Previous logic can't update the mappings `properties parameters` and `_source` only support adding a new property.
### Now
1. As the OAP core merges the index of metrics, properties would not be deleted still.
2. Would not update the current index to avoid conflict, a new index follows the new template to create.
**Warning**, if there are properties conflicts, same key with different values, they would override each other according to booting sequence. Unless we change booting process as merging modules before merging with existing templates and indices, we can't add check mechanism and warnings.
* Add `Column.shardingKeyIdx` for column definition for BanyanDB.
```
Sharding key is used to group time series data per metric of one entity in one place (same sharding or same
column for column-oriented database).
For example,
ServiceA's traffic gauge, service call per minute, includes following timestamp values, then it should be sharded by service ID
[ServiceA(encoded ID): 01-28 18:30 values-1, 01-28 18:31 values-2, 01-28 18:32 values-3, 01-28 18:32 values-4]
BanyanDB is the 1st storage implementation supporting this. It would make continuous time series metrics stored closely and compressed better.
NOTICE, this sharding concept is NOT just for splitting data into different database instances or physical files.
```
* Add `JD_PRESERVE_LINE_FEEDS=true` in official code style file. Then our comments don't have to use many blank lines to keep format.
* Add storage column attribute `indexOnly`, support ElasticSearch only index and not store some fields.
* Add `indexOnly=true` to `SegmentRecord.tags`, to reduce unnecessary storage.
* Fix IoTDB Storage Option insert null index value.
* Set the default value of SW_STORAGE_IOTDB_SESSIONPOOL_SIZE to 8
* Bump up iotdb-session to 0.12.4
* Update doc
The ES persistence execution is now asynchronous and the execution
latency only counts the time to insert the requests into the bulk
processor, instead of the time after the requests are flushed into the
storage, this patch fixes that issue.
There is the same issue in prepare latency but that needs more changes
so I'll leave it to another pull request.
* [maven-release-plugin] prepare release v8.8.0
* [maven-release-plugin] prepare for next development iteration
* Create changes-8.8.0.md
* Reset changelog for 8.9.0
吴晟 Wu Sheng
刘威
mrproliu
Kai
kezhenxu94
Brandon Fergerson
Daniel Qian
Kirs
zhang-wei
nicolchen