PostgreSQL functions

This page defines the functions supported for PostgreSQL databases in the preview release of the PostgreSQL interface feature.

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) 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(float8, float8) atan2(1,0) → 1.5707963267948966 Inverse tangent of y/x, result in radians.
ceil(float8) 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) → 8.15484548538 Raise e to the specified exponent (e^x).
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) 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(int8, int8) mod(9,4) → 1 Remainder of y/x.
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) → 42
trunc(-42.8::FLOAT8) → -42
Truncates to integer (towards zero).

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, NULL, 22::text) → abcde222 Concatenates the text representations of all the arguments. NULL arguments are ignored. 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 example below, the result includes 3 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') → t
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'th 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) → \xba7816bf8f01cfea414140de5dae2223​b00361a396177a9cb410ff61f20015ad Computes the SHA-256 hash of the binary string.
sha512(bytea) sha512('abc'::bytea) → \xddaf35a193617abacc417349ae204131​12e6fa4e89a97ea20a9eeee64b55d39a​2192992a274fc1a836ba3c23a3feebbd​454d4423643ce80e2a9ac94fa54ca49f Computes the SHA-512 hash of the binary string.
substr(bytes bytea, start int8) Extracts the substring of bytes starting at the start'th byte.
substr(bytes bytea, start int8, count int8) substr('\x1234567890'::bytea, 3, 2) → \x5678 Extracts the substring of bytes starting at the start'th byte, and extending for count bytes.

Date/time functions

Function Example / Notes Description
now() Returns timestamptz.
now() → 2019-12-23 14:39:53.662522-05
Current date and time.
to_timestamp(int8) Returns timestamptz.
to_timestamp(1284352323) → 2010-09-13 04:32:03+00
Convert Unix epoch (seconds since 1970-01-01 00:00:00+00) to timestamp with time zone.

Aggregate functions

Function Example / Notes Description
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) 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 convertible to a common data type, which will be the type of the result.

greatest(ANY REPEATED) Returns the largest value from a list of any number of expressions. The expressions must all be convertible to a common 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) Returns the smallest value from a list of any number of expressions. The expressions must all be convertible to a common 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(ANY, 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.

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) Returns a substring of string, starting at the start'th character and continuing for count characters.
substring(string bytea, start int8) Returns a substring of string, from the start'th 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'th character and continuing for count characters.
substring(string text, start int8) substring("documentation", 2) → ocumentation Returns a substring of string, from the start'th character to the end of the string.