baidu palo

be/src/exprs/hll_hash_function.cpp

@@ -0,0 +1,74 @@
+// Modifications copyright (C) 2017, Baidu.com, Inc.
+// Copyright 2017 The Apache Software Foundation
+
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+#include "exprs/hll_hash_function.h"
+
+#include "exprs/expr.h"
+#include "runtime/tuple_row.h"
+#include "runtime/datetime_value.h"
+#include "util/path_builder.h"
+#include "runtime/string_value.hpp"
+#include "exprs/aggregate_functions.h"
+#include "exprs/cast_functions.h"
+#include "olap/olap_common.h"
+#include "olap/utils.h"
+
+namespace palo {
+
+using palo_udf::BigIntVal;
+using palo_udf::StringVal;
+ 
+void HllHashFunctions::init() {
+}
+
+StringVal HllHashFunctions::create_string_result(palo_udf::FunctionContext* ctx, 
+                                                     const StringVal& val, const bool is_null) {
+    std::string result;
+    if (is_null) {
+        // HLL_DATA_EMPTY
+        result = "0";
+    } else {
+        // HLL_DATA_EXPLHLL_DATA_EXPLICIT
+        uint64_t hash = HashUtil::murmur_hash64A(val.ptr, val.len, HashUtil::MURMUR_SEED);
+        char buf[10];
+        buf[0] = HLL_DATA_EXPLICIT;
+        buf[1] = 1;
+        *((uint64_t*)(buf + 2)) = hash;
+        result = std::string(buf, 10);
+    }
+    return AnyValUtil::from_buffer_temp(ctx, result.c_str(), result.length());
+}
+
+StringVal HllHashFunctions::hll_hash(palo_udf::FunctionContext* ctx, 
+                                     const StringVal& input) {
+    return create_string_result(ctx, input, input.is_null);
+}
+    
+StringVal HllHashFunctions::hll_cardinality(palo_udf::FunctionContext* ctx, 
+                                            const StringVal& input) {
+    if (input.is_null) {
+        return StringVal::null();
+    }
+    StringVal dst;
+    AggregateFunctions::hll_union_agg_init(ctx, &dst);
+    AggregateFunctions::hll_union_agg_update(ctx, input, &dst);
+    return AggregateFunctions::hll_union_agg_finalize(ctx, dst);
+}
+}