Merge pull request #2545 from yahonda/move-describe-to-schema-statements

Move Connection#describe to SchemaStatements helpers

Author: yahonda

lib/active_record/connection_adapters/oracle_enhanced/connection.rb

@@ -16,102 +16,19 @@ def self.create(config)
           end
         end
 
-        attr_reader :raw_connection
+        attr_reader :raw_connection, :owner
 
         private
-          # Used always by JDBC connection as well by OCI connection when describing tables over database link
-          def describe(name)
-            name = name.to_s
-            if name.include?("@")
-              raise ArgumentError "db link is not supported"
-            else
-              default_owner = @owner
-            end
-            real_name = OracleEnhanced::Quoting.valid_table_name?(name) ? name.upcase : name
-            if real_name.include?(".")
-              table_owner, table_name = real_name.split(".")
-            else
-              table_owner, table_name = default_owner, real_name
-            end
-            sql = <<~SQL.squish
-              SELECT owner, table_name, 'TABLE' name_type
-              FROM all_tables
-              WHERE owner = :table_owner
-                AND table_name = :table_name
-              UNION ALL
-              SELECT owner, view_name table_name, 'VIEW' name_type
-              FROM all_views
-              WHERE owner = :table_owner
-                AND view_name = :table_name
-              UNION ALL
-              SELECT table_owner, table_name, 'SYNONYM' name_type
-              FROM all_synonyms
-              WHERE owner = :table_owner
-                AND synonym_name = :table_name
-              UNION ALL
-              SELECT table_owner, table_name, 'SYNONYM' name_type
-              FROM all_synonyms
-              WHERE owner = 'PUBLIC'
-                AND synonym_name = :real_name
-            SQL
-            if result = _select_one(sql, "CONNECTION", [table_owner, table_name, table_owner, table_name, table_owner, table_name, real_name])
-              case result["name_type"]
-              when "SYNONYM"
-                describe("#{result['owner'] && "#{result['owner']}."}#{result['table_name']}")
-              else
-                [result["owner"], result["table_name"]]
-              end
-            else
-              raise OracleEnhanced::ConnectionException, %Q{"DESC #{name}" failed; does it exist?}
-            end
-          end
-
           # Oracle column names by default are case-insensitive, but treated as upcase;
           # for neatness, we'll downcase within Rails. EXCEPT that folks CAN quote
           # their column names when creating Oracle tables, which makes then case-sensitive.
           # I don't know anybody who does this, but we'll handle the theoretical case of a
           # camelCase column name. I imagine other dbs handle this different, since there's a
           # unit test that's currently failing test_oci.
-          #
-          # `_oracle_downcase` is expected to be called only from
-          # `ActiveRecord::ConnectionAdapters::OracleEnhanced::OCIConnection`
-          # or `ActiveRecord::ConnectionAdapters::OracleEnhanced::JDBCConnection`.
-          # Other method should call `ActiveRecord:: ConnectionAdapters::OracleEnhanced::Quoting#oracle_downcase`
-          # since this is kind of quoting, not connection.
-          # To avoid it is called from anywhere else, added _ at the beginning of the method name.
           def _oracle_downcase(column_name)
             return nil if column_name.nil?
             /[a-z]/.match?(column_name) ? column_name : column_name.downcase
           end
-
-          # _select_one and _select_value methods are expected to be called
-          # only from `ActiveRecord::ConnectionAdapters::OracleEnhanced::Connection#describe`
-          # Other methods should call `ActiveRecord::ConnectionAdapters::DatabaseStatements#select_one`
-          # and  `ActiveRecord::ConnectionAdapters::DatabaseStatements#select_value`
-          # To avoid called from its subclass added a underscore in each method.
-
-          # Returns a record hash with the column names as keys and column values
-          # as values.
-          # binds is a array of native values in contrast to ActiveRecord::Relation::QueryAttribute
-          def _select_one(arel, name = nil, binds = [])
-            cursor = prepare(arel)
-            cursor.bind_params(binds)
-            cursor.exec
-            columns = cursor.get_col_names.map do |col_name|
-              _oracle_downcase(col_name)
-            end
-            row = cursor.fetch
-            columns.each_with_index.to_h { |x, i| [x, row[i]] } if row
-          ensure
-            cursor.close
-          end
-
-          # Returns a single value from a record
-          def _select_value(arel, name = nil, binds = [])
-            if result = _select_one(arel, name, binds)
-              result.values.first
-            end
-          end
       end
 
       # Returns array with major and minor version of database (e.g. [12, 1])

lib/active_record/connection_adapters/oracle_enhanced/jdbc_connection.rb

@@ -522,11 +522,6 @@ def write_lob(lob, value, is_binary = false)
           end
         end
 
