optimize searching for files... takes 300s query down to 15s.

SQLite3 does not do joins in a sane manner, so we emulate them
w/ subqueries for a large boost.  Not sure if adding distinct would
improve things or not, the query plan does not change between the
two (but the lower ops may), but in a quick test, it didn't seem
to make a difference (not evaluated statistically)...

ui/medashare/cli.py

@@ -1622,7 +1622,7 @@ def cmd_search(options, persona, objstr, cache):
 	propmap = aliased(orm.PropertyMapping)
 
 	# propobj only returns what can match query
-	propobj = select(propmap.obj)
+	propobj = select(propmap.obj).distinct()
 
 	onlyexclusions = True
 
@@ -1668,18 +1668,28 @@ def cmd_search(options, persona, objstr, cache):
 	# metadataobjects
 	mdomd = aliased(orm.MetaDataObject)
 
+	# Don't know if distinct is needed/warrented for the
+	# in_ sub queries
 	sel = select(mdofile.data).where(
 		# we are operating on files
 		mdofile.type == 'file',
 		# we get all the hashes for the files
-		mdofile.uuid == htfile.uuid,
-		htfile.hash == htmd.hash,
-		mdomd.uuid == htmd.uuid,
-		mdomd.type == 'metadata',
+		mdofile.uuid.in_(
+			select(htfile.uuid).where(
+				htfile.hash == htmd.hash,
+				# we get all the hashes for selected metadata
+				htmd.uuid.in_(
+					select(mdomd.uuid).where(
+						mdomd.type == 'metadata',
+						mdomd.uuid.in_(propobj)
+					)
+				)
+			)
+		)
 	)
 
 	if onlyexclusions:
-		sel = sel.where(mdomd.uuid.in_(propobj))
+		# add in all the files that doesn't have metadata
 
 		# base object (file)
 		mdofile = aliased(orm.MetaDataObject)
@@ -1705,8 +1715,6 @@ def cmd_search(options, persona, objstr, cache):
 		)
 
 		sel = sel.union(selwomd)
-	else:
-		sel = sel.where(mdomd.uuid.in_(propobj))
 
 	sel = sel.execution_options(yield_per=10)