Compression: support ALP compression algorithm for floating-point

dbms/src/IO/Compression/ALP/Analyze.h

@@ -0,0 +1,57 @@
+// Copyright 2024 PingCAP, Inc.
+//
+// Licensed 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.
+
+#pragma once
+
+#include <IO/Compression/ALP/Compression.h>
+
+#include <random>
+#include <span>
+
+namespace DB::ALP
+{
+
+template <typename T>
+class Analyze
+{
+public:
+    using State = CompressionState<T>;
+
+    static void run(const std::span<const T> & vectors, size_t n_samples, State & state)
+    {
+        std::vector<std::vector<T>> vectors_sampled;
+        vectors_sampled.reserve(n_samples);
+
+        std::random_device rd;
+        std::mt19937 gen(rd());
+        std::uniform_int_distribution<> dis(0, vectors.size() - 1);
+
+        // Sample vectors.
+        // Each vector is a sample of SAMPLES_PER_VECTOR randomly selected values.
+        for (size_t i = 0; i < n_samples; ++i)
+        {
+            std::vector<T> sample;
+            sample.reserve(Constants::SAMPLES_PER_VECTOR);
+            for (size_t j = 0; j < Constants::SAMPLES_PER_VECTOR; ++j)
+            {
+                auto random_idx = dis(gen);
+                sample.push_back(vectors[random_idx]);
+            }
+            vectors_sampled.emplace_back(std::move(sample));
+        }
+        Compression<T, true>::findTopKCombinations(vectors_sampled, state);
+    }
+};
+
+}; // namespace DB::ALP