- All Implemented Interfaces:
- Direct Known Subclasses:
public abstract class Filter extends WrappingIterator implements OptionDescriberA SortedKeyValueIterator that filters entries from its source iterator. Subclasses must implement an accept method: public boolean accept(Key k, Value v); Key/Value pairs for which the accept method returns true are said to match the filter. By default, this class iterates over entries that match its filter. This iterator takes an optional "negate" boolean parameter that defaults to false. If negate is set to true, this class instead omits entries that match its filter, thus iterating over entries that do not match its filter.
Constructors Constructor Description
All Methods Static Methods Instance Methods Abstract Methods Concrete Methods Modifier and Type Method Description
accept(Key k, Value v)
deepCopy(IteratorEnvironment env)Creates a deep copy of this iterator as though seek had not yet been called.
describeOptions()Gets an iterator options object that contains information needed to configure this iterator.
findTop()Iterates over the source until an acceptable key/value pair is found.
init(SortedKeyValueIterator<Key,Value> source, Map<String,String> options, IteratorEnvironment env)Initializes the iterator.
next()Advances to the next K,V pair.
seek(Range range, Collection<ByteSequence> columnFamilies, boolean inclusive)Seeks to the first key in the Range, restricting the resulting K,V pairs to those with the specified columns.
setNegate(IteratorSetting is, boolean negate)A convenience method for setting the negation option on a filter.
validateOptions(Map<String,String> options)Check to see if an options map contains all options required by an iterator and that the option values are in the expected formats.
Methods inherited from class org.apache.accumulo.core.iterators.WrappingIterator
getSource, getTopKey, getTopValue, hasTop, setSource
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
public SortedKeyValueIterator<Key,Value> deepCopy(IteratorEnvironment env)Creates a deep copy of this iterator as though seek had not yet been called. init should be called on an iterator before deepCopy is called. init should not need to be called on the copy that is returned by deepCopy; that is, when necessary init should be called in the deepCopy method on the iterator it returns. The behavior is unspecified if init is called after deepCopy either on the original or the copy. A proper implementation would call deepCopy on the source.
public void next() throws IOExceptionAdvances to the next K,V pair. Note that in minor compaction scope and in non-full major compaction scopes the iterator may see deletion entries. These entries should be preserved by all iterators except ones that are strictly scan-time iterators that will never be configured for the minc or majc scopes. Deletion entries are only removed during full major compactions.
public void seek(Range range, Collection<ByteSequence> columnFamilies, boolean inclusive) throws IOExceptionSeeks to the first key in the Range, restricting the resulting K,V pairs to those with the specified columns. An iterator does not have to stop at the end of the range. The whole range is provided so that iterators can make optimizations. Seek may be called multiple times with different parameters after
SortedKeyValueIterator.init(org.apache.accumulo.core.iterators.SortedKeyValueIterator<K, V>, java.util.Map<java.lang.String, java.lang.String>, org.apache.accumulo.core.iterators.IteratorEnvironment)is called. Iterators that examine groups of adjacent key/value pairs (e.g. rows) to determine their top key and value should be sure that they properly handle a seek to a key in the middle of such a group (e.g. the middle of a row). Even if the client always seeks to a range containing an entire group (a,c), the tablet server could send back a batch of entries corresponding to (a,b], then reseek the iterator to range (b,c) when the scan is continued.
columnFamiliesis used, at the lowest level, to determine which data blocks inside of an RFile need to be opened for this iterator. This set of data blocks is also the set of locality groups defined for the given table. If no columnFamilies are provided, the data blocks for all locality groups inside of the correct RFile will be opened and seeked in an attempt to find the correct start key, regardless of the startKey in the
range. In an Accumulo instance in which multiple locality groups exist for a table, it is important to ensure that
columnFamiliesis properly set to the minimum required column families to ensure that data from separate locality groups is not inadvertently read.
- Specified by:
Rangeof keys to iterate over.
Collectionof column families to include or exclude.
booleanthat indicates whether to include (true) or exclude (false) column families.
IOException- if an I/O error occurs.
protected void findTop()Iterates over the source until an acceptable key/value pair is found.
trueif the key/value pair is accepted by the filter.
public void init(SortedKeyValueIterator<Key,Value> source, Map<String,String> options, IteratorEnvironment env) throws IOExceptionInitializes the iterator. Data should not be read from the source in this method.
- Specified by:
SortedKeyValueIteratorsource to read data from.
Mapmap of string option names to option values.
IteratorEnvironmentenvironment in which iterator is being run.
public OptionDescriber.IteratorOptions describeOptions()Description copied from interface:
OptionDescriberGets an iterator options object that contains information needed to configure this iterator. This object will be used by the accumulo shell to prompt the user to input the appropriate information.
validateOptionsDescription copied from interface:
OptionDescriberCheck to see if an options map contains all options required by an iterator and that the option values are in the expected formats.
public static void setNegate(IteratorSetting is, boolean negate)A convenience method for setting the negation option on a filter.
is- IteratorSetting object to configure.
negate- if false, filter accepts k/v for which the accept method returns true; if true, filter accepts k/v for which the accept method returns false.