PostgreSQL functions

This page defines the functions supported for PostgreSQL-dialect databases.

Supported PostgreSQL functions

Mathematical functions

Unless otherwise specified, functions return the same data type as provided in the argument.

Function Example / Notes Description
abs(float8 | int8 | numeric) abs(-17) → 17 Absolute value.
acos(float8) acos(1) → 0 Inverse cosine, result in radians.
asin(float8) asin(1) → 1.5707963267948966 Inverse sine, result in radians.
atan(float8) atan(1) → 0.7853981633974483 Inverse tangent, result in radians.
atan2(x float8, y float8) atan2(1,0) → 1.5707963267948966 Inverse tangent of x/y, result in radians.
ceil(float8 | numeric) ceil(42.2::FLOAT8) → 43
ceil(-42.8::FLOAT8) → -42
Nearest integer greater than or equal to argument.
cos(float8) cos(0) → 1 Cosine, argument in radians.
dexp(float8) dexp(3) → 20.085536923187668 Raise e to the specified exponent (e^x).
div(x numeric, y numeric) div(9, 4) → 2 Integer quotient of x/y (truncates towards zero).
dlog10(float8) Returns the base 10 logarithm of the provided value.
dlog1(float8) Returns the value's natural logarithm.
dpow(float8, float8) Returns the value of the first number raised to the power of the second number.
dsqrt(float8) Returns the argument's square root.
exp(float8) exp(1.0::FLOAT8) → 2.7182818284590452 Exponential (e raised to the given power).
floor(float8 | numeric) floor(42.8::FLOAT8) → 42
floor(-42.8) → -43
Nearest integer less than or equal to argument.
ln(float8) ln(2.0::FLOAT8) → 0.6931471805599453 Natural logarithm.
log(float8) log(100.0::FLOAT8) → 2 Base 10 logarithm.
mod(x int8, y int8)
mod(x numeric, y numeric)
mod(9,4) → 1 Remainder of x/y.
power(float8, float8) power(9.0::FLOAT8, 3.0::FLOAT8) → 729 a raised to the power of b.

pow is an alias of power.

round(float8) round(42.4::FLOAT8) → 42 Rounds to nearest integer.
sign(float8) sign(-8.4::FLOAT8) → -1 Sign of the argument (-1, 0, or +1).
sin(float8) sin(1) → 0.8414709848078965 Sine, argument in radians.
sqrt(float8) sqrt(2::FLOAT8) → 1.4142135623730951 Square root.
tan(float8) tan(1) → 1.5574077246549023 Tangent, argument in radians.
trunc(float8) trunc(42.8::FLOAT8) → 42
trunc(-42.8::FLOAT8) → -42
Truncates to integer (towards zero).
trunc(x numeric, y integer) trunc(42.4382, 2) → 42.43 Truncates x to y decimal places.

Array functions

Function Example / Notes Description
array_cat(anyarray, anyarray) array_cat(ARRAY['cat', 'dog'], ARRAY['bird', 'turtle']) → {"cat", "dog", "bird", "turtle"} Concatenates two arrays.
array_length(anyarray, 1) array_length(daysofweek, 1) → 7 Returns the size of the array. The first parameter is an array. The second parameter specifies the dimension you want the length of, and since only one dimensional arrays are supported, this value is always 1.
array_to_string (array text_array, delimiter text [, null_string text ] ) array_to_string(ARRAY['a', NULL, 'c', 'd', 'e'] ',', '*')
→ 'a',*,'c','d','e'

array_to_string(ARRAY['a', NULL, 'c', 'd', 'e'], ',')
→ 'a','c','d','e'

array_to_string(ARRAY['a', NULL, 'c', 'd', 'e'], ',', NULL)
→ NULL

array_to_string(ARRAY['a', NULL, 'c', 'd', 'e'], NULL, '*')
→ NULL
Converts the values of the elements in a text array to their string representations. The first argument is the array which must be a text array. The second argument is a user-specified delimiter. The third (optional) argument is a user-specified null_string that the function substitutes for NULL values.

If you don't pass a null_string, and the function encounters a NULL value, the NULL value is not included in the results of the function.

If you pass NULL for either the delimiter argument or the null_string argument, then the entire array_to_string function returns NULL.

