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From els...@apache.org
Subject [37/50] [abbrv] ACCUMULO-1327 converted latex manual to asciidoc
Date Fri, 09 May 2014 15:29:15 GMT
http://git-wip-us.apache.org/repos/asf/accumulo/blob/900d6abb/docs/src/main/latex/accumulo_user_manual/chapters/design.tex
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-
-% Licensed to the Apache Software Foundation (ASF) under one or more
-% contributor license agreements. See the NOTICE file distributed with
-% The ASF licenses this file to You under the Apache License, Version 2.0
-% (the "License"); you may not use this file except in compliance with
-% the License. You may obtain a copy of the License at
-%
-%
-% Unless required by applicable law or agreed to in writing, software
-% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-% See the License for the specific language governing permissions and
-
-\chapter{Accumulo Design}
-
-\section{Data Model}
-
-Accumulo provides a richer data model than simple key-value stores, but is not a
-fully relational database. Data is represented as key-value pairs, where the key and
-value are comprised of the following elements:
-
-\begin{center}
-$\begin{array}{|c|c|c|c|c|c|} \hline -\multicolumn{5}{|c|}{\mbox{Key}} & \multirow{3}{*}{\mbox{Value}}\\ \cline{1-5} -\multirow{2}{*}{\mbox{Row ID}}& \multicolumn{3}{|c|}{\mbox{Column}} & \multirow{2}{*}{\mbox{Timestamp}} & \\ \cline{2-4} -& \mbox{Family} & \mbox{Qualifier} & \mbox{Visibility} & & \\ \hline -\end{array}$
-\end{center}
-
-All elements of the Key and the Value are represented as byte arrays except for
-Timestamp, which is a Long. Accumulo sorts keys by element and lexicographically
-in ascending order. Timestamps are sorted in descending order so that later
-versions of the same Key appear first in a sequential scan. Tables consist of a set of
-sorted key-value pairs.
-
-\section{Architecture}
-
-Accumulo is a distributed data storage and retrieval system and as such consists of
-several architectural components, some of which run on many individual servers.
-Much of the work Accumulo does involves maintaining certain properties of the
-data, such as organization, availability, and integrity, across many commodity-class
-machines.
-
-\section{Components}
-
-An instance of Accumulo includes many TabletServers, one Garbage Collector process,
-one Master server and many Clients.
-
-\subsection{Tablet Server}
-
-The TabletServer manages some subset of all the tablets (partitions of tables). This includes receiving writes from clients, persisting writes to a
-write-ahead log, sorting new key-value pairs in memory, periodically
-flushing sorted key-value pairs to new files in HDFS, and responding
-to reads from clients, forming a merge-sorted view of all keys and
-values from all the files it has created and the sorted in-memory
-store.
-
-TabletServers also perform recovery of a tablet
-that was previously on a server that failed, reapplying any writes
-found in the write-ahead log to the tablet.
-
-\subsection{Garbage Collector}
-
-Accumulo processes will share files stored in HDFS. Periodically, the Garbage
-Collector will identify files that are no longer needed by any process, and
-delete them. Multiple garbage collectors can be run to provide hot-standby support.
-They will perform leader election among themselves to choose a single active instance.
-
-\subsection{Master}
-
-The Accumulo Master is responsible for detecting and responding to TabletServer
-failure. It tries to balance the load across TabletServer by assigning tablets carefully
-and instructing TabletServers to unload tablets when necessary. The Master ensures all
-tablets are assigned to one TabletServer each, and handles table creation, alteration,
-and deletion requests from clients. The Master also coordinates startup, graceful
-shutdown and recovery of changes in write-ahead logs when Tablet servers fail.
-
-Multiple masters may be run. The masters will choose among themselves a single master,
-and the others will become backups if the master should fail.
-
-\subsection{Tracer}
-
-The Accumulo Tracer process supports the distributed timing API provided by Accumulo.
-One to many of these processes can be run on a cluster which will write the timing
-information to a given Accumulo table for future reference. Seeing the section on
-
-\subsection{Monitor}
-
-The Accumulo Monitor is a web application that provides a wealth of information about
-the state of an instance. The Monitor shows graphs and tables which contain information
-about read/write rates, cache hit/miss rates, and Accumulo table information such as scan
-rate and active/queued compactions. Additionally, the Monitor should always be the first
-point of entry when attempting to debug an Accumulo problem as it will show high-level problems
-in addition to aggregated errors from all nodes in the cluster. See the section on Monitoring
-
-Multiple Monitors can be run to provide hot-standby support in the face of failure. Due to the
-forwarding of logs from remote hosts to the Monitor, only one Monitor process should be active
-at one time. Leader election will be performed internally to choose the active Monitor.
-
-\subsection{Client}
-
-Accumulo includes a client library that is linked to every application. The client
-library contains logic for finding servers managing a particular tablet, and
-communicating with TabletServers to write and retrieve key-value pairs.
-
-\section{Data Management}
-
-Accumulo stores data in tables, which are partitioned into tablets. Tablets are
-partitioned on row boundaries so that all of the columns and values for a particular
-row are found together within the same tablet. The Master assigns Tablets to one
-TabletServer at a time. This enables row-level transactions to take place without
-using distributed locking or some other complicated synchronization mechanism. As
-clients insert and query data, and as machines are added and removed from the
-cluster, the Master migrates tablets to ensure they remain available and that the
-ingest and query load is balanced across the cluster.
-
-\begin{center}
-\includegraphics[scale=0.4]{images/data_distribution.png}
-\end{center}
-
-\section{Tablet Service}
-
-
-When a write arrives at a TabletServer it is written to a Write-Ahead Log and
-then inserted into a sorted data structure in memory called a MemTable. When the
-MemTable reaches a certain size the TabletServer writes out the sorted key-value
-pairs to a file in HDFS called Indexed Sequential Access Method (ISAM)
-file. This process is called a minor compaction. A new MemTable is then created
-and the fact of the compaction is recorded in the Write-Ahead Log.
-
-When a request to read data arrives at a TabletServer, the TabletServer does a
-binary search across the MemTable as well as the in-memory indexes associated
-with each ISAM file to find the relevant values. If clients are performing a
-scan, several key-value pairs are returned to the client in order from the
-MemTable and the set of ISAM files by performing a merge-sort as they are read.
-
-\section{Compactions}
-
-In order to manage the number of files per tablet, periodically the TabletServer
-performs Major Compactions of files within a tablet, in which some set of ISAM
-files are combined into one file. The previous files will eventually be removed
-by the Garbage Collector. This also provides an opportunity to permanently
-remove deleted key-value pairs by omitting key-value pairs suppressed by a
-delete entry when the new file is created.
-
-\section{Splitting}
-
-When a table is created it has one tablet. As the table grows its initial
-tablet eventually splits into two tablets. Its likely that one of these
-tablets will migrate to another tablet server. As the table continues to grow,
-its tablets will continue to split and be migrated. The decision to
-automatically split a tablet is based on the size of a tablets files. The
-size threshold at which a tablet splits is configurable per table. In addition
-to automatic splitting, a user can manually add split points to a table to
-create new tablets. Manually splitting a new table can parallelize reads and
-writes giving better initial performance without waiting for automatic
-splitting.
-
-As data is deleted from a table, tablets may shrink. Over time this can lead
-to small or empty tablets. To deal with this, merging of tablets was
-introduced in Accumulo 1.4. This is discussed in more detail later.
-
-\section{Fault-Tolerance}
-
-If a TabletServer fails, the Master detects it and automatically reassigns the tablets
-assigned from the failed server to other servers. Any key-value pairs that were in
-memory at the time the TabletServer fails are automatically reapplied from the Write-Ahead
-Log(WAL) to prevent any loss of data.
-
-Tablet servers write their WALs directly to HDFS so the logs are available to all tablet
-servers for recovery. To make the recovery process efficient, the updates within a log are
-grouped by tablet.  TabletServers can quickly apply the mutations from the sorted logs
-that are destined for the tablets they have now been assigned.
