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From chenliang...@apache.org
Subject [29/35] incubator-carbondata-site git commit: Updated website for CarbonData release 1.0.0
Date Sat, 04 Feb 2017 02:38:28 GMT
http://git-wip-us.apache.org/repos/asf/incubator-carbondata-site/blob/0d4cdb1c/content/docs/latest/data-management.html
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+<!--
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+      http://www.apache.org/licenses/LICENSE-2.0
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+    under the License.
+-->
+<!--<script src="../../js/mdNavigation.js" type="text/javascript"></script>-->
+<h1>Data Management</h1><p>This tutorial is going to introduce you to the
conceptual details of data management like:</p>
+<ul>
+  <li><a href="#loading-data">Loading Data</a></li>
+  <li><a href="#deleting-data">Deleting Data</a></li>
+  <li><a href="#compacting-data">Compacting Data</a></li>
+  <li><a href="#updating-data">Updating Data</a></li>
+</ul><h2 id="loading-data">Loading Data</h2>
+<ul>
+  <li><strong>Scenario</strong></li>
+</ul><p>After creating a table, you can load data to the table using the <a
href="mainpage.html?page=dml">LOAD DATA</a> command. The loaded data is available
for querying.  When data load is triggered, the data is encoded in CarbonData format and copied
into HDFS CarbonData store path (specified in carbon.properties file)  in compressed, multi
dimensional columnar format for quick analysis queries. The same command can be used to load
new data or to  update the existing data. Only one data load can be triggered for one table.
The high cardinality columns of the dictionary encoding are  automatically recognized and
these columns will not be used for dictionary encoding.</p>
+<ul>
+  <li><strong>Procedure</strong></li>
+</ul><p>Data loading is a process that involves execution of multiple steps to
read, sort and encode the data in CarbonData store format.  Each step is executed on different
threads. After data loading process is complete, the status (success/partial success) is updated
to  CarbonData store metadata. The table below lists the possible load status.</p>
+<table class="table table-striped table-bordered">
+  <thead>
+    <tr>
+      <th>Status </th>
+      <th>Description </th>
+    </tr>
+  </thead>
+  <tbody>
+    <tr>
+      <td>Success </td>
+      <td>All the data is loaded into table and no bad records found. </td>
+    </tr>
+    <tr>
+      <td>Partial Success </td>
+      <td>Data is loaded into table and bad records are found. Bad records are stored
at carbon.badrecords.location. </td>
+    </tr>
+  </tbody>
+</table><p>In case of failure, the error will be logged in error log. Details
of loads can be seen with <a href="mainpage.html?page=dml">SHOW SEGMENTS</a> command.
The show segment command output consists of :</p>
+<ul>
+  <li>SegmentSequenceID</li>
+  <li>START_TIME OF LOAD</li>
+  <li>END_TIME OF LOAD</li>
+  <li>LOAD STATUS</li>
+</ul><p>The latest load will be displayed first in the output.</p><p>Refer
to <a href="mainpage.html?page=dml">DML operations on CarbonData</a> for load
commands.</p>
+<h2 id="deleting-data">Deleting Data</h2>
+<ul>
+  <li><strong>Scenario</strong></li>
+</ul><p>If you have loaded wrong data into the table, or too many bad records
are present and you want to modify and reload the data, you can delete required data loads.
 The load can be deleted using the Segment Sequence Id or if the table contains date field
then the data can be deleted using the date field.  If there are some specific records that
need to be deleted based on some filter condition(s) we can delete by records.</p>
+<ul>
+  <li><strong>Procedure</strong></li>
+</ul><p>The loaded data can be deleted in the following ways:</p>
+<ul>
+  <li><p>Delete by Segment ID</p><p>After you get the segment ID
of the segment that you want to delete, execute the DELETE command for the selected segment.
 The status of deleted segment is updated to Marked for delete / Marked for Update.</p></li>
+</ul>
+<table class="table table-striped table-bordered">
+  <thead>
+    <tr>
+      <th>SegmentSequenceId </th>
+      <th>Status </th>
+      <th>Load Start Time </th>
+      <th>Load End Time </th>
+    </tr>
+  </thead>
+  <tbody>
+    <tr>
+      <td>0 </td>
+      <td>Success </td>
+      <td>2015-11-19 19:14:... </td>
+      <td>2015-11-19 19:14:... </td>
+    </tr>
+    <tr>
+      <td>1 </td>
+      <td>Marked for Update </td>
+      <td>2015-11-19 19:54:... </td>
+      <td>2015-11-19 20:08:... </td>
+    </tr>
+    <tr>
+      <td>2 </td>
+      <td>Marked for Delete </td>
+      <td>2015-11-19 20:25:... </td>
+      <td>2015-11-19 20:49:... </td>
+    </tr>
+  </tbody>
+</table>
+<ul>
+  <li><p>Delete by Date Field</p><p>If the table contains date field,
you can delete the data based on a specific date.</p></li>
+  <li><p>Delete by Record</p><p>To delete records from CarbonData
table based on some filter Condition(s).</p><p>For delete commands refer to <a
href="mainpage.html?page=dml">DML operations on CarbonData</a>.</p></li>
+  <li><p><strong>NOTE</strong>:</p>
+  <ul>
+    <li>When the delete segment DML is called, segment will not be deleted physically
from the file system. Instead the segment status will be marked as "Marked for Delete". For
the query execution, this deleted segment will be excluded.</li>
+  </ul>
+  <ul>
+    <li>The deleted segment will be deleted physically during the next load operation
and only after the maximum query execution time configured using "max.query.execution.time".
