diff --git a/docs/user_manual/Small_Materialized_Aggrates.md b/docs/user_manual/Small_Materialized_Aggrates.md
new file mode 100644
index 0000000000000000000000000000000000000000..e13a623afb144a3f785fdfc59f3e7e880667463c
--- /dev/null
+++ b/docs/user_manual/Small_Materialized_Aggrates.md
@@ -0,0 +1,42 @@
+# Small Materialized Aggragates
+
+**SMA** (**S**mall **M**aterialized **A**ggrates) is used to speed up the query process on materialized data cube in TDengine. TDengine 3.0 gives more flexibility on the SMA configurations.
+
+There are two kinds of SMA in TDengine:
+1. Block-wise SMA
+2. Time-range-wise SMA
+
+<!-- 
+```plantuml
+    @startmindmap mind_map_test
+    * SMA
+    ** Block-wise SMA
+    ** Time-range-wise SMA
+    @endmindmap
+```  -->
+
+![SMA in TDengine 3.0](http://www.plantuml.com/plantuml/png/Kr1GK70eBaaiAidDp4l9JInG0D7nG4PyIMfn2HTGMa5B8TZN4SBIKd3AoK_ErYtFB4v55Wt9p4tLBKhCIqz5bN981HeACHW0)
+## Block-wise SMA
+Block-wise SMA is created by default when the data are committed. Since time-series data are saved as block data in files, a corresponding SMA is create when the data block is written. The default block-wise SMA includes:
+1. sum(*)
+2. max(*)
+3. min(*)
+
+By default, the system will create SMA for each column except those columns with type *binary* and *nchar*. However, users can change the behavior by the keyword **NOSMA** to disable the SMA for a certain column like below:
+```SQL
+# create a super table with the SMA on column b disabled
+create table st (ts timestamp, a int, b int NOSMA, c double) tags (tg1 binary(10), tg2 int);
+```
+
+## Time-range-wise SMA
+In addition to the default block-wise SMA, users can create their own SMAs ondemand. Below is an example to create a SMA.
+```SQL
+# create a SMA every 10 minutes with SMA of sum, max and min
+create sma_indx sma_10min on st (sum(*), max(*), min(*), twa(*)) interval(10m);
+```
+Users can also drop a time-range-wise SMA like below:
+```SQL
+# drop the sma index
+drop sma_index sma_5min on st;
+```
+**NOTE: Creating an SMA index is a heavy operation which may take a long time and block the write operation. So create the time-range-wise SMA when creating the table or when there are not too much data.**
\ No newline at end of file
diff --git a/source/server/vnode/CMakeLists.txt b/source/server/vnode/CMakeLists.txt
index 573cea79b5066db8e826d32378584d62abc6734d..a4a9cff002a16f990e3010e06ed4461864c1ed64 100644
--- a/source/server/vnode/CMakeLists.txt
+++ b/source/server/vnode/CMakeLists.txt
@@ -1,26 +1,4 @@
 add_subdirectory(meta)
 add_subdirectory(tq)
 add_subdirectory(tsdb)
-
-aux_source_directory(src VNODE_SRC)
-add_library(vnode STATIC ${VNODE_SRC})
-target_include_directories(
-    vnode
-    PUBLIC "${CMAKE_SOURCE_DIR}/include/server/vnode"
-    private "${CMAKE_CURRENT_SOURCE_DIR}/inc"
-)
-target_link_libraries(
-    vnode
-    PUBLIC transport
-    PUBLIC meta
-    PUBLIC tq
-    PUBLIC tsdb
-    PUBLIC wal
-    PUBLIC sync
-    PUBLIC cjson
-)
-
-# test
-if(${BUILD_TEST})
-    add_subdirectory(test)
-endif(${BUILD_TEST})
\ No newline at end of file
+add_subdirectory(impl)
\ No newline at end of file
diff --git a/source/server/vnode/impl/CMakeLists.txt b/source/server/vnode/impl/CMakeLists.txt
new file mode 100644
index 0000000000000000000000000000000000000000..81744df79c008114e807052fe48fe3166caf7580
--- /dev/null
+++ b/source/server/vnode/impl/CMakeLists.txt
@@ -0,0 +1,22 @@
+aux_source_directory(src VNODE_SRC)
+add_library(vnode STATIC ${VNODE_SRC})
+target_include_directories(
+    vnode
+    PUBLIC "${CMAKE_SOURCE_DIR}/include/server/vnode"
+    private "${CMAKE_CURRENT_SOURCE_DIR}/inc"
+)
+target_link_libraries(
+    vnode
+    PUBLIC transport
+    PUBLIC meta
+    PUBLIC tq
+    PUBLIC tsdb
+    PUBLIC wal
+    PUBLIC sync
+    PUBLIC cjson
+)
+
+# test
+if(${BUILD_TEST})
+    add_subdirectory(test)
+endif(${BUILD_TEST})
\ No newline at end of file
diff --git a/source/server/vnode/inc/vnodeCommit.h b/source/server/vnode/impl/inc/vnodeCommit.h
similarity index 100%
rename from source/server/vnode/inc/vnodeCommit.h
rename to source/server/vnode/impl/inc/vnodeCommit.h
diff --git a/source/server/vnode/inc/vnodeFile.h b/source/server/vnode/impl/inc/vnodeFile.h
similarity index 100%
rename from source/server/vnode/inc/vnodeFile.h
rename to source/server/vnode/impl/inc/vnodeFile.h
diff --git a/source/server/vnode/inc/vnodeInt.h b/source/server/vnode/impl/inc/vnodeInt.h
similarity index 100%
rename from source/server/vnode/inc/vnodeInt.h