-        # To allow private method called from `JDBCConnection`
-        def describe(name)
-          super
-        end
-
         # Return java.sql.SQLException error code
         def error_code(exception)
           case exception

lib/active_record/connection_adapters/oracle_enhanced/oci_connection.rb

@@ -237,10 +237,6 @@ def write_lob(lob, value, is_binary = false)
           lob.write value
         end
 
-        def describe(name)
-          super
-        end
-
         # Return OCIError error code
         def error_code(exception)
           case exception

lib/active_record/connection_adapters/oracle_enhanced/schema_statements.rb

@@ -53,7 +53,7 @@ def table_exists?(table_name)
         end
 
         def data_source_exists?(table_name)
-          (_owner, _table_name) = _connection.describe(table_name)
+          (_owner, _table_name) = resolve_data_source_name(table_name)
           true
         rescue
           false
@@ -87,7 +87,7 @@ def synonyms
         end
 
         def indexes(table_name) # :nodoc:
-          (_owner, table_name) = _connection.describe(table_name)
+          (_owner, table_name) = resolve_data_source_name(table_name)
           default_tablespace_name = default_tablespace
 
           result = select_all(<<~SQL.squish, "SCHEMA", [bind_string("table_name", table_name)])
@@ -368,7 +368,7 @@ def index_name(table_name, options) # :nodoc:
         #
         # Will always query database and not index cache.
         def index_name_exists?(table_name, index_name)
-          (_owner, table_name) = _connection.describe(table_name)
+          (_owner, table_name) = resolve_data_source_name(table_name)
           result = select_value(<<~SQL.squish, "SCHEMA", [bind_string("table_name", table_name), bind_string("index_name", index_name.to_s.upcase)])
             SELECT 1 FROM all_indexes i
             WHERE i.owner = SYS_CONTEXT('userenv', 'current_schema')
@@ -511,7 +511,7 @@ def change_column_comment(table_name, column_name, comment_or_changes)
 
         def table_comment(table_name) # :nodoc:
           # TODO
-          (_owner, table_name) = _connection.describe(table_name)
+          (_owner, table_name) = resolve_data_source_name(table_name)
           select_value(<<~SQL.squish, "SCHEMA", [bind_string("table_name", table_name)])
             SELECT comments FROM all_tab_comments
             WHERE owner = SYS_CONTEXT('userenv', 'current_schema')
@@ -527,7 +527,7 @@ def table_options(table_name) # :nodoc:
 
         def column_comment(table_name, column_name) # :nodoc:
           # TODO: it  does not exist in Abstract adapter
-          (_owner, table_name) = _connection.describe(table_name)
+          (_owner, table_name) = resolve_data_source_name(table_name)
           select_value(<<~SQL.squish, "SCHEMA", [bind_string("table_name", table_name), bind_string("column_name", column_name.upcase)])
             SELECT comments FROM all_col_comments
             WHERE owner = SYS_CONTEXT('userenv', 'current_schema')
@@ -555,7 +555,7 @@ def tablespace(table_name)
 
         # get table foreign keys for schema dump
         def foreign_keys(table_name) # :nodoc:
-          (_owner, desc_table_name) = _connection.describe(table_name)
+          (_owner, desc_table_name) = resolve_data_source_name(table_name)
 
           fk_info = select_all(<<~SQL.squish, "SCHEMA", [bind_string("desc_table_name", desc_table_name)])
             SELECT r.table_name to_table
@@ -733,6 +733,73 @@ def rebuild_primary_key_index_to_default_tablespace(table_name, options)
 
