4 files changed, 20 insertions, 14 deletions
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/database_statements.rb b/activerecord/lib/active_record/connection_adapters/postgresql/database_statements.rb
index 092543259f..520a50506f 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/database_statements.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/database_statements.rb
@@ -85,7 +85,9 @@ module ActiveRecord
         # Queries the database and returns the results in an Array-like object
         def query(sql, name = nil) #:nodoc:
           log(sql, name) do
-            result_as_array @connection.async_exec(sql)
+            ActiveSupport::Dependencies.interlock.permit_concurrent_loads do
+              result_as_array @connection.async_exec(sql)
+            end
           end
         end
 
@@ -95,7 +97,9 @@ module ActiveRecord
         # need it specifically, you may want consider the <tt>exec_query</tt> wrapper.
         def execute(sql, name = nil)
           log(sql, name) do
-            @connection.async_exec(sql)
+            ActiveSupport::Dependencies.interlock.permit_concurrent_loads do
+              @connection.async_exec(sql)
+            end
           end
         end
 
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/oid/bit.rb b/activerecord/lib/active_record/connection_adapters/postgresql/oid/bit.rb
index 74bff229ea..302d393277 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/oid/bit.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/oid/bit.rb
@@ -34,11 +34,11 @@ module ActiveRecord
             end
 
             def binary?
-              /\A[01]*\Z/ === value
+              /\A[01]*\Z/.match?(value)
             end
 
             def hex?
-              /\A[0-9A-F]*\Z/i === value
+              /\A[0-9A-F]*\Z/i.match?(value)
             end
 
             protected
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 29a77580f5..69f797da3a 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb
@@ -86,7 +86,7 @@ module ActiveRecord
             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
+            WHERE c.relkind IN ('r','v','m') -- (r)elation/table, (v)iew, (m)aterialized view
             AND n.nspname = ANY (current_schemas(false))
           SQL
         end
@@ -108,13 +108,13 @@ module ActiveRecord
           name = Utils.extract_schema_qualified_name(name.to_s)
           return false unless name.identifier
 
-          select_value(<<-SQL, "SCHEMA").to_i > 0
-              SELECT COUNT(*)
+          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 ('r','v','m') -- (r)elation/table, (v)iew, (m)aterialized view
-              AND c.relname = '#{name.identifier}'
-              AND n.nspname = #{name.schema ? "'#{name.schema}'" : 'ANY (current_schemas(false))'}
+              AND c.relname = #{quote(name.identifier)}
+              AND n.nspname = #{name.schema ? quote(name.schema) : "ANY (current_schemas(false))"}
           SQL
         end
 
@@ -137,8 +137,8 @@ module ActiveRecord
             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))'}
+            AND c.relname = #{quote(name.identifier)}
+            AND n.nspname = #{name.schema ? quote(name.schema) : "ANY (current_schemas(false))"}
           SQL
         end
 
@@ -239,7 +239,9 @@ module ActiveRecord
         end
 
         def table_options(table_name) # :nodoc:
-          { comment: table_comment(table_name) }
+          if comment = table_comment(table_name)
+            { comment: comment }
+          end
         end
 
         # Returns a comment stored in database for given table
@@ -439,7 +441,7 @@ module ActiveRecord
             WITH pk_constraint AS (
               SELECT conrelid, unnest(conkey) AS connum FROM pg_constraint
               WHERE contype = 'p'
-                AND conrelid = '#{quote_table_name(table_name)}'::regclass
+                AND conrelid = #{quote(quote_table_name(table_name))}::regclass
             ), cons AS (
               SELECT conrelid, connum, row_number() OVER() AS rownum FROM pk_constraint
             )
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/type_metadata.rb b/activerecord/lib/active_record/connection_adapters/postgresql/type_metadata.rb
index bcef8ac715..311988625f 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/type_metadata.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/type_metadata.rb
@@ -8,7 +8,7 @@ module ActiveRecord
         @type_metadata = type_metadata
         @oid = oid
         @fmod = fmod
-        @array = /\[\]$/ === type_metadata.sql_type
+        @array = /\[\]$/.match?(type_metadata.sql_type)
       end
 
       def sql_type