From 004672aa6c482b212e36b9e794d107be456a11da Mon Sep 17 00:00:00 2001
From: unarist <m.unarist@gmail.com>
Date: Tue, 6 Jun 2017 23:07:06 +0900
Subject: Fix tag search order and not to use tsvector (#3611)

* Sort results by the name
* Switch search method to simple `LIKE` matching instead of tsvector/tsquery

Previously we used scores from ts_rank_cd() to sort results, but it didn't work
because the function returns same score for all results. It's not for calculate
similarity of single words. Sometimes this bug even push out exact matching tag
from results.

Additionally, PostgreSQL supports prefix searching with standard btree index.
Using it offers simpler code, but also less index size and some speed.
---
 .../20170606113804_change_tag_search_index_to_btree.rb       | 12 ++++++++++++
 1 file changed, 12 insertions(+)
 create mode 100644 db/migrate/20170606113804_change_tag_search_index_to_btree.rb

(limited to 'db/migrate')

diff --git a/db/migrate/20170606113804_change_tag_search_index_to_btree.rb b/db/migrate/20170606113804_change_tag_search_index_to_btree.rb
new file mode 100644
index 000000000..5248e1720
--- /dev/null
+++ b/db/migrate/20170606113804_change_tag_search_index_to_btree.rb
@@ -0,0 +1,12 @@
+class ChangeTagSearchIndexToBtree < ActiveRecord::Migration[5.1]
+
+  def up
+    remove_index :tags, name: :hashtag_search_index
+    execute 'CREATE INDEX hashtag_search_index ON tags (name text_pattern_ops);'
+  end
+
+  def down
+    remove_index :tags, name: :hashtag_search_index
+    execute 'CREATE INDEX hashtag_search_index ON tags USING gin(to_tsvector(\'simple\', tags.name));'
+  end
+end
-- 
cgit