Cloudera Docs

Impala date and time functions

The underlying Impala data type for date and time data is TIMESTAMP and DATE.

Some of the datetime functions are affected by the setting of the ‑‑use_local_tz_for_unix_timestamp_conversions startup flag for the impalad daemon.
  • This setting is off by default, meaning that functions such as FROM_UNIXTIME() and UNIX_TIMESTAMP() consider the input values to always represent the UTC time zone.
  • This setting also applies when you CAST() a BIGINT value to TIMESTAMP, or a TIMESTAMP value to BIGINT. When this setting is enabled, these functions and operations convert to and from values representing the local time zone. See TIMESTAMP data type for details about how Impala handles time zone considerations for the TIMESTAMP data type.

Function reference:

Impala supports the following data and time functions:

ADD_MONTHS(TIMESTAMP / DATE date, INT months), ADD_MONTHS(TIMESTAMP / DATE date, BIGINT months)
Purpose: Adds months to date and returns the new date value.
Return type:
  • If date is TIMESTAMP, returns TIMESTAMP.
  • If date is DATE, returns DATE.

Usage notes:

Same as MONTHS_ADD(). Available in Impala 1.4 and higher. For compatibility when porting code with vendor extensions.

ADDDATE(TIMESTAMP / DATE date, INT / BIGINT days)
Purpose: Adds days to date and returns the new date value.

The days value can be negative, which gives the same result as the SUBDATE() function.

Return type:
  • If date is TIMESTAMP, returns TIMESTAMP.
  • If date is DATE, returns DATE.
CURRENT_DATE()
Purpose: Returns the current date.

Any references to the CURRENT_DATE() function are evaluated at the start of a query. All calls to CURRENT_DATE() within the same query return the same value, and the value does not depend on how long the query takes.

Return type: DATE

CURRENT_TIMESTAMP()
Purpose: Alias for the NOW() function.

Return type: TIMESTAMP

DATE_ADD(TIMESTAMP / DATE date, INT / BIGINT days), DATE_ADD(TIMESTAMP / DATE date, interval_expression)
Purpose: Adds a specified number of days to the date argument.
With an INTERVAL expression as the second argument, you can calculate a delta value using other units such as weeks, years, hours, seconds, and so on.
Return type:
  • If date is TIMESTAMP, returns TIMESTAMP.
  • If date is DATE, returns DATE.

The following examples show the shorthand notation of an INTERVAL expression, instead of specifying the precise number of days. The INTERVAL notation also lets you work with units smaller than a single day. 


select now() as right_now, date_add(now(), interval 3 weeks) as in_3_weeks;
+-------------------------------+-------------------------------+
| right_now                     | in_3_weeks                    |
+-------------------------------+-------------------------------+
| 2016-05-20 11:05:39.173331000 | 2016-06-10 11:05:39.173331000 |
+-------------------------------+-------------------------------+

select now() as right_now, date_add(now(), interval 6 hours) as in_6_hours;
+-------------------------------+-------------------------------+
| right_now                     | in_6_hours                    |
+-------------------------------+-------------------------------+
| 2016-05-20 11:13:51.492536000 | 2016-05-20 17:13:51.492536000 |
+-------------------------------+-------------------------------+

Like all date/time functions that deal with months, date_add() handles nonexistent dates past the end of a month by setting the date to the last day of the month. The following example shows how the nonexistent date April 31st is normalized to April 30th: 


select date_add(cast('2016-01-31' as timestamp), interval 3 months) as 'april_31st';
+---------------------+
| april_31st          |
+---------------------+
| 2016-04-30 00:00:00 |
+---------------------+
DATE_CMP(DATE date1, DATE date2)
Purpose: Compares date1 and date2 and returns:
  • 0 if the dates are identical.
  • 1 if date1 > date2.
  • -1 if date1 < date2.
  • NULL if date1 or date2 is NULL.

Return type: INT

DATE_PART(STRING part, TIMESTAMP / DATE date)
Purpose: Similar to EXTRACT(), with the argument order reversed. Supports the same date and time units as EXTRACT(). For compatibility with SQL code containing vendor extensions.

Return type: BIGINT

DATE_SUB(TIMESTAMP startdate, INT days), DATE_SUB(TIMESTAMP startdate, interval_expression)
Purpose: Subtracts a specified number of days from a TIMESTAMP value. With an INTERVAL expression as the second argument, you can calculate a delta value using other units such as weeks, years, hours, seconds, and so on.
Return type:
  • If date is TIMESTAMP, returns TIMESTAMP.
  • If date is DATE, returns DATE.