rename to source/server/vnode/impl/inc/vnodeInt.h
diff --git a/source/server/vnode/inc/vnodeMain.h b/source/server/vnode/impl/inc/vnodeMain.h
similarity index 100%
rename from source/server/vnode/inc/vnodeMain.h
rename to source/server/vnode/impl/inc/vnodeMain.h
diff --git a/source/server/vnode/inc/vnodeMemAllocator.h b/source/server/vnode/impl/inc/vnodeMemAllocator.h
similarity index 100%
rename from source/server/vnode/inc/vnodeMemAllocator.h
rename to source/server/vnode/impl/inc/vnodeMemAllocator.h
diff --git a/source/server/vnode/inc/vnodeMgmt.h b/source/server/vnode/impl/inc/vnodeMgmt.h
similarity index 100%
rename from source/server/vnode/inc/vnodeMgmt.h
rename to source/server/vnode/impl/inc/vnodeMgmt.h
diff --git a/source/server/vnode/inc/vnodeRead.h b/source/server/vnode/impl/inc/vnodeRead.h
similarity index 100%
rename from source/server/vnode/inc/vnodeRead.h
rename to source/server/vnode/impl/inc/vnodeRead.h
diff --git a/source/server/vnode/inc/vnodeReadMsg.h b/source/server/vnode/impl/inc/vnodeReadMsg.h
similarity index 100%
rename from source/server/vnode/inc/vnodeReadMsg.h
rename to source/server/vnode/impl/inc/vnodeReadMsg.h
diff --git a/source/server/vnode/inc/vnodeWrite.h b/source/server/vnode/impl/inc/vnodeWrite.h
similarity index 100%
rename from source/server/vnode/inc/vnodeWrite.h
rename to source/server/vnode/impl/inc/vnodeWrite.h
diff --git a/source/server/vnode/inc/vnodeWriteMsg.h b/source/server/vnode/impl/inc/vnodeWriteMsg.h
similarity index 100%
rename from source/server/vnode/inc/vnodeWriteMsg.h
rename to source/server/vnode/impl/inc/vnodeWriteMsg.h
diff --git a/source/server/vnode/src/vnodeCommit.c b/source/server/vnode/impl/src/vnodeCommit.c
similarity index 100%
rename from source/server/vnode/src/vnodeCommit.c
rename to source/server/vnode/impl/src/vnodeCommit.c
diff --git a/source/server/vnode/src/vnodeFile.c b/source/server/vnode/impl/src/vnodeFile.c
similarity index 100%
rename from source/server/vnode/src/vnodeFile.c
rename to source/server/vnode/impl/src/vnodeFile.c
diff --git a/source/server/vnode/src/vnodeInt.c b/source/server/vnode/impl/src/vnodeInt.c
similarity index 100%
rename from source/server/vnode/src/vnodeInt.c
rename to source/server/vnode/impl/src/vnodeInt.c
diff --git a/source/server/vnode/src/vnodeMain.c b/source/server/vnode/impl/src/vnodeMain.c
similarity index 100%
rename from source/server/vnode/src/vnodeMain.c
rename to source/server/vnode/impl/src/vnodeMain.c
diff --git a/source/server/vnode/src/vnodeMemAllocator.c b/source/server/vnode/impl/src/vnodeMemAllocator.c
similarity index 100%
rename from source/server/vnode/src/vnodeMemAllocator.c
rename to source/server/vnode/impl/src/vnodeMemAllocator.c
diff --git a/source/server/vnode/src/vnodeMgmt.c b/source/server/vnode/impl/src/vnodeMgmt.c
similarity index 100%
rename from source/server/vnode/src/vnodeMgmt.c
rename to source/server/vnode/impl/src/vnodeMgmt.c
diff --git a/source/server/vnode/src/vnodeRead.c b/source/server/vnode/impl/src/vnodeRead.c
similarity index 100%
rename from source/server/vnode/src/vnodeRead.c
rename to source/server/vnode/impl/src/vnodeRead.c
diff --git a/source/server/vnode/src/vnodeReadMsg.c b/source/server/vnode/impl/src/vnodeReadMsg.c
similarity index 100%
rename from source/server/vnode/src/vnodeReadMsg.c
rename to source/server/vnode/impl/src/vnodeReadMsg.c
diff --git a/source/server/vnode/src/vnodeWrite.c b/source/server/vnode/impl/src/vnodeWrite.c
similarity index 100%
rename from source/server/vnode/src/vnodeWrite.c
rename to source/server/vnode/impl/src/vnodeWrite.c
diff --git a/source/server/vnode/src/vnodeWriteMsg.c b/source/server/vnode/impl/src/vnodeWriteMsg.c
similarity index 100%
rename from source/server/vnode/src/vnodeWriteMsg.c
rename to source/server/vnode/impl/src/vnodeWriteMsg.c
diff --git a/source/server/vnode/test/CMakeLists.txt b/source/server/vnode/impl/test/CMakeLists.txt
similarity index 100%
rename from source/server/vnode/test/CMakeLists.txt
rename to source/server/vnode/impl/test/CMakeLists.txt
diff --git a/source/server/vnode/test/vnodeMemAllocatorTest.cpp b/source/server/vnode/impl/test/vnodeMemAllocatorTest.cpp
similarity index 100%
rename from source/server/vnode/test/vnodeMemAllocatorTest.cpp
rename to source/server/vnode/impl/test/vnodeMemAllocatorTest.cpp
diff --git a/source/server/vnode/test/vnodeTests.cpp b/source/server/vnode/impl/test/vnodeTests.cpp
similarity index 100%
rename from source/server/vnode/test/vnodeTests.cpp
rename to source/server/vnode/impl/test/vnodeTests.cpp