WL#4454 change sql_insert.cc::last_uniq_key to match keys in any order

Introduce a flag that will enable the REPLACE
command to work correctly with an underlying
storage engine that does not report unique key
conflicts in the ascending order.

sql/handler.h:
  WL#4454 change sql_insert.cc::last_uniq_key to match keys in any order
  
  Adds the flag that will be set by a
  SE that does not report unique key
  conflicts in the ascending order.
sql/sql_insert.cc:
  WL#4454 change sql_insert.cc::last_uniq_key to match keys in any order
  
  modifies the function used for a last row
  replace optimization to check for the
  HA_DUPLICATE_KEY_NOT_IN_ORDER flag.

1 files changed, 23 insertions, 0 deletions

diff --git a/sql/handler.h b/sql/handler.h
index 05a9e13653c..8e8f417739e 100644
--- a/sql/handler.h
+++ b/sql/handler.h
@@ -127,6 +127,29 @@
 */
 #define HA_BINLOG_ROW_CAPABLE  (LL(1) << 34)
 #define HA_BINLOG_STMT_CAPABLE (LL(1) << 35)
+/*
+    When a multiple key conflict happens in a REPLACE command mysql
+    expects the conflicts to be reported in the ascending order of
+    key names.
+
+    For e.g.
+
+    CREATE TABLE t1 (a INT, UNIQUE (a), b INT NOT NULL, UNIQUE (b), c INT NOT
+                     NULL, INDEX(c));
+
+    REPLACE INTO t1 VALUES (1,1,1),(2,2,2),(2,1,3);
+
+    MySQL expects the conflict with 'a' to be reported before the conflict with
+    'b'.
+
+    If the underlying storage engine does not report the conflicting keys in
+    ascending order, it causes unexpected errors when the REPLACE command is
+    executed.
+
+    This flag helps the underlying SE to inform the server that the keys are not
+    ordered.
+*/
+#define HA_DUPLICATE_KEY_NOT_IN_ORDER    (LL(1) << 36)
 
 /*
   Set of all binlog flags. Currently only contain the capabilities