Abstract: This section describes the time zone knowledge and usage of GaussDB(DWS).
This article was published by Leapdb in the Time Zone everyone knows.
background
Time zones Like other industrial standards, the standardization process is a complex and lengthy process. **GaussDB(DWS) is a high-performance analytical database product for global users, and supports time zones in accordance with industry standards. ** This section describes GaussDB(DWS) in terms of time zone concepts, time zone usage and working principles, and faQs.
I hope it helps you understand GaussDB(DWS) and time zone concepts.
Concept paper
In the past, when countries around the world were agricultural, people determined time by looking at the position of the sun every day, which resulted in different times in different longitudes. At that time, people traveled mainly by foot and horses, and the problem of inconsistent time in different places was less prominent. But in the nineteenth century, with the invention of the train, people suddenly traveled much longer distances in a day, to different places and there was an urgent need for a universal way to unify time in different places. On Aug. 12, 1853, two trains collided head-on in the eastern U.S. state of Rhode Island, killing 14 people. The cause of the accident seems implausible today – the watches of the engineers in two cars were two minutes apart.
- The concept of time zones was first used in 1863. Time zones partly solve this problem by setting a standard time for a region.
- 1870s Canadian railway engineer Fleming first proposed the world according to a unified standard division of time zones.
- On November 18, 1883, the United States Railroad officially implemented five time zones.
- In 1884, the International Conference on the Washington Meridian officially adopted the time zone division, known as the Universal standard time system. As a result, the emergence of world standard time zones, like other global standards, has been a slow process of development.
1
Time zones TIME zones are regions on the earth that use the same definition of time. In the past, people determined time by looking at the position of the sun (hour Angle), which made it different in places with different longitudes (local time). The concept of time zones was first used in 1863. Time zones partly solve this problem by setting a standard time for a region. Different countries in the world are located in different parts of the earth, so the time of sunrise and sunset is bound to vary from country to country, especially those with a large east-west span. These deviations are known as jet lag.
Greenwich Mean Time (GMT) is Greenwich Mean Time at the Royal Greenwich Observatory on the outskirts of London, England, because prime meridian is defined as the longitude that passes there. Because the Earth moves at an uneven speed in its elliptical orbit, its daily rotation is somewhat irregular and is slowly slowing down. As a result, Greenwich Time is no longer used as standard time.
Coordinated Universal Time (UTC) is the actuarial Time based on the average solar Time (based on Greenwich Mean Time (GMT)), the new Time scale modified by the motion of the Earth’s axis, and the International atomic Time in seconds. UTC is more accurate than GMT. For current watches, GMT and UTC are no different in functionality and accuracy.
Daylight Saving Time (DST) is also known as Summer Time in the United Kingdom. It is a system of artificially set local time to save energy. The unified time used during this system is called “daylight saving time”. The summer that is earlier in dawn commonly is factitious adjusts time fast one hour, can make the person gets up early and goes to bed early, reduce illume quantity, in order to make full use of illuminant resource, economize illume thereby use electricity. Different countries adopt daylight saving time.
Time zone notation If the time is expressed in Coordinated Universal Time (UTC), a “Z” (no space) is immediately followed by the time. “Z” is the symbol of time zone 0 in COORDINATED Universal Time. Therefore, “09:30 UTC” is written as “09:30z” or “0930Z”. “14:45:15 UTC” is “14:45:15z” or “144515Z”. UTC time is also called Zulu time because of the NATO phonetic alphabet “Zulu” for “Z”.
UTC offset A UTC offset is the time and date difference between Coordinated Universal Time (UTC) and a specific place, expressed in hours and minutes. It is usually displayed in ±[hh]:[mm], ±[hh][mm], or ±[hh] format. So, if the time being described is one hour earlier than UTC (such as Winter time in Berlin), the UTC offset will be “+01:00”, “+0100”, or simply “+01”.
