Function dumpExtension

src/bin/pg_dump/pg_dump.c:11640–11762

* dumpExtension * writes out to fout the queries to recreate an extension */

 *	  writes out to fout the queries to recreate an extension
 */
static void
dumpExtension(Archive *fout, const ExtensionInfo *extinfo)
{
	DumpOptions *dopt = fout->dopt;
	PQExpBuffer q;
	PQExpBuffer delq;
	char	   *qextname;

	/* Skip if not to be dumped */
	if (!extinfo->dobj.dump || dopt->dataOnly)
		return;

	q = createPQExpBuffer();
	delq = createPQExpBuffer();

	qextname = pg_strdup(fmtId(extinfo->dobj.name));

	appendPQExpBuffer(delq, "DROP EXTENSION %s;\n", qextname);

	if (!dopt->binary_upgrade)
	{
		/*
		 * In a regular dump, we simply create the extension, intentionally
		 * not specifying a version, so that the destination installation's
		 * default version is used.
		 *
		 * Use of IF NOT EXISTS here is unlike our behavior for other object
		 * types; but there are various scenarios in which it's convenient to
		 * manually create the desired extension before restoring, so we
		 * prefer to allow it to exist already.
		 */
		appendPQExpBuffer(q, "CREATE EXTENSION IF NOT EXISTS %s WITH SCHEMA %s;\n",
						  qextname, fmtId(extinfo->namespace));
	}
	else
	{
		/*
		 * In binary-upgrade mode, it's critical to reproduce the state of the
		 * database exactly, so our procedure is to create an empty extension,
		 * restore all the contained objects normally, and add them to the
		 * extension one by one.  This function performs just the first of
		 * those steps.  binary_upgrade_extension_member() takes care of
		 * adding member objects as they're created.
		 */
		int			i;
		int			n;

		appendPQExpBufferStr(q, "-- For binary upgrade, create an empty extension and insert objects into it\n");

		/*
		 * We unconditionally create the extension, so we must drop it if it
		 * exists.  This could happen if the user deleted 'plpgsql' and then
		 * readded it, causing its oid to be greater than g_last_builtin_oid.
		 */
		appendPQExpBuffer(q, "DROP EXTENSION IF EXISTS %s;\n", qextname);

		appendPQExpBufferStr(q,
							 "SELECT pg_catalog.binary_upgrade_create_empty_extension(");