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https://issues.apache.org/jira/browse/PARQUET-2226?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17677031#comment-17677031
 ] 

ASF GitHub Bot commented on PARQUET-2226:
-----------------------------------------

yabola commented on code in PR #1020:
URL: https://github.com/apache/parquet-mr/pull/1020#discussion_r1070591022


##########
parquet-column/src/test/java/org/apache/parquet/column/values/bloomfilter/TestBlockSplitBloomFilter.java:
##########
@@ -181,6 +182,60 @@ public void testBloomFilterNDVs(){
     assertTrue(bytes < 5 * 1024 * 1024);
   }
 
+  @Test
+  public void testMergeBloomFilter() throws IOException {
+    Random random = new Random();
+    int numBytes = BlockSplitBloomFilter.optimalNumOfBits(1024 * 1024, 0.01) / 
8;
+    BloomFilter otherBloomFilter = new BlockSplitBloomFilter(numBytes);
+    BloomFilter mergedBloomFilter = new BlockSplitBloomFilter(numBytes);
+
+    Set<String> originStrings = new HashSet<>();
+    Set<String> testStrings = new HashSet<>();
+    Set<Integer> testInts = new HashSet<>();
+    Set<Double> testDoubles = new HashSet<>();
+    Set<Float> testFloats = new HashSet<>();
+    for (int i = 0; i < 1024; i++) {
+
+      String originStrValue = RandomStringUtils.randomAlphabetic(1, 64);
+      originStrings.add(originStrValue);
+      
mergedBloomFilter.insertHash(otherBloomFilter.hash(Binary.fromString(originStrValue)));
+
+      String testString = RandomStringUtils.randomAlphabetic(1, 64);
+      testStrings.add(testString);
+      
otherBloomFilter.insertHash(otherBloomFilter.hash(Binary.fromString(testString)));
+
+      int testInt = random.nextInt();
+      testInts.add(testInt);
+      otherBloomFilter.insertHash(otherBloomFilter.hash(testInt));
+
+      double testDouble = random.nextDouble();
+      testDoubles.add(testDouble);
+      otherBloomFilter.insertHash(otherBloomFilter.hash(testDouble));
+
+      float testFloat = random.nextFloat();
+      testFloats.add(testFloat);
+      otherBloomFilter.insertHash(otherBloomFilter.hash(testFloat));
+    }
+    mergedBloomFilter.merge(otherBloomFilter);
+    for (String testString : originStrings) {
+      
assertTrue(mergedBloomFilter.findHash(mergedBloomFilter.hash(Binary.fromString(testString))));

Review Comment:
   If the BloomFilter to be merged is not empty, there is a small probability 
that the two BloomFilters will be inconsistent when judging whether there is a 
hash value (I added random value).
   
   But if the BloomFilter to be merged is empty in the beginning, the result 
from these two BloomFilter should be always the same.





> Support merge Bloom Filter
> --------------------------
>
>                 Key: PARQUET-2226
>                 URL: https://issues.apache.org/jira/browse/PARQUET-2226
>             Project: Parquet
>          Issue Type: Improvement
>            Reporter: Mars
>            Priority: Major
>
> We need to collect Parquet's bloom filter of multiple files, and then 
> synthesize a more comprehensive bloom filter for common use. 
> Guava supports similar api operations
> https://guava.dev/releases/31.0.1-jre/api/docs/src-html/com/google/common/hash/BloomFilter.html#line.252



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