Country time adjustment
Tunisia has abolished daylight saving time in Tunisia since 2010. Tunisia has moved the start of daylight saving time from June 1 to May 2 and the end of Daylight saving time from August 21 to August 8. Macquarie Island, located between Australia and Antarctica, has decided not to join the rest of Australia in adopting daylight saving time from April 4, 2010, resulting in the creation of a new time zone, Antarctica/Macquarie, or MIST 4. North Korea – With effect from 5 May 2018, the time zone has been adjusted from GMT+8:30 to GMT+9:00. As a result, the standard time in Pyongyang has been moved forward by 30 minutes from 00:00:00 to 00:30:00 on Saturday, 5 May 2018. When GMT is 0:00 a.m., Pyongyang time is 9:00 a.m., the same time zone as South Korea and Japan. 5. North Korea – On 15 August 2015, the GMT+9 time zone was abandoned and the GMT+8:30 standard time was “restored” to the Korean Imperial time zone by 30 minutes, making it the only country in the world currently using this time zone. When GMT is 0:00 a.m., Pyongyang time is 8:30 a.m. 6. Chile – On January 28, 2015, Chile adopted a new official standard time. They merged the original standard time and Daylight Saving Time into one, making daylight saving time permanent. The new official time is GMT-3 on the Chilean mainland and GMT-5 on Easter Island. 7. Russia – From the dawn of the last Sunday in October 2014 (26 October 2014), the permanent winter time system will be adopted, and the whole country will be set back by one hour. Moscow time will therefore be changed from GMT+4 to GMT+3.
As you can see, both time zones and daylight saving time change frequently.
2. Universal time format
Refer mainly to Posix 1003.1 Section 8.3. The TZ environment variable in the operating system represents time zone information and is mainly used for ctime, localtime, mktime, and so on. The TZ time zone name can be in two formats: time zone name format and POSIX time zone format.
2.1 Time zone name format
:characters The format starts with a colon, followed by implementation-dependent character processing. On Linux, time zone information is read from a file. For example, TZ=”:Pacific/Auckland”.
2.2 POSIX Time zone format
STD offset[DST [offset][, startDate [/time], endDate [/time]] STD offset[DST [offset][, startDate [/time], endDate [/time]]
Format: ‘STD offset[DST [offset][, startDate [/time], endDate [/time]]’
The meanings of the parameters are as follows:
1. STD && DST stands for both standard and daylight saving time zones, STD is required and DST is optional (DST field means daylight saving time is supported). These two fields have two formats:
- A. A character string with a reference symbol <>. The character string in the reference symbol can be letters, numbers, +, or -, but does not contain the reference symbol <>.
- B. The other, without the reference symbol <>, can only be letters.
The field length is greater than or equal to 3 and less than or equal to TZNAME_MAX (Linux is 6). If the string length is not specified, the parsing rule is not defined (Linux does not recognize it).
2. Offset represents the local time plus the UTC time.
The format is hh[:mm[:ss]], 0<=hh<= 24,0 <=mm&&ss<=59. Hh is required and can be 1 bit, mm and ss are optional.
- If it is preceded by a plus sign, it means west of the prime meridian. Represents the amount of time added to this time to obtain UTC time. Plus plus is not a plus.
- If it’s preceded by a minus sign -, that means east of the prime meridian. Represents how much time is subtracted from this time to get UTC time.
Offset after STD is required, offset after DST is optional, and if not, one hour ahead of standard time is default.
Rule says 3. When to begin to daylight saving time, when the end of the summer time, the agreement did not mention how to deal with the situation there is no rule, from the point of Linux system, there is no default rule by M3.2.0/02:00:00, M11.1.0/02:00:00 processing.
The format is date[/time],date[/time]. Date has three forms:
A. Jn, 1 <= n <= 365, excluding February 29 in leap years; B. n, 0 <= n <= 365, including February 29 in leap years; C. Mm. N.d, where m is the month (1 <= m <= 12), n is the week of a month (1 <= n <= 5), 5 is the last one, and D is the day of a week (0 <= d <= 6, starting from Sunday).
4. The format of time is the same as that of offset, except that there is no + or -. If there is no time field, the default value is 02:00:00.
For example: “UTC – 8:00:00 DST – 09:00:00 M3.2.0/02:00:00, M11.1.0/02:00:00”, said the local time to UTC east 8 hours, support daylight saving time and daylight saving time for UTC minus nine hours (and) an hour earlier, Daylight saving time begins at 2am on the 0th day of the second week in March and ends at 2am on the 0th day of the first week in November. CST6CDT M3.2.0/2:00:00, M11.1.0/2:00:00
POSIX time zone formats have not been widely adopted because they cannot represent times that are not in use of the Gregorian calendar (such as Greece).
3. Universal time zone database
Local time zones and daylight saving time rules are managed independently by their respective governments, which often change them with limited notice. And their historical data and future plans are only intermittently recorded. The Universal Time Zone database attempts to organize and organize data related to this domain.
