Support EXPLAIN CREATE MATERIALIZED VIEW

See 21973

check.sh

@@ -104,6 +104,7 @@ grep -v "array_fill on " |
 grep -v "mz_aclitem grantor cannot be PUBLIC role" |
 grep -v "is out of range for type numeric: exceeds maximum precision" |
 grep -v "requested length too large" |
+grep -v "cannot materialize call to" | # CREATE MATERIALIZED VIEW
 
 grep -v "operator is not unique" | # random nulls
 grep -v "cannot be matched" | # random nulls
@@ -113,6 +114,7 @@ grep -v "CAST does not support casting from" | # random nulls
 grep -v "number of columns must be a positive integer literal" |
 grep -v "regex_extract requires a string literal as its first argument" |
 grep -v -E "column \".*\" does not exist" | # https://github.com/MaterializeInc/materialize/issues/20533
+grep -v -E "role \".*\" does not exist" |
 grep -v "SET clause does not support casting from interval to integer" |
 
 grep -v "Expected joined table, found" | # Should fix for multi table join

grammar.cc

@@ -742,13 +742,13 @@ void explain_stmt::out(std::ostream &out) {
     out << "with (";
     switch(d6()) {
     case 1:
-      out << "arity, join_impls";
+      out << "arity, join_impls, humanized_exprs";
       break;
     case 2:
-      out << "arity, join_impls, keys, types";
+      out << "arity, join_impls, keys, types, humanized_exprs";
       break;
     case 3:
-      out << "keys, types";
+      out << "keys, types, humanized_exprs";
       break;
     case 4:
       out << "keys";
@@ -775,5 +775,8 @@ void explain_stmt::out(std::ostream &out) {
   if (for_supported) {
     out << "for ";
   }
+  if(with_supported && d6() > 3) {
+    out << "create materialized view mv as ";
+  }
   out << *q;
 }