Author: stack
Date: Fri Sep 4 23:33:45 2009
New Revision: 811568
URL: http://svn.apache.org/viewvc?rev=811568&view=rev
Log:
HBASE-1812 Document fact that Scanners do not respect row locks
Modified:
hadoop/hbase/trunk/src/java/org/apache/hadoop/hbase/client/HTable.java
hadoop/hbase/trunk/src/java/org/apache/hadoop/hbase/client/package-info.java
Modified: hadoop/hbase/trunk/src/java/org/apache/hadoop/hbase/client/HTable.java
URL:
http://svn.apache.org/viewvc/hadoop/hbase/trunk/src/java/org/apache/hadoop/hbase/client/HTable.java?rev=811568&r1=811567&r2=811568&view=diff
==============================================================================
--- hadoop/hbase/trunk/src/java/org/apache/hadoop/hbase/client/HTable.java
(original)
+++ hadoop/hbase/trunk/src/java/org/apache/hadoop/hbase/client/HTable.java Fri
Sep 4 23:33:45 2009
@@ -56,7 +56,10 @@
/**
* Used to communicate with a single HBase table.
* <p>
- * This class is not MT safe for writes.
+ * This class is not thread safe for writes.
+ * Gets, puts, and deletes take out a row lock for the duration
+ * of their operation. Scans (currently) do not respect
+ * row locking.
*/
public class HTable implements HTableInterface {
private final HConnection connection;
Modified:
hadoop/hbase/trunk/src/java/org/apache/hadoop/hbase/client/package-info.java
URL:
http://svn.apache.org/viewvc/hadoop/hbase/trunk/src/java/org/apache/hadoop/hbase/client/package-info.java?rev=811568&r1=811567&r2=811568&view=diff
==============================================================================
---
hadoop/hbase/trunk/src/java/org/apache/hadoop/hbase/client/package-info.java
(original)
+++
hadoop/hbase/trunk/src/java/org/apache/hadoop/hbase/client/package-info.java
Fri Sep 4 23:33:45 2009
@@ -30,14 +30,13 @@
<p>To administer HBase, create and drop tables, list and alter tables,
use {...@link org.apache.hadoop.hbase.client.HBaseAdmin}. Once created,
table access is via an instance
of {...@link org.apache.hadoop.hbase.client.HTable}. You add content to a
table a row at a time. To insert,
- create an instance of a {...@link org.apache.hadoop.hbase.client.Put} object
and after setting it appropriately,
- commit your update using {...@link
org.apache.hadoop.hbase.client.HTable#put(Put)}.
- To fetch your inserted
- value, use {...@link org.apache.hadoop.hbase.client.Get}. The Get can be
specified to be broad -- get all
- on a particular row -- or narrow; return only a single cell value.
- When finished with your Get settings, invoke {...@link
org.apache.hadoop.hbase.client.HTable#get(Get)}. Use
- {...@link org.apache.hadoop.hbase.client.Scan} to set up a scanner -- a
Cursor-like access. After
- configuring your Scan instance, call {...@link
org.apache.hadoop.hbase.client.HTable#getScanner(Scan)} and then
+ create an instance of a {...@link org.apache.hadoop.hbase.client.Put} object.
Specify value, target column
+ and optionally a timestamp. Commit your update using {...@link
org.apache.hadoop.hbase.client.HTable#put(Put)}.
+ To fetch your inserted value, use {...@link
org.apache.hadoop.hbase.client.Get}. The Get can be specified to be broad --
get all
+ on a particular row -- or narrow; i.e. return only a single cell value.
After creating an instance of
+ Get, invoke {...@link org.apache.hadoop.hbase.client.HTable#get(Get)}. Use
+ {...@link org.apache.hadoop.hbase.client.Scan} to set up a scanner -- a
Cursor- like access. After
+ creating and configuring your Scan instance, call {...@link
org.apache.hadoop.hbase.client.HTable#getScanner(Scan)} and then
invoke next on the returned object. Both {...@link
org.apache.hadoop.hbase.client.HTable#get(Get)} and
{...@link org.apache.hadoop.hbase.client.HTable#getScanner(Scan)} return a
{...@link org.apache.hadoop.hbase.client.Result}.
@@ -47,6 +46,9 @@
You can remove individual cells or entire families, etc. Pass it to
{...@link org.apache.hadoop.hbase.client.HTable#delete(Delete)} to execute.
</p>
+ <p>Puts, Gets and Deletes take out a lock on the target row for the duration
of their operation.
+ Scans (currently) operate without respect for row locks.
+ </p>
<p>Client code accessing a cluster finds the cluster by querying ZooKeeper.
This means that the ZooKeeper quorum to use must be on the client CLASSPATH.
Usually this means make sure the client can find your
<code>hbase-site.xml</code>.