The Time zone database, often referred to as TZ, TZData or ZoneInfo, is a collection of code and data that represents the history of local time in many representative locations around the globe, updated irregularly according to regime changes to time zone boundaries and daylight saving time rules. Each entry in the database represents the time zone information for a civilian clock that has been widely accepted since 1970. The database is referenced by many projects, such as: the GNU C Library (used in GNU/Linux), Android, FreeBSD, NetBSD, OpenBSD, Chromium OS, Cygwin, MariaDB, MINIX, MySQL, WebOS, AIX, BlackBerry 10, iOS, macOS, Microsoft Windows, OpenVMS, Oracle Database, and Oracle Solaris. Like other widely used software products, GaussDB uses the universal time zone data maintained by IANA.
The database was created by David Olson and edited and maintained by Paul Eggert. It is also called an Olson database in some places. Its distinctive feature is a common naming convention for time zones designed by Paul Eggert. Each time zone is given a unique name in a “region/location” format, such as “America/New_York”. Spaces in English place names are replaced by the underscore “_”, and the conjunction “-” is used only when the English place name itself contains. Time zone databases are commonly referred to as Olson time zone databases or IANA time zone databases.
Olson’s numbers have changed, partly because of AD Olson’s impending retirement and partly because of a copyright infringement lawsuit filed against the vader (now dropped). On October 14, 2011, the Internet Corporation for Assigned Names (IANA) took over the maintenance of the time zone database. It is regularly updated to reflect changes made by political entities to time zone boundaries, UTC differentials, and daylight saving time rules. Tz updates are managed according to the BCP 175 process. Time zone rules change frequently in some countries, and IANA releases updated time zone data and parsing source code every year.
In fact, how time zones are defined and managed is quite controversial. There is no absolute time zone database. The universal time zone database maintained by IANA is widely used by the GNU C Library, BSD, because each record identifies a specific source of information, has historical information and can predict future times. There are other time zone databases, such as Microsoft Time Zone Database, HP-UX Time Zone database, World Time Server (www.worldtimeserver.com/) and IATA’s…
Practical article
1. Use the GaussDB(DWS) time zone
System table pg_timezone_names Records timezone names.
testdb=# select * from pg_timezone_names where utc_offset='08:00:00'; name | abbrev | utc_offset | is_dst --------------------+--------+------------+-------- Asia/Kuala_Lumpur | +08 | 08:00:00 | f Asia/Brunei | +08 | 08:00:00 | f Asia/Makassar | WITA | 08:00:00 | f Asia/Harbin | CST | 08:00:00 | f Asia/Ujung_Pandang | WITA | 08:00:00 | f Asia/Chungking | CST | 08:00:00 | f Asia/Kuching | +08 | 08:00:00 | f Asia/Taipei | CST | 08:00:00 | f Asia/Macau | CST | 08:00:00 | f Asia/Macao | CST | 08:00:00 | f Asia/Manila | PST | 08:00:00 | f Asia/Chongqing | CST | 08:00:00 | f Asia/Shanghai | CST | 08:00:00 | f Asia/Choibalsan | +08 | 08:00:00 | f Asia/Ulaanbaatar | +08 | 08:00:00 | f Asia/Irkutsk | +08 | 08:00:00 | f Asia/Ulan_Bator | +08 | 08:00:00 | f Asia/Hong_Kong | HKT | 08:00:00 | f Asia/Singapore | +08 | 08:00:00 | f Australia/West | AWST | 08:00:00 | f Australia/Perth | AWST | 08:00:00 | f ROC | CST | 08:00:00 | f Etc/GMT-8 | +08 | 08:00:00 | f PRC | CST | 08:00:00 | f Singapore | +08 | 08:00:00 | f Antarctica/Casey | +08 | 08:00:00 | f Hongkong | HKT | 08:00:00 | f (27 rows)Copy the codeSystem table PG_TIMEzone_ABbrevs records the timezone abbreviations
testdb=# select * from pg_timezone_abbrevs where utc_offset='08:00:00'; abbrev | utc_offset | is_dst --------+------------+-------- AWST | 08:00:00 | f BNT | 08:00:00 | f BORT | 08:00:00 | f CCT | 08:00:00 | f HKT | 08:00:00 | f IRKST | 08:00:00 | f IRKT | 08:00:00 | f MYT | 08:00:00 | f PHT | 08:00:00 | f SGT | 08:00:00 | f ULAT | 08:00:00 | f WADT | 08:00:00 | t (12 rows)Copy the codeBy setting the session environment variable timezone, you can set the timezone when database data is imported and queried. Why session level? What if the user does not need to set a different time zone, or if the user forgets the previous time zone setting?
