psql implementation of #index_name_exists?

1 files changed, 13 insertions, 0 deletions

diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb b/activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb
index 571257f6dd..ae8ede4b42 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb
@@ -126,6 +126,19 @@ module ActiveRecord
           SQL
         end
 
+        def index_name_exists?(table_name, index_name, default)
+          exec_query(<<-SQL, 'SCHEMA').rows.first[0].to_i > 0
+            SELECT COUNT(*)
+            FROM pg_class t
+            INNER JOIN pg_index d ON t.oid = d.indrelid
+            INNER JOIN pg_class i ON d.indexrelid = i.oid
+            WHERE i.relkind = 'i'
+              AND i.relname = '#{index_name}'
+              AND t.relname = '#{table_name}'
+              AND i.relnamespace IN (SELECT oid FROM pg_namespace WHERE nspname = ANY (current_schemas(false)) )
+          SQL
+        end
+
         # Returns an array of indexes for the given table.
         def indexes(table_name, name = nil)
            result = query(<<-SQL, 'SCHEMA')