Functions and Operators

Basic Mathematical Operators

Operator Description
+numeric Returns numeric
numeric Returns negative value of numeric
numeric1 + numeric2 Sum of numeric1 and numeric2
numeric1 numeric2 Difference of numeric1 and numeric2
numeric1 * numeric2 Product of numeric1 and numeric2
numeric1 / numeric2 Quotient (numeric1 divided by numeric2)

Mathematical Operator Precedence

  1. Parenthesization
  2. Multiplication and division
  3. Addition and subtraction

Comparison Operators

Operator Description
= Equals
<> Not equals
> Greater than
>= Greater than or equal to
< Less than
<= Less than or equal to
BETWEEN x AND y Is a value within a range
NOT BETWEEN x AND y Is a value not within a range
IS NULL Is a value that is null
IS NOT NULL Is a value that is not null
NULLIF(x, y) Compare expressions x and y. If different, return x. If they are the same, return null. For example, if a dataset uses ‘NA’ for null values, you can use this statement to return null using SELECT NULLIF(field_name,'NA').
IS TRUE True if a value resolves to TRUE.
IS NOT TRUE True if a value resolves to FALSE.

Mathematical Functions

Function Description
ABS(x) Returns the absolute value of x
CEIL(x) Returns the smallest integer not less than the argument
DEGREES(x) Converts radians to degrees
EXP(x) Returns the value of e to the power of x
FLOOR(x) Returns the largest integer not greater than the argument
LN(x) Returns the natural logarithm of x
LOG(x) Returns the natural logarithm of x
LOG10(x) Returns the base-10 logarithm of the specified float expression x
MOD(x, y) Returns the remainder of int x divided by int y
PI() Returns the value of pi
POWER(x, y) Returns the value of x raised to the power of y
RADIANS(x) Converts degrees to radians
ROUND(x) Rounds x to the nearest integer value, but does not change the data type. For example, the double value 4.1 rounds to the double value 4.
ROUND_TO_DIGIT (x, y) Rounds x to y decimal places
SIGN(x) Returns the sign of x as -1, 0, 1 if x is negative, zero, or positive
SQRT(x) Returns the square root of x.
TRUNCATE(x, y) Truncates x to y decimal places

Trigonometric Functions

Function Description
ACOS(x) Returns the arc cosine of x
ASIN(x) Returns the arc sine of x
ATAN(x) Returns the arc tangent of x
ATAN2(x, y) Returns the arc tangent of x and y
COS(x) Returns the cosine of x
COT(x) Returns the cotangent of x
SIN(x) Returns the sine of x
TAN(x) Returns the tangent of x

Geometric Functions

Function Description
DISTANCE_IN_METERS(fromLon, fromLat, toLon, toLat) Calculates distance in meters between two WGS-84 positions.
CONV_4326_900913_X(x) Converts WGS-84 latitude to WGS-84 Web Mercator x coordinate.
CONV_4326_900913_Y(y) Converts WGS-84 longitude to WGS-84 Web Mercator y coordinate.

String Functions

Function Description
CHAR_LENGTH(str) Returns the number of characters in a string
LENGTH(str) Returns the length of a string in bytes
Note String functions only work with unencoded fields (ENCODING set to none).

Pattern-matching Functions

Name Example Description
str LIKE pattern 'ab' LIKE 'ab' Returns true if the string matches the pattern
str NOT LIKE pattern 'ab' NOT LIKE 'cd' Returns true if the string does not match the pattern
str ILIKE pattern 'AB' ILIKE 'ab' Case-insensitive LIKE
str REGEXP POSIX pattern '^[a-z]+r$' Lowercase string ending with r
REGEXP_LIKE ( str , POSIX pattern ) '^[hc]at' cat or hat

Usage Notes

The following wildcard characters are supported by LIKE and ILIKE:

  • % matches any number of characters, including zero characters.
  • _ matches exactly one character.