Examples:

The following example shows the simplest usage, of subtracting a specified number of days from a TIMESTAMP value: 


select now() as right_now, date_sub(now(), 7) as last_week;
+-------------------------------+-------------------------------+
| right_now                     | last_week                     |
+-------------------------------+-------------------------------+
| 2016-05-20 11:21:30.491011000 | 2016-05-13 11:21:30.491011000 |
+-------------------------------+-------------------------------+

The following examples show the shorthand notation of an INTERVAL expression, instead of specifying the precise number of days. The INTERVAL notation also lets you work with units smaller than a single day. 


select now() as right_now, date_sub(now(), interval 3 weeks) as 3_weeks_ago;
+-------------------------------+-------------------------------+
| right_now                     | 3_weeks_ago                   |
+-------------------------------+-------------------------------+
| 2016-05-20 11:23:05.176953000 | 2016-04-29 11:23:05.176953000 |
+-------------------------------+-------------------------------+

select now() as right_now, date_sub(now(), interval 6 hours) as 6_hours_ago;
+-------------------------------+-------------------------------+
| right_now                     | 6_hours_ago                   |
+-------------------------------+-------------------------------+
| 2016-05-20 11:23:35.439631000 | 2016-05-20 05:23:35.439631000 |
+-------------------------------+-------------------------------+

Like all date/time functions that deal with months, date_add() handles nonexistent dates past the end of a month by setting the date to the last day of the month. The following example shows how the nonexistent date April 31st is normalized to April 30th: 


select date_sub(cast('2016-05-31' as timestamp), interval 1 months) as 'april_31st';
+---------------------+
| april_31st          |
+---------------------+
| 2016-04-30 00:00:00 |
+---------------------+
DATE_TRUNC(STRING unit, TIMESTAMP / DATE ts)
Purpose: Returns the ts value truncated to the specified unit.

Argument: The unit argument is not case-sensitive. This argument string can be one of:

Unit Supported for TIMESTAMP Supported for DATE
'MICROSECONDS' Yes No
'MILLISECONDS' Yes No
'SECOND' Yes No
'MINUTE' Yes No
'HOUR' Yes No
'DAY' Yes Yes
'WEEK' Yes Yes
'MONTH' Yes Yes
'YEAR' Yes Yes
'DECADE' Yes Yes
'CENTURY' Yes Yes
'MILLENNIUM' Yes Yes

Usage notes:

Although this function is similar to calling TRUNC() with a TIMESTAMP or DATE argument, the order of arguments and the recognized units are different between TRUNC() and DATE_TRUNC(). Therefore, these functions are not interchangeable.

This function is typically used in GROUP BY queries to aggregate results from the same hour, day, week, month, quarter, and so on. You can also use this function in an INSERT ... SELECT into a partitioned table to divide TIMESTAMP or DATE values into the correct partition.

Return type:
  • TIMESTAMP if the second argument, ts, is TIMESTAMP.
  • DATE if the second argument, ts, is DATE.

Examples:

DATE_TRUNC('HOUR', NOW()) returns 2017-12-05 13:00:00.

DATE_TRUNC('MILLENNIUM', DATE'2019-08-02') returns 2001-01-01.

DATEDIFF(TIMESTAMP / DATE enddate, TIMESTAMP / DATE startdate)
Purpose: Returns the number of days from startdate to enddate.

If enddate > startdate, the return value is positive.

If enddate < startdate, the return value is negative.

If enddate = startdate, the return value is zero.

Return type: INT

Usage notes:

The time portions of the enddate and startdate values are ignored. For example, 11:59 PM on one day and 12:01 AM on the next day represent a DATEDIFF() of -1 because the date/time values represent different days, even though the TIMESTAMP values differ by only 2 minutes.

DAY(TIMESTAMP / DATE date), DAYOFMONTH(TIMESTAMP / DATE date)
Purpose: Returns the day value from the date argument. The value represents the day of the month, therefore is in the range 1-31, or less for months without 31 days.

Returns NULL for nonexistent dates, e.g. Feb 30, or misformatted date strings, e.g. '1999-02-013'.

Return type: INT

DAYNAME(TIMESTAMP / DATE date)
Purpose: Returns the day name of the date argument. The range of return values is 'Sunday' to 'Saturday'. Used in report-generating queries, as an alternative to calling DAYOFWEEK() and turning that numeric return value into a string using a CASE expression.

Return type: STRING

DAYOFWEEK(TIMESTAMP / DATE date)
Purpose: Returns the day field of the date arguement, corresponding to the day of the week. The range of return values is 1 (Sunday) to 7 (Saturday).

Return type: INT

DAYOFYEAR(TIMESTAMP / DATE date)
Purpose: Returns the day field from the date argument, corresponding to the day of the year. The range of return values is 1 (January 1) to 366 (December 31 of a leap year).

Return type: INT

DAYS_ADD(TIMESTAMP / DATE date, INT / BIGINT days)
Purpose: Returns the value with the number of days added to date.
Return type:
  • If date is TIMESTAMP, returns TIMESTAMP.
  • If date is DATE, returns DATE.
DAYS_SUB(TIMESTAMP / DATE date, INT / BIGINT days)
Purpose: Returns the value with the number of days subtracted from date.
Return type:
  • If date is TIMESTAMP, returns TIMESTAMP.
  • If date is DATE, returns DATE.
EXTRACT(TIMESTAMP / DATE ts, STRING unit), EXTRACT(unit FROM TIMESTAMP / DATE ts)
Purpose: Returns one of the numeric date or time fields, specified by unit, from ts.

