kevinjmh commented on a change in pull request #3444: [CARBONDATA-3581] Support page level bloom filter
URL:
https://github.com/apache/carbondata/pull/3444#discussion_r348913736
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File path: core/src/main/java/org/apache/carbondata/core/bloom/BloomFilterUtil.java
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@@ -0,0 +1,97 @@
+/*
+ * 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.
+ */
+package org.apache.carbondata.core.bloom;
+
+import java.io.IOException;
+import java.lang.reflect.Field;
+import java.util.BitSet;
+
+import org.apache.carbondata.core.constants.CarbonCommonConstants;
+import org.apache.carbondata.core.constants.CarbonV3DataFormatConstants;
+
+import org.apache.hadoop.util.bloom.BloomFilter;
+import org.roaringbitmap.RoaringBitmap;
+
+public class BloomFilterUtil {
+
+ /**
+ * Calculate page bloom parameters by item size and fpp
+ * Formula:
+ * Number of bits (m) = -n*ln(p) / (ln(2)^2)
+ * Number of hashes(k) = m/n * ln(2)
+ *
+ * @param n Number of items in the filter
+ * @param p False positive probability
+ *
+ */
+ public static int[] getBloomParameters(int n, double p) {
+ double numOfBit = -n * Math.log(p) / (Math.pow(Math.log(2), 2));
+ double numOfHash = numOfBit / n * Math.log(2);
+ return new int[]{(int) Math.ceil(numOfBit), (int) Math.ceil(numOfHash)};
+ }
+
+ public static int[] getPageBloomParameters() {
+ return getBloomParameters(
+ CarbonV3DataFormatConstants.NUMBER_OF_ROWS_PER_BLOCKLET_COLUMN_PAGE_DEFAULT,
Review comment:
You're right. I did try dynamic bloom parameter by dynamic size before. The benefit of setting the maximum pagesize(32000) are:
1. avoid problem of multiple parameters choosing as bloom datamap, only FPP needed to be set;
2. same parameter of bloom has same hash function, so that we only need to hash one time then we can check all pages in blocklet;
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