Date/Time Functions

Function Description
DATE_TRUNC(date_part, timestamp) Truncates the timestamp to the specified date_part. Note that date_part is not enclosed in single quotes.
Example
SELECT DATE_TRUNC(MINUTE, arr_timestamp) Arrival \
FROM flights_2008_10k LIMIT 10;
EXTRACT(date_part FROM timestamp) Returns the specified date_part from timestamp. Note that date_part is not enclosed in single quotes.
Example
SELECT EXTRACT(HOUR FROM arr_timestamp) Arrival_Hour \
FROM flights_2008_10k LIMIT 10;
INTERVAL 'count' date_part Adds or Subtracts count date_part units from a timestamp. Note that 'count' is enclosed in single quotes and date_part is not enclosed in single quotes.
Example
SELECT arr_timestamp + INTERVAL '10' YEAR \
FROM flights_2008_10k LIMIT 10;
NOW() Returns the current timestamp.
Example
SELECT NOW() FROM flights_2008_10k LIMIT 1;
TIMESTAMPADD(date_part, count, timestamp | date) Adds an interval of count date_part to timestamp or date and returns signed date_part units in the provided timestamp or date form. Note that neither count nor date_part are enclosed in single quotes.
Example
SELECT TIMESTAMPADD(DAY, 14, arr_timestamp) Fortnight \
FROM flights_2008_10k LIMIT 10;
TIMESTAMPDIFF(date_part, timestamp1, timestamp2) Subtracts timestamp1 from timestamp2 and returns the result in signed date_part units. Note that date_part is not enclosed in single quotes.
Example
SELECT TIMESTAMPDIFF(MINUTE, arr_timestamp, dep_timestamp) Flight_Time \
FROM flights_2008_10k LIMIT 10;
DATEDIFF('date_part', date, date) Returns the difference between two dates, calculated to the lowest level of the 'date_part' you specify. For example, if you set the 'date_part' as DAY, only the year, month, and day are used to calculate the result. Other fields, such as hour and minute, are ignored.

Note that 'date_part' must be enclosed in single quotes.
Example
SELECT DATEDIFF('YEAR', plane_issue_date, now()) Years_In_Service \
FROM flights_2008_10k LIMIT 10;
DATEADD('date_part', interval, date | timestamp) Returns a date after a specified time/date interval has been added. Note that 'date_part' must be enclosed in single quotes.
Example
SELECT DATEADD('MINUTE', 6000, dep_timestamp) Arrival_Estimate \
FROM flights_2008_10k LIMIT 10;
DATEPART('interval', date | timestamp) Returns a specified part of a given date or timestamp as an integer value. Note that 'interval' must be enclosed in single quotes.
Example
SELECT DATEPART('YEAR', plane_issue_date) Year_Issued \
FROM flights_2008_10k LIMIT 10;

Usage Notes

Supported date_part types:

DATE_TRUNC [YEAR, QUARTER, MONTH, DAY, HOUR, MINUTE, SECOND, MILLISECOND, 
            MICROSECOND, NANOSECOND, MILLENNIUM, CENTURY, DECADE, WEEK, 
            QUARTERDAY]
EXTRACT    [YEAR, QUARTER, MONTH, DAY, HOUR, MINUTE, SECOND, MILLISECOND, 
            MICROSECOND, NANOSECOND, DOW, ISODOW, DOY, EPOCH, QUARTERDAY, 
            WEEK]
DATEDIFF   [YEAR, QUARTER, MONTH, DAY, HOUR, MINUTE, SECOND, MILLISECOND, 
            MICROSECOND, NANOSECOND, MILLENNIUM, CENTURY, DECADE, WEEK,
            QUARTERDAY]

Supported interval types:

DATEADD  [DECADE, YEAR, QUARTER, MONTH, WEEK, WEEKDAY, DAY, 
               HOUR, MINUTE, SECOND, MILLISECOND, MICROSECOND, NANOSECOND]
TIMESTAMPADD  [YEAR, QUARTER, MONTH, WEEKDAY, DAY, HOUR, MINUTE,
               SECOND, MILLISECOND, MICROSECOND, NANOSECOND]
DATEPART      [YEAR, QUARTER, MONTH, DAYOFYEAR, QUARTERDAY, WEEKDAY, DAY, HOUR,
               MINUTE, SECOND, MILLISECOND, MICROSECOND, NANOSECOND]

Accepted Date, Time, and Timestamp Formats

Datatype Formats Examples
DATE YYYY-MM-DD 2013-10-31
DATE MM/DD/YYYY 10/31/2013
DATE DD-MON-YY 31-Oct-13
DATE DD/Mon/YYYY 31/Oct/2013
EPOCH 1383262225
TIME HH:MM 23:49
TIME HHMMSS 234901
TIME HH:MM:SS 23:49:01
TIMESTAMP DATE TIME 31-Oct-13 23:49:01
TIMESTAMP DATETTIME 31-Oct-13T23:49:01
TIMESTAMP DATE:TIME 11/31/2013:234901
TIMESTAMP DATE TIME ZONE 31-Oct-13 11:30:25 -0800
TIMESTAMP DATE HH.MM.SS PM 31-Oct-13 11.30.25pm
TIMESTAMP DATE HH:MM:SS PM 31-Oct-13 11:30:25pm
TIMESTAMP   1383262225

