Fix for "text type with an unknown/unsupported collation cannot be ha…

…shed" error (vitessio#13852)

go/test/endtoend/preparestmt/stmt_methods_test.go

@@ -436,3 +436,24 @@ func TestShowColumns(t *testing.T) {
  require.Len(t, cols, 6)
  require.False(t, rows.Next())
 }
+
+func TestBinaryColumn(t *testing.T) {
+ defer cluster.PanicHandler(t)
+ dbo := Connect(t, "interpolateParams=false")
+ defer dbo.Close()
+
+ _, err := dbo.Query(`SELECT DISTINCT
+ BINARY table_info.table_name AS table_name,
+ table_info.create_options AS create_options,
+ table_info.table_comment AS table_comment
+ FROM information_schema.tables AS table_info
+ JOIN information_schema.columns AS column_info
+ ON BINARY column_info.table_name = BINARY table_info.table_name
+ WHERE
+ table_info.table_schema = ?
+ AND column_info.table_schema = ?
+ -- Exclude views.
+ AND table_info.table_type = 'BASE TABLE'
+ ORDER BY BINARY table_info.table_name`, keyspaceName, keyspaceName)
+ require.NoError(t, err)
+}

go/vt/vtgate/semantics/semantic_state.go

@@ -260,6 +260,15 @@ func (st *SemTable) TypeForExpr(e sqlparser.Expr) (sqltypes.Type, collations.ID,
  if typ, found := st.ExprTypes[e]; found {
  return typ.Type, typ.Collation, true
  }
+
+ // We add a lot of WeightString() expressions to queries at late stages of the planning,
+ // which means that they don't have any type information. We can safely assume that they
+ // are VarBinary, since that's the only type that WeightString() can return.
+ _, isWS := e.(*sqlparser.WeightStringFuncExpr)
+ if isWS {
+ return sqltypes.VarBinary, collations.CollationBinaryID, true
+ }
+
  return sqltypes.Unknown, collations.Unknown, false
 }