Andres Freund <and...@anarazel.de> writes:
> On 2020-02-13 18:57:10 -0500, Tom Lane wrote:
>> Maybe we could decide that the time for supporting easy updates from
>> pre-9.1 is past, and just remove all the unpackaged-to-XXX scripts?
>> Maybe even remove the "FROM version" option altogether.

> Yea, that strikes me as a reasonable thing to do. These days that just
> seems to be dangerous, without much advantage.

Here's a patch to remove the core-code support and documentation for
that.  I have not included the actual deletion of the contrib modules'
'unpackaged' scripts, as that seems both long and boring.

                        regards, tom lane

diff --git a/doc/src/sgml/contrib.sgml b/doc/src/sgml/contrib.sgml
index 08bb110..261a559 100644
--- a/doc/src/sgml/contrib.sgml
+++ b/doc/src/sgml/contrib.sgml
@@ -88,22 +88,6 @@ CREATE EXTENSION <replaceable>module_name</replaceable>;
  </para>
 
  <para>
-  If your database was brought forward by dump and reload from a pre-9.1
-  version of <productname>PostgreSQL</productname>, and you had been using the pre-9.1
-  version of the module in it, you should instead do
-
-<programlisting>
-CREATE EXTENSION <replaceable>module_name</replaceable> FROM unpackaged;
-</programlisting>
-
-  This will update the pre-9.1 objects of the module into a proper
-  <firstterm>extension</firstterm> object.  Future updates to the module will be
-  managed by <xref linkend="sql-alterextension"/>.
-  For more information about extension updates, see
-  <xref linkend="extend-extensions"/>.
- </para>
-
- <para>
   Note, however, that some of these modules are not <quote>extensions</quote>
   in this sense, but are loaded into the server in some other way, for instance
   by way of
diff --git a/doc/src/sgml/extend.sgml b/doc/src/sgml/extend.sgml
index ffe068b..9ec1af7 100644
--- a/doc/src/sgml/extend.sgml
+++ b/doc/src/sgml/extend.sgml
@@ -917,33 +917,6 @@ SELECT pg_catalog.pg_extension_config_dump('my_config', 'WHERE NOT standard_entr
     </para>
 
     <para>
-     The update mechanism can be used to solve an important special case:
-     converting a <quote>loose</quote> collection of objects into an extension.
-     Before the extension mechanism was added to
-     <productname>PostgreSQL</productname> (in 9.1), many people wrote
-     extension modules that simply created assorted unpackaged objects.
-     Given an existing database containing such objects, how can we convert
-     the objects into a properly packaged extension?  Dropping them and then
-     doing a plain <command>CREATE EXTENSION</command> is one way, but it's not
-     desirable if the objects have dependencies (for example, if there are
-     table columns of a data type created by the extension).  The way to fix
-     this situation is to create an empty extension, then use <command>ALTER
-     EXTENSION ADD</command> to attach each pre-existing object to the extension,
-     then finally create any new objects that are in the current extension
-     version but were not in the unpackaged release.  <command>CREATE
-     EXTENSION</command> supports this case with its <literal>FROM</literal> <replaceable
-     class="parameter">old_version</replaceable> option, which causes it to not run the
-     normal installation script for the target version, but instead the update
-     script named
-     <literal><replaceable>extension</replaceable>--<replaceable>old_version</replaceable>--<replaceable>target_version</replaceable>.sql</literal>.
-     The choice of the dummy version name to use as <replaceable
-     class="parameter">old_version</replaceable> is up to the extension author, though
-     <literal>unpackaged</literal> is a common convention.  If you have multiple
-     prior versions you need to be able to update into extension style, use
-     multiple dummy version names to identify them.
-    </para>
-
-    <para>
      <command>ALTER EXTENSION</command> is able to execute sequences of update
      script files to achieve a requested update.  For example, if only
      <literal>foo--1.0--1.1.sql</literal> and <literal>foo--1.1--2.0.sql</literal> are
diff --git a/doc/src/sgml/ref/create_extension.sgml b/doc/src/sgml/ref/create_extension.sgml
index d76ac3e..6a21bff 100644
--- a/doc/src/sgml/ref/create_extension.sgml
+++ b/doc/src/sgml/ref/create_extension.sgml
@@ -24,7 +24,6 @@ PostgreSQL documentation
 CREATE EXTENSION [ IF NOT EXISTS ] <replaceable class="parameter">extension_name</replaceable>
     [ WITH ] [ SCHEMA <replaceable class="parameter">schema_name</replaceable> ]
              [ VERSION <replaceable class="parameter">version</replaceable> ]
-             [ FROM <replaceable class="parameter">old_version</replaceable> ]
              [ CASCADE ]
 </synopsis>
  </refsynopsisdiv>
@@ -48,8 +47,9 @@ CREATE EXTENSION [ IF NOT EXISTS ] <replaceable class="parameter">extension_name
 
