Index: src/docbkx/book.xml
===================================================================
--- src/docbkx/book.xml (revision 1146196)
+++ src/docbkx/book.xml (working copy)
@@ -261,6 +261,17 @@
that includes versioning. Take that into consideration when making your design, as well as block size for the ColumnFamily.
+
+
+ In-Memory ColumnFamilies
+
+ ColumnFamilies can optionally be defined as in-memory. Data is still persisted to disk, just like any other ColumnFamily.
+ In-memory blocks have the highest priority in the , but it is not a guarantee that the entire table
+ will be in memory.
+
+ See HColumnDescriptor for more information.
+
+
@@ -984,9 +995,19 @@
-
-
-
+
+
+
+ Block Cache
+ The Block Cache contains three levels of block priority to allow for scan-resistance and in-memory ColumnFamilies. A block is added with an in-memory
+ flag if the containing ColumnFamily is defined in-memory, otherwise a block becomes a single access priority. Once a block is accessed again, it changes to multiple access.
+ This is used to prevent scans from thrashing the cache, adding a least-frequently-used element to the eviction algorithm. Blocks from in-memory ColumnFamilies
+ are the last to be evicted.
+
+
+ For more information, see the LruBlockCache source
+
+