LazilyInitializedUnfilteredRowIterator (apache-cassandra API)
Date: 2018-02-14

org.apache.cassandra.db.rows

## Class LazilyInitializedUnfilteredRowIterator

- java.lang.Object
- - org.apache.cassandra.utils.AbstractIterator<Unfiltered>
  - - org.apache.cassandra.db.rows.LazilyInitializedUnfilteredRowIterator

- All Implemented Interfaces:
    com.google.common.collect.PeekingIterator<Unfiltered>, java.lang.AutoCloseable, java.util.Iterator<Unfiltered>, BaseRowIterator<Unfiltered>, UnfilteredRowIterator, CloseableIterator<Unfiltered>
  Direct Known Subclasses:
    UnfilteredRowIteratorWithLowerBound

      public abstract class LazilyInitializedUnfilteredRowIterator
      extends AbstractIterator<Unfiltered>
      implements UnfilteredRowIterator

  Abstract class to create UnfilteredRowIterator that lazily initialize themselves. This is used during partition range queries when we know the partition key but want to defer the initialization of the rest of the UnfilteredRowIterator until we need those informations. See `BigTableScanner.KeyScanningIterator` for instance.

- - ### Constructor Summary

    Constructors
    Constructor and Description
    `LazilyInitializedUnfilteredRowIterator(DecoratedKey partitionKey)`

  - ### Method Summary

    All Methods Instance Methods Abstract Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `void` | `close()`
    `PartitionColumns` | `columns()` A subset of the columns for the (static and regular) rows returned by this iterator.
    `protected Unfiltered` | `computeNext()`
    `boolean` | `initialized()`
    `protected abstract UnfilteredRowIterator` | `initializeIterator()`
    `boolean` | `isReverseOrder()` Whether or not the rows returned by this iterator are in reversed clustering order.
    `protected void` | `maybeInit()`
    `CFMetaData` | `metadata()` The metadata for the table this iterator on.
    `DecoratedKey` | `partitionKey()` The partition key of the partition this in an iterator over.
    `DeletionTime` | `partitionLevelDeletion()` The partition level deletion for the partition this iterate over.
    `Row` | `staticRow()` The static part corresponding to this partition (this can be an empty row but cannot be `null`).
    `EncodingStats` | `stats()` Return "statistics" about what is returned by this iterator.

    - ### Methods inherited from class org.apache.cassandra.utils.AbstractIterator

      `endOfData, hasNext, next, peek, remove`

    - ### Methods inherited from class java.lang.Object

      `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

    - ### Methods inherited from interface org.apache.cassandra.db.rows.UnfilteredRowIterator

      `isEmpty`

    - ### Methods inherited from interface java.util.Iterator

      `forEachRemaining, hasNext, next, remove`

- - ### Constructor Detail

    - #### LazilyInitializedUnfilteredRowIterator

          public LazilyInitializedUnfilteredRowIterator(DecoratedKey partitionKey)

  - ### Method Detail

    - #### initializeIterator

          protected abstract UnfilteredRowIterator initializeIterator()

    - #### maybeInit

          protected void maybeInit()

    - #### initialized

          public boolean initialized()

    - #### metadata

          public CFMetaData metadata()

      Description copied from interface: `BaseRowIterator`
      The metadata for the table this iterator on.
      Specified by:
        `metadata` in interface `BaseRowIterator<Unfiltered>`

    - #### columns

          public PartitionColumns columns()

      Description copied from interface: `BaseRowIterator`
      A subset of the columns for the (static and regular) rows returned by this iterator. Every row returned by this iterator must guarantee that it has only those columns.
      Specified by:
        `columns` in interface `BaseRowIterator<Unfiltered>`

    - #### isReverseOrder

          public boolean isReverseOrder()

      Description copied from interface: `BaseRowIterator`
      Whether or not the rows returned by this iterator are in reversed clustering order.
      Specified by:
        `isReverseOrder` in interface `BaseRowIterator<Unfiltered>`

    - #### partitionKey

          public DecoratedKey partitionKey()

      Description copied from interface: `BaseRowIterator`
      The partition key of the partition this in an iterator over.
      Specified by:
        `partitionKey` in interface `BaseRowIterator<Unfiltered>`

    - #### partitionLevelDeletion

          public DeletionTime partitionLevelDeletion()

      Description copied from interface: `UnfilteredRowIterator`
      The partition level deletion for the partition this iterate over.
      Specified by:
        `partitionLevelDeletion` in interface `UnfilteredRowIterator`

    - #### staticRow

          public Row staticRow()

      Description copied from interface: `BaseRowIterator`
      The static part corresponding to this partition (this can be an empty row but cannot be `null`).
      Specified by:
        `staticRow` in interface `BaseRowIterator<Unfiltered>`

    - #### stats

          public EncodingStats stats()

      Description copied from interface: `UnfilteredRowIterator`
      Return "statistics" about what is returned by this iterator. Those are used for performance reasons (for delta-encoding for instance) and code should not expect those to be exact.
      Specified by:
        `stats` in interface `UnfilteredRowIterator`

    - #### computeNext

          protected Unfiltered computeNext()

      Specified by:
        `computeNext` in class `AbstractIterator<Unfiltered>`

    - #### close

          public void close()

      Specified by:
        `close` in interface `java.lang.AutoCloseable`
      Specified by:
        `close` in interface `CloseableIterator<Unfiltered>`

Copyright © 2018 The Apache Software Foundation