Argument: The unit argument value is not case-sensitive. The unit string can be one of:

Unit Supported for TIMESTAMP ts Supported for DATE ts
'EPOCH' Yes No
'MILLISECOND' Yes No
'SECOND' Yes No
'MINUTE' Yes No
'HOUR' Yes No
'DAY' Yes Yes
'MONTH' Yes Yes
'QUARTER' Yes Yes
'YEAR' Yes Yes

Usage notes:

Typically used in GROUP BY queries to arrange results by hour, day, month, and so on. You can also use this function in an INSERT ... SELECT statement to insert into a partitioned table to split up TIMESTAMP values into individual parts, if the partitioned table has separate partition key columns representing year, month, day, and so on. If you need to divide by more complex units of time, such as by week or by quarter, use the TRUNC() function instead.

Return type: BIGINT

Examples:

EXTRACT(DAY FROM DATE'2019-08-17') returns 17.

If you specify 'MILLISECOND' for the unit argument, the function returns the seconds component and the milliseconds component.

EXTRACT(CAST('2006-05-12 18:27:28.123456789' AS TIMESTAMP), 'MILLISECOND') returns 28123.

FROM_TIMESTAMP(TIMESTAMP datetime, STRING pattern), FROM_TIMESTAMP(STRING datetime, STRING pattern)
Purpose: Converts a TIMESTAMP value into a string representing the same value.

Return type: STRING

Usage notes:

The FROM_TIMESTAMP() function provides a flexible way to convert TIMESTAMP values into arbitrary string formats for reporting purposes.

Because Impala implicitly converts string values into TIMESTAMP, you can pass date/time values represented as strings (in the standard yyyy-MM-dd HH:mm:ss.SSS format) to this function. The result is a string using different separator characters, order of fields, spelled-out month names, or other variation of the date/time string representation.

The allowed tokens for the pattern string are the same as for the FROM_UNIXTIME() function.

FROM_UNIXTIME(BIGINT unixtime[, STRING pattern])
Purpose: Converts the number of seconds from the Unix epoch to the specified time into a string in the local time zone.

Return type: STRING

The pattern string supports the following subset of Java SimpleDateFormat.

Pattern Description
y Year
M Month
d Day
H Hour
m Minute
s Second
S Fractional second
+/-hh:mm Time zone offset
+/-hhmm Time zone offset
+/-hh Time zone offset

The following rules apply to the pattern string:

  • The pattern string is case-sensitive.
  • All fields are variable length, and thus must use separators to specify the boundaries of the fields, with the exception of the time zone values.
  • Time zone offset formats must be at the end of the pattern string.
  • Formatting character groups can appear in any order along with any separators except for the time zone offset. For example:
    • yyyy/MM/dd
    • dd-MMM-yy
    • (dd)(MM)(yyyy) HH:mm:ss
    • yyyy-MM-dd HH:mm:ss+hh:mm

In Impala 1.3 and later, you can switch the order of elements, use alternative separator characters, and use a different number of placeholders for each unit. Adding more instances of y, d, H, and so on produces output strings zero-padded to the requested number of characters. The exception is M for months, where M produces a non-padded value such as 3, MM produces a zero-padded value such as 03, MMM produces an abbreviated month name such as Mar, and sequences of 4 or more M are not allowed.

A date string including all fields could be 'yyyy-MM-dd HH:mm:ss.SSSSSS', 'dd/MM/yyyy HH:mm:ss.SSSSSS', 'MMM dd, yyyy HH.mm.ss (SSSSSS)' or other combinations of placeholders and separator characters.

Usage notes:

The way this function deals with time zones when converting to or from TIMESTAMP values is affected by the ‑‑use_local_tz_for_unix_timestamp_conversions startup flag for the impalad daemon.

FROM_UTC_TIMESTAMP(TIMESTAMP ts, STRING timezone)
Purpose: Converts a specified UTC timestamp value into the appropriate value for a specified time zone.

Return type: TIMESTAMP

Usage notes: Often used to translate UTC time zone data stored in a table back to the local date and time for reporting. The opposite of the TO_UTC_TIMESTAMP() function.

To determine the time zone of the server you are connected to, you can call the TIMEOFDAY() function, which includes the time zone specifier in its return value. Remember that with cloud computing, the server you interact with might be in a different time zone than you are, or different sessions might connect to servers in different time zones, or a cluster might include servers in more than one time zone.

See discussion of time zones in TIMESTAMP data type for information about using this function for conversions between the local time zone and UTC.

HOUR(TIMESTAMP ts)
Purpose: Returns the hour field from a TIMESTAMP field.