             execute("ALTER INDEX #{quote_column_name(index_name)} REBUILD TABLESPACE #{tablespace}")
           end
+
+          # Resolves an Oracle data-source name to its underlying [owner, table_name]
+          # by following synonyms through the catalog. Defaults the schema to
+          # `_connection.owner` (the adapter's configured default schema, taken
+          # from `config[:schema]` or `config[:username]`) when the name is not
+          # schema-qualified. This is distinct from
+          # `SYS_CONTEXT('USERENV', 'CURRENT_SCHEMA')`, which can differ after
+          # `ALTER SESSION SET CURRENT_SCHEMA`.
+          # Raises OracleEnhanced::ConnectionException if the object does not
+          # exist or if synonym resolution produces a looping chain.
+          def resolve_data_source_name(name)
+            visited = Set.new
+            loop do
+              schema, identifier = extract_schema_qualified_name(name)
+              real_name = schema ? "#{schema}.#{identifier}" : identifier
+              owner = schema || _connection.owner
+
+              unless visited.add?([owner, identifier])
+                raise OracleEnhanced::ConnectionException,
+                      %Q{"DESC #{name}" failed; looping chain of synonyms}
+              end
+
+              binds = [
+                bind_string("table_owner", owner),
+                bind_string("table_name", identifier),
+                bind_string("table_owner", owner),
+                bind_string("table_name", identifier),
+                bind_string("table_owner", owner),
+                bind_string("table_name", identifier),
+                bind_string("real_name", real_name),
+              ]
+              result = select_one(<<~SQL.squish, "SCHEMA", binds)
+                SELECT owner, table_name, 'TABLE' name_type
+                FROM all_tables WHERE owner = :table_owner AND table_name = :table_name
+                UNION ALL
+                SELECT owner, view_name table_name, 'VIEW' name_type
+                FROM all_views WHERE owner = :table_owner AND view_name = :table_name
+                UNION ALL
+                SELECT table_owner, table_name, 'SYNONYM' name_type
+                FROM all_synonyms WHERE owner = :table_owner AND synonym_name = :table_name
+                UNION ALL
+                SELECT table_owner, table_name, 'SYNONYM' name_type
+                FROM all_synonyms WHERE owner = 'PUBLIC' AND synonym_name = :real_name
+              SQL
+
+              raise OracleEnhanced::ConnectionException, %Q{"DESC #{name}" failed; does it exist?} unless result
+
+              if result["name_type"] == "SYNONYM"
+                name = "#{result['owner'] && "#{result['owner']}."}#{result['table_name']}"
+              else
+                return [result["owner"], result["table_name"]]
+              end
+            end
+          end
+
+          # Splits "schema.identifier" into its parts, returning [schema, identifier].
+          # Mirrors Rails' PostgreSQL/MySQL adapters: a non-qualified name yields
+          # schema = nil. Oracle-specific bits: rejects db links and upcases valid
+          # identifiers so catalog lookups match the stored upper-case names.
+          def extract_schema_qualified_name(string)
+            string = string.to_s
+            raise ArgumentError, "db link is not supported" if string.include?("@")
+
+            string = string.upcase if OracleEnhanced::Quoting.valid_table_name?(string)
+            schema, identifier = string.split(".") if string.include?(".")
+            [schema, identifier || string]
+          end
       end
     end
   end

lib/active_record/connection_adapters/oracle_enhanced_adapter.rb

@@ -519,7 +519,7 @@ def prefetch_primary_key?(table_name = nil)
         table_name = table_name.to_s
         do_not_prefetch = @do_not_prefetch_primary_key[table_name]
         if do_not_prefetch.nil?
-          owner, desc_table_name = _connection.describe(table_name)
+          owner, desc_table_name = resolve_data_source_name(table_name)
           @do_not_prefetch_primary_key[table_name] = do_not_prefetch = !has_primary_key?(table_name, owner, desc_table_name)
         end
         !do_not_prefetch
@@ -588,7 +588,7 @@ def default_tablespace
       end
 
       def column_definitions(table_name)
-        (owner, desc_table_name) = _connection.describe(table_name)
+        (owner, desc_table_name) = resolve_data_source_name(table_name)
 
         select_all(<<~SQL.squish, "SCHEMA", [bind_string("owner", owner), bind_string("table_name", desc_table_name)])
           SELECT cols.column_name AS name, cols.data_type AS sql_type,
@@ -620,7 +620,7 @@ def clear_table_columns_cache(table_name)
       # Find a table's primary key and sequence.
       # *Note*: Only primary key is implemented - sequence will be nil.
       def pk_and_sequence_for(table_name, owner = nil, desc_table_name = nil) # :nodoc:
-        (owner, desc_table_name) = _connection.describe(table_name)
+        (owner, desc_table_name) = resolve_data_source_name(table_name)
 
         seqs = select_values_forcing_binds(<<~SQL.squish, "SCHEMA", [bind_string("owner", owner), bind_string("sequence_name", default_sequence_name(desc_table_name))])
           select us.sequence_name
@@ -662,7 +662,7 @@ def has_primary_key?(table_name, owner = nil, desc_table_name = nil) # :nodoc:
       end
 
       def primary_keys(table_name) # :nodoc:
-        (_owner, desc_table_name) = _connection.describe(table_name)
+        (_owner, desc_table_name) = resolve_data_source_name(table_name)
 
         pks = select_values_forcing_binds(<<~SQL.squish, "SCHEMA", [bind_string("table_name", desc_table_name)])
           SELECT cc.column_name