postgresql 为什么Java LocalTime 01：32：13.283256在数据库中存储为时间00：32：13？滞后1小时

6tqwzwtp 于 2022-12-18 发布在 PostgreSQL

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为什么将值设置为1小时后？
如果Europe/Dublin或Europe/London的偏移量与UTC相同，为什么db中的值与原始JVM值不同？

JVM: Europe/Dublin - TimeZone.getDefault().getID() or
JVM: Europe/London - TimeZone.getDefault().getID()

// LocalTime.ofInstant(now, Clock.systemDefaultZone().getZone())
01:32:13.283256

与当前UTC相同，无偏移。
使用配置属性为Spring / Hibernate设置的JDBC连接时区：

spring.jpa.properties.hibernate.jdbc.time_zone=UTC

型
数据库查询：

select * from item;

 id | local_time 
----+------------
  1 | 00:32:13

local_time具有time列类型。

postgresql

来源：https://stackoverflow.com/questions/74717698/why-is-java-localtime-013213-283256-stored-as-time-003213-in-database-1-hou

1条答案

按热度按时间

8ftvxx2r1#

这反映了1970年都柏林全年都是UTC+1的事实。
从TZ数据库的europe文件中：

# From Paul Eggert (2018-02-15):
# In January 2018 we discovered that the negative SAVE values in the
# Eire rules cause problems with tests for ICU:
# https://mm.icann.org/pipermail/tz/2018-January/025825.html
# and with tests for OpenJDK:
# https://mm.icann.org/pipermail/tz/2018-January/025822.html
#
# To work around this problem, the build procedure can translate the
# following data into two forms, one with negative SAVE values and the
# other form with a traditional approximation for Irish timestamps
# after 1971-10-31 02:00 UTC; although this approximation has tm_isdst
# flags that are reversed, its UTC offsets are correct and this often
# suffices.  This source file currently uses only nonnegative SAVE
# values, but this is intended to change and downstream code should
# not rely on it.
#
# The following is like GB-Eire and EU, except with standard time in
# summer and negative daylight saving time in winter.  It is for when
# negative SAVE values are used.
# Rule  NAME    FROM    TO      -       IN      ON      AT      SAVE    LETTER/S
Rule    Eire    1971    only    -       Oct     31       2:00u  -1:00   -
Rule    Eire    1972    1980    -       Mar     Sun>=16  2:00u  0       -
Rule    Eire    1972    1980    -       Oct     Sun>=23  2:00u  -1:00   -
Rule    Eire    1981    max     -       Mar     lastSun  1:00u  0       -
Rule    Eire    1981    1989    -       Oct     Sun>=23  1:00u  -1:00   -
Rule    Eire    1990    1995    -       Oct     Sun>=22  1:00u  -1:00   -
Rule    Eire    1996    max     -       Oct     lastSun  1:00u  -1:00   -

# Zone  NAME            STDOFF  RULES   FORMAT  [UNTIL]
                #STDOFF -0:25:21.1
Zone    Europe/Dublin   -0:25:21 -      LMT     1880 Aug  2
                        -0:25:21 -      DMT     1916 May 21  2:00s
                        -0:25:21 1:00   IST     1916 Oct  1  2:00s
                         0:00   GB-Eire %s      1921 Dec  6 # independence
                         0:00   GB-Eire GMT/IST 1940 Feb 25  2:00s
                         0:00   1:00    IST     1946 Oct  6  2:00s
                         0:00   -       GMT     1947 Mar 16  2:00s
                         0:00   1:00    IST     1947 Nov  2  2:00s
                         0:00   -       GMT     1948 Apr 18  2:00s
                         0:00   GB-Eire GMT/IST 1968 Oct 27
# Vanguard section, for zic and other parsers that support negative DST.
                         1:00   Eire    IST/GMT
# Rearguard section, for parsers lacking negative DST; see ziguard.awk.
#                        1:00   -       IST     1971 Oct 31  2:00u
#                        0:00   GB-Eire GMT/IST 1996
#                        0:00   EU      GMT/IST
# End of rearguard section.

伦敦也有同样的问题：

# Zone  NAME            STDOFF  RULES   FORMAT  [UNTIL] 
Zone    Europe/London   -0:01:15 -      LMT     1847 Dec  1
                         0:00   GB-Eire %s      1968 Oct 27
                         1:00   -       BST     1971 Oct 31  2:00u
                         0:00   GB-Eire %s      1996    
                         0:00   EU      GMT/BST 

# From Paul Eggert (2018-02-15):
# In January 2018 we discovered that the negative SAVE values in the
# Eire rules cause problems with tests for ICU:
# https://mm.icann.org/pipermail/tz/2018-January/025825.html
# and with tests for OpenJDK:
# https://mm.icann.org/pipermail/tz/2018-January/025822.html
#
# To work around this problem, the build procedure can translate the
# following data into two forms, one with negative SAVE values and the 
# other form with a traditional approximation for Irish timestamps
# after 1971-10-31 02:00 UTC; although this approximation has tm_isdst
# flags that are reversed, its UTC offsets are correct and this often
# suffices.  This source file currently uses only nonnegative SAVE
# values, but this is intended to change and downstream code should
# not rely on it.
#
# The following is like GB-Eire and EU, except with standard time in 
# summer and negative daylight saving time in winter.  It is for when
# negative SAVE values are used.
# Rule  NAME    FROM    TO      -       IN      ON      AT      SAVE    LETTER/S
Rule    Eire    1971    only    -       Oct     31       2:00u  -1:00   -
Rule    Eire    1972    1980    -       Mar     Sun>=16  2:00u  0       -       
Rule    Eire    1972    1980    -       Oct     Sun>=23  2:00u  -1:00   -
Rule    Eire    1981    max     -       Mar     lastSun  1:00u  0       -       
Rule    Eire    1981    1989    -       Oct     Sun>=23  1:00u  -1:00   -
Rule    Eire    1990    1995    -       Oct     Sun>=22  1:00u  -1:00   -
Rule    Eire    1996    max     -       Oct     lastSun  1:00u  -1:00   -

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postgresql 为什么Java LocalTime 01：32：13.283256在数据库中存储为时间00：32：13？滞后1小时

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