-
-TabletServer failures are noted on the Master's monitor page, accessible via\\
-
-\begin{center}
-\includegraphics[scale=0.4]{images/failure_handling.png}
-\end{center}
-

http://git-wip-us.apache.org/repos/asf/accumulo/blob/900d6abb/docs/src/main/latex/accumulo_user_manual/chapters/development_clients.tex
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-
-% Licensed to the Apache Software Foundation (ASF) under one or more
-% contributor license agreements. See the NOTICE file distributed with
-% The ASF licenses this file to You under the Apache License, Version 2.0
-% (the "License"); you may not use this file except in compliance with
-% the License. You may obtain a copy of the License at
-%
-%
-% Unless required by applicable law or agreed to in writing, software
-% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-% See the License for the specific language governing permissions and
-
-\chapter{Development Clients}
-
-Normally, Accumulo consists of lots of moving parts. Even a stand-alone version of
-Accumulo requires Hadoop, Zookeeper, the Accumulo master, a tablet server, etc. If
-you want to write a unit test that uses Accumulo, you need a lot of infrastructure
-in place before your test can run.
-
-\section{Mock Accumulo}
-
-Mock Accumulo supplies mock implementations for much of the client API. It presently
-does not enforce users, logins, permissions, etc. It does support Iterators and Combiners.
-Note that MockAccumulo holds all data in memory, and will not retain any data or
-settings between runs.
-
-While normal interaction with the Accumulo client looks like this:
-
-\begingroup\fontsize{8pt}{8pt}\selectfont\begin{verbatim}
-Instance instance = new ZooKeeperInstance(...);
-\end{verbatim}\endgroup
-
-To interact with the MockAccumulo, just replace the ZooKeeperInstance with MockInstance:
-
-\begingroup\fontsize{8pt}{8pt}\selectfont\begin{verbatim}
-Instance instance = new MockInstance();
-\end{verbatim}\endgroup
-
-In fact, you can use the "fake" option to the Accumulo shell and interact with
-MockAccumulo:
-
-\begingroup\fontsize{8pt}{8pt}\selectfont\begin{verbatim}
-$./bin/accumulo shell --fake -u root -p '' - -Shell - Apache Accumulo Interactive Shell -- -- version: 1.6 -- instance name: fake -- instance id: mock-instance-id -- -- type 'help' for a list of available commands -- -root@fake> createtable test -root@fake test> insert row1 cf cq value -root@fake test> insert row2 cf cq value2 -root@fake test> insert row3 cf cq value3 -root@fake test> scan -row1 cf:cq [] value -row2 cf:cq [] value2 -row3 cf:cq [] value3 -root@fake test> scan -b row2 -e row2 -row2 cf:cq [] value2 -root@fake test> -\end{verbatim}\endgroup - -When testing Map Reduce jobs, you can also set the Mock Accumulo on the AccumuloInputFormat -and AccumuloOutputFormat classes: - -\begingroup\fontsize{8pt}{8pt}\selectfont\begin{verbatim} -// ... set up job configuration -AccumuloInputFormat.setMockInstance(job, "mockInstance"); -AccumuloOutputFormat.setMockInstance(job, "mockInstance"); -\end{verbatim}\endgroup - -\section{Mini Accumulo Cluster} - -While the Mock Accumulo provides a lightweight implementation of the client API for unit -testing, it is often necessary to write more realistic end-to-end integration tests that -take advantage of the entire ecosystem. The Mini Accumulo Cluster makes this possible by -configuring and starting Zookeeper, initializing Accumulo, and starting the Master as well -as some Tablet Servers. It runs against the local filesystem instead of having to start -up HDFS. - -To start it up, you will need to supply an empty directory and a root password as arguments: - -\begingroup\fontsize{8pt}{8pt}\selectfont\begin{verbatim} -File tempDirectory = // JUnit and Guava supply mechanisms for creating temp directories -MiniAccumuloCluster accumulo = new MiniAccumuloCluster(tempDirectory, "password"); -accumulo.start(); -\end{verbatim}\endgroup - -Once we have our mini cluster running, we will want to interact with the Accumulo client API: - -\begingroup\fontsize{8pt}{8pt}\selectfont\begin{verbatim} -Instance instance = new ZooKeeperInstance(accumulo.getInstanceName(), accumulo.getZooKeepers()); -Connector conn = instance.getConnector("root", new PasswordToken("password")); -\end{verbatim}\endgroup - -Upon completion of our development code, we will want to shutdown our MiniAccumuloCluster: - -\begingroup\fontsize{8pt}{8pt}\selectfont\begin{verbatim} -accumulo.stop() -// delete your temporary folder -\end{verbatim}\endgroup http://git-wip-us.apache.org/repos/asf/accumulo/blob/900d6abb/docs/src/main/latex/accumulo_user_manual/chapters/high_speed_ingest.tex ---------------------------------------------------------------------- diff --git a/docs/src/main/latex/accumulo_user_manual/chapters/high_speed_ingest.tex b/docs/src/main/latex/accumulo_user_manual/chapters/high_speed_ingest.tex deleted file mode 100644 index ab766d0..0000000 --- a/docs/src/main/latex/accumulo_user_manual/chapters/high_speed_ingest.tex +++ /dev/null @@ -1,133 +0,0 @@ - -% Licensed to the Apache Software Foundation (ASF) under one or more -% contributor license agreements. See the NOTICE file distributed with -% this work for additional information regarding copyright ownership. -% The ASF licenses this file to You under the Apache License, Version 2.0 -% (the "License"); you may not use this file except in compliance with -% the License. You may obtain a copy of the License at -% -% http://www.apache.org/licenses/LICENSE-2.0 -% -% Unless required by applicable law or agreed to in writing, software -% distributed under the License is distributed on an "AS IS" BASIS, -% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. -% See the License for the specific language governing permissions and -% limitations under the License. - -\chapter{High-Speed Ingest} - -Accumulo is often used as part of a larger data processing and storage system. To -maximize the performance of a parallel system involving Accumulo, the ingestion -and query components should be designed to provide enough parallelism and -concurrency to avoid creating bottlenecks for users and other systems writing to -and reading from Accumulo. There are several ways to achieve high ingest -performance. - -\section{Pre-Splitting New Tables} - -New tables consist of a single tablet by default. As mutations are applied, the table -grows and splits into multiple tablets which are balanced by the Master across -TabletServers. This implies that the aggregate ingest rate will be limited to fewer -servers than are available within the cluster until the table has reached the point -where there are tablets on every TabletServer. - -Pre-splitting a table ensures that there are as many tablets as desired available -before ingest begins to take advantage of all the parallelism possible with the cluster -hardware. Tables can be split anytime by using the shell: - -\begingroup\fontsize{8pt}{8pt}\selectfont\begin{verbatim} -user@myinstance mytable> addsplits -sf /local_splitfile -t mytable -\end{verbatim}\endgroup - -For the purposes of providing parallelism to ingest it is not necessary to create more -tablets than there are physical machines within the cluster as the aggregate ingest -rate is a function of the number of physical machines. Note that the aggregate ingest -rate is still subject to the number of machines running ingest clients, and the -distribution of rowIDs across the table. The aggregation ingest rate will be -suboptimal if there are many inserts into a small number of rowIDs. - -\section{Multiple Ingester Clients} - -Accumulo is capable of scaling to very high rates of ingest, which is dependent upon -not just the number of TabletServers in operation but also the number of ingest -clients. This is because a single client, while capable of batching mutations and -sending them to all TabletServers, is ultimately limited by the amount of data that -can be processed on a single machine. The aggregate ingest rate will scale linearly -with the number of clients up to the point at which either the aggregate I/O of -TabletServers or total network bandwidth capacity is reached. - -In operational settings where high rates of ingest are paramount, clusters are often -configured to dedicate some number of machines solely to running Ingester Clients. -The exact ratio of clients to TabletServers necessary for optimum ingestion rates -will vary according to the distribution of resources per machine and by data type. - -\section{Bulk Ingest} - -Accumulo supports the ability to import files produced by an external process such -as MapReduce into an existing table. In some cases it may be faster to load data this -way rather than via ingesting through clients using BatchWriters. This allows a large -number of machines to format data the way Accumulo expects. The new files can -then simply be introduced to Accumulo via a shell command. - -To configure MapReduce to format data in preparation for bulk loading, the job -should be set to use a range partitioner instead of the default hash partitioner. The -range partitioner uses the split points of the Accumulo table that will receive the -data. The split points can be obtained from the shell and used by the MapReduce -RangePartitioner. Note that this is only useful if the existing table is already split -into multiple tablets. - -\begingroup\fontsize{8pt}{8pt}\selectfont\begin{verbatim} -user@myinstance mytable> getsplits -aa -ab -ac -... -zx -zy -zz -\end{verbatim}\endgroup - -Run the MapReduce job, using the AccumuloFileOutputFormat to create the files to -be introduced to Accumulo. Once this is complete, the files can be added to -Accumulo via the shell: - -\begingroup\fontsize{8pt}{8pt}\selectfont\begin{verbatim} -user@myinstance mytable> importdirectory /files_dir /failures -\end{verbatim}\endgroup - -Note that the paths referenced are directories within the same