Adjusting indexes to make favorites query more efficient, based on feedback from ops.

fave_user_id_idx index changed from (user_id) to (user_id,modified), so the timestamp ordering can be done straight from the index while we're looking up the user's notices.
Added to 08to09.sql and 08to09_pg.sql; may need to be run manually by folks doing development.
(No harm if you don't update it, the favorites tab/rss feed will just stay inefficent.)

db/08to09.sql

@@ -42,3 +42,6 @@ create table login_token (
     constraint primary key (user_id)
 ) ENGINE=InnoDB CHARACTER SET utf8 COLLATE utf8_bin;
 
+alter table fave
+    drop index fave_user_id_idx,
+    add index fave_user_id_idx (user_id,modified);

db/08to09_pg.sql

@@ -48,3 +48,6 @@ create table login_token (
     constraint primary key (user_id)
 );
 
+alter table fave
+    drop index fave_user_id_idx,
+    add index fave_user_id_idx using btree(user_id,modified);

db/statusnet.sql

@@ -165,7 +165,7 @@ create table fave (
 
     constraint primary key (notice_id, user_id),
     index fave_notice_id_idx (notice_id),
-    index fave_user_id_idx (user_id),
+    index fave_user_id_idx (user_id,modified),
     index fave_modified_idx (modified)
 
 ) ENGINE=InnoDB CHARACTER SET utf8 COLLATE utf8_bin;

db/statusnet_pg.sql

@@ -171,7 +171,7 @@ create table fave (
 
 );
 create index fave_notice_id_idx on fave using btree(notice_id);
-create index fave_user_id_idx on fave using btree(user_id);
+create index fave_user_id_idx on fave using btree(user_id,modified);
 create index fave_modified_idx on fave using btree(modified);
 
 /* tables for OAuth */