1 files changed, 48 insertions, 11 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 69aa02ccf4..aaf5b2898b 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb
@@ -73,6 +73,16 @@ module ActiveRecord
           select_values("SELECT tablename FROM pg_tables WHERE schemaname = ANY(current_schemas(false))", 'SCHEMA')
         end
 
+        def data_sources # :nodoc
+          select_values(<<-SQL, 'SCHEMA')
+            SELECT c.relname
+            FROM pg_class c
+            LEFT JOIN pg_namespace n ON n.oid = c.relnamespace
+            WHERE c.relkind IN ('r', 'v','m') -- (r)elation/table, (v)iew, (m)aterialized view
+            AND n.nspname = ANY (current_schemas(false))
+          SQL
+        end
+
         # Returns true if table exists.
         # If the schema is not specified as part of +name+ then it will only find tables within
         # the current schema search path (regardless of permissions to access tables in other schemas)
@@ -89,6 +99,31 @@ module ActiveRecord
               AND n.nspname = #{name.schema ? "'#{name.schema}'" : 'ANY (current_schemas(false))'}
           SQL
         end
+        alias data_source_exists? table_exists?
+
+        def views # :nodoc:
+          select_values(<<-SQL, 'SCHEMA')
+            SELECT c.relname
+            FROM pg_class c
+            LEFT JOIN pg_namespace n ON n.oid = c.relnamespace
+            WHERE c.relkind IN ('v','m') -- (v)iew, (m)aterialized view
+            AND n.nspname = ANY (current_schemas(false))
+          SQL
+        end
+
+        def view_exists?(view_name) # :nodoc:
+          name = Utils.extract_schema_qualified_name(view_name.to_s)
+          return false unless name.identifier
+
+          select_values(<<-SQL, 'SCHEMA').any?
+            SELECT c.relname
+            FROM pg_class c
+            LEFT JOIN pg_namespace n ON n.oid = c.relnamespace
+            WHERE c.relkind IN ('v','m') -- (v)iew, (m)aterialized view
+            AND c.relname = '#{name.identifier}'
+            AND n.nspname = #{name.schema ? "'#{name.schema}'" : 'ANY (current_schemas(false))'}
+          SQL
+        end
 
         def drop_table(table_name, options = {}) # :nodoc:
           execute "DROP TABLE#{' IF EXISTS' if options[:if_exists]} #{quote_table_name(table_name)}#{' CASCADE' if options[:force] == :cascade}"
@@ -353,17 +388,19 @@ module ActiveRecord
           nil
         end
 
-        # Returns just a table's primary key
-        def primary_key(table)
-          pks = query(<<-end_sql, 'SCHEMA')
-            SELECT attr.attname
-            FROM pg_attribute attr
-            INNER JOIN pg_constraint cons ON attr.attrelid = cons.conrelid AND attr.attnum = any(cons.conkey)
-            WHERE cons.contype = 'p'
-              AND cons.conrelid = '#{quote_table_name(table)}'::regclass
-          end_sql
-          return nil unless pks.count == 1
-          pks[0][0]
+        def primary_keys(table_name) # :nodoc:
+          select_values(<<-SQL.strip_heredoc, 'SCHEMA')
+            WITH pk_constraint AS (
+              SELECT conrelid, unnest(conkey) AS connum FROM pg_constraint
+              WHERE contype = 'p'
+                AND conrelid = '#{quote_table_name(table_name)}'::regclass
+            ), cons AS (
+              SELECT conrelid, connum, row_number() OVER() AS rownum FROM pk_constraint
+            )
+            SELECT attr.attname FROM pg_attribute attr
+            INNER JOIN cons ON attr.attrelid = cons.conrelid AND attr.attnum = cons.connum
+            ORDER BY cons.rownum
+          SQL
         end
 
         # Renames a table.