Add copy_ wrappers to Pool

The `copy_to_table()` and friends are currently missing from the `Pool`
interface, add them in.

Fixes: #641.

asyncpg/pool.py

@@ -522,7 +522,7 @@ async def execute(self, query: str, *args, timeout: float=None) -> str:
 
         Pool performs this operation using one of its connections.  Other than
         that, it behaves identically to
-        :meth:`Connection.execute() <connection.Connection.execute>`.
+        :meth:`Connection.execute() <asyncpg.connection.Connection.execute>`.
 
         .. versionadded:: 0.10.0
         """
@@ -534,7 +534,8 @@ async def executemany(self, command: str, args, *, timeout: float=None):
 
         Pool performs this operation using one of its connections.  Other than
         that, it behaves identically to
-        :meth:`Connection.executemany() <connection.Connection.executemany>`.
+        :meth:`Connection.executemany()
+        <asyncpg.connection.Connection.executemany>`.
 
         .. versionadded:: 0.10.0
         """
@@ -546,7 +547,7 @@ async def fetch(self, query, *args, timeout=None) -> list:
 
         Pool performs this operation using one of its connections.  Other than
         that, it behaves identically to
-        :meth:`Connection.fetch() <connection.Connection.fetch>`.
+        :meth:`Connection.fetch() <asyncpg.connection.Connection.fetch>`.
 
         .. versionadded:: 0.10.0
         """
@@ -558,7 +559,8 @@ async def fetchval(self, query, *args, column=0, timeout=None):
 
         Pool performs this operation using one of its connections.  Other than
         that, it behaves identically to
-        :meth:`Connection.fetchval() <connection.Connection.fetchval>`.
+        :meth:`Connection.fetchval()
+        <asyncpg.connection.Connection.fetchval>`.
 
         .. versionadded:: 0.10.0
         """
@@ -571,13 +573,178 @@ async def fetchrow(self, query, *args, timeout=None):
 
         Pool performs this operation using one of its connections.  Other than
         that, it behaves identically to
-        :meth:`Connection.fetchrow() <connection.Connection.fetchrow>`.
+        :meth:`Connection.fetchrow() <asyncpg.connection.Connection.fetchrow>`.
 
         .. versionadded:: 0.10.0
         """
         async with self.acquire() as con:
             return await con.fetchrow(query, *args, timeout=timeout)
 