HDFS instance over -which Accumulo is running. Accumulo places any files that failed to be added to the -second directory specified. - -A complete example of using Bulk Ingest can be found at\\ -accumulo/docs/examples/README.bulkIngest - -\section{Logical Time for Bulk Ingest} - -Logical time is important for bulk imported data, for which the client code may -be choosing a timestamp. At bulk import time, the user can choose to enable -logical time for the set of files being imported. When its enabled, Accumulo -uses a specialized system iterator to lazily set times in a bulk imported file. -This mechanism guarantees that times set by unsynchronized multi-node -applications (such as those running on MapReduce) will maintain some semblance -of causal ordering. This mitigates the problem of the time being wrong on the -system that created the file for bulk import. These times are not set when the -file is imported, but whenever it is read by scans or compactions. At import, a -time is obtained and always used by the specialized system iterator to set that -time. - -The timestamp assigned by Accumulo will be the same for every key in the file. -This could cause problems if the file contains multiple keys that are identical -except for the timestamp. In this case, the sort order of the keys will be -undefined. This could occur if an insert and an update were in the same bulk -import file. - -\section{MapReduce Ingest} -It is possible to efficiently write many mutations to Accumulo in parallel via a -MapReduce job. In this scenario the MapReduce is written to process data that lives -in HDFS and write mutations to Accumulo using the AccumuloOutputFormat. See -the MapReduce section under Analytics for details. - -An example of using MapReduce can be found under\\ -accumulo/docs/examples/README.mapred - http://git-wip-us.apache.org/repos/asf/accumulo/blob/900d6abb/docs/src/main/latex/accumulo_user_manual/chapters/introduction.tex ---------------------------------------------------------------------- diff --git a/docs/src/main/latex/accumulo_user_manual/chapters/introduction.tex b/docs/src/main/latex/accumulo_user_manual/chapters/introduction.tex deleted file mode 100644 index 09d9f14..0000000 --- a/docs/src/main/latex/accumulo_user_manual/chapters/introduction.tex +++ /dev/null @@ -1,27 +0,0 @@ - -% Licensed to the Apache Software Foundation (ASF) under one or more -% contributor license agreements. See the NOTICE file distributed with -% this work for additional information regarding copyright ownership. -% The ASF licenses this file to You under the Apache License, Version 2.0 -% (the "License"); you may not use this file except in compliance with -% the License. You may obtain a copy of the License at -% -% http://www.apache.org/licenses/LICENSE-2.0 -% -% Unless required by applicable law or agreed to in writing, software -% distributed under the License is distributed on an "AS IS" BASIS, -% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. -% See the License for the specific language governing permissions and -% limitations under the License. - -\chapter{Introduction} -Apache Accumulo is a highly scalable structured store based on Google's BigTable. -Accumulo is written in Java and operates over the Hadoop Distributed File System -(HDFS), which is part of the popular Apache Hadoop project. Accumulo supports -efficient storage and retrieval of structured data, including queries for ranges, and -provides support for using Accumulo tables as input and output for MapReduce -jobs. - -Accumulo features automatic load-balancing and partitioning, data compression -and fine-grained security labels. - http://git-wip-us.apache.org/repos/asf/accumulo/blob/900d6abb/docs/src/main/latex/accumulo_user_manual/chapters/multivolume.tex ---------------------------------------------------------------------- diff --git a/docs/src/main/latex/accumulo_user_manual/chapters/multivolume.tex b/docs/src/main/latex/accumulo_user_manual/chapters/multivolume.tex deleted file mode 100644 index 0a0e6fe..0000000 --- a/docs/src/main/latex/accumulo_user_manual/chapters/multivolume.tex +++ /dev/null @@ -1,85 +0,0 @@ - -% Licensed to the Apache Software Foundation (ASF) under one or more -% contributor license agreements. See the NOTICE file distributed with -% this work for additional information regarding copyright ownership. -% The ASF licenses this file to You under the Apache License, Version 2.0 -% (the "License"); you may not use this file except in compliance with -% the License. You may obtain a copy of the License at -% -% http://www.apache.org/licenses/LICENSE-2.0 -% -% Unless required by applicable law or agreed to in writing, software -% distributed under the License is distributed on an "AS IS" BASIS, -% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. -% See the License for the specific language governing permissions and -% limitations under the License. - -\chapter{Multi-Volume Installations} - -This is an advanced configuration setting for very large clusters -under a lot of write pressure. - -The HDFS NameNode holds all of the metadata about the files in -HDFS. For fast performance, all of this information needs to be stored -in memory. A single NameNode with 64G of memory can store the -metadata for tens of millions of files.However, when scaling beyond a -thousand nodes, an active Accumulo system can generate lots of updates -to the file system, especially when data is being ingested. The large -number of write transactions to the NameNode, and the speed of a -single edit log, can become the limiting factor for large scale -Accumulo installations. - -You can see the effect of slow write transactions when the Accumulo -Garbage Collector takes a long time (more than 5 minutes) to delete -the files Accumulo no longer needs. If your Garbage Collector -routinely runs in less than a minute, the NameNode is performing well. - -However, if you do begin to experience slow-down and poor GC -performance, Accumulo can be configured to use multiple NameNode -servers. The configuration instance.volumes'' should be set to a -comma-separated list, using full URI references to different NameNode -servers: - -\begingroup\fontsize{8pt}{8pt}\selectfont\begin{verbatim} - <property> - <name>instance.volumes</name> - <value>hdfs://ns1:9001,hdfs://ns2:9001</value> - </property> -\end{verbatim}\endgroup - -The introduction of multiple volume support in 1.6 changed the way Accumulo -stores pointers to files. It now stores fully qualified URI references to -files. Before 1.6, Accumulo stored paths that were relative to a table -directory. After an upgrade these relative paths will still exist and are -resolved using instance.dfs.dir, instance.dfs.uri, and Hadoop configuration in -the same way they were before 1.6. - -If the URI for a namenode changes (e.g. namenode was running on host1 and its -moved to host2), then Accumulo will no longer function. Even if Hadoop and -Accumulo configurations are changed, the fully qualified URIs stored in -Accumulo will still contain the old URI. To handle this Accumulo has the -following configuration property for replacing URI stored in its metadata. The -example configuration below will replace ns1 with nsA and ns2 with nsB in -Accumulo metadata. For this property to take affect, Accumulo will need to be -restarted. - -\begingroup\fontsize{8pt}{8pt}\selectfont\begin{verbatim} - <property> - <name>instance.volumes.replacements</name> - <value>hdfs://ns1:9001 hdfs://nsA:9001, hdfs://ns2:9001 hdfs://nsB:9001</value> - </property> -\end{verbatim}\endgroup - -Using viewfs or HA namenode, introduced in Hadoop 2, offers another option for -managing the fully qualified URIs stored in Accumulo. Viewfs and HA namenode -both introduce a level of indirection in the Hadoop configuration. For -example assume viewfs:///nn1 maps to hdfs://nn1 in the Hadoop configuration. -If viewfs://nn1 is used by Accumulo, then its easy to map viewfs://nn1 to -hdfs://nnA by changing the Hadoop configuration w/o doing anything to Accumulo. -A production system should probably use a HA namenode. Viewfs may be useful on -a test system with a single non HA namenode. - -You may also want to configure your cluster to use Federation, -available in Hadoop 2.0, which allows DataNodes to respond to multiple -NameNode servers, so you do not have to partition your DataNodes by -NameNode. http://git-wip-us.apache.org/repos/asf/accumulo/blob/900d6abb/docs/src/main/latex/accumulo_user_manual/chapters/security.tex ---------------------------------------------------------------------- diff --git a/docs/src/main/latex/accumulo_user_manual/chapters/security.tex b/docs/src/main/latex/accumulo_user_manual/chapters/security.tex deleted file mode 100644 index 83cfb21..0000000 --- a/docs/src/main/latex/accumulo_user_manual/chapters/security.tex +++ /dev/null @@ -1,179 +0,0 @@ - -% Licensed to the Apache Software Foundation (ASF) under one or more -% contributor license agreements. See the NOTICE file distributed with -% this work for additional information regarding copyright ownership. -% The ASF licenses this file to You under the Apache License, Version 2.0 -% (the "License"); you may not use this file except in compliance with -% the License. You may obtain a copy of the License at -% -% http://www.apache.org/licenses/LICENSE-2.0 -% -% Unless required by applicable law or agreed to in writing, software -% distributed under the License is distributed on an "AS IS" BASIS, -% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. -% See the License for the specific language governing permissions and -% limitations under the License. - -\chapter{Security} - -Accumulo extends the BigTable data model to implement a security mechanism -known as cell-level security. Every key-value pair has its own security label, stored -under the column visibility element of the key, which is used to determine whether -a given user meets the security requirements to read the value. This enables data of -various security levels to be stored within the same row, and users of varying -degrees of access to query the same table, while preserving data confidentiality. - -\section{Security Label Expressions} - -When mutations are applied, users can specify a security label for each value. This is -done as the Mutation is created by passing a ColumnVisibility object to the put() -method: - -\begingroup\fontsize{8pt}{8pt}\selectfont\begin{verbatim} -Text rowID = new Text("row1"); -Text colFam = new Text("myColFam"); -Text colQual = new Text("myColQual"); -ColumnVisibility colVis = new ColumnVisibility("public"); -long timestamp = System.currentTimeMillis(); - -Value value = new Value("myValue"); - -Mutation mutation = new Mutation(rowID); -mutation.put(colFam, colQual, colVis, timestamp, value); -\end{verbatim}\endgroup - -\section{Security Label Expression Syntax} - -Security labels consist of a set of user-defined tokens that are required to read the -value the label is associated with. The set of tokens required can be specified using -syntax that supports logical AND and OR combinations of tokens, as well as nesting -groups of tokens together. - -For example, suppose within our organization we want to label our data values with -security labels defined in terms of user roles. We might have tokens such as: - -\begingroup\fontsize{8pt}{8pt}\selectfont\begin{verbatim} -admin -audit -system -\end{verbatim}\endgroup - -These can be specified alone or combined using logical operators: - -\begingroup\fontsize{8pt}{8pt}\selectfont\begin{verbatim} -// Users must have admin privileges: -admin - -// Users must have admin and audit privileges -admin&audit - -// Users with either admin or audit privileges -admin|audit - -// Users must have audit and one or both of admin or system -(admin|system)&audit -\end{verbatim}\endgroup - -When both \verb^|^ and \verb^&^ operators are used, parentheses must be used to specify -precedence of the operators. - -\section{Authorization} - -When clients attempt to read data from Accumulo, any security labels present are -examined against the set of authorizations passed by the client code when the -Scanner or BatchScanner are created. If the authorizations are determined to be -insufficient to satisfy the security label, the value is suppressed from the set of -results sent back to the client. - -Authorizations are specified as a comma-separated list of tokens the user possesses: - -\begingroup\fontsize{8pt}{8pt}\selectfont\begin{verbatim} -// user possess both admin and system level access -Authorization auths = new Authorization("admin","system"); - -Scanner s = connector.createScanner("table", auths); -\end{verbatim}\endgroup - -\section{User Authorizations} - -Each Accumulo user has a set of associated security labels. To manipulate -these in the shell while using the default authorizor, use the setuaths and getauths commands. -These may also be modified for the default authorizor using the java security operations API. - -When a user creates a scanner a set of Authorizations is passed. If the -authorizations passed to the scanner are not a subset of the users -authorizations, then an exception will be thrown. - -To prevent users from writing data they can not read, add the visibility -constraint to a table. Use the -evc option in the createtable shell command to -enable this constraint. For existing tables use the following shell command to -enable the visibility constraint. Ensure the constraint number does not -conflict with any existing constraints. - -\begingroup\fontsize{8pt}{8pt}\selectfont\begin{verbatim} -config -t table -s table.constraint.1=org.apache.accumulo.core.security.VisibilityConstraint -\end{verbatim}\endgroup - -Any user with the alter table permission can add or remove this constraint. -This constraint is not applied to bulk imported data, if this a concern then -disable the bulk import permission. - -\section{Pluggable Security} - -New in 1.5 of Accumulo is a pluggable security mechanism. It can be broken into three actions- -authentication, authorization, and permission handling. By default all of these are handled in -Zookeeper, which is how things were handled in Accumulo 1.4 and before. It is worth noting at this -point, that it is a new feature in 1.5 and may be adjusted in future releases without the standard -deprecation cycle. - -Authentication simply handles the ability for a user to verify their integrity. A combination of -principal and authentication token are used to verify a user is who they say they are. An -authentication token should be constructed, either directly through it's constructor, but it is -advised to use the init(Property) method to populate an authentication token. It is expected that a -user knows what the appropriate token to use for their system is. The default token is -PasswordToken. - -Once a user is authenticated by the Authenticator, the user has access to the other actions within -Accumulo. All actions in Accumulo are ACLed, and this ACL check is handled by the Permission -Handler. This is what manages all of the permissions, which are divided in system and per table -level. From there, if a user is doing an action which requires authorizations, the Authorizor is -queried to determine what authorizations the user has. - -This setup allows a variety of different mechanisms to be used for handling different aspects of -Accumulo's security. A system like Kerberos can be used for authentication, then a system like LDAP -could be used to determine if a user has a specific permission, and then it may default back to the -default ZookeeperAuthorizor to determine what Authorizations a user is ultimately allowed to use. -This is a pluggable system so custom components can be created depending on your need. - -\section{Secure Authorizations Handling} - -For applications serving many users, it is not expected that an Accumulo user -will be created for each application user. In this case an Accumulo user with -all authorizations needed by any of the applications users must be created. To -service queries, the application should create a scanner with the application -user's authorizations. These authorizations could be obtained from a trusted 3rd -party. - -Often production systems will integrate with Public-Key Infrastructure (PKI) and -designate client code within the query layer to negotiate with PKI servers in order -to authenticate users and retrieve their authorization tokens (credentials). This -requires users to specify only the information necessary to authenticate themselves -to the system. Once user identity is established, their credentials can be accessed by -the client code and passed to Accumulo outside of the reach of the user. - -\section{Query Services Layer} - -Since the primary method of interaction with Accumulo is through the Java API, -production environments often call for the implementation of a Query layer. This -can be done using web services in containers such as Apache Tomcat, but is not a -requirement. The Query Services Layer provides a mechanism for providing a -platform on which user facing applications can be built. This allows the application -designers to isolate potentially complex query logic, and enables a convenient point -at which to perform essential security functions. - -Several production environments choose to implement authentication at this layer, -where users identifiers are used to retrieve their access credentials which are then -cached within the query layer and presented to Accumulo through the -Authorizations mechanism. - -Typically, the query services layer sits between Accumulo and user workstations. http://git-wip-us.apache.org/repos/asf/accumulo/blob/900d6abb/docs/src/main/latex/accumulo_user_manual/chapters/shell.tex ---------------------------------------------------------------------- diff --git a/docs/src/main/latex/accumulo_user_manual/chapters/shell.tex b/docs/src/main/latex/accumulo_user_manual/chapters/shell.tex deleted file mode 100644 index f3c11ff..0000000 --- a/docs/src/main/latex/accumulo_user_manual/chapters/shell.tex +++ /dev/null @@ -1,138 +0,0 @@ - -% Licensed to the Apache Software Foundation (ASF) under one or more -% contributor license agreements. See the NOTICE file distributed with -% this work for additional information regarding copyright ownership. -% The ASF licenses this file to You under the Apache License, Version 2.0 -% (the "License"); you may not use this file except in compliance with -% the License. You may obtain a copy of the License at -% -% http://www.apache.org/licenses/LICENSE-2.0 -% -% Unless required by applicable law or agreed to in writing, software -% distributed under the License is distributed on an "AS IS" BASIS, -% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. -% See the License for the specific language governing permissions and -% limitations under the License. - -\chapter{Accumulo Shell} -Accumulo provides a simple shell that can be used to examine the contents and -configuration settings of tables, insert/update/delete values, and change -configuration settings. - -The shell can be started by the following command: - -\begingroup\fontsize{8pt}{8pt}\selectfont\begin{verbatim} -$ACCUMULO_HOME/bin/accumulo shell -u [username]
-\end{verbatim}\endgroup
-
-The shell will prompt for the corresponding password to the username specified
-and then display the following prompt:
-
-\begingroup\fontsize{8pt}{8pt}\selectfont\begin{verbatim}
-Shell - Apache Accumulo Interactive Shell
--
-- version 1.5
-- instance name: myinstance
-- instance id: 00000000-0000-0000-0000-000000000000
--
-- type 'help' for a list of available commands
--
-\end{verbatim}\endgroup
-
-
-The Accumulo shell can be used to create and delete tables, as well as to configure
-table and instance specific options.