   <para>
    The user who runs <command>CREATE EXTENSION</command> becomes the
-   owner of the extension for purposes of later privilege checks, as well
-   as the owner of any objects created by the extension's script.
+   owner of the extension for purposes of later privilege checks, and
+   normally also becomes the owner of any objects created by the
+   extension's script.
   </para>
 
   <para>
@@ -142,33 +142,6 @@ CREATE EXTENSION [ IF NOT EXISTS ] <replaceable class="parameter">extension_name
      </varlistentry>
 
      <varlistentry>
-      <term><replaceable class="parameter">old_version</replaceable></term>
-      <listitem>
-       <para>
-        <literal>FROM</literal> <replaceable class="parameter">old_version</replaceable>
-        must be specified when, and only when, you are attempting to install
-        an extension that replaces an <quote>old style</quote> module that is just
-        a collection of objects not packaged into an extension.  This option
-        causes <command>CREATE EXTENSION</command> to run an alternative installation
-        script that absorbs the existing objects into the extension, instead
-        of creating new objects.  Be careful that <literal>SCHEMA</literal> specifies
-        the schema containing these pre-existing objects.
-       </para>
-
-       <para>
-        The value to use for <replaceable
-        class="parameter">old_version</replaceable> is determined by the
-        extension's author, and might vary if there is more than one version
-        of the old-style module that can be upgraded into an extension.
-        For the standard additional modules supplied with pre-9.1
-        <productname>PostgreSQL</productname>, use <literal>unpackaged</literal>
-        for <replaceable class="parameter">old_version</replaceable> when
-        updating a module to extension style.
-       </para>
-      </listitem>
-     </varlistentry>
-
-     <varlistentry>
       <term><literal>CASCADE</literal></term>
       <listitem>
        <para>
@@ -220,16 +193,6 @@ CREATE EXTENSION [ IF NOT EXISTS ] <replaceable class="parameter">extension_name
 CREATE EXTENSION hstore;
 </programlisting>
   </para>
-
-  <para>
-   Update a pre-9.1 installation of <literal>hstore</literal> into
-   extension style:
-<programlisting>
-CREATE EXTENSION hstore SCHEMA public FROM unpackaged;
-</programlisting>
-   Be careful to specify the schema in which you installed the existing
-   <literal>hstore</literal> objects.
-  </para>
  </refsect1>
 
  <refsect1>
diff --git a/src/backend/commands/extension.c b/src/backend/commands/extension.c
index ddd46f4..a0db7db 100644
--- a/src/backend/commands/extension.c
+++ b/src/backend/commands/extension.c
@@ -1357,7 +1357,6 @@ static ObjectAddress
 CreateExtensionInternal(char *extensionName,
 						char *schemaName,
 						const char *versionName,
-						const char *oldVersionName,
 						bool cascade,
 						List *parents,
 						bool is_create)
@@ -1367,6 +1366,8 @@ CreateExtensionInternal(char *extensionName,
 	Oid			extowner = GetUserId();
 	ExtensionControlFile *pcontrol;
 	ExtensionControlFile *control;
+	char	   *filename;
+	struct stat fst;
 	List	   *updateVersions;
 	List	   *requiredExtensions;
 	List	   *requiredSchemas;
@@ -1401,56 +1402,6 @@ CreateExtensionInternal(char *extensionName,
 	 * does what is needed, we try to find a sequence of update scripts that
 	 * will get us there.
 	 */
-	if (oldVersionName)
-	{
-		/*
-		 * "FROM old_version" was specified, indicating that we're trying to
-		 * update from some unpackaged version of the extension.  Locate a
-		 * series of update scripts that will do it.
-		 */
-		check_valid_version_name(oldVersionName);
-
-		if (strcmp(oldVersionName, versionName) == 0)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-					 errmsg("FROM version must be different from installation target version \"%s\"",
-							versionName)));
-
-		updateVersions = identify_update_path(pcontrol,
-											  oldVersionName,
-											  versionName);
-
-		if (list_length(updateVersions) == 1)
-		{
-			/*
-			 * Simple case where there's just one update script to run. We
-			 * will not need any follow-on update steps.
-			 */
-			Assert(strcmp((char *) linitial(updateVersions), versionName) == 0);
-			updateVersions = NIL;
-		}
-		else
-		{
-			/*
-			 * Multi-step sequence.  We treat this as installing the version
-			 * that is the target of the first script, followed by successive
-			 * updates to the later versions.
-			 */
-			versionName = (char *) linitial(updateVersions);
-			updateVersions = list_delete_first(updateVersions);
-		}
-	}
-	else
-	{
-		/*
-		 * No FROM, so we're installing from scratch.  If there is an install
-		 * script for the desired version, we only need to run that one.
-		 */
-		char	   *filename;
-		struct stat fst;
-
-		oldVersionName = NULL;
-
 		filename = get_extension_script_filename(pcontrol, NULL, versionName);
 		if (stat(filename, &fst) == 0)
 		{
@@ -1484,7 +1435,6 @@ CreateExtensionInternal(char *extensionName,
 			/* Otherwise, install best starting point and then upgrade */
 			versionName = evi_start->name;
 		}
-	}
 
