diff options
Diffstat (limited to 'doc')
| -rw-r--r-- | doc/src/sgml/config.sgml | 6 | ||||
| -rw-r--r-- | doc/src/sgml/datatype.sgml | 39 | ||||
| -rw-r--r-- | doc/src/sgml/datetime.sgml | 35 | ||||
| -rw-r--r-- | doc/src/sgml/installation.sgml | 2 |
4 files changed, 52 insertions, 30 deletions
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index 949443931cd..6ee17d84772 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -6003,9 +6003,9 @@ SET XML OPTION { DOCUMENT | CONTENT }; Sets the collection of time zone abbreviations that will be accepted by the server for datetime input. The default is <literal>'Default'</>, which is a collection that works in most of the world; there are - also <literal>'Australia'</literal> and <literal>'India'</literal>, and other collections can be defined - for a particular installation. See <xref - linkend="datetime-appendix"> for more information. + also <literal>'Australia'</literal> and <literal>'India'</literal>, + and other collections can be defined for a particular installation. + See <xref linkend="datetime-config-files"> for more information. </para> </listitem> </varlistentry> diff --git a/doc/src/sgml/datatype.sgml b/doc/src/sgml/datatype.sgml index 3e83dbbe4c0..223ba6ade8e 100644 --- a/doc/src/sgml/datatype.sgml +++ b/doc/src/sgml/datatype.sgml @@ -2325,7 +2325,7 @@ January 8 04:05:06 1999 PST but continue to be prone to arbitrary changes, particularly with respect to daylight-savings rules. <productname>PostgreSQL</productname> uses the widely-used - <literal>zoneinfo</> (Olson) time zone database for information about + IANA (Olson) time zone database for information about historical time zone rules. For times in the future, the assumption is that the latest known rules for a given time zone will continue to be observed indefinitely far into the future. @@ -2390,8 +2390,8 @@ January 8 04:05:06 1999 PST The recognized time zone names are listed in the <literal>pg_timezone_names</literal> view (see <xref linkend="view-pg-timezone-names">). - <productname>PostgreSQL</productname> uses the widely-used - <literal>zoneinfo</> time zone data for this purpose, so the same + <productname>PostgreSQL</productname> uses the widely-used IANA + time zone data for this purpose, so the same time zone names are also recognized by much other software. </para> </listitem> @@ -2427,7 +2427,7 @@ January 8 04:05:06 1999 PST When a daylight-savings zone abbreviation is present, it is assumed to be used according to the same daylight-savings transition rules used in the - <literal>zoneinfo</> time zone database's <filename>posixrules</> entry. + IANA time zone database's <filename>posixrules</> entry. In a standard <productname>PostgreSQL</productname> installation, <filename>posixrules</> is the same as <literal>US/Eastern</>, so that POSIX-style time zone specifications follow USA daylight-savings @@ -2438,9 +2438,25 @@ January 8 04:05:06 1999 PST </itemizedlist> In short, this is the difference between abbreviations - and full names: abbreviations always represent a fixed offset from - UTC, whereas most of the full names imply a local daylight-savings time - rule, and so have two possible UTC offsets. + and full names: abbreviations represent a specific offset from UTC, + whereas many of the full names imply a local daylight-savings time + rule, and so have two possible UTC offsets. As an example, + <literal>2014-06-04 12:00 America/New_York</> represents noon local + time in New York, which for this particular date was Eastern Daylight + Time (UTC-4). So <literal>2014-06-04 12:00 EDT</> specifies that + same time instant. But <literal>2014-06-04 12:00 EST</> specifies + noon Eastern Standard Time (UTC-5), regardless of whether daylight + savings was nominally in effect on that date. + </para> + + <para> + To complicate matters, some jurisdictions have used the same timezone + abbreviation to mean different UTC offsets at different times; for + example, in Moscow <literal>MSK</> has meant UTC+3 in some years and + UTC+4 in others. <application>PostgreSQL</> interprets such + abbreviations according to whatever they meant (or had most recently + meant) on the specified date; but, as with the <literal>EST</> example + above, this is not necessarily the same as local civil time on that date. </para> <para> @@ -2457,13 +2473,14 @@ January 8 04:05:06 1999 PST </para> <para> - In all cases, timezone names are recognized case-insensitively. - (This is a change from <productname>PostgreSQL</productname> versions - prior to 8.2, which were case-sensitive in some contexts but not others.) + In all cases, timezone names and abbreviations are recognized + case-insensitively. (This is a change from <productname>PostgreSQL</> + versions prior to 8.2, which were