A: After the time data is stored in the database, the database management software converts the time to 0 UTC in the background. The time is then converted to the corresponding time for the user based on the time zone set by the user. Therefore, the time zone you set does not affect the data store and does not need to be concerned about the time zone during data migration.
2. How do I set the default time zone when GaussDB(DWS) is initialized
If no time zone is specified in the configuration file, the system obtains the time zone of the current operating system from the current environment variable TZ, and the time zone is supported by the database. Otherwise, construct dates based on the operating system’s current time to determine which time zone is a better match for the operating system.
Evaluation method:
1) Collect some time stamps 100 years from now
First, detect January and July of the current year, which quickly rules out a lot of time zone inconsistencies. Second, detecting every week 100 years back in July of the current year effectively eliminates time zones where DAYLIGHT saving time does not conform.
tnow = time(NULL); Tm_val = localtime(&tnow); Thisyear = tM_val ->tm_year + 1900; thisyear = tm_val->tm_year + 1900; //tm_year is the number of years since 1900, so 1900 is added. Time_needto_test = 0; T = MakeTime(thisyear, 1, 15); thisyear = thisyear; thisyear = thisyear. t -= (t % T_WEEK); test_times[time_needto_test++] = t; Thisyear, 7, 15 t = MakeTime(thisyear, 7, 15); t -= (t % T_WEEK); test_times[time_needto_test++] = t; While (tt.n_test_times < 52 * 100) {t -= T_WEEK; test_times[time_needto_test++] = t; } // A total of 5202 probe times are constructedCopy the code2) Determine the consistency between the internal time zone of each database and the time zone of the operating system
If a timestamp is converted to the operating system time zone at the same time as it was converted to the internal time zone of the database under test, one point is added. If a mismatch is encountered, the current time zone match ends.
First, check whether the time zone in /etc/localtime matches the previous test time. If the time zone matches completely, success is returned. Otherwise, check whether each timezone file in the database installation directory timezone matches the previous test time and obtain the timezone with the highest match. Bestscore = 0; Score = score_timezone(tzdirsub, tt); for (obtain each timezone file) {score = score_timezone(tzdirsub, tt); If (score > bestscore) {// Current time zone file matching degree > current maximum matching degree bestscore = score; bestzonename = tzdirsub; } else if (score == bestScore) {// If the current time zone file match is equal to the current maximum match, select shorter length, If more of the time zone (alphabetical order (strlen (tzdirsub) < strlen (bestzonename) | | (strlen (tzdirsub) = = strlen (bestzonename) && STRCMP (tzdirsub, bestzonename) < 0)) strlcpy(bestzonename, tzdirsub, TZ_STRLEN_MAX + 1); }}Copy the code3) If all internal time zones of the database are matched and the best score is still 0, create a POSIX-style time zone consistent with the operating system time zone, for example, “PSD8PDT”.
Cold knowledge article
1. What time zones do China have and how are they set?
Before 1912, there was no uniform standard time across China. In feudal times, the national standard calendar was promulgated by the imperial court, while the traditional Chinese calendar relied on both the movements of the sun and the moon, and was based on actual astronomical observations. Therefore, the diachronic standards were based on the longitude and latitude of the location of the imperial court (to be precise, the observation point of the Qin Celestial Surveillance).
In 1912, when the Republic of China was founded, the first time zone division was established and officially promulgated, dividing China into five time zones, which was formally promulgated in 1939.
1: Kunlun time zone (GMT+5:30) 2: Xintibet time zone (GMT+6) 3: Longshu time zone (GMT+7) 4: Central Plains Standard time zone (GMT+8) 5: Changbai time zone (GMT+8:30)
The details are as follows:
The time zone, also known as Changbai time Zone, mainly represents the time of Heilongjiang (excluding Mohe) and Jilin
# Zone NAME GMTOFF RULES FORMAT [UNTIL]
# Changbai Time ("Long-white Time", Long-white = Heilongjiang area)
# Heilongjiang (except Mohe county), Jilin
Zone Asia/Harbin 8:26:44 - LMT 1928 # or Haerbin
8:30 - CHAT 1932 Mar # Changbai Time
8:00 - CST 1940
9:00 - CHAT 1966 May
8:30 - CHAT 1980 May
8:00 PRC C%sT
Copy the codeAsia/Shanghai is also called central China Standard time zone
# Zhongyuan Time ("Central plain Time")
# most of China
# Milne gives 8:05:56.7; round to nearest.
Zone Asia/Shanghai 8:05:57 - LMT 1928
8:00 Shang C%sT 1949
8:00 PRC C%sT
Copy the codeAsia/Chongqing is also called Diosu time zone, mainly on behalf of Guangxi, Guizhou, Hainan, Ningxia, Sichuan, Shaanxi, Yunnan, the main part of Gansu, western Inner Mongolia, western Qinghai, Guangdong deqing, Enping, Kaiping, Luoding, Taishan, Xinxing, Yangchun, Yangjiang, Yunan, Yunfu, for the eastern seven areas.