Return type: INT

HOURS_ADD(TIMESTAMP date, INT hours), HOURS_ADD(TIMESTAMP date, BIGINT hours)
Purpose: Returns the specified date and time plus some number of hours.

Return type: TIMESTAMP

HOURS_SUB(TIMESTAMP date, INT hours), HOURS_SUB(TIMESTAMP date, BIGINT hours)
Purpose: Returns the specified date and time minus some number of hours.

Return type: TIMESTAMP

INT_MONTHS_BETWEEN(TIMESTAMP / DATE enddate, TIMESTAMP / DATE startdate)
Purpose: Returns the number of months from startdate to enddate, representing only the full months that passed.

Return type: INT

Usage notes:

Typically used in business contexts, for example to determine whether a specified number of months have passed or whether some end-of-month deadline was reached.

The method of determining the number of elapsed months includes some special handling of months with different numbers of days that creates edge cases for dates between the 28th and 31st days of certain months. See MONTHS_BETWEEN() for details. The INT_MONTHS_BETWEEN() result is essentially the FLOOR() of the MONTHS_BETWEEN() result.

If either value is NULL, which could happen for example when converting a nonexistent date string such as '2015-02-29' to a TIMESTAMP, the result is also NULL.

If the first argument represents an earlier time than the second argument, the result is negative.

LAST_DAY(TIMESTAMP / DATE ts)
Purpose: Returns the beginning of the last calendar day in the same month of ts.
Return type:
  • Returns TIMESTAMP if ts is of the TIMESTAMP type.
  • Returns DATE if ts is of the DATE type.

Usage notes:

If the input argument does not represent a valid Impala TIMESTAMP including both date and time portions, the function returns NULL. For example, if the input argument is a string that cannot be implicitly cast to TIMESTAMP, does not include a date portion, or is out of the allowed range for Impala TIMESTAMP values, the function returns NULL.

MICROSECONDS_ADD(TIMESTAMP date, INT microseconds), MICROSECONDS_ADD(TIMESTAMP date, BIGINT microseconds)
Purpose: Returns the specified date and time plus some number of microseconds.

Return type: TIMESTAMP

MICROSECONDS_SUB(TIMESTAMP date, INT microseconds), MICROSECONDS_SUB(TIMESTAMP date, BIGINT microseconds)
Purpose: Returns the specified date and time minus some number of microseconds.

Return type: TIMESTAMP

MILLISECOND(TIMESTAMP ts)
Purpose: Returns the millisecond portion of a TIMESTAMP value.

Return type: INT

Usage notes:

The millisecond value is truncated, not rounded, if the TIMESTAMP value contains more than 3 significant digits to the right of the decimal point.

MILLISECONDS_ADD(TIMESTAMP date, INT milliseconds), MILLISECONDS_ADD(TIMESTAMP date, BIGINT milliseconds)
Purpose: Returns the specified date and time plus some number of milliseconds.

Return type: TIMESTAMP

MILLISECONDS_SUB(TIMESTAMP date, INT milliseconds), MILLISECONDS_SUB(TIMESTAMP date, BIGINT milliseconds)
Purpose: Returns the specified date and time minus some number of milliseconds.

Return type: TIMESTAMP

MINUTE(TIMESTAMP date)
Purpose: Returns the minute field from a TIMESTAMP value.

Return type: INT

MINUTES_ADD(TIMESTAMP date, INT minutes), MINUTES_ADD(TIMESTAMP date, BIGINT minutes)
Purpose: Returns the specified date and time plus some number of minutes.

Return type: TIMESTAMP

MINUTES_SUB(TIMESTAMP date, INT minutes), MINUTES_SUB(TIMESTAMP date, BIGINT minutes)
Purpose: Returns the specified date and time minus some number of minutes.

Return type: TIMESTAMP

MONTH(TIMESTAMP / DATE date)
Purpose: Returns the month field, represented as an integer, from the date argument.

Return type: INT

MONTHNAME(TIMESTAMP / DATE date)
Purpose: Returns the month name of the date argument.

Return type: STRING

MONTHS_ADD(TIMESTAMP / DATE date, INT / BIGINT months)
Purpose: Returns the value with the number of months added to date.
Return type:
  • If date is TIMESTAMP, returns TIMESTAMP.
  • If date is DATE, returns DATE.

Usage notes:

If date is the last day of a month, the return date will fall on the last day of the target month, e.g. MONTHS_ADD(DATE'2019-01-31', 1) returns DATE'2019-02-28'.

MONTHS_BETWEEN(TIMESTAMP / DATE enddate, TIMESTAMP / DATE startdate)
Purpose: Returns the number of months from startdate to enddate.
This result can include a fractional part representing extra days in addition to the full months between the dates. The fractional component is computed by dividing the difference in days by 31 (regardless of the month).