case-sensitive in some contexts but + not others.) </para> <para> - Neither full names nor abbreviations are hard-wired into the server; + Neither timezone names nor abbreviations are hard-wired into the server; they are obtained from configuration files stored under <filename>.../share/timezone/</> and <filename>.../share/timezonesets/</> of the installation directory diff --git a/doc/src/sgml/datetime.sgml b/doc/src/sgml/datetime.sgml index 444b0ec2b93..ffd07151282 100644 --- a/doc/src/sgml/datetime.sgml +++ b/doc/src/sgml/datetime.sgml @@ -374,22 +374,27 @@ these formats: <synopsis> -<replaceable>time_zone_name</replaceable> <replaceable>offset</replaceable> -<replaceable>time_zone_name</replaceable> <replaceable>offset</replaceable> D +<replaceable>zone_abbreviation</replaceable> <replaceable>offset</replaceable> +<replaceable>zone_abbreviation</replaceable> <replaceable>offset</replaceable> D +<replaceable>zone_abbreviation</replaceable> <replaceable>time_zone_name</replaceable> @INCLUDE <replaceable>file_name</replaceable> @OVERRIDE </synopsis> </para> <para> - A <replaceable>time_zone_name</replaceable> is just the abbreviation - being defined. The <replaceable>offset</replaceable> is the zone's + A <replaceable>zone_abbreviation</replaceable> is just the abbreviation + being defined. The <replaceable>offset</replaceable> is the equivalent offset in seconds from UTC, positive being east from Greenwich and negative being west. For example, -18000 would be five hours west of Greenwich, or North American east coast standard time. <literal>D</> - indicates that the zone name represents local daylight-savings time - rather than standard time. Since all known time zone offsets are on - 15 minute boundaries, the number of seconds has to be a multiple of 900. + indicates that the zone name represents local daylight-savings time rather + than standard time. Alternatively, a <replaceable>time_zone_name</> can + be given, in which case that time zone definition is consulted, and the + abbreviation's meaning in that zone is used. This alternative is + recommended only for abbreviations whose meaning has historically varied, + as looking up the meaning is noticeably more expensive than just using + a fixed integer value. </para> <para> @@ -400,9 +405,9 @@ <para> The <literal>@OVERRIDE</> syntax indicates that subsequent entries in the - file can override previous entries (i.e., entries obtained from included - files). Without this, conflicting definitions of the same timezone - abbreviation are considered an error. + file can override previous entries (typically, entries obtained from + included files). Without this, conflicting definitions of the same + timezone abbreviation are considered an error. </para> <para> @@ -410,14 +415,14 @@ all the non-conflicting time zone abbreviations for most of the world. Additional files <filename>Australia</> and <filename>India</> are provided for those regions: these files first include the - <literal>Default</> file and then add or modify timezones as needed. + <literal>Default</> file and then add or modify abbreviations as needed. </para> <para> For reference purposes, a standard installation also contains files <filename>Africa.txt</>, <filename>America.txt</>, etc, containing information about every time zone abbreviation known to be in use - according to the <literal>zoneinfo</> timezone database. The zone name + according to the IANA timezone database. The zone name definitions found in these files can be copied and pasted into a custom configuration file as needed. Note that these files cannot be directly referenced as <varname>timezone_abbreviations</> settings, because of @@ -426,9 +431,9 @@ <note> <para> - If an error occurs while reading the time zone data sets, no new value is - applied but the old set is kept. If the error occurs while starting the - database, startup fails. + If an error occurs while reading the time zone abbreviation set, no new + value is applied and the old set is kept. If the error occurs while + starting the database, startup fails. </para> </note> diff --git a/doc/src/sgml/installation.sgml b/doc/src/sgml/installation.sgml index a3c9bea3665..68931d25b66 100644 --- a/doc/src/sgml/installation.sgml +++ b/doc/src/sgml/installation.sgml @@ -1108,7 +1108,7 @@ su - postgres <para> <productname>PostgreSQL</> includes its own time zone database, which it requires for date and time operations. This time zone - database is in fact compatible with the <quote>zoneinfo</> time zone + database is in fact compatible with the IANA time zone database provided by many operating systems such as FreeBSD, Linux, and Solaris, so it would be redundant to install it again. When this option is used, the system-supplied time zone database |