MDEV-4456 Reverse discovery of ARCHIVE table on SELECT after disappearance of ARZ file

Implement discovery of table non-existence, and related changes:

1. Split GTS_FORCE_DISCOVERY (that was meaning two different things in
two different functions) into GTS_FORCE_DISCOVERY and GTS_USE_DISCOVERY.
2. Move GTS_FORCE_DISCOVERY implementation into open_table_def().
3. In recover_from_failed_open() clear old errors *before* discovery,
not after successful discovery. The final error should come
from the discovery.
4. On forced discovery delete table .frm first. Discovery will write
a new one, if desired.
5. If the frm file exists, but not the table in the engine, force
rediscovery if the engine supports it.

1 files changed, 2 insertions, 1 deletions

diff --git a/sql/table.h b/sql/table.h
index 068cbe9a763..c7282cee093 100644
--- a/sql/table.h
+++ b/sql/table.h
@@ -2495,7 +2495,8 @@ enum get_table_share_flags {
   GTS_TABLE                = 1,
   GTS_VIEW                 = 2,
   GTS_NOLOCK               = 4,
-  GTS_FORCE_DISCOVERY      = 8
+  GTS_USE_DISCOVERY        = 8,
+  GTS_FORCE_DISCOVERY      = 16
 };
 
 size_t max_row_length(TABLE *table, const uchar *data);