Return type: DOUBLE

Usage notes:

Typically used in business contexts, for example to determine whether a specified number of months have passed or whether some end-of-month deadline was reached.

If the only consideration is the number of full months and any fractional value is not significant, use INT_MONTHS_BETWEEN() instead.

The method of determining the number of elapsed months includes some special handling of months with different numbers of days that creates edge cases for dates between the 28th and 31st days of certain months.

If either value is NULL, which could happen for example when converting a nonexistent date string such as '2015-02-29' to a TIMESTAMP, the result is also NULL.

If the first argument represents an earlier time than the second argument, the result is negative.

The time portion of the input arguements are ignored.

MONTHS_SUB(TIMESTAMP / DATE date, INT / BIGINT months)
Purpose: Returns the value with the number of months subtracted from date.
Return type:
  • If date is TIMESTAMP, returns TIMESTAMP.
  • If date is DATE, returns DATE.

Usage notes:

If date is the last day of a month, the return date will fall on the last day of the target month, e.g. MONTHS_SUB(DATE'2019-02-28', 1) returns DATE'2019-01-31'.

NANOSECONDS_ADD(TIMESTAMP date, INT nanoseconds), NANOSECONDS_ADD(TIMESTAMP date, BIGINT nanoseconds)
Purpose: Returns the specified date and time plus some number of nanoseconds.

Return type: TIMESTAMP

Kudu considerations:

The nanosecond portion of an Impala TIMESTAMP value is rounded to the nearest microsecond when that value is stored in a Kudu table.

NANOSECONDS_SUB(TIMESTAMP date, INT nanoseconds), NANOSECONDS_SUB(TIMESTAMP date, BIGINT nanoseconds)
Purpose: Returns the specified date and time minus some number of nanoseconds.

Return type: TIMESTAMP

Kudu considerations:

The nanosecond portion of an Impala TIMESTAMP value is rounded to the nearest microsecond when that value is stored in a Kudu table.

NEXT_DAY(TIMESTAMP / DATE date, STRING weekday)
Purpose: Returns the date of the weekday that follows the specified date.

Argument: The weekday is not case-sensitive.

The following values are accepted for weekday: "Sunday"/"Sun", "Monday"/"Mon", "Tuesday"/"Tue", "Wednesday"/"Wed", "Thursday"/"Thu", "Friday"/"Fri", "Saturday"/"Sat"

Return type:
  • Returns TIMESTAMP if date is of the TIMESTAMP type.
  • Returns DATE if date is of the DATE type.

Examples:

NEXT_DAY('2013-12-25','Saturday') returns '2013-12-28 00:00:00' which is the first Saturday after December 25, 2013.

NOW()
Purpose: Returns the current date and time (in the local time zone) as a TIMESTAMP value.

Return type: TIMESTAMP

Usage notes:

To find a date/time value in the future or the past relative to the current date and time, add or subtract an INTERVAL expression to the return value of NOW().

To produce a TIMESTAMP representing the current date and time that can be shared or stored without interoperability problems due to time zone differences, use the TO_UTC_TIMESTAMP() function and specify the time zone of the server. When TIMESTAMP data is stored in UTC form, any application that queries those values can convert them to the appropriate local time zone by calling the inverse function, FROM_UTC_TIMESTAMP().

To determine the time zone of the server you are connected to, you can call the timeofday() function, which includes the time zone specifier in its return value. Remember that with cloud computing, the server you interact with might be in a different time zone than you are, or different sessions might connect to servers in different time zones, or a cluster might include servers in more than one time zone.

Any references to the NOW() function are evaluated at the start of a query. All calls to NOW() within the same query return the same value, and the value does not depend on how long the query takes.

QUARTER(TIMESTAMP / DATE date)
Purpose: Returns the quarter in the input date argument as an integer value, 1, 2, 3, or 4, where 1 represents January 1 through March 31.

Return type: INT

SECOND(TIMESTAMP date)
Purpose: Returns the second field from a TIMESTAMP value.

Return type: INT

SECONDS_ADD(TIMESTAMP date, INT seconds), SECONDS_ADD(TIMESTAMP date, BIGINT seconds)
Purpose: Returns the specified date and time plus some number of seconds.

Return type: TIMESTAMP

SECONDS_SUB(TIMESTAMP date, INT seconds), SECONDS_SUB(TIMESTAMP date, BIGINT seconds)
Purpose: Returns the specified date and time minus some number of seconds.

Return type: TIMESTAMP

SUBDATE(TIMESTAMP / DATE date, INT / BIGINT days)
Purpose: Subtracts days from date and returns the new date value.

The days value can be negative, which gives the same result as the ADDDATE() function.

Return type:
  • If date is TIMESTAMP, returns TIMESTAMP.
  • If date is DATE, returns DATE.
TIMEOFDAY()
Purpose: Returns a string representation of the current date and time, according to the time of the local system, including any time zone designation.

