Avoid indexing search_names on MySQL

Author: jpic

cities_light/migrations/0003_auto__add_field_city_search_names.py

@@ -4,42 +4,18 @@
 from south.v2 import SchemaMigration
 from django.db import models
 
-class Migration(SchemaMigration):
-
-    def forwards(self, orm):
-        if not db.dry_run:
-            print """
-
-            BIG FAT WARNING
-
-            This migration adds a TextField (search_names), with an index.
-            MySQL does not support indexing TEXT/BLOB columns.
-
-            On MySQL, this migration should fail like:
-
-            FATAL ERROR - The following SQL query failed: CREATE INDEX `cities_light_city_cd532746` ON `cities_light_city` (`search_names`);
-            The error was: (1170, "BLOB/TEXT column 'search_names' used in key specification without a key length")
+from cities_light.settings import INDEX_SEARCH_NAMES
 
-            Since the search_names column should be created anyway, you can get
-            past this with:
+if INDEX_SEARCH_NAMES:
+    INDEX_SEARCH_NAMES_STRING = 'True'
+else:
+    INDEX_SEARCH_NAMES_STRING = 'False'
 
-            ./manage.py migrate cities_light --fake 0003
-            # continue migrating
-            ./manage.py migrate cities_light
-
-
-            If you can think of any better solution, please report it to
-            GitHub's project page:
-
-            https://github.com/yourlabs/django-cities-light/issues/
-
-
-            If you are on anything else than MySQL, you can ignore this message
-            and enjoy indexing on search_names.
-            """
+class Migration(SchemaMigration):
 
+    def forwards(self, orm):
         # Adding field 'City.search_names'
-        db.add_column('cities_light_city', 'search_names', self.gf('django.db.models.fields.TextField')(default='', max_length=4000, db_index=True, blank=True), keep_default=False)
+        db.add_column('cities_light_city', 'search_names', self.gf('django.db.models.fields.TextField')(default='', max_length=4000, db_index=INDEX_SEARCH_NAMES, blank=True), keep_default=False)
 
 
     def backwards(self, orm):
@@ -58,7 +34,7 @@ def backwards(self, orm):
             'longitude': ('django.db.models.fields.DecimalField', [], {'null': 'True', 'max_digits': '8', 'decimal_places': '5', 'blank': 'True'}),
             'name': ('django.db.models.fields.CharField', [], {'max_length': '200', 'db_index': 'True'}),
             'name_ascii': ('django.db.models.fields.CharField', [], {'max_length': '200', 'db_index': 'True'}),
-            'search_names': ('django.db.models.fields.TextField', [], {'default': "''", 'max_length': '4000', 'db_index': 'True', 'blank': 'True'}),
+            'search_names': ('django.db.models.fields.TextField', [], {'default': "''", 'max_length': '4000', 'db_index': INDEX_SEARCH_NAMES_STRING, 'blank': 'True'}),
             'slug': ('autoslug.fields.AutoSlugField', [], {'unique_with': '()', 'max_length': '50', 'populate_from': 'None', 'db_index': 'True'})
         },
         'cities_light.country': {

cities_light/models.py

@@ -158,8 +158,8 @@ class City(Base):
     name = models.CharField(max_length=200, db_index=True)
     display_name = models.CharField(max_length=200)
 
-    search_names = ToSearchTextField(max_length=4000, db_index=True,
-        blank=True, default='')
+    search_names = ToSearchTextField(max_length=4000,
+        db_index=INDEX_SEARCH_NAMES, blank=True, default='')
 
     latitude = models.DecimalField(max_digits=8, decimal_places=5,
         null=True, blank=True)

cities_light/settings.py

@@ -39,14 +39,20 @@
 DATA_DIR
     Absolute path to download and extract data into. Default is
     cities_light/data. Overridable in settings.CITIES_LIGHT_DATA_DIR
+
+INDEX_SEARCH_NAMES
+    If your database engine for cities_light supports indexing TextFields (ie.
+    it is **not** MySQL), then this should be set to True. You might have to
+    override this setting if using several databases for your project.
 """
 
 import os.path
 
 from django.conf import settings
 
 __all__ = ['COUNTRY_SOURCES', 'REGION_SOURCES', 'CITY_SOURCES',
-    'TRANSLATION_LANGUAGES', 'TRANSLATION_SOURCES', 'SOURCES', 'DATA_DIR']
+    'TRANSLATION_LANGUAGES', 'TRANSLATION_SOURCES', 'SOURCES', 'DATA_DIR',
+    'INDEX_SEARCH_NAMES',]
 
 COUNTRY_SOURCES = getattr(settings, 'CITIES_LIGHT_COUNTRY_SOURCES',
     ['http://download.geonames.org/export/dump/countryInfo.txt'])
@@ -65,3 +71,11 @@
 DATA_DIR = getattr(settings, 'CITIES_LIGHT_DATA_DIR',
     os.path.normpath(os.path.join(
         os.path.dirname(os.path.realpath(__file__)), 'data')))
+
+# MySQL doesn't support indexing TextFields
+INDEX_SEARCH_NAMES = getattr(settings, 'CITIES_LIGHT_INDEX_SEARCH_NAMES', None)
+if INDEX_SEARCH_NAMES is None:
+    INDEX_SEARCH_NAMES = True
+    for database in settings.DATABASES.values():
+        if 'mysql' in database['ENGINE'].lower():
+            INDEX_SEARCH_NAMES = False