Support for Postgres BTree index INCLUDE (<col>, ...)

[theelderbeever]

Motivation

Postgres BTree indexex allow for an INCLUDE statement where the included columns values are stored in the leaf nodes of the index. This is an optimization to store data with the index for columns that are fetched commonly but, not necessarily filtered on.

Proposed Solutions

Index::create()
        .name(name)
        .index_type(IndexType::BTree)
        .table(table)
        .col(col)
        .include(other_cols) // postgres feature gate
        .is_unique_key();

CREATE UNIQUE INDEX an_index ON table USING BTREE (col) INCLUDE (other_cols)

Additional Information

I am unsure if this is supported on other databases.

CREATE INDEX