public class OrIterator extends Object implements SortedKeyValueIterator<Key,Value>, OptionDescriber
SortedKeyValueIterator
. It returns Keys in row+colqual
order instead
of row+colfam+colqual
order. This is required for the implementation of this iterator (to
work in conjunction with the IntersectingIterator
) but is a code-smell. This iterator
should only be used at query time, never at compaction time.
The table structure should have the following form:
row term:docId => valueUsers configuring this iterator must set the option
COLUMNS_KEY
. This value is a
comma-separated list of column families that should be "OR"'ed together.
For example, given the following data and a value of or.iterator.columns="steve,bob"
in
the iterator options map:
row1 bob:4 row1 george:2 row1 steve:3 row2 bob:9 row2 frank:8 row2 steve:12 row3 michael:15 row3 steve:20Would return:
row1 steve:3 row1 bob:4 row2 bob:9 row2 steve:12 row3 steve:20
Modifier and Type | Class and Description |
---|---|
protected static class |
OrIterator.TermSource |
OptionDescriber.IteratorOptions
Modifier and Type | Field and Description |
---|---|
static String |
COLUMNS_KEY |
Constructor and Description |
---|
OrIterator() |
Modifier and Type | Method and Description |
---|---|
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.
|
Key |
getTopKey()
Returns top key.
|
Value |
getTopValue()
Returns top value.
|
boolean |
hasTop()
Returns true if the iterator has more elements.
|
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.
|
void |
setTerms(SortedKeyValueIterator<Key,Value> source,
Collection<String> terms,
IteratorEnvironment env) |
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.
|
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
enableYielding
public static final String COLUMNS_KEY
public SortedKeyValueIterator<Key,Value> deepCopy(IteratorEnvironment env)
SortedKeyValueIterator
deepCopy
in interface SortedKeyValueIterator<Key,Value>
env
- IteratorEnvironment environment in which iterator is being run.public void setTerms(SortedKeyValueIterator<Key,Value> source, Collection<String> terms, IteratorEnvironment env)
public final void next() throws IOException
SortedKeyValueIterator
next
in interface SortedKeyValueIterator<Key,Value>
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>
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.public final Key getTopKey()
SortedKeyValueIterator
For performance reasons, iterators reserve the right to reuse objects returned by
getTopKey when SortedKeyValueIterator.next()
is called, changing the data that the object
references. Iterators that need to save an object returned by getTopKey ought to copy
the object's data into a new object in order to avoid aliasing bugs.
getTopKey
in interface SortedKeyValueIterator<Key,Value>
public final Value getTopValue()
SortedKeyValueIterator
For performance reasons, iterators reserve the right to reuse objects returned by
getTopValue when SortedKeyValueIterator.next()
is called, changing the underlying data that the
object references. Iterators that need to save an object returned by getTopValue ought
to copy the object's data into a new object in order to avoid aliasing bugs.
getTopValue
in interface SortedKeyValueIterator<Key,Value>
public final boolean hasTop()
SortedKeyValueIterator
hasTop
in interface SortedKeyValueIterator<Key,Value>
public void init(SortedKeyValueIterator<Key,Value> source, Map<String,String> options, IteratorEnvironment env) throws IOException
SortedKeyValueIterator
init
in interface SortedKeyValueIterator<Key,Value>
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 valuesCopyright © 2011–2018 The Apache Software Foundation. All rights reserved.