public abstract class Filter extends WrappingIterator implements OptionDescriber
OptionDescriber.IteratorOptions
Constructor and Description |
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Filter() |
Modifier and Type | Method and Description |
---|---|
abstract boolean |
accept(Key k,
Value v) |
SortedKeyValueIterator<Key,Value> |
deepCopy(IteratorEnvironment env)
Creates a deep copy of this iterator as though seek had not yet been called.
|
OptionDescriber.IteratorOptions |
describeOptions()
Gets an iterator options object that contains information needed to configure this iterator.
|
protected void |
findTop()
Iterates over the source until an acceptable key/value pair is found.
|
void |
init(SortedKeyValueIterator<Key,Value> source,
Map<String,String> options,
IteratorEnvironment env)
Initializes the iterator.
|
void |
next()
Advances to the next K,V pair.
|
void |
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.
|
static void |
setNegate(IteratorSetting is,
boolean negate)
A convenience method for setting the negation option on a filter.
|
boolean |
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.
|
getSource, getTopKey, getTopValue, hasTop, setSource
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
enableYielding
protected static final String NEGATE
public SortedKeyValueIterator<Key,Value> deepCopy(IteratorEnvironment env)
SortedKeyValueIterator
deepCopy
in interface SortedKeyValueIterator<Key,Value>
deepCopy
in class WrappingIterator
env
- IteratorEnvironment environment in which iterator is being run.public void next() throws IOException
SortedKeyValueIterator
next
in interface SortedKeyValueIterator<Key,Value>
next
in class WrappingIterator
IOException
- if an I/O error occurs.public void seek(Range range, Collection<ByteSequence> columnFamilies, boolean inclusive) throws IOException
SortedKeyValueIterator
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.
columnFamilies
is 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 columnFamilies
is properly set to the minimum required column families to
ensure that data from separate locality groups is not inadvertently read.seek
in interface SortedKeyValueIterator<Key,Value>
seek
in class WrappingIterator
range
- Range of keys to iterate over.columnFamilies
- Collection of column families to include or exclude.inclusive
- boolean that indicates whether to include (true) or exclude (false) column
families.IOException
- if an I/O error occurs.protected void findTop()
public abstract boolean accept(Key k, Value v)
public void init(SortedKeyValueIterator<Key,Value> source, Map<String,String> options, IteratorEnvironment env) throws IOException
SortedKeyValueIterator
init
in interface SortedKeyValueIterator<Key,Value>
init
in class WrappingIterator
source
- SortedKeyValueIterator source to read data from.options
- Map map of string option names to option values.env
- IteratorEnvironment environment in which iterator is being run.IOException
- unused.public OptionDescriber.IteratorOptions describeOptions()
OptionDescriber
describeOptions
in interface OptionDescriber
public boolean validateOptions(Map<String,String> options)
OptionDescriber
validateOptions
in interface OptionDescriber
options
- a map of option names to option valuespublic static void setNegate(IteratorSetting is, boolean negate)
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.Copyright © 2011–2018 The Apache Software Foundation. All rights reserved.