NULL相关规则

[18110526...@163.com]

Hi, all:
In the new cluster version, we will change the syntax for NULL as follows:

NULL Filter:  IS NULL / IS NOT NULL

NULL Operation:  
1.comparison operators: the result is NULL if you use arithmetic comparison 
operators such as ‘=‘, ‘<‘ or ‘>=‘ to NULL.

2.logic operators: you can treat NULL as False in logic operation.


These rules refer to the mysql syntax, you can see here.  
https://dev.mysql.com/doc/refman/5.7/en/working-with-null.html 



Weihao Li

Timecho

Re: JDBC vs Java API

[Xiangdong Huang]

Qingxin's chart shows the performance difference clearly.
In most case,insertTablet  > insertRecords > insertRecord > JDBC.

---
Xiangdong Huang
School of Software, Tsinghua University

 黄向东
清华大学 软件学院


冯 庆新  于2022年6月6日周一 08:57写道：

> Hello Trevor Hart
>
> Can you access this web link:
> http://111.202.73.147:13000/d/5ZvuEYE7z/atm-biao-zhun-da-qi-ya-huan-jing?orgId=1=26
> Is this one ok?
>
> Config items in benchmark:
> DB_SWITCH=IoTDB-013-JDBC  / SESSION_BY_TABLET / SESSION_BY_RECORDS /
> SESSION_BY_RECORD
> GROUP_NUMBER=10
> LOOP=1000
> DEVICE_NUMBER=50
> SENSOR_NUMBER=500
> BATCH_SIZE_PER_WRITE=100
> POINT_STEP=1000
> OP_INTERVAL=0
> IS_OUT_OF_ORDER=false
>
> B.R
> qingxin.feng
>
>
> 发件人: Trevor Hart
> 发送时间: 2022年6月6日 8:46
> 收件人: dev
> 主题: JDBC vs Java API
>
> Hello Team
>
>
>
> Does anyone have any published benchmark results of JDBC vs the Java API?
>
>
>
> Firstly Im aware of https://github.com/thulab/iotdb-benchmark but I dont
> see any published results for the various API methods.
>
>
>
> I currently use JDBC for my non-realtime ingestion of data and while Ive
> never encountered any bottle necks I am aware that the documentation says
> that JDBC is not recommended for high velocity data.
>
>
>
> Ive done some very basic ingestions benchmarking tests of inserting 1
> million rows and the Java API is around 2x faster. Is this the typical
> improvement between JDBC and Java API?
>
>
>
> For my simplistic test I am inserting 1 millions rows of timestamp &
> incrementing row id eg  insert into root.sg1.d1(timestamp,s1)
> values(${DateTime.Now}, ${n})
>
>
>
> With JDBC I get around 6000 rows per second.
>
>
>
> With the Java native API I get around 12000 rows per second using
> session.executeNonQueryStatement.
>
>
>
> I assume insertTablets and insertRecord(s) would be even faster?
>
>
>
> Thanks
>
> Trevor Hart
>
>

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