+    async def copy_from_table(
+        self,
+        table_name,
+        *,
+        output,
+        columns=None,
+        schema_name=None,
+        timeout=None,
+        format=None,
+        oids=None,
+        delimiter=None,
+        null=None,
+        header=None,
+        quote=None,
+        escape=None,
+        force_quote=None,
+        encoding=None
+    ):
+        """Copy table contents to a file or file-like object.
+
+        Pool performs this operation using one of its connections.  Other than
+        that, it behaves identically to
+        :meth:`Connection.copy_from_table()
+        <asyncpg.connection.Connection.copy_from_table>`.
+
+        .. versionadded:: 0.22.0
+        """
+        async with self.acquire() as con:
+            return await con.copy_from_table(
+                table_name,
+                output=output,
+                columns=columns,
+                schema_name=schema_name,
+                timeout=timeout,
+                format=format,
+                oids=oids,
+                delimiter=delimiter,
+                null=null,
+                header=header,
+                quote=quote,
+                escape=escape,
+                force_quote=force_quote,
+                encoding=encoding
+            )
+
+    async def copy_from_query(
+        self,
+        query,
+        *args,
+        output,
+        timeout=None,
+        format=None,
+        oids=None,
+        delimiter=None,
+        null=None,
+        header=None,
+        quote=None,
+        escape=None,
+        force_quote=None,
+        encoding=None
+    ):
+        """Copy the results of a query to a file or file-like object.
+
+        Pool performs this operation using one of its connections.  Other than
+        that, it behaves identically to
+        :meth:`Connection.copy_from_query()
+        <asyncpg.connection.Connection.copy_from_query>`.
+
+        .. versionadded:: 0.22.0
+        """
+        async with self.acquire() as con:
+            return await con.copy_from_query(
+                query,
+                *args,
+                output=output,
+                timeout=timeout,
+                format=format,
+                oids=oids,
+                delimiter=delimiter,
+                null=null,
+                header=header,
+                quote=quote,
+                escape=escape,
+                force_quote=force_quote,
+                encoding=encoding
+            )
+
+    async def copy_to_table(
+        self,
+        table_name,
+        *,
+        source,
+        columns=None,
+        schema_name=None,
+        timeout=None,
+        format=None,
+        oids=None,
+        freeze=None,
+        delimiter=None,
+        null=None,
+        header=None,
+        quote=None,
+        escape=None,
+        force_quote=None,
+        force_not_null=None,
+        force_null=None,
+        encoding=None
+    ):
+        """Copy data to the specified table.
+
+        Pool performs this operation using one of its connections.  Other than
+        that, it behaves identically to
+        :meth:`Connection.copy_to_table()
+        <asyncpg.connection.Connection.copy_to_table>`.
+
+        .. versionadded:: 0.22.0
+        """
+        async with self.acquire() as con:
+            return await con.copy_to_table(
+                table_name,
+                source=source,
+                columns=columns,
+                schema_name=schema_name,
+                timeout=timeout,
+                format=format,
+                oids=oids,
+                freeze=freeze,
+                delimiter=delimiter,
+                null=null,
+                header=header,
+                quote=quote,
+                escape=escape,
+                force_quote=force_quote,
+                force_not_null=force_not_null,
+                force_null=force_null,
+                encoding=encoding
+            )
+
+    async def copy_records_to_table(
+        self,
+        table_name,
+        *,
+        records,
+        columns=None,
+        schema_name=None,
+        timeout=None
+    ):
+        """Copy a list of records to the specified table using binary COPY.
+
+        Pool performs this operation using one of its connections.  Other than
+        that, it behaves identically to
+        :meth:`Connection.copy_records_to_table()
+        <asyncpg.connection.Connection.copy_records_to_table>`.
+
+        .. versionadded:: 0.22.0
+        """
+        async with self.acquire() as con:
+            return await con.copy_to_table(
+                table_name,
+                records=records,
+                columns=columns,
+                schema_name=schema_name,
+                timeout=timeout
+            )
+
     def acquire(self, *, timeout=None):
         """Acquire a database connection from the pool.
 
@@ -844,12 +1011,12 @@ def create_pool(dsn=None, *,
 
     .. warning::
         Prepared statements and cursors returned by
-        :meth:`Connection.prepare() <connection.Connection.prepare>` and
-        :meth:`Connection.cursor() <connection.Connection.cursor>` become
-        invalid once the connection is released.  Likewise, all notification
-        and log listeners are removed, and ``asyncpg`` will issue a warning
-        if there are any listener callbacks registered on a connection that
-        is being released to the pool.
+        :meth:`Connection.prepare() <asyncpg.connection.Connection.prepare>`
+        and :meth:`Connection.cursor() <asyncpg.connection.Connection.cursor>`
+        become invalid once the connection is released.  Likewise, all
+        notification and log listeners are removed, and ``asyncpg`` will
+        issue a warning if there are any listener callbacks registered on a
+        connection that is being released to the pool.
 
     :param str dsn:
         Connection arguments specified using as a single string in
@@ -915,10 +1082,11 @@ def create_pool(dsn=None, *,
     .. versionchanged:: 0.13.0
        An :exc:`~asyncpg.exceptions.InterfaceWarning` will be produced
        if there are any active listeners (added via
-       :meth:`Connection.add_listener() <connection.Connection.add_listener>`
+       :meth:`Connection.add_listener()
+       <asyncpg.connection.Connection.add_listener>`
        or :meth:`Connection.add_log_listener()
-       <connection.Connection.add_log_listener>`) present on the connection
-       at the moment of its release to the pool.
+       <asyncpg.connection.Connection.add_log_listener>`) present on the
+       connection at the moment of its release to the pool.
 
     .. versionchanged:: 0.22.0
        Added the *record_class* parameter.