By default it is 60 minutes.</li>
+  </ul>
+  <ul>
+    <li>If the user wants to force delete the segment physically then he can use CLEAN
FILES Command.</li>
+  </ul></li>
+</ul><p>Example :</p><p><code>
+CLEAN FILES FOR TABLE table1
+</code></p><p>This DML will physically delete the segment which are "Marked
for delete" immediately.</p>
+<h2 id="compacting-data">Compacting Data</h2>
+<ul>
+  <li><strong>Scenario</strong></li>
+</ul><p>Frequent data ingestion results in several fragmented CarbonData files
in the store directory. Since data is sorted only within each load, the indices perform only
within each  load. This means that there will be one index for each load and as number of
data load increases, the number of indices also increases. As each index works only on one
load,  the performance of indices is reduced. CarbonData provides provision for compacting
the loads. Compaction process combines several segments into one large segment by merge sorting
the data from across the segments. </p>
+<ul>
+  <li><strong>Procedure</strong></li>
+</ul><p>There are two types of compaction Minor and Major compaction.</p>
+<ul>
+  <li><p><strong>Minor Compaction</strong></p><p>In minor
compaction the user can specify how many loads to be merged. Minor compaction triggers for
every data load if the parameter carbon.enable.auto.load.merge is set. If any segments are
available to be merged, then compaction will  run parallel with data load. There are 2 levels
in minor compaction.</p>
+  <ul>
+    <li>Level 1: Merging of the segments which are not yet compacted.</li>
+    <li>Level 2: Merging of the compacted segments again to form a bigger segment.</li>
+  </ul></li>
+  <li><p><strong>Major Compaction</strong></p><p>In Major
compaction, many segments can be merged into one big segment. User will specify the compaction
size until which segments can be merged. Major compaction is usually done during the off-peak
time. </p></li>
+</ul><p>There are number of parameters related to Compaction that can be set
in carbon.properties file </p>
+<table class="table table-striped table-bordered">
+  <thead>
+    <tr>
+      <th>Parameter </th>
+      <th>Default </th>
+      <th>Application </th>
+      <th>Description </th>
+      <th>Valid Values </th>
+    </tr>
+  </thead>
+  <tbody>
+    <tr>
+      <td>carbon.compaction.level.threshold </td>
+      <td>4, 3 </td>
+      <td>Minor </td>
+      <td>This property is for minor compaction which decides how many segments to
be merged. Example: If it is set as 2, 3 then minor compaction will be triggered for every
2 segments. 3 is the number of level 1 compacted segment which is further compacted to new
segment. </td>
+      <td>NA </td>
+    </tr>
+    <tr>
+      <td>carbon.major.compaction.size </td>
+      <td>1024 MB </td>
+      <td>Major </td>
+      <td>Major compaction size can be configured using this parameter. Sum of the
segments which is below this threshold will be merged. </td>
+      <td>NA </td>
+    </tr>
+    <tr>
+      <td>carbon.numberof.preserve.segments </td>
+      <td>0 </td>
+      <td>Minor/Major </td>
+      <td>If the user wants to preserve some number of segments from being compacted
then he can set this property. Example: carbon.numberof.preserve.segments=2 then 2 latest
segments will always be excluded from the compaction. No segments will be preserved by default.
</td>
+      <td>0-100 </td>
+    </tr>
+    <tr>
+      <td>carbon.allowed.compaction.days </td>
+      <td>0 </td>
+      <td>Minor/Major </td>
+      <td>Compaction will merge the segments which are loaded within the specific number
of days configured. Example: If the configuration is 2, then the segments which are loaded
in the time frame of 2 days only will get merged. Segments which are loaded 2 days apart will
not be merged. This is disabled by default. </td>
+      <td>0-100 </td>
+    </tr>
+    <tr>
+      <td>carbon.number.of.cores.while.compacting </td>
+      <td>2 </td>
+      <td>Minor/Major </td>
+      <td>Number of cores which is used to write data during compaction. </td>
+      <td>0-100 </td>
+    </tr>
+  </tbody>
+</table><p>For compaction commands refer to <a href="mainpage.html?page=dml">DDL
operations on CarbonData</a></p>
+<h2 id="updating-data">Updating Data</h2>
+<ul>
+  <li><p><strong>Scenario</strong></p><p>Sometimes after
the data has been ingested into the System, it is required to be updated. Also there may be
situations where some specific columns need to be updated on the basis of column expression
and optional filter conditions.</p></li>
+  <li><p><strong>Procedure</strong></p><p>To update we
need to specify the column expression with an optional filter condition(s).</p><p>For
update commands refer to <a href="mainpage.html?page=dml">DML operations on CarbonData</a>.</p></li>
+</ul>
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