String functions

Function Example / Notes Description
btrim(text) btrim(' xyxyyx ') → xyxyyx Removes leading and trailing whitespace from the given string.
btrim(string text, characters text) btrim('xyxtrimyyx', 'xyz') → trim Removes the longest string containing only characters in characters from the start and end of string.
concat(text, text[, text][, text]) concat('abcde'::text, 2::text, 22::text) -> abcde222 Concatenates the text representations of all the arguments. Note that all literals must be cast to text.

textcat also concatenates text and does not require explicit casting of literals.

length(text) Returns int8.
length('mike') → 4
Returns the number of characters in the string.
lower(text) lower('PostgreSQL') → postgresql Converts the string to all lower case.
lpad(text, int8) lpad('hi', 7) → ␣␣␣␣␣hi Extends the string to the specified length by prepending spaces. If the string is already longer than length then it is truncated on the right.
lpad(string text, length int8, fill text) lpad('hi', 7, 'xy') → xyxyxhi Extends the string to length length by prepending the characters fill, repeated. If the string is already longer than length then it is truncated on the right.
ltrim(text) ltrim(' test') → test Removes leading spaces from a string.
ltrim(string text, characters text) ltrim('zzzytest', 'xyz') → test Removes the longest string containing only characters in characters from the start of string.
regexp_replace(string text, pattern text, replacement text) regexp_replace('Thomas', '.[mN]a.', 'M') → ThM Replaces substrings resulting from the first match of a POSIX regular expression. See the open-source PostgreSQL POSIX Regular Expressions documentation for more details.
repeat(text, int8) Returns text.
repeat('Pg', 4) → PgPgPgPg
Repeats a string the specified number of times.
replace(string text, from text, to text) replace('abcdefabcdef', 'cd', 'XX') → abXXefabXXef Replaces all occurrences in string of substring from with substring to.
reverse(text) reverse('abcde') → edcba Reverses the order of the characters in the string.
rpad(text, int8) Returns text. In the following example, the result includes three trailing spaces.
rpad('hi', 5) → hi␣␣␣
Extends the string to the specified length by appending spaces. If the string is already longer than the specified length then it is truncated.
rpad(string text, length int8, fill text) Returns text.
rpad('hi', 5, 'xy') → hixyx
Extends the string to length length by appending the characters fill, repeated if necessary. If the string is already longer than length then it is truncated.
rtrim(text) rtrim('test ') → test Removes trailing spaces from a string.
rtrim(string text, characters text) rtrim('testxxzx', 'xyz') → test Removes the longest string containing only characters in characters from the end of string.
starts_with(string text, prefix text) Returns Boolean.
starts_with('alphabet', 'alph') → true
Returns true if string starts with prefix.
strpos(string text, substring text) Returns int8.
strpos('high', 'ig') → 2
Returns first starting index of the specified substring within string, or zero if it's not present.
substr(text, int8) substr('alphabet', 3) → phabet Extracts the substring of the provided text starting at the specified character.
substr(string text, start int8, count int8) Returns text.
substr('alphabet', 3, 2) → ph
Extracts the substring of string starting at the start character, and extending for count characters.
textconcat(text, text[, text][, text]) concat('abcde', 2, NULL, 22) → abcde222 Concatenates the text representations of all the arguments. NULL arguments are ignored.
upper(text) upper('hello') → HELLO Converts the string to all upper case.

Binary string functions

Function Example / Notes Description
btrim(bytes bytea, bytesremoved bytea) btrim('\x1234567890'::bytea, '\x9012'::bytea) → \x345678 Removes the longest string containing only bytes appearing in bytesremoved from the start and end of bytes.
length(bytea) Returns int8.
length('\x1234567890'::bytea) → 5
Returns the number of bytes in the binary string.
sha256(bytea) sha256('abc'::bytea) → ungWv48Bz+pBQUDeXa4iI7ADYaOWF3qctBD/YfIAFa0= Computes the SHA-256 hash of the binary string.
sha512(bytea) sha512('abc'::bytea) → 3a81oZNherrMQXNJriBBMRLm+k6JqX6iCp7u5ktV05ohkpkqJ0/BqDa6PCOj/uu9RU1EI2Q86A4qmslPpUyknw== Computes the SHA-512 hash of the binary string.
substr(bytes bytea, start int8) substr('\x1234567890'::bytea, 3) -> \x567890 Extracts the substring of bytes starting at the start byte.
substr(bytes bytea, start int8, count int8) substr('\x1234567890'::bytea, 3, 2) → \x5678 Extracts the substring of bytes starting at the start byte, and extending for count bytes.

Date/time functions

Function Example / Notes Description
current_date SELECT CURRENT_DATE;
Result: 2022-05-13
Current date
current_timestamp SELECT CURRENT_TIMESTAMP;
Result: 2022-05-13T16:30:29.880850967Z
Current date and time.
make_date(int8, int8, int8) make_date(2013, 7, 15) → 2013-07-15 Create date from year, month and day fields (negative years signify BC)
now() Returns timestamptz.
now() → 2022-05-02T19:17:45.145511221Z
Current date and time.
to_timestamp(int8) Returns timestamptz.
to_timestamp(1284352323) → 2010-09-13T04:32:03Z
Convert Unix epoch (seconds since 1970-01-01 00:00:00+00) to timestamp with time zone.