Usage Notes

  • For two-digit years, years 69-99 are assumed to be previous century (for example, 1969), and 0-68 are assumed to be current century (for example, 2016).
  • For four-digit years, negative years (BC) are not supported.
  • Hours are expressed in 24-hour format.
  • When time components are separated by colons, you can write them as one or two digits.
  • Months are case insensitive. You can spell them out or abbreviate to three characters.
  • For timestamps, decimal seconds are ignored. Time zone offsets are written as +/-HHMM.
  • For timestamps, a numeric string is converted to +/- seconds since January 1, 1970. Supported timestamps range from -30610224000 (January 1, 1000) through 29379456000 (December 31, 2900).
  • On output, dates are formatted as YYYY-MM-DD. Times are formatted as HH:MM:SS.
  • Linux EPOCH values range from -30610224000 (1/1/1000) through 185542587100800 (1/1/5885487). Complete range in years: +/-5,883,517 around epoch.

Statistical and Aggregate Functions

Both double-precision (standard) and single-precision floating point statistical functions are provided. Single-precision functions run faster on GPUs but might cause overflow errors.

Double-precision FP Function Single-precision FP Function Description
AVG(x) Returns the average value of x
COUNT() Returns the count of the number of rows returned
COUNT(DISTINCT x) Returns the count of distinct values of x
APPROX_COUNT_DISTINCT(x, e) Returns the approximate count of distinct values of x with defined expected error rate e
MAX(x) Returns the maximum value of x
MIN(x) Returns the minimum value of x
SUM(x) Returns the sum of the values of x
SAMPLE(x) Returns one sample value from aggregated column x. For example, the following query returns population grouped by city, along with one value from the state column for each group:
SELECT city, SAMPLE(state), sum (population)
FROM census_table
GROUP BY city

Note: This was previously LAST_SAMPLE, which is now deprecated.

CORRELATION(x, y) CORRELATION_FLOAT(x, y) Alias of CORR. Returns the coefficient of correlation of a set of number pairs.
CORR(x, y) CORR_FLOAT(x, y) Returns the coefficient of correlation of a set of number pairs.
COVAR_POP(x, y) COVAR_POP_FLOAT(x, y) Returns the population covariance of a set of number pairs.
COVAR_SAMP(x, y) COVAR_SAMP_FLOAT(x, y) Returns the sample covariance of a set of number pairs.
STDDEV(x) STDDEV_FLOAT(x) Alias of STDDEV_SAMP. Returns sample standard deviation of the value.
STDDEV_POP(x) STDDEV_POP_FLOAT(x) Returns the population standard the standard deviation of the value.
STDDEV_SAMP(x) STDDEV_SAMP_FLOAT(x) Returns the sample standard deviation of the value.
VARIANCE(x) VARIANCE_FLOAT(x) Alias of VAR_SAMP. Returns the sample variance of the value.
VAR_POP(x) VAR_POP_FLOAT(x) Returns the population variance sample variance of the value.
VAR_SAMP(x) VAR_SAMP_FLOAT(x) Returns the sample variance of the value.

Usage Notes

  • COUNT(DISTINCT x), especially when used in conjunction with GROUP BY, can require a very large amount of memory to keep track of all distinct values in large tables with large cardinalities. To avoid this large overhead, use APPROX_COUNT_DISTINCT.
  • APPROX_COUNT_DISTINCT(x, e) gives an approximate count of the value x, based on an expected error rate defined in e. The error rate is an integer value from 1 to 100. The lower the value of e, the higher the precision, and the higher the memory cost. Select a value for e based on the level of precision required. On large tables with large cardinalities, consider using APPROX_COUNT_DISTINCT when possible to preserve memory. When data cardinalities permit, OmniSci uses the precise implementation of COUNT(DISTINCT x) for APPROX_COUNT_DISTINCT.
    Set the default error rate using the -hll-precision-bits configuration paramenter.
  • Currently, OmniSci does not support grouping by non-dictionary-encoded strings. However, with the SAMPLE aggregate function, you can select non-dictionary-encoded strings that are presumed to be unique in a group. For example:
    SELECT user_name, SAMPLE(user_decription) FROM tweets GROUP BY user_name;
    
    If the aggregated column (user_description in the example above) is not unique within a group, SAMPLE selects a value that might be nondeterministic because of the parallel nature of OmniSci query execution.