 	/*
 	 * Fetch control parameters for installation target version
@@ -1624,7 +1574,7 @@ CreateExtensionInternal(char *extensionName,
 	 * Execute the installation script file
 	 */
 	execute_extension_script(extensionOid, control,
-							 oldVersionName, versionName,
+							 NULL, versionName,
 							 requiredSchemas,
 							 schemaName, schemaOid);
 
@@ -1691,7 +1641,6 @@ get_required_extension(char *reqExtensionName,
 			addr = CreateExtensionInternal(reqExtensionName,
 										   origSchemaName,
 										   NULL,
-										   NULL,
 										   cascade,
 										   cascade_parents,
 										   is_create);
@@ -1719,11 +1668,9 @@ CreateExtension(ParseState *pstate, CreateExtensionStmt *stmt)
 {
 	DefElem    *d_schema = NULL;
 	DefElem    *d_new_version = NULL;
-	DefElem    *d_old_version = NULL;
 	DefElem    *d_cascade = NULL;
 	char	   *schemaName = NULL;
 	char	   *versionName = NULL;
-	char	   *oldVersionName = NULL;
 	bool		cascade = false;
 	ListCell   *lc;
 
@@ -1787,16 +1734,6 @@ CreateExtension(ParseState *pstate, CreateExtensionStmt *stmt)
 			d_new_version = defel;
 			versionName = defGetString(d_new_version);
 		}
-		else if (strcmp(defel->defname, "old_version") == 0)
-		{
-			if (d_old_version)
-				ereport(ERROR,
-						(errcode(ERRCODE_SYNTAX_ERROR),
-						 errmsg("conflicting or redundant options"),
-						 parser_errposition(pstate, defel->location)));
-			d_old_version = defel;
-			oldVersionName = defGetString(d_old_version);
-		}
 		else if (strcmp(defel->defname, "cascade") == 0)
 		{
 			if (d_cascade)
@@ -1815,7 +1752,6 @@ CreateExtension(ParseState *pstate, CreateExtensionStmt *stmt)
 	return CreateExtensionInternal(stmt->extname,
 								   schemaName,
 								   versionName,
-								   oldVersionName,
 								   cascade,
 								   NIL,
 								   true);
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 1b0edf5..96e7fdb 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4460,7 +4460,7 @@ DropTableSpaceStmt: DROP TABLESPACE name
  *
  *		QUERY:
  *             CREATE EXTENSION extension
- *             [ WITH ] [ SCHEMA schema ] [ VERSION version ] [ FROM oldversion ]
+ *             [ WITH ] [ SCHEMA schema ] [ VERSION version ]
  *
  *****************************************************************************/
 
@@ -4500,7 +4500,10 @@ create_extension_opt_item:
 				}
 			| FROM NonReservedWord_or_Sconst
 				{
-					$$ = makeDefElem("old_version", (Node *)makeString($2), @1);
+					ereport(ERROR,
+							(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+							 errmsg("CREATE EXTENSION ... FROM is no longer supported"),
+							 parser_errposition(@1)));
 				}
 			| CASCADE
 				{

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