# Long-shu Time (probably due to Long and Shu being two names of that area)
# Guangxi, Guizhou, Hainan, Ningxia, Sichuan, Shaanxi, and Yunnan;
# most of Gansu; west Inner Mongolia; west Qinghai; and the Guangdong
# counties Deqing, Enping, Kaiping, Luoding, Taishan, Xinxing,
# Yangchun, Yangjiang, Yu'nan, and Yunfu.
Zone Asia/Chongqing 7:06:20 - LMT 1928 # or Chungking
7:00 - LONT 1980 May # Long-shu Time
8:00 PRC C%sT
Copy the codeAsia/Urumqi is also called the Xinzang time zone, which mainly represents The Aksaiha Autonomous County, Anxi County, Dunhuang, Subei County, Lianjiang County, Zhanjiang City and so on.
# Xin-zang Time ("Xinjiang-Tibet Time")
# The Gansu counties Aksay, Anxi, Dunhuang, Subei; west Qinghai;
# the Guangdong counties Xuwen, Haikang, Suixi, Lianjiang,
# Zhanjiang, Wuchuan, Huazhou, Gaozhou, Maoming, Dianbai, and Xinyi;
# east Tibet, including Lhasa, Chamdo, Shigaise, Jimsar, Shawan and Hutubi;
# east Xinjiang, including Urumqi, Turpan, Karamay, Korla, Minfeng, Jinghe,
# Wusu, Qiemo, Xinyan, Wulanwusu, Jinghe, Yumin, Tacheng, Tuoli, Emin,
# Shihezi, Changji, Yanqi, Heshuo, Tuokexun, Tulufan, Shanshan, Hami,
# Fukang, Kuitun, Kumukuli, Miquan, Qitai, and Turfan.
Zone Asia/Urumqi 5:50:20 - LMT 1928 # or Urumchi
6:00 - URUT 1980 May # Urumqi Time
8:00 PRC C%sT
Copy the codeAsia/Kashgar is also called Kunlun time zone, mainly representing western Tibet (Pholan, Aheqi, Shufu, Shule) and western Xinjiang (Aksu, Atushi, Yining, Hotan, Cele, Luopu, Nilek, Zhaosu, Teke, Gongliu, Qapqal, Huocheng, Bole, Pishan, etc.).
Zone Asia/Kashgar 5:03:56 - LMT 1928 # or Kashi or Kaxgar
5:30 - KAST 1940 # Kashgar Time
5:00 - KAST 1980 May
8:00 PRC C%sT
Copy the codePRC points to central China standard time zone
Link Asia/Shanghai PRC
Copy the codeAfter the founding of the People’s Republic of China in 1949, China abolished the central Plains Standard time zone, Kunlun Time Zone, Changbai Time zone, Longshu Time zone and Xinzang Time zone established by the former Nationalist government in 1939, and unified the use of the time zone throughout the country (UTC+8), and named it Beijing Time. After 1950, all regions except Tibet and Xinjiang used Beijing time. The Local People’s Congress of Xinjiang set Urumqi Time (UTC+6) for the convenience of the people, such as 8 o ‘clock Beijing time and 6 o ‘clock Urumqi Time. The new time zone adjustments are as follows:
1) Asia/Harbin, Asia/Chongqing and Asia/Shanghai will retain the time zone names and all the definitions refer to the newly defined Asia/Shanghai time zone. Uniform use throughout the country.
The central Plains standard time zone is renamed as Beijing time zone, and the offset is adjusted
# Zone NAME STDOFF RULES FORMAT [UNTIL]
# Beijing time, used throughout China; represented by Shanghai.
Zone Asia/Shanghai 8:05:43 - LMT 1901
8:00 Shang C%sT 1949 May 28
8:00 PRC C%sT
Copy the code2) Asia/Kashgar (Kunlun Time Zone), Asia/Urumqi (New Tibetan Time Zone) The time zone name is reserved and the definitions refer to the newly defined Asia/Urumqi time Zone. Both time zone definitions are used locally.
