## org.apache.cassandra.io.sstable
Class IndexHelper

    java.lang.Object
      org.apache.cassandra.io.sstable.IndexHelper

    public class IndexHelper

extends java.lang.Object

Provides helper to serialize, deserialize and use column indexes.

Nested Class Summary
`static class` `IndexHelper.IndexInfo`

Constructor Summary
`IndexHelper()`

Method Summary
`static Filter` `defreezeBloomFilter(FileDataInput file, boolean usesOldBloomFilter)`
`static Filter` `defreezeBloomFilter(FileDataInput file, long maxSize, boolean useOldBuffer)` De-freeze the bloom filter.
`static java.util.ArrayList<IndexHelper.IndexInfo>` `deserializeIndex(FileDataInput in)` Deserialize the index into a structure and return it
`static java.util.Comparator<IndexHelper.IndexInfo>` `getComparator(AbstractType nameComparator, boolean reversed)`
`static int` `indexFor(java.nio.ByteBuffer name, java.util.List<IndexHelper.IndexInfo> indexList, AbstractType comparator, boolean reversed)` The index of the IndexInfo in which a scan starting with @name should begin.
`static void` `skipBloomFilter(java.io.DataInput in)` Skip the bloom filter
`static void` `skipIndex(java.io.DataInput in)` Skip the index

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Constructor Detail

### IndexHelper

    public IndexHelper()

Method Detail

### skipBloomFilter

    public static void skipBloomFilter(java.io.DataInput in)
                                throws java.io.IOException

  Skip the bloom filter

  Parameters:
    `in` - the data input from which the bloom filter should be skipped
  Throws:
    `java.io.IOException`

### skipIndex

    public static void skipIndex(java.io.DataInput in)
                          throws java.io.IOException

  Skip the index

  Parameters:
    `in` - the data input from which the index should be skipped
  Throws:
    `java.io.IOException` - if an I/O error occurs.

### deserializeIndex

    public static java.util.ArrayList<IndexHelper.IndexInfo> deserializeIndex(FileDataInput in)
                                                                       throws java.io.IOException

  Deserialize the index into a structure and return it

  Parameters:
    `in` - - input source
  Returns:
    ArrayList<IndexInfo> - list of de-serialized indexes
  Throws:
    `java.io.IOException` - if an I/O error occurs.

### defreezeBloomFilter

    public static Filter defreezeBloomFilter(FileDataInput file,
                                             boolean usesOldBloomFilter)
                                      throws java.io.IOException

  Throws:
    `java.io.IOException`

### defreezeBloomFilter

    public static Filter defreezeBloomFilter(FileDataInput file,
                                             long maxSize,
                                             boolean useOldBuffer)
                                      throws java.io.IOException

  De-freeze the bloom filter.

  Parameters:
    `file` - - source file
    `maxSize` - - sanity check: if filter claimes to be larger than this it is bogus
    `useOldBuffer` - - do we need to reuse old buffer?
  Returns:
    bloom filter summarizing the column information
  Throws:
    `java.io.IOException` - if an I/O error occurs. Guarantees that file's current position will be just after the bloom filter, even if the filter cannot be deserialized, UNLESS EOFException is thrown.

### indexFor

    public static int indexFor(java.nio.ByteBuffer name,
                               java.util.List<IndexHelper.IndexInfo> indexList,
                               AbstractType comparator,
                               boolean reversed)

  The index of the IndexInfo in which a scan starting with @name should begin.

  Parameters:
    `name` - name of the index
    `indexList` - list of the indexInfo objects
    `comparator` - comparator type
    `reversed` - is name reversed
  Returns:
    int index

### getComparator

    public static java.util.Comparator<IndexHelper.IndexInfo> getComparator(AbstractType nameComparator,
                                                                            boolean reversed)

Copyright © 2012 The Apache Software Foundation