Return type: STRING

Usage notes:

The result value represents similar information as the now() function, only as a STRING type and with somewhat different formatting. For example, the day of the week and the time zone identifier are included. This function is intended primarily for compatibility with SQL code from other systems that also have a timeofday() function. Prefer to use now() if practical for any new Impala code.

TIMESTAMP_CMP(TIMESTAMP t1, TIMESTAMP t2)
Purpose: Tests if one TIMESTAMP value is newer than, older than, or identical to another TIMESTAMP

  • If the first argument represents a later point in time than the second argument, the result is 1.

  • If the first argument represents an earlier point in time than the second argument, the result is -1.

  • If the first and second arguments represent identical points in time, the result is 0.

  • If either argument is NULL, the result is NULL.

Return type: INT (either -1, 0, 1, or NULL)

Usage notes:

A comparison function for TIMESTAMP values that only tests whether the date and time increases, decreases, or stays the same. Similar to the SIGN() function for numeric values.

TO_DATE(TIMESTAMP ts)
Purpose: Returns a string representation of the date field from the ts argument.

Return type: STRING

TO_TIMESTAMP(BIGINT unixtime), TO_TIMESTAMP(STRING date, STRING pattern)
Purpose: Converts an integer or string representing a date/time value into the corresponding TIMESTAMP value.

Return type: TIMESTAMP

Usage notes:

An integer argument represents the number of seconds past the epoch (midnight on January 1, 1970). It is the converse of the UNIX_TIMESTAMP() function, which produces a BIGINT representing the number of seconds past the epoch.

A string argument, plus another string argument representing the pattern, turns an arbitrary string representation of a date and time into a true TIMESTAMP value. The ability to parse many kinds of date and time formats allows you to deal with temporal data from diverse sources, and if desired to convert to efficient TIMESTAMP values during your ETL process. Using TIMESTAMP directly in queries and expressions lets you perform date and time calculations without the overhead of extra function calls and conversions each time you reference the applicable columns.

Examples:

The following examples demonstrate how to convert an arbitrary string representation to TIMESTAMP based on a pattern string: 


select to_timestamp('Sep 25, 1984', 'MMM dd, yyyy');
+----------------------------------------------+
| to_timestamp('sep 25, 1984', 'mmm dd, yyyy') |
+----------------------------------------------+
| 1984-09-25 00:00:00                          |
+----------------------------------------------+

select to_timestamp('1984/09/25', 'yyyy/MM/dd');
+------------------------------------------+
| to_timestamp('1984/09/25', 'yyyy/mm/dd') |
+------------------------------------------+
| 1984-09-25 00:00:00                      |
+------------------------------------------+

The following examples show how to convert a BIGINT representing seconds past epoch into a TIMESTAMP value: 


-- One day past the epoch.
select to_timestamp(24 * 60 * 60);
+----------------------------+
| to_timestamp(24 * 60 * 60) |
+----------------------------+
| 1970-01-02 00:00:00        |
+----------------------------+

-- 60 seconds in the past.
select now() as 'current date/time',
  unix_timestamp(now()) 'now in seconds',
  to_timestamp(unix_timestamp(now()) - 60) as '60 seconds ago';
+-------------------------------+----------------+---------------------+
| current date/time             | now in seconds | 60 seconds ago      |
+-------------------------------+----------------+---------------------+
| 2017-10-01 22:03:46.885624000 | 1506895426     | 2017-10-01 22:02:46 |
+-------------------------------+----------------+---------------------+
TO_UTC_TIMESTAMP(TIMESTAMP ts, STRING timezone)
Purpose: Converts a specified timestamp value in a specified time zone into the corresponding value for the UTC time zone.

Return type: TIMESTAMP

Usage notes:

Often used in combination with the now() function, to translate local date and time values to the UTC time zone for consistent representation on disk. The opposite of the FROM_UTC_TIMESTAMP() function.

See discussion of time zones in TIMESTAMP data type for information about using this function for conversions between the local time zone and UTC.

Examples:

The simplest use of this function is to turn a local date/time value to one with the standardized UTC time zone. Because the time zone specifier is not saved as part of the Impala TIMESTAMP value, all applications that refer to such data must agree in advance which time zone the values represent. If different parts of the ETL cycle, or different instances of the application, occur in different time zones, the ideal reference point is to convert all TIMESTAMP values to UTC for storage. 


select now() as 'Current time in California USA',
  to_utc_timestamp(now(), 'PDT') as 'Current time in Greenwich UK';
+--------------------------------+-------------------------------+
| current time in california usa | current time in greenwich uk  |
+--------------------------------+-------------------------------+
| 2016-06-01 15:52:08.980072000  | 2016-06-01 22:52:08.980072000 |
+--------------------------------+-------------------------------+

