[incubator-iotdb] branch master updated: update delete doc (#1020)

[qi...@apache.org]

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qiaojialin pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/incubator-iotdb.git


The following commit(s) were added to refs/heads/master by this push:
     new 2033acf  update delete doc (#1020)
2033acf is described below

commit 2033acf8a3a69d0a032d3ed9f90692efcd265bdf
Author: Jialin Qiao <qj...@mails.tsinghua.edu.cn>
AuthorDate: Fri Apr 10 17:40:34 2020 +0800

    update delete doc (#1020)
---
 docs/SystemDesign/4-StorageEngine/6-DataManipulation.md | 17 ++++++++++-------
 .../SystemDesign/4-StorageEngine/6-DataManipulation.md  | 16 ++++++++++------
 .../db/engine/storagegroup/StorageGroupProcessor.java   |  2 +-
 3 files changed, 21 insertions(+), 14 deletions(-)

diff --git a/docs/SystemDesign/4-StorageEngine/6-DataManipulation.md b/docs/SystemDesign/4-StorageEngine/6-DataManipulation.md
index 60d6253..78dd676 100644
--- a/docs/SystemDesign/4-StorageEngine/6-DataManipulation.md
+++ b/docs/SystemDesign/4-StorageEngine/6-DataManipulation.md
@@ -70,14 +70,17 @@ Old data is automatically deleted by merging, see:
 * Corresponding interface
   * JDBC's execute interface, using delete SQL statements
 
-* Main entrance: public void delete(String deviceId, String measurementId, long timestamp) StorageEngine.java
-    * Find the corresponding StorageGroupProcessor
-    * Find all TsfileProcessor affected
-    * Pre-write log
-    * Find all TsfileResources affected
-    * Record the point in time of deletion in the mod file
-    * If the file is not closed (the corresponding TsfileProcessor exists), delete the data in memory
+Each StorageGroupProcessor maintains a ascending version for each partition, which is managed by SimpleFileVersionController.
+Each memtable will apply a version when submitted to flush. After flushing to TsFile, a current position-version will added to TsFileMetadata. 
+This information will be used to set version to ChunkMetadata when query.
 
+* main entrance: public void delete(String deviceId, String measurementId, long timestamp) StorageEngine.java
+  * Find the corresponding StorageGroupProcessor
+  * Find all impacted working TsFileProcessors to write WAL
+  * Find all impacted TsFileResources to record a Modification in its mods file, the Modification format is: path，deleteTime，version
+  * If the TsFile is not closed，get its TsFileProcessor
+    * If there exists the working memtable, delete data in it
+    * If there exists flushing memtable，record the deleted time in it for query.（Notice that the Modification is recorded in mods for these memtables）
 
 ## Data TTL setting
 
diff --git a/docs/zh/SystemDesign/4-StorageEngine/6-DataManipulation.md b/docs/zh/SystemDesign/4-StorageEngine/6-DataManipulation.md
index 8b60018..51f024b 100644
--- a/docs/zh/SystemDesign/4-StorageEngine/6-DataManipulation.md
+++ b/docs/zh/SystemDesign/4-StorageEngine/6-DataManipulation.md
@@ -71,13 +71,17 @@
 * 对应的接口
 	* JDBC 的 execute 接口，使用delete SQL语句
 	
+每个 StorageGroupProsessor 中针对每个分区会维护一个自增的版本号，由 SimpleFileVersionController 管理。
+每个内存缓冲区 memtable 在持久化的时候会申请一个版本号。持久化到 TsFile 后，会在 TsFileMetadata 中记录此 memtable 对应的 多个 ChunkGroup 的终止位置和版本号。
+查询时会根据此信息对 ChunkMetadata 赋 version。
+	
 * 总入口: public void delete(String deviceId, String measurementId, long timestamp) StorageEngine.java
-    * 找到对应的 StorageGroupProcessor
-    * 找到受影响的所有TsfileProcessor
-    * 写写前日志
-    * 找到受影响的所有TsfileResource
-    * 在mod文件中记录删除的时间点
-    * 如果文件没有关闭（存在对应的TsfileProcessor），则删除内存中的数据
+  * 找到对应的 StorageGroupProcessor
+  * 找到受影响的所有 working TsFileProcessor 记录写前日志
+  * 找到受影响的所有 TsFileResource，在其对应的 mods 文件中记录一条记录：path，deleteTime，version
+  * 如果文件没有关闭，拿到对应的 TsFileProcessor
+    * 如果存在 working memtable：则删除内存中的数据
+    * 如果存在 正在 flush 的 memtable，记录一条记录，查询时跳过删掉的数据（注意此时文件中已经为这些 memtable 记录了 mods）
 
 
 ## 数据TTL设置
diff --git a/server/src/main/java/org/apache/iotdb/db/engine/storagegroup/StorageGroupProcessor.java b/server/src/main/java/org/apache/iotdb/db/engine/storagegroup/StorageGroupProcessor.java
index d3afe72..27d0acf 100755
--- a/server/src/main/java/org/apache/iotdb/db/engine/storagegroup/StorageGroupProcessor.java
+++ b/server/src/main/java/org/apache/iotdb/db/engine/storagegroup/StorageGroupProcessor.java
@@ -1149,7 +1149,7 @@ public class StorageGroupProcessor {
 
       // time partition to divide storage group
       long timePartitionId = StorageEngine.getTimePartition(timestamp);
-      // write log
+      // write log to impacted working TsFileProcessors
       logDeletion(timestamp, deviceId, measurementId, timePartitionId);
 
       Path fullPath = new Path(deviceId, measurementId);