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From st...@apache.org
Subject svn commit: r811574 - in /hadoop/hbase/branches/0.20: CHANGES.txt src/java/org/apache/hadoop/hbase/client/HTable.java src/java/org/apache/hadoop/hbase/client/package-info.java
Date Fri, 04 Sep 2009 23:40:59 GMT
Author: stack
Date: Fri Sep  4 23:40:59 2009
New Revision: 811574

URL: http://svn.apache.org/viewvc?rev=811574&view=rev
Log:
HBASE-1812 Document fact that Scanners do not respect row locks

Modified:
    hadoop/hbase/branches/0.20/CHANGES.txt
    hadoop/hbase/branches/0.20/src/java/org/apache/hadoop/hbase/client/HTable.java
    hadoop/hbase/branches/0.20/src/java/org/apache/hadoop/hbase/client/package-info.java

Modified: hadoop/hbase/branches/0.20/CHANGES.txt
URL: http://svn.apache.org/viewvc/hadoop/hbase/branches/0.20/CHANGES.txt?rev=811574&r1=811573&r2=811574&view=diff
==============================================================================
--- hadoop/hbase/branches/0.20/CHANGES.txt (original)
+++ hadoop/hbase/branches/0.20/CHANGES.txt Fri Sep  4 23:40:59 2009
@@ -343,6 +343,7 @@
    HBASE-1790  filters are not working correctly (HBASE-1710 HBASE-1807 too)
    HBASE-1779  ThriftServer logged error if getVer() result is empty
    HBASE-1778  Improve PerformanceEvaluation (Schubert Zhang via Stack)
+   HBASE-1812  Document fact that Scanners do not respect row locks
 
   IMPROVEMENTS
    HBASE-1089  Add count of regions on filesystem to master UI; add percentage

Modified: hadoop/hbase/branches/0.20/src/java/org/apache/hadoop/hbase/client/HTable.java
URL: http://svn.apache.org/viewvc/hadoop/hbase/branches/0.20/src/java/org/apache/hadoop/hbase/client/HTable.java?rev=811574&r1=811573&r2=811574&view=diff
==============================================================================
--- hadoop/hbase/branches/0.20/src/java/org/apache/hadoop/hbase/client/HTable.java (original)
+++ hadoop/hbase/branches/0.20/src/java/org/apache/hadoop/hbase/client/HTable.java Fri Sep
 4 23:40:59 2009
@@ -54,9 +54,11 @@
 
 
 /**
- * Used to communicate with a single HBase table
- * <p>
- * This class is not MT safe for writing.
+ * Used to communicate with a single HBase table.
+ * 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 {
   private final HConnection connection;

Modified: hadoop/hbase/branches/0.20/src/java/org/apache/hadoop/hbase/client/package-info.java
URL: http://svn.apache.org/viewvc/hadoop/hbase/branches/0.20/src/java/org/apache/hadoop/hbase/client/package-info.java?rev=811574&r1=811573&r2=811574&view=diff
==============================================================================
--- hadoop/hbase/branches/0.20/src/java/org/apache/hadoop/hbase/client/package-info.java (original)
+++ hadoop/hbase/branches/0.20/src/java/org/apache/hadoop/hbase/client/package-info.java Fri
Sep  4 23:40:59 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>.



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