-
-\begingroup\fontsize{8pt}{8pt}\selectfont\begin{verbatim}
-root@myinstance> tables
-accumulo.root
-
-root@myinstance> createtable mytable
-
-root@myinstance mytable>
-
-root@myinstance mytable> tables
-accumulo.root
-mytable
-
-root@myinstance mytable> createtable testtable
-
-root@myinstance testtable>
-
-root@myinstance testtable> deletetable testtable
-deletetable { testtable } (yes|no)? yes
-Table: [testtable] has been deleted.
-
-root@myinstance>
-\end{verbatim}\endgroup
-
-The Shell can also be used to insert updates and scan tables. This is useful for
-inspecting tables.
-
-\begingroup\fontsize{8pt}{8pt}\selectfont\begin{verbatim}
-root@myinstance mytable> scan
-
-root@myinstance mytable> insert row1 colf colq value1
-insert successful
-
-root@myinstance mytable> scan
-row1 colf:colq [] value1
-\end{verbatim}\endgroup
-
-The value in brackets "[]" would be the visibility labels. Since none were used, this is empty for this row.
-You can use the "-st" option to scan to see the timestamp for the cell, too.
-
-\section{Table Maintenance}
-
-The \textbf{compact} command instructs Accumulo to schedule a compaction of the table during which
-files are consolidated and deleted entries are removed.
-
-\begingroup\fontsize{8pt}{8pt}\selectfont\begin{verbatim}
-root@myinstance mytable> compact -t mytable
-07 16:13:53,201 [shell.Shell] INFO : Compaction of table mytable started for given range
-\end{verbatim}\endgroup
-
-The \textbf{flush} command instructs Accumulo to write all entries currently in memory for a given table
-to disk.
-
-\begingroup\fontsize{8pt}{8pt}\selectfont\begin{verbatim}
-root@myinstance mytable> flush -t mytable
-07 16:14:19,351 [shell.Shell] INFO : Flush of table mytable
-initiated...
-\end{verbatim}\endgroup
-
-
-The Shell can be used to add, remove, and grant privileges to users.
-
-\begingroup\fontsize{8pt}{8pt}\selectfont\begin{verbatim}
-root@myinstance mytable> createuser bob
-Enter new password for 'bob': *********
-
-root@myinstance mytable> authenticate bob
-Enter current password for 'bob': *********
-Valid
-
-root@myinstance mytable> grant System.CREATE_TABLE -s -u bob
-
-root@myinstance mytable> user bob
-Enter current password for 'bob': *********
-
-bob@myinstance mytable> userpermissions
-System permissions: System.CREATE_TABLE
-Table permissions (mytable): NONE
-
-bob@myinstance mytable> createtable bobstable
-bob@myinstance bobstable>
-
-bob@myinstance bobstable> user root
-Enter current password for 'root': *********
-
-root@myinstance bobstable> revoke System.CREATE_TABLE -s -u bob
-\end{verbatim}\endgroup
-

http://git-wip-us.apache.org/repos/asf/accumulo/blob/900d6abb/docs/src/main/latex/accumulo_user_manual/chapters/table_configuration.tex
----------------------------------------------------------------------
diff --git a/docs/src/main/latex/accumulo_user_manual/chapters/table_configuration.tex b/docs/src/main/latex/accumulo_user_manual/chapters/table_configuration.tex
deleted file mode 100644
index a19cb52..0000000
--- a/docs/src/main/latex/accumulo_user_manual/chapters/table_configuration.tex
+++ /dev/null
@@ -1,663 +0,0 @@
-
-% Licensed to the Apache Software Foundation (ASF) under one or more
-% contributor license agreements. See the NOTICE file distributed with
-% The ASF licenses this file to You under the Apache License, Version 2.0
-% (the "License"); you may not use this file except in compliance with
-% the License. You may obtain a copy of the License at
-%
-%
-% Unless required by applicable law or agreed to in writing, software
-% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-% See the License for the specific language governing permissions and
-
-\chapter{Table Configuration}
-
-Accumulo tables have a few options that can be configured to alter the default
-behavior of Accumulo as well as improve performance based on the data stored.
-These include locality groups, constraints, bloom filters, iterators, and block
-cache. For a complete list of available configuration options, see
-Appendix~\ref{app:config}.
-
-\section{Locality Groups}
-Accumulo supports storing sets of column families separately on disk to allow
-clients to efficiently scan over columns that are frequently used together and to avoid
-scanning over column families that are not requested. After a locality group is set,
-Scanner and BatchScanner operations will automatically take advantage of them
-whenever the fetchColumnFamilies() method is used.
-
-By default, tables place all column families into the same default'' locality group.
-Additional locality groups can be configured anytime via the shell or
-programmatically as follows:
-
-\subsection{Managing Locality Groups via the Shell}
-
-\begingroup\fontsize{8pt}{8pt}\selectfont\begin{verbatim}
-usage: setgroups <group>=<col fam>{,<col fam>}{ <group>=<col fam>{,<col
-fam>}} [-?] -t <table>
-
-user@myinstance mytable> setgroups group_one=colf1,colf2 -t mytable
-
-user@myinstance mytable> getgroups -t mytable
-\end{verbatim}\endgroup
-
-\subsection{Managing Locality Groups via the Client API}
-
-\begingroup\fontsize{8pt}{8pt}\selectfont\begin{verbatim}
-Connector conn;
-
-HashMap<String,Set<Text>> localityGroups = new HashMap<String, Set<Text>>();
-
-
-HashSet<Text> contentColumns = new HashSet<Text>();
-
-localityGroups.put("content", contentColumns);
-
-conn.tableOperations().setLocalityGroups("mytable", localityGroups);
-
-// existing locality groups can be obtained as follows
-Map<String, Set<Text>> groups =
-    conn.tableOperations().getLocalityGroups("mytable");
-\end{verbatim}\endgroup
-
-The assignment of Column Families to Locality Groups can be changed anytime. The
-physical movement of column families into their new locality groups takes place via
-the periodic Major Compaction process that takes place continuously in the
-background. Major Compaction can also be scheduled to take place immediately
-through the shell:
-
-\begingroup\fontsize{8pt}{8pt}\selectfont\begin{verbatim}
-user@myinstance mytable> compact -t mytable
-\end{verbatim}\endgroup
-
-\section{Constraints}
-
-Accumulo supports constraints applied on mutations at insert time. This can be
-used to disallow certain inserts according to a user defined policy. Any mutation
-that fails to meet the requirements of the constraint is rejected and sent back to the
-client.
-
-Constraints can be enabled by setting a table property as follows:
-
-\begingroup\fontsize{8pt}{8pt}\selectfont\begin{verbatim}
-user@myinstance mytable> constraint -t mytable -a com.test.ExampleConstraint com.test.AnotherConstraint
-user@myinstance mytable> constraint -l
-com.test.ExampleConstraint=1
-com.test.AnotherConstraint=2
-\end{verbatim}\endgroup
-
-Currently there are no general-purpose constraints provided with the Accumulo
-distribution. New constraints can be created by writing a Java class that implements
-the following interface:
-
-\begingroup\fontsize{8pt}{8pt}\selectfont\begin{verbatim}
-org.apache.accumulo.core.constraints.Constraint
-\end{verbatim}\endgroup
-
-To deploy a new constraint, create a jar file containing the class implementing the
-new constraint and place it in the lib directory of the Accumulo installation. New
-constraint jars can be added to Accumulo and enabled without restarting but any
-change to an existing constraint class requires Accumulo to be restarted.
-
-An example of constraints can be found in\\
-\texttt{accumulo/examples/simple/src/main/java/accumulo/examples/simple/constraints} .
-
-\section{Bloom Filters}
-As mutations are applied to an Accumulo table, several files are created per tablet. If
-bloom filters are enabled, Accumulo will create and load a small data structure into
-memory to determine whether a file contains a given key before opening the file.
