On 01-01-18 03:14, Shane Dev wrote: > Hello, > > I have a directed acyclic graph defined as follows - > > sqlite> .sch > CREATE TABLE nodes(id integer primary key, description text); > CREATE TABLE edges(parent not null references nodes, child not null > references nodes, primary key(parent, child)); > > Now I want to find the "roots" of the graph - i.e nodes which are not > children of other nodes - > > select * from nodes where not exists (select * from edges where child= > nodes.id); > > This works but is very slow when there are a million nodes and edges.
Changing this to: select * from nodes where not exists (select 1 from edges where child= nodes.id); saved in my test about 10% of time > Is there any way to speed it up? _______________________________________________ sqlite-users mailing list sqlite-users@mailinglists.sqlite.org http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