Once a value is converted to the UTC time zone by TO_UTC_TIMESTAMP(), it can be converted back to the local time zone with FROM_UTC_TIMESTAMP(). You can combine these functions using different time zone identifiers to convert a TIMESTAMP between any two time zones. This example starts with a TIMESTAMP value representing Pacific Daylight Time, converts it to UTC, and converts it to the equivalent value in Eastern Daylight Time. 


select now() as 'Current time in California USA',
  from_utc_timestamp
  (
    to_utc_timestamp(now(), 'PDT'),
    'EDT'
  ) as 'Current time in New York, USA';
+--------------------------------+-------------------------------+
| current time in california usa | current time in new york, usa |
+--------------------------------+-------------------------------+
| 2016-06-01 18:14:12.743658000  | 2016-06-01 21:14:12.743658000 |
+--------------------------------+-------------------------------+
TRUNC(TIMESTAMP / DATE ts, STRING unit)
Purpose: Returns the ts truncated to the unit specified.

Argument: The unit argument is not case-sensitive. This argument string can be one of:

Unit Supported for TIMESTAMP ts Supported for DATE ts Description

'SYYYY'

'YYYY'

'YEAR'

'SYEAR'

'YYY'

'YY'

'Y'

Yes Yes Year

'Q'

Yes Yes Quarter

'MONTH'

'MON'

'MM'

'RM'

Yes Yes Month

'WW'

Yes Yes The most recent date that is the same day of the week as the first day of the year

'W'

Yes Yes The most recent date that is the same day of the week as the first day of the month

'DDD'

'DD'

'J'

Yes Yes Day

'DAY'

'DY'

'D'

Yes Yes Starting day of the week (Monday)

'HH'

'HH12'

'HH24'

Yes No Hour. A TIMESTAMP value truncated to the hour is always represented in 24-hour notation, even for the HH12 argument string.
'MI' Yes No Minute

Usage notes:

The TIMESTAMP form is typically used in GROUP BY queries to aggregate results from the same hour, day, week, month, quarter, and so on. You can also use this function in an INSERT ... SELECT into a partitioned table to divide TIMESTAMP values into the correct partition.

Return type:
  • TIMESTAMP if the first argument, ts, is TIMESTAMP.
  • DATE if the first argument, ts, is DATE.

Example:

TRUNC(DATE'2019-05-08','YEAR') returns 2019-01-01.

TRUNC(DATE'2019-05-08', 'QUARTER') returns 2019-04-01.

UNIX_TIMESTAMP(), UNIX_TIMESTAMP(STRING datetime), UNIX_TIMESTAMP(STRING datetime, STRING pattern), UNIX_TIMESTAMP(TIMESTAMP datetime)
Purpose: Returns a Unix time, which is a number of seconds elapsed since '1970-01-01 00:00:00' UTC. If called with no argument, the current date and time is converted to its Unix time. If called with arguments, the first argument represented as the TIMESTAMP or STRING is converted to its Unix time.

Return type: BIGINT

Usage notes:

See FROM_UNIXTIME() for details about the patterns you can use in the pattern string to represent the position of year, month, day, and so on in the date string. In Impala 1.3 and higher, you have more flexibility to switch the positions of elements and use different separator characters.

You can include a trailing uppercase Z qualifier to indicate Zulu time, a synonym for UTC.

You can include a timezone offset specified as minutes and hours, provided you also specify the details in the pattern string argument. The offset is specified in the pattern string as a plus or minus sign followed by hh:mm, hhmm, or hh. The hh must be lowercase, to distinguish it from the HH represent hours in the actual time value. Currently, only numeric timezone offsets are allowed, not symbolic names.

Built-in functions that accept or return integers representing TIMESTAMP values use the BIGINT type for parameters and return values, rather than INT. This change lets the date and time functions avoid an overflow error that would otherwise occur on January 19th, 2038 (known as the Year 2038 problem or Y2K38 problem). This change affects the FROM_UNIXTIME() and UNIX_TIMESTAMP() functions. You might need to change application code that interacts with these functions, change the types of columns that store the return values, or add CAST() calls to SQL statements that call these functions.

UNIX_TIMESTAMP() and FROM_UNIXTIME() are often used in combination to convert a TIMESTAMP value into a particular string format. For example, FROM_UNIXTIME(UNIX_TIMESTAMP(NOW() + interval 3 days), 'yyyy/MM/dd HH:mm').

The way this function deals with time zones when converting to or from TIMESTAMP values is affected by the ‑‑use_local_tz_for_unix_timestamp_conversions startup flag for the impalad daemon. See TIMESTAMP data type for details about how Impala handles time zone considerations for the TIMESTAMP data type.

Examples:

The following examples show different ways of turning the same date and time into an integer value. A pattern string that Impala recognizes by default is interpreted as a UTC date and time. The trailing Z is a confirmation that the timezone is UTC. If the date and time string is formatted differently, a second argument specifies the position and units for each of the date and time values.

