parts are expressions rather than plain columns.
Non-key columns carried by the index (SQL Server INCLUDE / PostgreSQL INCLUDE).
Access method or index type as the database names it (btree, gin, NONCLUSTERED, BTREE, …).
An existing index on a table, as read from the database catalog. Primary-key indexes are included (IsPrimaryKey = true).