MDEV-14836: Assertion `m_status == DA_ERROR' failed in

Diagnostics_area::sql_errno upon query from I_S with LIMIT ROWS EXAMINED

open_normal_and_derived_table() fails because the query was already killed
as rows examined by the query are more than the limit. However, this isn't a
real error.
Fix: Check if there is actually an error before calling thd->sql_errno()
and later send a warning in handle_select() if no real error.

mysql-test/r/information_schema.result

@@ -2184,3 +2184,16 @@ SCHEMA_NAME
 #
 # End of 10.1 tests
 #
+#
+# Start of 10.2 Test
+#
+# MDEV-14836: Assertion `m_status == DA_ERROR' failed in
+# Diagnostics_area::sql_errno upon query from I_S with LIMIT ROWS EXAMINED
+#
+SELECT * FROM INFORMATION_SCHEMA.`COLUMNS` LIMIT ROWS EXAMINED 10;
+TABLE_CATALOG	TABLE_SCHEMA	TABLE_NAME	COLUMN_NAME	ORDINAL_POSITION	COLUMN_DEFAULT	IS_NULLABLE	DATA_TYPE	CHARACTER_MAXIMUM_LENGTH	CHARACTER_OCTET_LENGTH	NUMERIC_PRECISION	NUMERIC_SCALE	DATETIME_PRECISION	CHARACTER_SET_NAME	COLLATION_NAME	COLUMN_TYPE	COLUMN_KEY	EXTRA	PRIVILEGES	COLUMN_COMMENT	IS_GENERATED	GENERATION_EXPRESSION
+Warnings:
+Warning	1931	Query execution was interrupted. The query examined at least 666 rows, which exceeds LIMIT ROWS EXAMINED (10). The query result may be incomplete
+#
+# End of 10.2 Test
+#

mysql-test/t/information_schema.test

@@ -1906,3 +1906,16 @@ SELECT SCHEMA_NAME from information_schema.schemata where schema_name=REPEAT('a'
 --echo #
 --echo # End of 10.1 tests
 --echo #
+
+--echo #
+--echo # Start of 10.2 Test
+--echo #
+--echo # MDEV-14836: Assertion `m_status == DA_ERROR' failed in
+--echo # Diagnostics_area::sql_errno upon query from I_S with LIMIT ROWS EXAMINED
+--echo #
+
+SELECT * FROM INFORMATION_SCHEMA.`COLUMNS` LIMIT ROWS EXAMINED 10;
+
+--echo #
+--echo # End of 10.2 Test
+--echo #

sql/sql_show.cc

@@ -4430,7 +4430,7 @@ fill_schema_table_by_open(THD *thd, bool is_show_fields_or_keys,
     Again we don't do this for SHOW COLUMNS/KEYS because
     of backward compatibility.
   */
-  if (!is_show_fields_or_keys && result &&
+  if (!is_show_fields_or_keys && result && thd->is_error() &&
       (thd->get_stmt_da()->sql_errno() == ER_NO_SUCH_TABLE ||
        thd->get_stmt_da()->sql_errno() == ER_WRONG_OBJECT))
   {
@@ -5614,15 +5614,21 @@ static int get_schema_column_record(THD *thd, TABLE_LIST *tables,
         I.e. we are in SELECT FROM INFORMATION_SCHEMA.COLUMS
         rather than in SHOW COLUMNS
       */
-      push_warning(thd, Sql_condition::WARN_LEVEL_WARN,
-                   thd->get_stmt_da()->sql_errno(),
-                   thd->get_stmt_da()->message());
-      thd->clear_error();
+      if (thd->is_error())
+      {
+        /*
+          The the query was aborted because examined rows exceeded limit.
+          Don't send the warning here. It is done later, in handle_select().
+        */
+        push_warning(thd, Sql_condition::WARN_LEVEL_WARN,
+                     thd->get_stmt_da()->sql_errno(),
+                     thd->get_stmt_da()->message());
+        thd->clear_error();
+      }
       res= 0;
     }
     DBUG_RETURN(res);
   }
-
   show_table= tables->table;
   count= 0;
   ptr= show_table->field;