-This can speed up lookups considerably.
-
-To enable bloom filters, enter the following command in the Shell:
-
-\begingroup\fontsize{8pt}{8pt}\selectfont\begin{verbatim}
-user@myinstance> config -t mytable -s table.bloom.enabled=true
-\end{verbatim}\endgroup
-
-An extensive example of using Bloom Filters can be found at\\
-
-\section{Iterators}
-Iterators provide a modular mechanism for adding functionality to be executed by
-TabletServers when scanning or compacting data. This allows users to efficiently
-summarize, filter, and aggregate data. In fact, the built-in features of cell-level
-security and column fetching are implemented using Iterators.
-Some useful Iterators are provided with Accumulo and can be found in the org.apache.accumulo.core.iterators.user package.
-In each case, any custom Iterators must be included in Accumulo's classpath,
-typically by including a jar in \texttt{\$ACCUMULO\_HOME/lib} or -\texttt{\$ACCUMULO\_HOME/lib/ext}, although the VFS classloader allows for
-classpath manipulation using a variety of schemes including URLs and HDFS URIs.
-
-\subsection{Setting Iterators via the Shell}
-
-Iterators can be configured on a table at scan, minor compaction and/or major
-compaction scopes. If the Iterator implements the OptionDescriber interface, the
-setiter command can be used which will interactively prompt the user to provide
-values for the given necessary options.
-
-\begingroup\fontsize{8pt}{8pt}\selectfont\begin{verbatim}
-usage: setiter [-?] -ageoff | -agg | -class <name> | -regex |
--reqvis | -vers   [-majc] [-minc] [-n <itername>] -p <pri>
-[-scan] [-t <table>]
-
-user@myinstance mytable> setiter -t mytable -scan -p 15 -n myiter -class com.company.MyIterator
-\end{verbatim}\endgroup
-
-The config command can always be used to manually configure iterators which is useful
-in cases where the Iterator does not implement the OptionDescriber interface.
-
-\begingroup\fontsize{8pt}{8pt}\selectfont\begin{verbatim}
-config -t mytable -s table.iterator.scan.myiter=15,com.company.MyIterator
-config -t mytable -s table.iterator.minc.myiter=15,com.company.MyIterator
-config -t mytable -s table.iterator.majc.myiter=15,com.company.MyIterator
-config -t mytable -s table.iterator.scan.myiter.opt.myoptionname=myoptionvalue
-config -t mytable -s table.iterator.minc.myiter.opt.myoptionname=myoptionvalue
-config -t mytable -s table.iterator.majc.myiter.opt.myoptionname=myoptionvalue
-\end{verbatim}\endgroup
-
-\subsection{Setting Iterators Programmatically}
-
-\begingroup\fontsize{8pt}{8pt}\selectfont\begin{verbatim}
-    15, // priority
-    "myiter", // name this iterator
-    "com.company.MyIterator" // class name
-));
-\end{verbatim}\endgroup
-
-Some iterators take additional parameters from client code, as in the following
-example:
-
-\begingroup\fontsize{8pt}{8pt}\selectfont\begin{verbatim}
-IteratorSetting iter = new IteratorSetting(...);
-\end{verbatim}\endgroup
-
-Tables support separate Iterator settings to be applied at scan time, upon minor
-compaction and upon major compaction. For most uses, tables will have identical
-iterator settings for all three to avoid inconsistent results.
-
-\subsection{Versioning Iterators and Timestamps}
-
-Accumulo provides the capability to manage versioned data through the use of
-timestamps within the Key. If a timestamp is not specified in the key created by the
-client then the system will set the timestamp to the current time. Two keys with
-identical rowIDs and columns but different timestamps are considered two versions
-of the same key. If two inserts are made into Accumulo with the same rowID,
-column, and timestamp, then the behavior is non-deterministic.
-
-Timestamps are sorted in descending order, so the most recent data comes first.
-Accumulo can be configured to return the top k versions, or versions later than a
-given date. The default is to return the one most recent version.
-
-The version policy can be changed by changing the VersioningIterator options for a
-table as follows:
-
-\begingroup\fontsize{8pt}{8pt}\selectfont\begin{verbatim}
-user@myinstance mytable> config -t mytable -s table.iterator.scan.vers.opt.maxVersions=3
-
-user@myinstance mytable> config -t mytable -s table.iterator.minc.vers.opt.maxVersions=3
-
-user@myinstance mytable> config -t mytable -s table.iterator.majc.vers.opt.maxVersions=3
-\end{verbatim}\endgroup
-
-When a table is created, by default its configured to use the
-VersioningIterator and keep one version. A table can be created without the
-VersioningIterator with the -ndi option in the shell. Also the Java API
-has the following method
-
-\begingroup\fontsize{8pt}{8pt}\selectfont\begin{verbatim}
-connector.tableOperations.create(String tableName, boolean limitVersion).
-\end{verbatim}\endgroup
-
-
-\subsubsection{Logical Time}
-
-Accumulo 1.2 introduces the concept of logical time. This ensures that timestamps
-set by Accumulo always move forward. This helps avoid problems caused by
-TabletServers that have different time settings. The per tablet counter gives unique
-one up time stamps on a per mutation basis. When using time in milliseconds, if
-two things arrive within the same millisecond then both receive the same
-timestamp. When using time in milliseconds, Accumulo set times will still
-always move forward and never backwards.
-
-A table can be configured to use logical timestamps at creation time as follows:
-
-\begingroup\fontsize{8pt}{8pt}\selectfont\begin{verbatim}
-user@myinstance> createtable -tl logical
-\end{verbatim}\endgroup
-
-\subsubsection{Deletes}
-Deletes are special keys in Accumulo that get sorted along will all the other data.
-When a delete key is inserted, Accumulo will not show anything that has a
-timestamp less than or equal to the delete key. During major compaction, any keys
-older than a delete key are omitted from the new file created, and the omitted keys
-are removed from disk as part of the regular garbage collection process.
-
-\subsection{Filters}
-When scanning over a set of key-value pairs it is possible to apply an arbitrary
-filtering policy through the use of a Filter. Filters are types of iterators that return
-only key-value pairs that satisfy the filter logic. Accumulo has a few built-in filters
-that can be configured on any table: AgeOff, ColumnAgeOff, Timestamp, NoVis, and RegEx. More can be added
-by writing a Java class that extends the\\
-org.apache.accumulo.core.iterators.Filter class.
-
-The AgeOff filter can be configured to remove data older than a certain date or a fixed
-amount of time from the present. The following example sets a table to delete
-everything inserted over 30 seconds ago:
-
-\begingroup\fontsize{8pt}{8pt}\selectfont\begin{verbatim}
-user@myinstance> createtable filtertest
-user@myinstance filtertest> setiter -t filtertest -scan -minc -majc -p 10 -n myfilter -ageoff
-AgeOffFilter removes entries with timestamps more than <ttl> milliseconds old
-----------> set org.apache.accumulo.core.iterators.user.AgeOffFilter parameter negate, default false
-                keeps k/v that pass accept method, true rejects k/v that pass accept method:
-----------> set org.apache.accumulo.core.iterators.user.AgeOffFilter parameter ttl, time to
-                live (milliseconds): 3000
-----------> set org.apache.accumulo.core.iterators.user.AgeOffFilter parameter currentTime, if set,
-                use the given value as the absolute time in milliseconds as the current time of day:
-user@myinstance filtertest>
-user@myinstance filtertest> scan
-user@myinstance filtertest> insert foo a b c
-user@myinstance filtertest> scan
-foo a:b [] c
-user@myinstance filtertest> sleep 4
-user@myinstance filtertest> scan
-user@myinstance filtertest>
-\end{verbatim}\endgroup
-
-To see the iterator settings for a table, use:
-
-\begingroup\fontsize{8pt}{8pt}\selectfont\begin{verbatim}
-user@example filtertest> config -t filtertest -f iterator
----------+---------------------------------------------+------------------
-SCOPE    | NAME                                        | VALUE
----------+---------------------------------------------+------------------
-table    | table.iterator.majc.myfilter .............. | 10,org.apache.accumulo.core.iterators.user.AgeOffFilter
-table    | table.iterator.majc.myfilter.opt.ttl ...... | 3000
-table    | table.iterator.majc.vers .................. | 20,org.apache.accumulo.core.iterators.VersioningIterator
-table    | table.iterator.majc.vers.opt.maxVersions .. | 1
-table    | table.iterator.minc.myfilter .............. | 10,org.apache.accumulo.core.iterators.user.AgeOffFilter
-table    | table.iterator.minc.myfilter.opt.ttl ...... | 3000
-table    | table.iterator.minc.vers .................. | 20,org.apache.accumulo.core.iterators.VersioningIterator
-table    | table.iterator.minc.vers.opt.maxVersions .. | 1
-table    | table.iterator.scan.myfilter .............. | 10,org.apache.accumulo.core.iterators.user.AgeOffFilter
-table    | table.iterator.scan.myfilter.opt.ttl ...... | 3000
-table    | table.iterator.scan.vers .................. | 20,org.apache.accumulo.core.iterators.VersioningIterator
-table    | table.iterator.scan.vers.opt.maxVersions .. | 1
----------+---------------------------------------------+------------------
-\end{verbatim}\endgroup
-
-\subsection{Combiners}
-
-Accumulo allows Combiners to be configured on tables and column
-families. When a Combiner is set it is applied across the values
-associated with any keys that share rowID, column family, and column qualifier.
