On 7 Oct 2015, at 8:42pm, Richard Hipp <drh at sqlite.org> wrote: > New documentation covering indexes on expressions has been added. > Please let me know if you think more is needed.
I tentatively suggest that modifications be made to the text describing <http://sqlite.org/draft/pragma.html#pragma_index_info> and <http://sqlite.org/draft/pragma.html#pragma_index_xinfo> . However it may be that such changes would just lengthen the explanation without adding anything useful, and that any programmer who tries out those PRAGMAs with the new indexes won't have any trouble understanding what they see. It also might be useful to produce a -2 in the second output column for index_xinfo, for columns which are calculations. I wonder what happens if an index is defined which uses an application-defined functions, and a later attempt is made to use the database without that function defined. I can see an argument for returning an error when any relevant SELECT is attempted. But I can also see an argument for returning an error only when an attempt is made to INSERT or UPDATE into the indexed table. Simon.
