Add a button for adding new expression columns to the Edit Index dialog.
Allow the user to edit the 'name' of existing expression columns in the
Edit Index dialog.
This adds a new field to the Edit Index dialog that allows the user to
change the partial index expression for an index.
Example:
CREATE INDEX i ON a(
col1 ASC,
col2 DESC
) WHERE id < 1000; -- This bit here
Change the layout of the dialog entirely. Instead of having checkboxes
that, if activated, move a column into the index, use two separate table
views, one for available columns and one for used columns. This makes it
easier to see the index structure on first sight. It also makes it
possible to see the order of the different index columns from the table
views. Additionally, now expression columns that are used in the index
are shown in the table views, even allowing them to be removed from the
index.
Just like the Edit Table dialog, this dialog handles both creating and
editing. For consistency's sake this dialog is therefore renamed to Edit
Index dialog.