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java.lang.Objectorg.apache.hadoop.hbase.client.Scan
public class Scan
Used to perform Scan operations.
All operations are identical to Get
with the exception of
instantiation. Rather than specifying a single row, an optional startRow
and stopRow may be defined. If rows are not specified, the Scanner will
iterate over all rows.
To scan everything for each row, instantiate a Scan object.
To modify scanner caching for just this scan, use setCaching
.
To further define the scope of what to get when scanning, perform additional methods as outlined below.
To get all columns from specific families, execute addFamily
for each family to retrieve.
To get specific columns, execute addColumn
for each column to retrieve.
To only retrieve columns within a specific range of version timestamps,
execute setTimeRange
.
To only retrieve columns with a specific timestamp, execute
setTimestamp
.
To limit the number of versions of each column to be returned, execute
setMaxVersions
.
To add a filter, execute setFilter
.
Constructor Summary | |
---|---|
Scan()
Create a Scan operation across all rows. |
|
Scan(byte[] startRow)
Create a Scan operation starting at the specified row. |
|
Scan(byte[] startRow,
byte[] stopRow)
Create a Scan operation for the range of rows specified. |
|
Scan(byte[] startRow,
Filter filter)
|
|
Scan(Scan scan)
Creates a new instance of this class while copying all values. |
Method Summary | |
---|---|
Scan |
addColumn(byte[] familyAndQualifier)
Parses a combined family and qualifier and adds either both or just the family in case there is not qualifier. |
Scan |
addColumn(byte[] family,
byte[] qualifier)
Get the column from the specified family with the specified qualifier. |
Scan |
addColumns(byte[][] columns)
Adds an array of columns specified using old format, family:qualifier. |
Scan |
addColumns(String columns)
Convenience method to help parse old style (or rather user entry on the command line) column definitions, e.g. |
Scan |
addFamily(byte[] family)
Get all columns from the specified family. |
int |
getCaching()
|
byte[][] |
getFamilies()
|
Map<byte[],NavigableSet<byte[]>> |
getFamilyMap()
Getting the familyMap |
Filter |
getFilter()
|
String |
getInputColumns()
Helps to convert the binary column families and qualifiers to a text representation, e.g. |
int |
getMaxVersions()
|
RowFilterInterface |
getOldFilter()
Deprecated. |
byte[] |
getStartRow()
|
byte[] |
getStopRow()
|
TimeRange |
getTimeRange()
|
boolean |
hasFamilies()
|
boolean |
hasFilter()
|
int |
numFamilies()
|
void |
readFields(DataInput in)
|
void |
setCaching(int caching)
Set the number of rows for caching that will be passed to scanners. |
Scan |
setFamilyMap(Map<byte[],NavigableSet<byte[]>> familyMap)
Setting the familyMap |
Scan |
setFilter(Filter filter)
Apply the specified server-side filter when performing the Scan. |
Scan |
setMaxVersions()
Get all available versions. |
Scan |
setMaxVersions(int maxVersions)
Get up to the specified number of versions of each column. |
Scan |
setOldFilter(RowFilterInterface filter)
Deprecated. |
Scan |
setStartRow(byte[] startRow)
Set the start row. |
Scan |
setStopRow(byte[] stopRow)
Set the stop row. |
Scan |
setTimeRange(long minStamp,
long maxStamp)
Get versions of columns only within the specified timestamp range, [minStamp, maxStamp). |
Scan |
setTimeStamp(long timestamp)
Get versions of columns with the specified timestamp. |
String |
toString()
|
void |
write(DataOutput out)
|
Methods inherited from class java.lang.Object |
---|
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait |
Constructor Detail |
---|
public Scan()
public Scan(byte[] startRow, Filter filter)
public Scan(byte[] startRow)
If the specified row does not exist, the Scanner will start from the next closest row after the specified row.
startRow
- row to start scanner at or afterpublic Scan(byte[] startRow, byte[] stopRow)
startRow
- row to start scanner at or after (inclusive)stopRow
- row to stop scanner before (exclusive)public Scan(Scan scan) throws IOException
scan
- The scan instance to copy from.
IOException
- When copying the values fails.Method Detail |
---|
public Scan addFamily(byte[] family)
Overrides previous calls to addColumn for this family.
family
- family namepublic Scan addColumn(byte[] family, byte[] qualifier)
Overrides previous calls to addFamily for this family.
family
- family namequalifier
- column qualifierpublic Scan addColumn(byte[] familyAndQualifier)
Note: It will through an error when the colon is missing.
familyAndQualifier
-
IllegalArgumentException
- When the colon is missing.public Scan addColumns(byte[][] columns)
Overrides previous calls to addFamily for any families in the input.
columns
- array of columns, formatted as family:qualifier
public Scan addColumns(String columns)
columns
- The columns to parse.
public String getInputColumns()
Bytes.toBytesBinary(String)
.
public Scan setTimeRange(long minStamp, long maxStamp) throws IOException
minStamp
- minimum timestamp value, inclusivemaxStamp
- maximum timestamp value, exclusive
IOException
- if invalid time rangepublic Scan setTimeStamp(long timestamp)
timestamp
- version timestamppublic Scan setStartRow(byte[] startRow)
startRow
- public Scan setStopRow(byte[] stopRow)
stopRow
- public Scan setMaxVersions()
public Scan setMaxVersions(int maxVersions)
maxVersions
- maximum versions for each columnpublic void setCaching(int caching)
HTable.getScannerCaching()
will apply.
Higher caching values will enable faster scanners but will use more memory.
caching
- the number of rows for cachingpublic Scan setFilter(Filter filter)
filter
- filter to run on the serverpublic Scan setOldFilter(RowFilterInterface filter)
filter
-
public Scan setFamilyMap(Map<byte[],NavigableSet<byte[]>> familyMap)
familyMap
- public Map<byte[],NavigableSet<byte[]>> getFamilyMap()
public int numFamilies()
public boolean hasFamilies()
public byte[][] getFamilies()
public byte[] getStartRow()
public byte[] getStopRow()
public int getMaxVersions()
public int getCaching()
public TimeRange getTimeRange()
public Filter getFilter()
public RowFilterInterface getOldFilter()
public boolean hasFilter()
public String toString()
toString
in class Object
public void readFields(DataInput in) throws IOException
readFields
in interface org.apache.hadoop.io.Writable
IOException
public void write(DataOutput out) throws IOException
write
in interface org.apache.hadoop.io.Writable
IOException
|
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