Aggregate functions

Function Example / Notes Description
array_agg(anynonarray) Inserts the given values, including nulls, into an array.
avg(float8 | int8 | numeric) Computes the average (arithmetic mean) of all the non-null input values.
bit_and(int8) Computes the bitwise AND of all non-null input values.
bit_or(int8) Computes the bitwise OR of all non-null input values.
bool_and(bool) Returns true if all non-null input values are true, otherwise false.
bool_or(bool) Returns true if any non-null input value is true, otherwise false.
count() Returns int8. Computes the number of input rows.
count(bool | bytea | float8 | int8 | text | timestamptz) Returns int8. Computes the number of input rows in which the input value is not null.
every(bool) Equivalent to bool_and().
max(float8 | int8 | numeric | text | timestamptz) Returns same type as input type. Computes the maximum of the non-null input values.
min(float8 | int8 | numeric | text | timestamptz) Computes the minimum of the non-null input values.
string_agg(value bytea, delimiter bytea) Concatenates the non-null input values into a string. Each value after the first is preceded by the corresponding delimiter (if it's not null).
string_agg(value text, delimiter text) Concatenates the non-null input values into a string. Each value after the first is preceded by the corresponding delimiter (if it's not null).
sum(float8 | int8 | numeric) Computes the sum of the non-null input values.

Conditional functions

Function Example / Notes Description
coalesce(ANY REPEATED) coalesce(NULL, 'abc', 'def') -> 'abc' Returns the first of its arguments that is not null. Null is returned only if all arguments are null. It is often used to substitute a default value for null values when data is retrieved for display.

The arguments must all be of the same data type, which will be the type of the result.

greatest(ANY REPEATED) greatest(6, 10, 3, 14, 2) -> 14 Returns the largest value from a list of any number of expressions. The expressions must all be of the same data type, which will be the type of the result. NULL values in the list are ignored. The result will be NULL only if all the expressions evaluate to NULL.
least(ANY REPEATED) least(6, 10, 3, 14, 2) -> 2 Returns the smallest value from a list of any number of expressions. The expressions must all be of the same data type, which will be the type of the result. NULL values in the list are ignored. The result will be NULL only if all the expressions evaluate to NULL.
nullif(value1 ANY, value2 ANY) Returns a null value if value1 equals value2; otherwise it returns value1. The two arguments must be of comparable types. To be specific, they are compared exactly as if you had written value1 = value2, so there must be a suitable = operator available.

The result has the same type as the first argument — but there is a subtlety. What is actually returned is the first argument of the implied = operator, and in some cases that will have been promoted to match the second argument's type. For example, NULLIF(1, 2.2) yields numeric, because there is no integer = numeric operator, only numeric = numeric.

ISNULL datatype ISNULL → boolean Tests whether value is null (nonstandard syntax).
NOTNULL datatype NOTNULL → boolean Tests whether value is not null (nonstandard syntax).
IS TRUE boolean IS TRUE → boolean

true IS TRUE → true
NULL::boolean IS TRUE → false (rather than NULL)
Tests whether boolean expression yields true.
IS NOT TRUE boolean IS NOT TRUE → boolean

true IS NOT TRUE → false
NULL::boolean IS NOT TRUE → true (rather than NULL)
Tests whether boolean expression yields false or unknown.
IS FALSE boolean IS FALSE → boolean

true IS FALSE → false
NULL::boolean IS FALSE → false (rather than NULL)
Tests whether boolean expression yields false.
IS NOT FALSE boolean IS NOT FALSE → boolean

true IS NOT FALSE → true
NULL::boolean IS NOT FALSE → true (rather than NULL)
Tests whether boolean expression yields true or unknown.
IS UNKNOWN boolean IS UNKNOWN → boolean

true IS UNKNOWN → false
NULL::boolean IS UNKNOWN → true (rather than NULL)
Tests whether boolean expression yields unknown.
IS NOT UNKNOWN boolean IS NOT UNKNOWN → boolean

true IS NOT UNKNOWN → true
NULL::boolean IS NOT UNKNOWN → false (rather than NULL)
Tests whether boolean expression yields true or false.

Pattern matching functions

Function Example / Notes Description
like(string bytea, pattern bytea) Returns Boolean.
Returns true if the string matches the supplied pattern. More information about LIKE is available from the postgresql.org documentation.
like(string text, pattern text) Returns Boolean.
Returns true if the string matches the supplied pattern. More information about LIKE is available from the postgresql.org documentation.
substring(string bytea, start int8, count int8) substring('\x1234567890'::bytea, 3, 2) → \x5678 Returns a substring of string, starting at the start character and continuing for count characters.
substring(string bytea, start int8) substring('\x1234567890'::bytea, 3) -> \x567890 Returns a substring of string, from the start character to the end of the string.
substring(string text, start int8, count int8) substring('documentation', 2, 2) → oc Returns a substring of string, starting at the start character and continuing for count characters.
substring(string text, start int8) substring('documentation', 2) → ocumentation Returns a substring of string, from the start character to the end of the string.