The prospect of hive digital currency
1、 Different definitions:
1. virtual currency:
virtual currency refers to non real currency
digital currency:digital currency is an alternative currency in the form of electronic currency. Both digital gold coin and cryptocurrency belong to digiccy
3. Cryptocurrency:
cryptocurrency is a kind of transaction medium that uses cryptography principles to ensure transaction security and control the creation of transaction units
4. Token (token):
a kind of article whose shape and size are similar to currency, but the scope of use is limited and has no currency effect, and its token is the homonym of token in English
Second, the characteristics are different:1; It can also be said that virtual currency is personalized currency. In another way, it can also be called information currency
2. Digital currency:
is an unregulated and digital currency, which is usually issued and managed by developers and accepted and used by members of specific virtual communities
Cryptocurrency:cryptocurrency is based on the decentralized consensus mechanism, which is opposite to the banking and financial system relying on the centralized regulatory system
4. Token (token):
usually needs to be exchanged for money, used in shops, playgrounds, mass transportation and other places, as a voucher to use services and exchange goods
extended data
at present, digital currency is more like an investment proct, because it lacks a strong guarantee agency to maintain its price stability, and its role as a value measure has not yet appeared, so it can not be used as a means of payment. As an investment proct, digital currency cannot develop without trading platform, operating company and investment company
digital currency is a double-edged sword. On the one hand, the blockchain technology it relies on has been decentralized and can be used in other fields except digital currency, which is one of the reasons why bitcoin is popular; On the other hand, if digital currency is widely used by the public as a kind of currency, it will have a huge impact on the effectiveness of monetary policy, financial infrastructure, financial market and financial stability
29 well-known companies in the world hold more than US $30 billion in digital assets
recently, a new trend has emerged, because many well-known companies have decided to use bitcoin (BTC) for reserves rather than traditional assets. After MicroStrategy bought $250 million worth of BTC, the trend became popular. Soon after, the company continued to buy more bitcoin. After several purchases, MicroStrategy has increased its holdings to 70470 BTC or. 336% of its supply. After the acquisition of MicroStrategy, square Inc. and other companies began to acquire. And ruffer investments joined the bitcoin buying trend
according to bitpointstudies.org, a portal, many companies hold more than 1.1 million bitcoins or more than $30 billion worth of encryption assets. After MicroStrategy, a billion dollar company, bought $250 million worth of bitcoin in August, the large amount of bitcoin reserves held by well-known companies began to expand. Now 29 companies hold cryptocurrency instead of traditional reserves such as stocks and cash
so far, a total of 29 companies have been listed on bitpointresearches.org, which divides all companies into three different parts. Publicly traded, private and ETF like holders
mining Corp., Voyager digital Ltd., riot blockchain, Inc., bit digital, Inc., coin citadel Inc., advanced bitcoin Technologies AG, digitalx, hive blockchain, cypherpunk Holdings Inc., big digital assets Inc, The 15 publicly traded companies, Argo blockchain and frmo Corp., have a total market value of about 100003 and 160; BTC, the private company holding bitcoin funds, includes four private companies, including mtgox KK, block.one, tezos foundation and stone ridge holdings group. Among the reserves of all four companies, the total market value of private companies is 317383-160 more than that of listed companies; BTC
at the bottom of bitpointstudies.org, there are nine ETF like holders, including grayscale bitcoin trust, coinshares, ruffer investment, 3iq the bitcoin fund, grayscale digital large cap, bitwise 10 crypto index fund, WisdomTree bitcoin, 21shares AG, etc & 160; Group's bitcoin ETP
including tahini & x27, a Canadian restaurant chain; S and snappa, a Canadian graphics software company. Tahini's restaurant chain revealed that it converted all of its cash reserves into BTC, while snappa said it spent 40% of its cash reserves on bitcoin transactions. Mogo, a Canadian listed company, has just announced that it will invest 1.5% of its reserves in bitcoin and plans to buy more next year. When tahini decided to tell his financial adviser that he would buy bitcoin immediately, he suggested using gold. The owner of the restaurant said the precious metal gold has become a reliable haven
the company tweeted: &“ We looked at our financial adviser and told him that because of bitcoin, gold would become a scam. " Tashini added: "he laughed and condescended back to the 6000 year argument."
main parameters
1, CodeGen
2, create hive table
3, Eval
4, export
5, import
6, import all tables
7, job
8, list databases
9, list tables
10, merge
11, metadata
12, version
13, help
CodeGen
map relational database table to a java file, and generate class, table, table, table, table, etc As well as the related jar package, the main functions are as follows:
1. Map the database table to a java file, in which there are corresponding fields of the table
2. The generated jar and class files will be used in the Metastore function
basic statement:
sqoop CodeGen – connect jdbc:mysql :// localhost:3306/hive – username root – password 123456 – table tbls2
create hive table
generate hive table corresponding to table structure of relational database table
basic statement:
sqoop create hive table – connect jdbc:mysql :// localhost:3306/hive -username root -password 123456 –t able TBLS –hive-table h_ Tbls2
Eval
can quickly use SQL statements to operate the relational database, which can make it possible to know whether the relevant SQL statements are correct in advance when using import to import data, and display the results on the console
basic statement:
sqoop Eval – connect jdbc:mysql :// localhost:3306/hive -User name root - password 123456 - query "select * from tbls limit 10"
export
import data from HDFS to relational database
basic statement:
sqoop export – connect jdbc:mysql :// localhost:3306/hive –username root –password
123456 –table TBL S2 – export dir sqoop / test
Import
import the data of relational database into hive. If there is no corresponding table in hive, the table with the same name as the relational database table will be automatically generated
basic statement:
sqoop import – connect jdbc:mysql :// localhost:3306/hive – user name root – password
123456 – table user – split by ID
import all tables
import all tables in the database into HDFS, and each table corresponds to an independent directory in HDFS
basic statement:
sqoop import all tables – connect jdbc:mysql :// localhost:3306/test