Improved index generation for dictionary

Former-commit-id: ad93c9a556ac1aea89499a03f5a14a210057585e

yomi_base/japanese2/dictionary.py

@@ -28,19 +28,17 @@ class Dictionary:
 
 
     def findTerm(self, word, partial=False):
+        self.requireIndex('Terms', 'expression')
+        self.requireIndex('Terms', 'reading')
+
         cursor = self.db.cursor()
-
-        if not self.hasIndex('TermIndex'):
-            cursor.execute('CREATE INDEX TermIndex ON Terms(expression, reading)')
-            self.db.commit()
-
         cursor.execute('SELECT * FROM Terms WHERE expression {0} ? OR reading=?'.format('LIKE' if partial else '='), (word, word))
         return cursor.fetchall()
 
 
     def findCharacter(self, character):
         cursor = self.db.cursor()
-        cursor.execute('SELECT * FROM Kanji WHERE character=?', character)
+        cursor.execute('SELECT * FROM Kanji WHERE character=? LIMIT 1', character)
         return cursor.fetchone()
 
 
@@ -60,7 +58,7 @@ class Dictionary:
 
     def findRadicalsByCharacter(self, character):
         cursor = self.db.cursor()
-        cursor.execute('SELECT radicals FROM Radicals WHERE character=?', character)
+        cursor.execute('SELECT radicals FROM Radicals WHERE character=? LIMIT 1', character)
 
         columns = cursor.fetchone()
         if columns is None:
@@ -80,6 +78,18 @@ class Dictionary:
         return map(operator.itemgetter(0), columns)
 
 
+    def requireIndex(self, table, column):
+        name = 'index_{0}_{1}'.format(table, column)
+        if not self.hasIndex(name):
+            self.buildIndex(name, table, column)
+
+
+    def buildIndex(self, name, table, column):
+        cursor = self.db.cursor()
+        cursor.execute('CREATE INDEX {0} ON {1}({2})'.format(name, table, column))
+        self.db.commit()
+
+
     def hasIndex(self, name):
         if name in self.indices:
             return True