-This is similar to the reduce step in MapReduce, which applied some function to all
-the values associated with a particular key.
-
-For example, if a summing combiner were configured on a table and the following
-mutations were inserted:
-
-\begingroup\fontsize{8pt}{8pt}\selectfont\begin{verbatim}
-Row     Family Qualifier Timestamp  Value
-rowID1  colfA  colqA     20100101   1
-rowID1  colfA  colqA     20100102   1
-\end{verbatim}\endgroup
-
-The table would reflect only one aggregate value:
-
-\begingroup\fontsize{8pt}{8pt}\selectfont\begin{verbatim}
-rowID1  colfA  colqA     -          2
-\end{verbatim}\endgroup
-
-Combiners can be enabled for a table using the setiter command in the shell. Below is an example.
-
-\begingroup\fontsize{8pt}{8pt}\selectfont\begin{verbatim}
-root@a14 perDayCounts> setiter -t perDayCounts -p 10 -scan -minc -majc -n daycount
-                       -class org.apache.accumulo.core.iterators.user.SummingCombiner
-TypedValueCombiner can interpret Values as a variety of number encodings
-  (VLong, Long, or String) before combining
-----------> set SummingCombiner parameter columns,
-            <col fam>[:<col qual>]{,<col fam>[:<col qual>]} : day
-----------> set SummingCombiner parameter type, <VARNUM|LONG|STRING>: STRING
-
-root@a14 perDayCounts> insert foo day 20080101 1
-root@a14 perDayCounts> insert foo day 20080101 1
-root@a14 perDayCounts> insert foo day 20080103 1
-root@a14 perDayCounts> insert bar day 20080101 1
-root@a14 perDayCounts> insert bar day 20080101 1
-
-root@a14 perDayCounts> scan
-bar day:20080101 []    2
-foo day:20080101 []    2
-foo day:20080103 []    1
-\end{verbatim}\endgroup
-
-Accumulo includes some useful Combiners out of the box. To find these look in
-the\\ \texttt{org.apache.accumulo.core.iterators.user} package.
-
-Additional Combiners can be added by creating a Java class that extends\\
-\texttt{org.apache.accumulo.core.iterators.Combiner} and adding a jar containing that
-class to Accumulo's lib/ext directory.
-
-An example of a Combiner can be found under
-
-\begingroup\fontsize{8pt}{8pt}\selectfont\begin{verbatim}
-accumulo/examples/simple/src/main/java/org/apache/accumulo/examples/simple/combiner/StatsCombiner.java
-\end{verbatim}\endgroup
-
-
-\section{Block Cache}
-
-In order to increase throughput of commonly accessed entries, Accumulo employs a block cache.
-This block cache buffers data in memory so that it doesn't have to be read off of disk.
-The RFile format that Accumulo prefers is a mix of index blocks and data blocks, where the index blocks are used to find the appropriate data blocks.
-Typical queries to Accumulo result in a binary search over several index blocks followed by a linear scan of one or more data blocks.
-
-The block cache can be configured on a per-table basis, and all tablets hosted on a tablet server share a single resource pool.
-To configure the size of the tablet server's block cache, set the following properties:
-
-\begingroup\fontsize{8pt}{8pt}\selectfont\begin{verbatim}
-tserver.cache.data.size: Specifies the size of the cache for file data blocks.
-tserver.cache.index.size: Specifies the size of the cache for file indices.
-\end{verbatim}\endgroup
-
-To enable the block cache for your table, set the following properties:
-
-\begingroup\fontsize{8pt}{8pt}\selectfont\begin{verbatim}
-table.cache.block.enable: Determines whether file (data) block cache is enabled.
-table.cache.index.enable: Determines whether index cache is enabled.
-\end{verbatim}\endgroup
-
-The block cache can have a significant effect on alleviating hot spots, as well as reducing query latency.
-It is enabled by default for the metadata tables.
-
-\section{Compaction}
-
-As data is written to Accumulo it is buffered in memory. The data buffered in
-memory is eventually written to HDFS on a per tablet basis. Files can also be
-added to tablets directly by bulk import. In the background tablet servers run
-major compactions to merge multiple files into one. The tablet server has to
-decide which tablets to compact and which files within a tablet to compact.
-This decision is made using the compaction ratio, which is configurable on a
-per table basis. To configure this ratio modify the following property:
-
-\begingroup\fontsize{8pt}{8pt}\selectfont\begin{verbatim}
-table.compaction.major.ratio
-\end{verbatim}\endgroup
-
-Increasing this ratio will result in more files per tablet and less compaction
-work. More files per tablet means more higher query latency. So adjusting
-this ratio is a trade off between ingest and query performance. The ratio
-defaults to 3.
-
-The way the ratio works is that a set of files is compacted into one file if the
-sum of the sizes of the files in the set is larger than the ratio multiplied by
-the size of the largest file in the set. If this is not true for the set of all
-files in a tablet, the largest file is removed from consideration, and the
-remaining files are considered for compaction. This is repeated until a
-compaction is triggered or there are no files left to consider.
-
-The number of background threads tablet servers use to run major compactions is
-configurable. To configure this modify the following property:
-
-\begingroup\fontsize{8pt}{8pt}\selectfont\begin{verbatim}
-tserver.compaction.major.concurrent.max
-\end{verbatim}\endgroup
-
-Also, the number of threads tablet servers use for minor compactions is
-configurable. To configure this modify the following property:
-
-\begingroup\fontsize{8pt}{8pt}\selectfont\begin{verbatim}
-tserver.compaction.minor.concurrent.max
-\end{verbatim}\endgroup
-
-The numbers of minor and major compactions running and queued is visible on the
-Accumulo monitor page. This allows you to see if compactions are backing up
-and adjustments to the above settings are needed. When adjusting the number of
-threads available for compactions, consider the number of cores and other tasks
-running on the nodes such as maps and reduces.
-
-If major compactions are not keeping up, then the number of files per tablet
-will grow to a point such that query performance starts to suffer. One way to
-handle this situation is to increase the compaction ratio. For example, if the
-compaction ratio were set to 1, then every new file added to a tablet by minor
-compaction would immediately queue the tablet for major compaction. So if a
-tablet has a 200M file and minor compaction writes a 1M file, then the major
-compaction will attempt to merge the 200M and 1M file. If the tablet server
-has lots of tablets trying to do this sort of thing, then major compactions
-will back up and the number of files per tablet will start to grow, assuming
-data is being continuously written. Increasing the compaction ratio will
-alleviate backups by lowering the amount of major compaction work that needs to
-be done.
-
-Another option to deal with the files per tablet growing too large is to adjust
-the following property:
-
-\begingroup\fontsize{8pt}{8pt}\selectfont\begin{verbatim}
-table.file.max
-\end{verbatim}\endgroup
-
-When a tablet reaches this number of files and needs to flush its in-memory
-data to disk, it will choose to do a merging minor compaction. A merging minor
-compaction will merge the tablet's smallest file with the data in memory at
-minor compaction time. Therefore the number of files will not grow beyond this
-limit. This will make minor compactions take longer, which will cause ingest
-performance to decrease. This can cause ingest to slow down until major
-compactions have enough time to catch up. When adjusting this property, also
-consider adjusting the compaction ratio. Ideally, merging minor compactions
-never need to occur and major compactions will keep up. It is possible to
-configure the file max and compaction ratio such that only merging minor
-compactions occur and major compactions never occur. This should be avoided
-because doing only merging minor compactions causes $O(N^2)$ work to be done.
