@InterfaceAudience.Private public interface KeyValueScanner extends Shipper, Closeable
Modifier and Type | Field and Description |
---|---|
static Cell |
NO_NEXT_INDEXED_KEY
The byte array represents for NO_NEXT_INDEXED_KEY; The actual value is irrelevant because this
is always compared by reference.
|
Modifier and Type | Method and Description |
---|---|
boolean |
backwardSeek(Cell key)
Seek the scanner at or before the row of specified Cell, it firstly tries to seek the scanner
at or after the specified Cell, return if peek KeyValue of scanner has the same row with
specified Cell, otherwise seek the scanner at the first Cell of the row which is the previous
row of specified KeyValue
|
void |
close()
Close the KeyValue scanner.
|
void |
enforceSeek()
Does the real seek operation in case it was skipped by seekToRowCol(KeyValue, boolean) (TODO:
Whats this?).
|
org.apache.hadoop.fs.Path |
getFilePath() |
Cell |
getNextIndexedKey() |
default long |
getScannerOrder()
Get the order of this KeyValueScanner.
|
boolean |
isFileScanner()
Returns true if this is a file scanner.
|
Cell |
next()
Return the next Cell in this scanner, iterating the scanner
|
Cell |
peek()
Look at the next Cell in this scanner, but do not iterate scanner.
|
boolean |
realSeekDone()
We optimize our store scanners by checking the most recent store file first, so we sometimes
pretend we have done a seek but delay it until the store scanner bubbles up to the top of the
key-value heap.
|
boolean |
requestSeek(Cell kv,
boolean forward,
boolean useBloom)
Similar to
seek(org.apache.hadoop.hbase.Cell) (or reseek(org.apache.hadoop.hbase.Cell) if forward is true) but only does a seek operation
after checking that it is really necessary for the row/column combination specified by the kv
parameter. |
boolean |
reseek(Cell key)
Reseek the scanner at or after the specified KeyValue.
|
boolean |
seek(Cell key)
Seek the scanner at or after the specified KeyValue.
|
boolean |
seekToLastRow()
Seek the scanner at the first KeyValue of last row
|
boolean |
seekToPreviousRow(Cell key)
Seek the scanner at the first Cell of the row which is the previous row of specified key
|
boolean |
shouldUseScanner(Scan scan,
HStore store,
long oldestUnexpiredTS)
Allows to filter out scanners (both StoreFile and memstore) that we don't want to use based on
criteria such as Bloom filters and timestamp ranges.
|
static final Cell NO_NEXT_INDEXED_KEY
Cell peek()
Cell next() throws IOException
IOException
boolean seek(Cell key) throws IOException
key
- seek valueIOException
boolean reseek(Cell key) throws IOException
key
- seek value (should be non-null)IOException
default long getScannerOrder()
void close()
close
in interface AutoCloseable
close
in interface Closeable
boolean shouldUseScanner(Scan scan, HStore store, long oldestUnexpiredTS)
scan
- the scan that we are selecting scanners forstore
- the store we are performing the scan on.oldestUnexpiredTS
- the oldest timestamp we are interested in for this query, based on TTLboolean requestSeek(Cell kv, boolean forward, boolean useBloom) throws IOException
seek(org.apache.hadoop.hbase.Cell)
(or reseek(org.apache.hadoop.hbase.Cell)
if forward is true) but only does a seek operation
after checking that it is really necessary for the row/column combination specified by the kv
parameter. This function was added to avoid unnecessary disk seeks by checking row-column Bloom
filters before a seek on multi-column get/scan queries, and to optimize by looking up more
recent files first.forward
- do a forward-only "reseek" instead of a random-access seekuseBloom
- whether to enable multi-column Bloom filter optimizationIOException
boolean realSeekDone()
void enforceSeek() throws IOException
realSeekDone()
first.IOException
boolean isFileScanner()
org.apache.hadoop.fs.Path getFilePath()
isFileScanner()
boolean backwardSeek(Cell key) throws IOException
key
- seek KeyValueIOException
boolean seekToPreviousRow(Cell key) throws IOException
key
- seek valueIOException
boolean seekToLastRow() throws IOException
IOException
Cell getNextIndexedKey()
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