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Subject [GitHub] mikewalch closed pull request #44: ACCUMULO-4750 Created caching documentation
Date Thu, 01 Jan 1970 00:00:00 GMT
mikewalch closed pull request #44: ACCUMULO-4750 Created caching documentation

This is a PR merged from a forked repository.
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diff --git a/_docs-2-0/administration/ b/_docs-2-0/administration/
new file mode 100644
index 0000000..be99cb5
--- /dev/null
+++ b/_docs-2-0/administration/
@@ -0,0 +1,46 @@
+title: Caching
+category: administration
+order: 11
+Accumulo tablet servers have a **block cache** that buffers data in memory to limit reads
from disk.
+This caching has the following benefits:
+* reduces latency when reading data
+* helps alleviate hotspots in tables
+The block cache stores index and data blocks. A typical Accumulo read operation will perform
a binary search
+over several index blocks followed by a linear scan of one or more data blocks. Each tablet
+has its own block cache that is shared by all hosted tablets. Therefore, block caches are
only enabled
+for tables where read performance is critical.
+## Configuration
+While the block cache is enabled by default for the Accumulo metadata tables, it must be
+for all other tables by setting the following table properties to `true`:
+* [table.cache.block.enable] - enables data block cache on the table
+* [table.cache.index.enable] - enables index block cache on the table
+These properties can be set in the Accumulo shell using the following command:
+    config -t mytable -s table.cache.block.enable=true
+Or programatically using [TableOperations.setProperty()][tableops]:
+conn.tableOperations().setProperty("mytable", "table.cache.block.enable", "true");
+The sizes of the index and data block caches can be changed from their defaults by setting
+the following properties:
+* []
+* [tserver.cache.index.size]
+[table.cache.block.enable]: {{ page.docs_baseurl }}/administration/configuration-properties#table_cache_block_enable
+[table.cache.index.enable]: {{ page.docs_baseurl }}/administration/configuration-properties#table_cache_index_enable
+[]: {{ page.docs_baseurl }}/administration/configuration-properties#tserver_cache_data_size
+[tserver.cache.index.size]: {{ page.docs_baseurl }}/administration/configuration-properties#tserver_cache_data_size
+[tableops]: {{ page.javadoc_core }}/org/apache/accumulo/core/client/admin/TableOperations.html#setProperty(java.lang.String,
java.lang.String, java.lang.String)
diff --git a/_docs-2-0/getting-started/ b/_docs-2-0/getting-started/
index 6e11b10..60090df 100644
--- a/_docs-2-0/getting-started/
+++ b/_docs-2-0/getting-started/
@@ -341,24 +341,8 @@ See the [combiner example][combiner-example] for example code.
 ## 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:
- Specifies the size of the cache for file data blocks.
-    tserver.cache.index.size: Specifies the size of the cache for file indices.
-To enable the block cache for your table, set the following properties:
-    table.cache.block.enable: Determines whether file (data) block cache is enabled.
-    table.cache.index.enable: Determines whether index cache is enabled.
-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.
+A Block Cache can be enabled on tables to limit reads from disk which can result
+in reduced read latency. Read the [Caching] documentation to learn more.
 ## Compaction
@@ -653,7 +637,6 @@ losing access to the table. See the [export example](
 for example code.
-[config]: /docs/{{ page.version }}/config/
 [constraint]: {{ page.javadoc_core }}/org/apache/accumulo/core/constraints/Constraint.html
 [iterators-user]: {{ page.javadoc_core }}/org/apache/accumulo/core/iterators/user/package-summary.html
@@ -665,3 +648,4 @@ for example code.
 [config-properties]: {{ page.docs_baseurl}}/administration/configuration-properties
 [Scanner]: {{ page.javadoc_core }}/org/apache/accumulo/core/client/Scanner.html
 [BatchScanner]: {{ page.javadoc_core}}/org/apache/accumulo/core/client/BatchScanner.html
+[Caching]: {{ page.docs_baseurl }}/administration/caching


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