Postgresql Default Timezone

PostgreSQL provides a various function for manipulating time values. It is one of them which is used to get the current time of day. It returns the current time value of day with the time zone in which it is called.

  • By default, DateTime is sent to PostgreSQL as a timestamp without time zone - no timezone conversion of any kind will occur, and your DateTime instance will be transferred as-is to PostgreSQL. This is the recommended way to store timestamps in the database.
  • Problem: You’d like to get the current date and time in a PostgreSQL database. You don’t need the time zone offset. Solution: We’ll use the function LOCALTIMESTAMP to get the current date and time without any time zone information: SELECT LOCALTIMESTAMP; Here’s the result of the query: 2019-09-24 20:14 Discussion: The PostgreSQL function LOCALTIMESTAMP returns the current.
  • As you see, after pausing 5 seconds, the current date and time increased. PostgreSQL NOW function as default values. You can use the NOW function as the default value for a column of a table. See the following example: First, create a new table named posts with the createdat column that has a default value provided by the NOW function.
  • From the docs on 9.1, I see. If timezone is not specified in postgresql.conf or as a server command-line option, the server attempts to use the value of the TZ environment variable as the default time zone.If TZ is not defined or is not any of the time zone names known to PostgreSQL, the server attempts to determine the operating system's default time zone by checking the behavior of the C.

Database:

Operators:

LOCALTIMESTAMP

Problem:

You’d like to get the current date and time in a PostgreSQL database. You don’t need the time zone offset.

Solution:

Postgresql Default Timezone

We’ll use the function LOCALTIMESTAMP to get the current date and time without any time zone information:

Here’s the result of the query:

Discussion:

The PostgreSQL function LOCALTIMESTAMP returns the current date and time (of the machine running that instance of PostgreSQL) as a timestamp value. It uses the 'YYYY-MM-DD hh:mm:ss.nnnnnnn' format, where:

  • YYYY is a 4-digit year.
  • MM is a 2-digit month.
  • DD is a 2-digit day.
  • hh is a 2-digit hour.
  • mm is a 2-digit minute.
  • ss is a 2-digit second.
  • nnnnnn are fractional seconds (from zero to 6-digit precision).

As you notice, this function has no brackets. However, if you want to display the date and time with a specific precision, put an integer from 0 to 6 as an argument in the brackets. This will return the date and time with your desired number of fractional seconds. For example, LOCALTIMESTAMP(1) denotes only one fractional second (i.e. one place after the decimal); 2 will return two places, etc. The default precision is 6, which is also the maximum number of fractional seconds; this is what you get if you don’t use brackets at all. Look at the next example:

Here’s the result of the query:

This result doesn’t contain fractional seconds because we put 0 as the argument.

This function returns the time at which the current transaction started. The difference between LOCALTIMESTAMP and CURRENT_TIMESTAMP is that the LOCALTIMESTAMP doesn’t include the time zone offset.

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In PostgreSQL, you can use the AT TIME ZONE clause to convert a timestamp to another timezone.

Syntax

You can use it with any of the following three variants:

Where zone is the timezone that you want the value on the left to be converted to.

Just to be clear, the only difference between the three variants is in the data type of the timestamp to be converted.

The three data types are:

  • timestamp with time zone
  • timestamp without time zone
  • time with time zone

The result you get will depend on the data type.

The following table outlines the result that each variant produces.

Variant 1

Here’s what happens when you convert a timestamp with time zone value.

Result:

When the original timestamp is a timestamp with time zone value, it is shifted to the specified timezone, and the result is returned without a timezone offset.

Here’s what happens if I change the timezone offset of the input value.

Result:

The resulting timestamp is shifted according to the input timezone.

And if you specify timestamp with time zone, but the original timestamp doesn’t actually include a timezone, then the local timezone is assumed.

Result:

In this case, the resulting timestamp has been put back eight hours. This means that my local timezone is eight hours ahead of Africa/Cairo.

We can see the timezone offset that was used by selecting the input value directly.

Result:

Variant 2

Here’s what happens when the original timestamp uses a timestamp without time zone value.

Postgresql default timezone

In other words, it doesn’t include a timezone.

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Result:

Postgresql

When the original timestamp doesn’t include a timezone, the result is displayed using the current TimeZone setting and the timezone offset is appended.

This applies any time you specify timestamp without time zone, even if the timestamp does in fact contain a timezone offset.

Result:

This is to be expected, because if I select just the timestamp without time zone value, this is what I get:

Postgresql Default Timezone

Result:

Variant 3

Here’s what happens when the original timestamp uses a time with time zone value.

Result:

It converts the given time with time zone value to the new time zone, and appends the timezone offset to the result.

Here’s what happens if I change the timezone offset of the input value.

Result:

The resulting timestamp is shifted according to the input timezone.

And if you specify time with time zone, but the original timestamp doesn’t actually include a timezone, the local timezone is assumed.

Result:

Timezone

In this case, the resulting timestamp has been put back eight hours (because my local timezone is eight hours ahead of Africa/Cairo).

We can see the timezone offset that was used by selecting the input value directly.

Result:

Time Without Timezone

Postgresql Timestamp Default Timezone

Although the Postgres documentation doesn’t include a time without time zone variant, here’s an example anyway.

Result:

Postgresql Time Default Timezone

So in this example the local timezone was assumed for the timezone to be converted.