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Posted to commits@iotdb.apache.org by qi...@apache.org on 2020/04/07 04:01:13 UTC
[incubator-iotdb] 03/03: update delete doc
This is an automated email from the ASF dual-hosted git repository.
qiaojialin pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/incubator-iotdb.git
commit 3565f133a4322e55911a964d16128959a6b69308
Author: qiaojialin <64...@qq.com>
AuthorDate: Tue Apr 7 12:00:59 2020 +0800
update delete doc
---
docs/SystemDesign/5-DataQuery/8-ModificationHandle.md | 18 ++++++++++++++----
.../SystemDesign/5-DataQuery/8-ModificationHandle.md | 18 ++++++++++++++----
2 files changed, 28 insertions(+), 8 deletions(-)
diff --git a/docs/SystemDesign/5-DataQuery/8-ModificationHandle.md b/docs/SystemDesign/5-DataQuery/8-ModificationHandle.md
index 1166250..2871332 100644
--- a/docs/SystemDesign/5-DataQuery/8-ModificationHandle.md
+++ b/docs/SystemDesign/5-DataQuery/8-ModificationHandle.md
@@ -21,25 +21,35 @@
# Modification handling in query
+Background:
+
Data deletion only record a mods file for disk data, the data is not really deleted. Therefore, we need to consider the modifications in query.
-Each timeseries is treated independently in query process. For each timeseries, there are 5 levels: TsFileResource -> TimeseriesMetadata -> ChunkMetadata -> IPageReader -> BatchData
+If a TsFile is influenced by deletion, a deletion operation will be recorded in its mods file. The log contains 3 parts: path, deleted time, version
+
+## Related class
+
+mods file: org.apache.iotdb.db.engine.modification.ModificationFile
-Query resource: TsFileResource and possibly exist mods file. If a TsFile is influenced by deletion, a modification log will be recorded in its mods file. The log contains 3 parts: path, deleted time, version
+deletion operation: org.apache.iotdb.db.engine.modification.Modification
+
+## Query process
+Each timeseries is treated independently in query process. For each timeseries, there are 5 levels: TsFileResource -> TimeseriesMetadata -> ChunkMetadata -> IPageReader -> BatchData
+
* TsFileResource -> TimeseriesMetadata
```
-// Set the statistics in TimeseriesMetadata unusable if the timeseries contains modifications
+// Set the statistics in TimeseriesMetadata unusable if the timeseries contains deletion operations
FileLoaderUtils.loadTimeseriesMetadata()
```
* TimeseriesMetadata -> List\<ChunkMetadata\>
```
-// For each ChunkMetadata, find the largest timestamp in all modifications whose version is larger than it. Set deleted time to ChunkMetadata.
+// For each ChunkMetadata, find the largest timestamp in all deletion operations whose version is larger than it. Set deleted time to ChunkMetadata.
// set the statistics in ChunkMetadata is unusable if it is affected by deletion
FileLoaderUtils.loadChunkMetadataList()
```
diff --git a/docs/zh/SystemDesign/5-DataQuery/8-ModificationHandle.md b/docs/zh/SystemDesign/5-DataQuery/8-ModificationHandle.md
index ce4ff7b..d3357ed 100644
--- a/docs/zh/SystemDesign/5-DataQuery/8-ModificationHandle.md
+++ b/docs/zh/SystemDesign/5-DataQuery/8-ModificationHandle.md
@@ -21,25 +21,35 @@
# 查询中的数据修改处理
+背景介绍：
+
数据删除操作对磁盘数据只记录了 mods 文件，并未真正执行删除逻辑，因此查询时需要考虑数据删除的逻辑。
-查询时每个时间序列会单独处理。针对一个时间序列，由大到小有 5 个层次：TsFileResource -> TimeseriesMetadata -> ChunkMetadata -> IPageReader -> BatchData
+如果一个文件中有数据被删除了，将删除操作记录到 mods 文件中。记录三列：删除的时间序列，删除范围的最大时间点，删除操作对应的版本。
+
+## 相关类
+
+mods 文件: org.apache.iotdb.db.engine.modification.ModificationFile
-查询资源：TsFileResource 以及可能存在的 mods 文件，如果一个文件中有数据被删除了，将删除操作记录到 mods 文件中。记录三列：删除的时间序列，删除范围的最大时间点，删除操作对应的版本。
+删除操作: org.apache.iotdb.db.engine.modification.Modification
+
+## 查询流程
+查询时每个时间序列会单独处理。针对一个时间序列，由大到小有 5 个层次：TsFileResource -> TimeseriesMetadata -> ChunkMetadata -> IPageReader -> BatchData
+
* TsFileResource -> TimeseriesMetadata
```
-// 只要这个时间序列有对应的 modification，就标记 TimeseriesMetadata 中的统计信息不可用
+// 只要这个时间序列有对应的删除操作，就标记 TimeseriesMetadata 中的统计信息不可用
FileLoaderUtils.loadTimeseriesMetadata()
```
* TimeseriesMetadata -> List\<ChunkMetadata\>
```
-// 对于每个 ChunkMetadata，找到比其 version 大的所有 modification 中最大时间戳, 设置到 ChunkMetadata 的 deleteAt 中，并标记 统计信息不可用
+// 对于每个 ChunkMetadata，找到比其 version 大的所有删除操作中最大时间戳, 设置到 ChunkMetadata 的 deleteAt 中，并标记 统计信息不可用
FileLoaderUtils.loadChunkMetadataList()
```