From a01c883e074cdd68d1155ec4280114a1f87cf7a7 Mon Sep 17 00:00:00 2001
From: drrtuy <drrtuy@gmail.com>
Date: Fri, 18 Jul 2025 15:55:22 +0000
Subject: [PATCH] feat(rbo,rules): mock Histogram for ES < 11.4

---
 dbcon/mysql/ha_mcs_execplan.cpp |  7 +++++++
 dbcon/mysql/idb_mysql.h         | 30 ++++++++++++++++++++++++++++++
 2 files changed, 37 insertions(+)

diff --git a/dbcon/mysql/ha_mcs_execplan.cpp b/dbcon/mysql/ha_mcs_execplan.cpp
index c3082ba5d..148a9ccba 100644
--- a/dbcon/mysql/ha_mcs_execplan.cpp
+++ b/dbcon/mysql/ha_mcs_execplan.cpp
@@ -6291,6 +6291,8 @@ int processLimitAndOffset(SELECT_LEX& select_lex, gp_walk_info& gwi, SCSEP& csep
 // Loop over available indexes to find and extract corresponding EI column statistics
 // for the first column of the index if any.
 // Statistics is stored in GWI context.
+// Mock for ES 10.6
+#if MYSQL_VERSION_ID >= 110401
 void extractColumnStatistics(Item_field* ifp, gp_walk_info& gwi)
 {
   for (uint j = 0; j < ifp->field->table->s->keys; j++)
@@ -6313,6 +6315,11 @@ void extractColumnStatistics(Item_field* ifp, gp_walk_info& gwi)
     }
   }
 }
+#else
+void extractColumnStatistics(Item_field* ifp, gp_walk_info& gwi)
+{
+}
+#endif
 
 /*@brief  Process SELECT part of a query or sub-query      */
 /***********************************************************
diff --git a/dbcon/mysql/idb_mysql.h b/dbcon/mysql/idb_mysql.h
index 89c0291c3..efc4260e3 100644
--- a/dbcon/mysql/idb_mysql.h
+++ b/dbcon/mysql/idb_mysql.h
@@ -74,7 +74,37 @@
 #include "rpl_rli.h"
 #include "my_dbug.h"
 #include "sql_show.h"
+#if MYSQL_VERSION_ID >= 110401
 #include "opt_histogram_json.h"
+#else
+// Mock Histogram_bucket for MySQL < 11.4
+struct Histogram_bucket
+{
+  std::string start_value;
+
+  double cum_fract;
+
+  longlong ndv;
+};
+
+class Histogram_json_hb final : public Histogram_base
+{
+  std::vector<Histogram_bucket> buckets;
+
+  std::string last_bucket_end_endp;
+
+public:
+  const std::vector<Histogram_bucket>& get_json_histogram() const
+  {
+    return buckets;
+  }
+
+  const std::string& get_last_bucket_end_endp() const
+  {
+    return last_bucket_end_endp;
+  }
+};
+#endif
 #pragma GCC diagnostic pop
 
 // Now clean up the pollution as best we can...