Improve initdb's query for generating default descriptions a little.

While poking into initdb's performance, I noticed that this query
wasn't being done very intelligently.  By forcing it to execute
obj_description() for each pg_proc/pg_operator join row, we were
essentially setting up a nestloop join to pg_description, which
is not a bright query plan when there are hundreds of outer rows.
Convert the check for a "deprecated" operator into a NOT EXISTS
so that it can be done as a hashed antijoin.  On my workstation
this reduces the time for this query from ~ 35ms to ~ 10ms.
Which is not a huge win, but it adds up over buildfarm runs.

In passing, insert forced query breaks (\n\n, in single-user mode)
after each SQL-query file that initdb sources, and after some
relatively new queries in setup_privileges().  This doesn't make
a lot of difference normally, but it will result in briefer, saner
error messages if anything goes wrong.

src/bin/initdb/initdb.c

@@ -1669,6 +1669,8 @@ setup_sysviews(FILE *cmdfd)
 		free(*line);
 	}
 
+	PG_CMD_PUTS("\n\n");
+
 	free(sysviews_setup);
 }
 
@@ -1707,16 +1709,17 @@ setup_description(FILE *cmdfd)
 
 	/* Create default descriptions for operator implementation functions */
 	PG_CMD_PUTS("WITH funcdescs AS ( "
-				"SELECT p.oid as p_oid, oprname, "
-				"coalesce(obj_description(o.oid, 'pg_operator'),'') as opdesc "
+				"SELECT p.oid as p_oid, o.oid as o_oid, oprname "
 				"FROM pg_proc p JOIN pg_operator o ON oprcode = p.oid ) "
 				"INSERT INTO pg_description "
 				"  SELECT p_oid, 'pg_proc'::regclass, 0, "
 				"    'implementation of ' || oprname || ' operator' "
 				"  FROM funcdescs "
-				"  WHERE opdesc NOT LIKE 'deprecated%' AND "
-				"  NOT EXISTS (SELECT 1 FROM pg_description "
-				"    WHERE objoid = p_oid AND classoid = 'pg_proc'::regclass);\n\n");
+				"  WHERE NOT EXISTS (SELECT 1 FROM pg_description "
+				"   WHERE objoid = p_oid AND classoid = 'pg_proc'::regclass) "
+				"  AND NOT EXISTS (SELECT 1 FROM pg_description "
+				"   WHERE objoid = o_oid AND classoid = 'pg_operator'::regclass"
+				"         AND description LIKE 'deprecated%');\n\n");
 
 	/*
 	 * Even though the tables are temp, drop them explicitly so they don't get
@@ -1780,6 +1783,8 @@ setup_dictionary(FILE *cmdfd)
 		free(*line);
 	}
 
+	PG_CMD_PUTS("\n\n");
+
 	free(conv_lines);
 }
 
@@ -1836,7 +1841,7 @@ setup_privileges(FILE *cmdfd)
 		"        relacl IS NOT NULL"
 		"        AND relkind IN (" CppAsString2(RELKIND_RELATION) ", "
 		CppAsString2(RELKIND_VIEW) ", " CppAsString2(RELKIND_MATVIEW) ", "
-		CppAsString2(RELKIND_SEQUENCE) ");",
+		CppAsString2(RELKIND_SEQUENCE) ");\n\n",
 		"INSERT INTO pg_init_privs "
 		"  (objoid, classoid, objsubid, initprivs, privtype)"
 		"    SELECT"
@@ -1852,7 +1857,7 @@ setup_privileges(FILE *cmdfd)
 		"        pg_attribute.attacl IS NOT NULL"
 		"        AND pg_class.relkind IN (" CppAsString2(RELKIND_RELATION) ", "
 		CppAsString2(RELKIND_VIEW) ", " CppAsString2(RELKIND_MATVIEW) ", "
-		CppAsString2(RELKIND_SEQUENCE) ");",
+		CppAsString2(RELKIND_SEQUENCE) ");\n\n",
 		"INSERT INTO pg_init_privs "
 		"  (objoid, classoid, objsubid, initprivs, privtype)"
 		"    SELECT"
@@ -1864,7 +1869,7 @@ setup_privileges(FILE *cmdfd)
 		"    FROM"
 		"        pg_proc"
 		"    WHERE"
-		"        proacl IS NOT NULL;",
+		"        proacl IS NOT NULL;\n\n",
 		"INSERT INTO pg_init_privs "
 		"  (objoid, classoid, objsubid, initprivs, privtype)"
 		"    SELECT"
@@ -1876,7 +1881,7 @@ setup_privileges(FILE *cmdfd)
 		"    FROM"
 		"        pg_type"
 		"    WHERE"
-		"        typacl IS NOT NULL;",
+		"        typacl IS NOT NULL;\n\n",
 		"INSERT INTO pg_init_privs "
 		"  (objoid, classoid, objsubid, initprivs, privtype)"
 		"    SELECT"
@@ -1888,7 +1893,7 @@ setup_privileges(FILE *cmdfd)
 		"    FROM"
 		"        pg_language"
 		"    WHERE"
-		"        lanacl IS NOT NULL;",
+		"        lanacl IS NOT NULL;\n\n",
 		"INSERT INTO pg_init_privs "
 		"  (objoid, classoid, objsubid, initprivs, privtype)"
 		"    SELECT"
@@ -1901,7 +1906,7 @@ setup_privileges(FILE *cmdfd)
 		"    FROM"
 		"        pg_largeobject_metadata"
 		"    WHERE"
-		"        lomacl IS NOT NULL;",
+		"        lomacl IS NOT NULL;\n\n",
 		"INSERT INTO pg_init_privs "
 		"  (objoid, classoid, objsubid, initprivs, privtype)"
 		"    SELECT"
@@ -1913,7 +1918,7 @@ setup_privileges(FILE *cmdfd)
 		"    FROM"
 		"        pg_namespace"
 		"    WHERE"
-		"        nspacl IS NOT NULL;",
+		"        nspacl IS NOT NULL;\n\n",
 		"INSERT INTO pg_init_privs "
 		"  (objoid, classoid, objsubid, initprivs, privtype)"
 		"    SELECT"
@@ -1926,7 +1931,7 @@ setup_privileges(FILE *cmdfd)
 		"    FROM"
 		"        pg_foreign_data_wrapper"
 		"    WHERE"
-		"        fdwacl IS NOT NULL;",
+		"        fdwacl IS NOT NULL;\n\n",
 		"INSERT INTO pg_init_privs "
 		"  (objoid, classoid, objsubid, initprivs, privtype)"
 		"    SELECT"
@@ -1939,7 +1944,7 @@ setup_privileges(FILE *cmdfd)
 		"    FROM"
 		"        pg_foreign_server"
 		"    WHERE"
-		"        srvacl IS NOT NULL;",
+		"        srvacl IS NOT NULL;\n\n",
 		NULL
 	};
 
@@ -1994,6 +1999,8 @@ setup_schema(FILE *cmdfd)
 		free(*line);
 	}
 
+	PG_CMD_PUTS("\n\n");
+
 	free(lines);
 
 	PG_CMD_PRINTF1("UPDATE information_schema.sql_implementation_info "