-The amount of work done by major compactions is $O(N*\log_R(N))$ where
-\textit{R} is the compaction ratio.
-
-Compactions can be initiated manually for a table. To initiate a minor
-compaction, use the flush command in the shell. To initiate a major compaction,
-use the compact command in the shell. The compact command will compact all
-tablets in a table to one file. Even tablets with one file are compacted. This
-is useful for the case where a major compaction filter is configured for a
-table. In 1.4 the ability to compact a range of a table was added. To use this
-feature specify start and stop rows for the compact command. This will only
-compact tablets that overlap the given row range.
-
-\section{Pre-splitting tables}
-
-Accumulo will balance and distribute tables across servers. Before a
-table gets large, it will be maintained as a single tablet on a single
-server. This limits the speed at which data can be added or queried
-to the speed of a single node. To improve performance when the a table
-is new, or small, you can add split points and generate new tablets.
-
-In the shell:
-
-\begingroup\fontsize{8pt}{8pt}\selectfont\begin{verbatim}
-root@myinstance> createtable newTable
-root@myinstance> addsplits -t newTable g n t
-\end{verbatim}\endgroup
-
-This will create a new table with 4 tablets. The table will be split
-on the letters g'', n'', and t'' which will work nicely if the
-data includes binary information or numeric information, or if the
-distribution of the row information is not flat, then you would pick
-different split points. Now ingest and query can proceed on 4 nodes
-which can improve performance.
-
-\section{Merging tablets}
-
-Over time, a table can get very large, so large that it has hundreds
-of thousands of split points. Once there are enough tablets to spread
-a table across the entire cluster, additional splits may not improve
-performance, and may create unnecessary bookkeeping. The distribution
-of data may change over time. For example, if row data contains date
-information, and data is continually added and removed to maintain a
-window of current information, tablets for older rows may be empty.
-
-Accumulo supports tablet merging, which can be used to reduce
-the number of split points. The following command will merge all rows
-from A'' to Z'' into a single tablet:
-
-\begingroup\fontsize{8pt}{8pt}\selectfont\begin{verbatim}
-root@myinstance> merge -t myTable -s A -e Z
-\end{verbatim}\endgroup
-
-If the result of a merge produces a tablet that is larger than the
-configured split size, the tablet may be split by the tablet server.
-Be sure to increase your tablet size prior to any merges if the goal
-is to have larger tablets:
-
-\begingroup\fontsize{8pt}{8pt}\selectfont\begin{verbatim}
-root@myinstance> config -t myTable -s table.split.threshold=2G
-\end{verbatim}\endgroup
-
-In order to merge small tablets, you can ask Accumulo to merge
-sections of a table smaller than a given size.
-
-\begingroup\fontsize{8pt}{8pt}\selectfont\begin{verbatim}
-root@myinstance> merge -t myTable -s 100M
-\end{verbatim}\endgroup
-
-By default, small tablets will not be merged into tablets that are
-already larger than the given size. This can leave isolated small
-tablets. To force small tablets to be merged into larger tablets use
-the -{}-force'' option:
-
-\begingroup\fontsize{8pt}{8pt}\selectfont\begin{verbatim}
-root@myinstance> merge -t myTable -s 100M --force
-\end{verbatim}\endgroup
-
-Merging away small tablets works on one section at a time. If your
-table contains many sections of small split points, or you are
-attempting to change the split size of the entire table, it will be
-faster to set the split point and merge the entire table:
-
-\begingroup\fontsize{8pt}{8pt}\selectfont\begin{verbatim}
-root@myinstance> config -t myTable -s table.split.threshold=256M
-root@myinstance> merge -t myTable
-\end{verbatim}\endgroup
-
-\section{Delete Range}
-
-Consider an indexing scheme that uses date information in each row.
-For example 20110823-15:20:25.013'' might be a row that specifies a
-date and time. In some cases, we might like to delete rows based on
-this date, say to remove all the data older than the current year.
-Accumulo supports a delete range operation which efficiently
-removes data between two rows. For example:
-
-\begingroup\fontsize{8pt}{8pt}\selectfont\begin{verbatim}
-root@myinstance> deleterange -t myTable -s 2010 -e 2011
-\end{verbatim}\endgroup
-
-This will delete all rows starting with 2010'' and it will stop at
-any row starting 2011''. You can delete any data prior to 2011
-with:
-
-\begingroup\fontsize{8pt}{8pt}\selectfont\begin{verbatim}
-root@myinstance> deleterange -t myTable -e 2011 --force
-\end{verbatim}\endgroup
-
-The shell will not allow you to delete an unbounded range (no start)
-unless you provide the -{}-force'' option.
-
-Range deletion is implemented using splits at the given start/end
-positions, and will affect the number of splits in the table.
-
-\section{Cloning Tables}
-
-A new table can be created that points to an existing table's data. This is a
-very quick metadata operation, no data is actually copied. The cloned table
-and the source table can change independently after the clone operation. One
-use case for this feature is testing. For example to test a new filtering
-iterator, clone the table, add the filter to the clone, and force a major
-compaction. To perform a test on less data, clone a table and then use delete
-range to efficiently remove a lot of data from the clone. Another use case is
-generating a snapshot to guard against human error. To create a snapshot,
-clone a table and then disable write permissions on the clone.
-
-The clone operation will point to the source table's files. This is why the
-flush option is present and is enabled by default in the shell. If the flush
-option is not enabled, then any data the source table currently has in memory
-will not exist in the clone.
-
-A cloned table copies the configuration of the source table. However the
-permissions of the source table are not copied to the clone. After a clone is
-created, only the user that created the clone can read and write to it.
-
-In the following example we see that data inserted after the clone operation is
-not visible in the clone.
-
-\begingroup\fontsize{8pt}{8pt}\selectfont\begin{verbatim}
-root@a14> createtable people
-root@a14 people> insert 890435 name last Doe
-root@a14 people> insert 890435 name first John
-root@a14 people> clonetable people test
-root@a14 people> insert 890436 name first Jane
-root@a14 people> insert 890436 name last Doe
-root@a14 people> scan
-890435 name:first []    John
-890435 name:last []    Doe
-890436 name:first []    Jane
-890436 name:last []    Doe
-root@a14 people> table test
-root@a14 test> scan
-890435 name:first []    John
-890435 name:last []    Doe
-root@a14 test>
-\end{verbatim}\endgroup
-
-The du command in the shell shows how much space a table is using in HDFS.
-This command can also show how much overlapping space two cloned tables have in
-HDFS. In the example below du shows table ci is using 428M. Then ci is cloned
-to cic and du shows that both tables share 428M. After three entries are
-inserted into cic and its flushed, du shows the two tables still share 428M but
-cic has 226 bytes to itself. Finally, table cic is compacted and then du shows
-that each table uses 428M.
-
-\begingroup\fontsize{8pt}{8pt}\selectfont\begin{verbatim}
-root@a14> du ci
-             428,482,573 [ci]
-root@a14> clonetable ci cic
-root@a14> du ci cic
-             428,482,573 [ci, cic]
-root@a14> table cic
-root@a14 cic> insert r1 cf1 cq1 v1
-root@a14 cic> insert r1 cf1 cq2 v2
-root@a14 cic> insert r1 cf1 cq3 v3
-root@a14 cic> flush -t cic -w
-27 15:00:13,908 [shell.Shell] INFO : Flush of table cic completed.
-root@a14 cic> du ci cic
-             428,482,573 [ci, cic]
-                     226 [cic]
-root@a14 cic> compact -t cic -w
-27 15:00:35,871 [shell.Shell] INFO : Compacting table ...
-27 15:03:03,303 [shell.Shell] INFO : Compaction of table cic completed for given range
-root@a14 cic> du ci cic
-             428,482,573 [ci]
-             428,482,612 [cic]
-root@a14 cic>
-\end{verbatim}\endgroup
-
-\section{Exporting Tables}
-
-Accumulo supports exporting tables for the purpose of copying tables to another
-cluster. Exporting and importing tables preserves the tables configuration,
-splits, and logical time. Tables are exported and then copied via the hadoop
-distcp command. To export a table, it must be offline and stay offline while
-discp runs. The reason it needs to stay offline is to prevent files from being
-deleted. A table can be cloned and the clone taken offline inorder to avoid