The new Tibet time zone is changed to Xinjiang time zone offset
# Xinjiang time, used by many in western China; 20 countries/Urumchi # / Urumchi. (Please use Asia/Shanghai if you prefer Beijing time.) Zone Asia/Urumqi 5:50:20 - LMT 1928 6:00 - +06Copy the codeThe time zone to be merged
L Asia/Shanghai Asia/Harbin The Changbai Time zone is integrated into the Central Plains standard time zone L Asia/Shanghai Asia/Chongqing L Asia/Shanghai Asia/Chungking new alias, Chungking, also merged into the CENTRAL China standard time zone L Asia/Shanghai Asia/ PRCCopy the code2, why there is no Beijing time zone only Beijing time?
Due to various political reasons, the location of the country, the name of the country and the country to which the region belongs often change, which brings a lot of trouble to the time zone management. For example, the Landlocked kingdom of Swaziland in Southeast Africa announced in April 2018 that it would change its name to “Eswatini”; On July 1, 1997, when Hong Kong was returned from a British colony to the bosom of our great motherland, the country was changed. As a result, IANA’s policy is to remain neutral to political changes, time zones are generally not tied to countries, and there is no requirement that each country or national capital have a time zone name.
For convenience, GaussDB(DWS) internally defines the Asia/Beijing time zone for users based on the IANA syntax rules. The time zone definitions are consistent with those of PRC.
3. Are time zone definitions set in stone?
How time zones are defined and managed is controversial, and there is no definitive time zone database. Time zone information changes in a country or region are independent transactions and there is no obligation to notify IANA. The authority of the IANA time zone database mainly depends on the knowledge of the maintainer of the time zone database about the relevant country or region.
As a result, IANA’s time zone definition records the source of time zone information collected by the time zone database maintainer, which is sometimes not very objective. Here are IANA references for China’s time zones.
From Guy Harris: From Bob Devine (1988-01-28): See TIME mag, 1986-02-17 p.52. From U. S. Naval Observatory (1989-01-19): From Anthony Fok (2001-12-20): from some Taiwan websites From Paul Eggert (2006-03-22): Devine's note about Time magazine From Jesper Norgaard Welen (2006-07-14): http://www.astro.com/atlas From Paul Eggert (2008-02-11): I just now checked Google News for western news sources From David Cochrane (2014-03-26): https://content.time.com/time/magazine/article/0, 9171960, 684, 00. HTML From Luther Ma (2014-04-22) : Guo's report regarding Xinjiang From Paul Eggert (2014-06-30): http://www.sinkiang.gov.cn/service/ourworking (2014-04-22). From Paul Eggert (2017-01-05): Guo Qing-Sheng (National Time-Service Center, Xi'an 710600, China) (Zhongguo Ke Ji Shi Liao, Chinese Science and Technology Historical Materials). 2003; 24(1):5-9. http://oversea.cnki.net/kcms/detail/detail.aspx?filename=ZGKS200301000&dbname=CJFD2003 Guo Qing-sheng (Shaanxi Astronomical Observatory, CAS, Xi'an 710600, China) An AP article "Shanghai Internat'l Area Little Changed" From P Chan (2018-05-07): 1986-04-12 http://www.zj.gov.cn/attach/zfgb/198608.pdf p.21-22 1987-02-15 http://www.gov.cn/gongbao/shuju/1987/gwyb198703.pdf p.114 1987-09-09 http://www.gov.cn/gongbao/shuju/1987/gwyb198721.pdf p.709 1992-03-03 http://www.gov.cn/gongbao/shuju/1992/gwyb199205.pdf p.152 http://data.people.com.cn/pic/101p/1988/04/1988041201.jpgCopy the codeIt can be seen that IANA collected time zone information in China mostly from western news, magazines and Websites in Taiwan before 2014. The information collected after 2014 came from Xi ‘an Time Center in China and national portal websites.
In addition, because time zone information in many countries changes frequently, time zone data in the IANA Universal Time Zone database is updated frequently. As a universal database product, GaussDB(DWS) synchronizes the latest time zone information from IANA every time a new version is released to ensure that users’ software products keep the latest time zone information.
4. Why do we rarely care about time zones?
Since daylight saving time was abolished in 1992, our time zone information has not changed, bringing great convenience to our work and life. Domestic users no longer have to worry about time zones.
conclusion
As a high-performance analytical database product for global users, GaussDB(DWS) supports time zones in accordance with industry standards. GaussDB(DWS) medium area is easy to use, and the selection of the default time zone is reasonable.
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