MDEV-431: Cassandra storage engine

- Support "DELETE FROM cassandra_table"

mysql-test/r/cassandra.result

@@ -22,4 +22,7 @@ select * from t1;
 rowkey	data1	data2
 	data1-value	123456
 	data1-value2	34543
+delete from t1;
+select * from t1;
+rowkey	data1	data2
 drop table t1;

mysql-test/t/cassandra.test

@@ -55,6 +55,11 @@ create table t1 (rowkey char(36) primary key, data1 varchar(60), data2 bigint) e
 insert into t1 values ('rowkey10', 'data1-value', 123456);
 insert into t1 values ('rowkey11', 'data1-value2', 34543);
 select * from t1;
+
+# Check if deletion works
+delete from t1;
+select * from t1;
+
 drop table t1;
 
 ############################################################################

storage/cassandra/cassandra_se.cc

@@ -95,6 +95,8 @@ public:
   /* Setup that's necessary before a multi-row read. (todo: use it before point lookups, too) */
   void clear_read_columns();
   void add_read_column(const char *name);
+  
+  bool truncate();
 };
 
 
@@ -398,3 +400,23 @@ void Cassandra_se_impl::add_read_column(const char *name_arg)
   slice_pred.column_names.push_back(name);
 }
 
+
+bool Cassandra_se_impl::truncate()
+{
+  bool res= true;
+  try {
+    
+    cass->truncate(column_family);
+    res= false;
+
+  } catch (InvalidRequestException ire) {
+    print_error("%s [%s]", ire.what(), ire.why.c_str());
+  } catch (UnavailableException ue) {
+    print_error("UnavailableException: %s", ue.what());
+  } catch (TimedOutException te) {
+    print_error("TimedOutException: %s", te.what());
+  }
+
+  return res;
+}
+

storage/cassandra/cassandra_se.h

@@ -45,6 +45,7 @@ public:
   virtual void clear_read_columns()=0;
   virtual void add_read_column(const char *name)=0;
   
+  virtual bool truncate()=0;
   /* Passing error messages up to ha_cassandra */
   char err_buffer[512];
   const char *error_str() { return err_buffer; }

storage/cassandra/ha_cassandra.cc

@@ -746,6 +746,18 @@ int ha_cassandra::rnd_next(uchar *buf)
   DBUG_RETURN(rc);
 }
 
+
+int ha_cassandra::delete_all_rows()
+{
+  bool bres;
+  DBUG_ENTER("ha_cassandra::delete_all_rows");
+
+  bres= se->truncate();
+
+  DBUG_RETURN(bres? HA_ERR_INTERNAL_ERROR: 0);
+}
+
+
 /////////////////////////////////////////////////////////////////////////////
 // Dummy implementations start
 /////////////////////////////////////////////////////////////////////////////
@@ -861,13 +873,6 @@ int ha_cassandra::delete_row(const uchar *buf)
 }
 
 
-int ha_cassandra::delete_all_rows()
-{
-  DBUG_ENTER("ha_cassandra::delete_all_rows");
-  DBUG_RETURN(HA_ERR_WRONG_COMMAND);
-}
-
-
 /**
   check_if_incompatible_data() called if ALTER TABLE can't detect otherwise
   if new and old definition are compatible