Function dumpSearchPath

src/bin/pg_dump/pg_dump.c:3839–3895

* dumpSearchPath: record the active search_path in the archive */

 * dumpSearchPath: record the active search_path in the archive
 */
static void
dumpSearchPath(Archive *AH)
{
	PQExpBuffer qry = createPQExpBuffer();
	PQExpBuffer path = createPQExpBuffer();
	PGresult   *res;
	char	  **schemanames = NULL;
	int			nschemanames = 0;
	int			i;

	/*
	 * We use the result of current_schemas(), not the search_path GUC,
	 * because that might contain wildcards such as "$user", which won't
	 * necessarily have the same value during restore.  Also, this way avoids
	 * listing schemas that may appear in search_path but not actually exist,
	 * which seems like a prudent exclusion.
	 */
	res = ExecuteSqlQueryForSingleRow(AH,
									  "SELECT pg_catalog.current_schemas(false)");

	if (!parsePGArray(PQgetvalue(res, 0, 0), &schemanames, &nschemanames))
		fatal("could not parse result of current_schemas()");

	/*
	 * We use set_config(), not a simple "SET search_path" command, because
	 * the latter has less-clean behavior if the search path is empty.  While
	 * that's likely to get fixed at some point, it seems like a good idea to
	 * be as backwards-compatible as possible in what we put into archives.
	 */
	for (i = 0; i < nschemanames; i++)
	{
		if (i > 0)
			appendPQExpBufferStr(path, ", ");
		appendPQExpBufferStr(path, fmtId(schemanames[i]));
	}

	appendPQExpBufferStr(qry, "SELECT pg_catalog.set_config('search_path', ");
	appendStringLiteralAH(qry, path->data, AH);
	appendPQExpBufferStr(qry, ", false);\n");

	pg_log_info("saving search_path = %s", path->data);

	ArchiveEntry(AH, nilCatalogId, createDumpId(),
				 ARCHIVE_OPTS(.tag = "SEARCHPATH",
							  .description = "SEARCHPATH",
							  .section = SECTION_PRE_DATA,
							  .createStmt = qry->data));

	/* Also save it in AH->searchpath, in case we're doing plain text dump */
	AH->searchpath = pg_strdup(qry->data);

	if (schemanames)
		free(schemanames);
	PQclear(res);
	destroyPQExpBuffer(qry);
	destroyPQExpBuffer(path);
}