The final two examples show how to specify a timezone offset of Pacific Daylight Saving Time, which is 7 hours earlier than UTC. You can use the numeric offset -07:00 and the equivalent suffix of -hh:mm in the pattern string, or specify the mnemonic name for the time zone in a call to TO_UTC_TIMESTAMP(). This particular date and time expressed in PDT translates to a different number than the same date and time expressed in UTC. 


-- 3 ways of expressing the same date/time in UTC and converting to an integer.

select unix_timestamp('2015-05-15 12:00:00');
+---------------------------------------+
| unix_timestamp('2015-05-15 12:00:00') |
+---------------------------------------+
| 1431691200                            |
+---------------------------------------+

select unix_timestamp('2015-05-15 12:00:00Z');
+----------------------------------------+
| unix_timestamp('2015-05-15 12:00:00z') |
+----------------------------------------+
| 1431691200                             |
+----------------------------------------+

select unix_timestamp
(
  'May 15, 2015 12:00:00',
  'MMM dd, yyyy HH:mm:ss'
) as may_15_month_day_year;
+-----------------------+
| may_15_month_day_year |
+-----------------------+
| 1431691200            |
+-----------------------+

-- 2 ways of expressing the same date and time but in a different timezone.
-- The resulting integer is different from the previous examples.

select unix_timestamp
(
  '2015-05-15 12:00:00-07:00',
  'yyyy-MM-dd HH:mm:ss-hh:mm'
) as may_15_year_month_day;
+-----------------------+
| may_15_year_month_day |
+-----------------------+
| 1431716400            |
+-----------------------+

select unix_timestamp
  (to_utc_timestamp(
    '2015-05-15 12:00:00',
    'PDT')
  ) as may_15_pdt;
+------------+
| may_15_pdt |
+------------+
| 1431716400 |
+------------+
UTC_TIMESTAMP()
Purpose: Returns a TIMESTAMP corresponding to the current date and time in the UTC time zone.

Return type: TIMESTAMP

Examples:

Similar to the NOW() or CURRENT_TIMESTAMP() functions, but does not use the local time zone as those functions do. Use UTC_TIMESTAMP() to record TIMESTAMP values that are interoperable with servers around the world, in arbitrary time zones, without the need for additional conversion functions to standardize the time zone of each value representing a date/time.

For working with date/time values represented as integer values, you can convert back and forth between TIMESTAMP and BIGINT with the UNIX_MICROS_TO_UTC_TIMESTAMP() and UTC_TO_UNIX_MICROS() functions. The integer values represent the number of microseconds since the Unix epoch (midnight on January 1, 1970).

Examples:

The following example shows how NOW() and CURRENT_TIMESTAMP() represent the current date/time in the local time zone (in this case, UTC-7), while utc_timestamp() represents the same date/time in the standardized UTC time zone: 


select now(), utc_timestamp();
+-------------------------------+-------------------------------+
| now()                         | utc_timestamp()               |
+-------------------------------+-------------------------------+
| 2017-10-01 23:33:58.919688000 | 2017-10-02 06:33:58.919688000 |
+-------------------------------+-------------------------------+

select current_timestamp(), utc_timestamp();
+-------------------------------+-------------------------------+
| current_timestamp()           | utc_timestamp()               |
+-------------------------------+-------------------------------+
| 2017-10-01 23:34:07.400642000 | 2017-10-02 06:34:07.400642000 |
+-------------------------------+-------------------------------+
WEEK(TIMESTAMP / DATE date), WEEKOFYEAR(TIMESTAMP / DATE date)
Purpose: Returns the corresponding week (1-53) from the date argument.

Return type: INT

WEEKS_ADD(TIMESTAMP / DATE date, INT / BIGINT weeks)
Purpose: Returns the value with the number of weeks added to date.
Return type:
  • If date is TIMESTAMP, returns TIMESTAMP.
  • If date is DATE, returns DATE.
WEEKS_SUB(TIMESTAMP / DATE date, INT / BIGINT weeks)
Purpose: Returns the value with the number of weeks subtracted from date.
Return type:
  • If date is TIMESTAMP, returns TIMESTAMP.
  • If date is DATE, returns DATE.
YEAR(TIMESTAMP / DATE date)
Purpose: Returns the year field from the date argument.

Return type: INT

YEARS_ADD(TIMESTAMP / DATE date, INT / BIGINT years)
Purpose: Returns the value with the number of years added to date.
Return type:
  • If date is TIMESTAMP, returns TIMESTAMP.
  • If date is DATE, returns DATE.

Usage notes:

If the equivalent date does not exist in the year of the result due to a leap year, the date is changed to the last day of the appropriate month.

YEARS_SUB(TIMESTAMP / DATE date, INT / BIGINT years)
Purpose: Returns the value with the number of years subtracted from date.
Return type:
  • If date is TIMESTAMP, returns TIMESTAMP.
  • If date is DATE, returns DATE.

Usage notes:

If the equivalent date does not exist in the year of the result due to a leap year, the date is changed to the last day of the appropriate month.