SnowConvert AI - PostgreSQL - Built-in functions

Applies to

  • PostgreSQL

  • Greenplum

  • Netezza

Note

For more information about built-in functions and their Snowflake equivalents, also see Common built-in functions.

Aggregate Functions

Aggregate functions compute a single result value from a set of input values. (PostgreSQL Language Reference Aggregate Functions).

PostgreSQL

Snowflake

AVG

AVG

Notes: PostgreSQL and Snowflake may show different precision/decimals due to data type rounding/formatting.

COUNT

COUNT

MAX

MAX

MEDIAN

MEDIAN

Notes: Snowflake does not allow the use of date types, while PostgreSQL does. (See SSC-FDM-PG0013).

MIN

MIN

PERCENTILE_CONT

PERCENTILE_CONT

STDDEV/STDDEV_SAMP (expression)

STDDEV/STDDEV_SAMP (expression)

STDDEV_POP (expression)

STDDEV_POP (expression)

SUM

SUM

VARIANCE/VAR_SAMP (expression)

VARIANCE/VAR_SAMP (expression)

VAR_POP (expression)

VAR_POP (expression)

Conditional expressions

PostgreSQL

Snowflake

COALESCE ( value [, …] )

COALESCE ( expression, expression, … )

GREATEST ( value [, …] )

GREATEST_IGNORE_NULLS ( <expr1> [, <expr2> … ] )

LEAST ( value [, …] )

LEAST_IGNORE_NULLS ( <expr1> [, <expr2> … ])

NULLIF

NULLIF

Notes: PostgreSQL’s NULLIF ignores trailing spaces in some string comparisons, unlike Snowflake. Therefore, the transformation adds RTRIM for equivalence.

Data type formatting functions

Data type formatting functions provide an easy way to convert values from one data type to another. For each of these functions, the first argument is always the value to be formatted and the second argument contains the template for the new format. (PostgreSQL Language Reference Data type formatting functions).

PostgreSQL

Snowflake

TO_CHAR

TO_CHAR

Notes: Snowflake’s support for this function is partial (see SSC-EWI-PG0005).

TO_DATE

TO_DATE

Notes: Snowflake’s TO_DATE fails on invalid dates like ‘20010631’ (June has 30 days), unlike PostgreSQL’s lenient TO_DATE. Use TRY_TO_DATE in Snowflake to handle these cases by returning NULL. (see SSC-EWI-PG0005, SSC-FDM-0032).

Date and time functions

PostgreSQL

Snowflake

AT TIME ZONE ‘timezone’

CONVERT_TIMEZONE ( <source_tz> , <target_tz> , <source_timestamp_ntz> )


CONVERT_TIMEZONE ( <target_tz> , <source_timestamp> )

Notes: PostgreSQL defaults to UTC; the Snowflake function requires explicit UTC specification. Therefore, it will be added as the target timezone.

CURRENT_DATE

CURRENT_DATE()

DATE_PART/PGDATE_PART

DATE_PART

Notes: this function is partially supported by Snowflake. (See SSC-EWI-PGOOO5).

DATE_TRUNC

DATE_TRUNC

Notes: Invalid date part formats are translated to Snowflake-compatible formats.

TO_TIMESTAMP

TO_TIMESTAMP

EXTRACT

EXTRACT

Notes: Part-time or Date time supported: DAY, DOW, DOY, EPOCH, HOUR, MINUTE, MONTH, QUARTER, SECOND, WEEK, YEAR.

TIMEZONE

CONVERT_TIMEZONE

Note

PostgreSQL timestamps default to microsecond precision (6 digits); Snowflake defaults to nanosecond precision (9 digits). Adjust precision as needed using ALTER SESSION (e.g., ALTER SESSION SET TIMESTAMP_OUTPUT_FORMAT = 'YYYY-MM-DD HH24:MI:SS.FF2';). Precision loss may occur depending on the data type used.

Since some formats are incompatible with Snowflake, adjusting the account parameters DATE_INPUT_FORMAT or TIME_INPUT_FORMAT might maintain functional equivalence between platforms.

JSON Functions

PostgreSQL

Snowflake

JSON_EXTRACT_PATH_TEXT

JSON_EXTRACT_PATH_TEXT

Notes:

  1. PostgreSQL treats newline, tab, and carriage return characters literally; Snowflake interprets them.
  2. A JSON literal and dot-separated path are required to access nested objects in the Snowflake function.
  3. Paths with spaces in variables must be quoted.

Math functions

PostgreSQL

Snowflake

ACOS

ACOS

ASIN

ASIN

ATAN

ATAN

ATAN2

ATAN2

CBRT

CBRT

CEIL/CEILING

CEIL

COS

COS

COT

COT

DEGREES

DEGREES

LN

LN

EXP

EXP

FLOOR

FLOOR

LOG

LOG

MOD

MOD

PI

PI

POWER/POW

POWER/POW

RADIANS

RADIANS

RANDOM

RANDOM

ROUND

ROUND

SIN

SIN

SIGN

SIGN

SQRT

SQRT

TAN

TAN

TRUNC

TRUNC

Note

PostgreSQL and Snowflake results may differ in scale.

String functions

String functions process and manipulate character strings or expressions that evaluate to character strings. (PostgreSQL Language Reference String functions).

PostgreSQL

Snowflake

ASCII

ASCII

BTRIM

TRIM

CHAR_LENGTH

LENGTH

CHARACTER_LENGTH

LENGTH

CHR

CHR

CONCAT

CONCAT

INITCAP

INITCAP

LEFT/RIGHT

LEFT/RIGHT

LOWER

LOWER

OCTET_LENGTH

OCTET_LENGTH

Notes: the results may vary between platforms (See SSC-FDM-PG0013).

QUOTE_IDENT (string)

CONCAT (‘”’, string, ‘”’)

REGEXP_REPLACE

REGEXP_REPLACE

Notes: This function includes a parameters argument that enables the user to interpret the pattern using the Perl Compatible Regular Expression (PCRE) dialect, represented by the p value, this is removed to avoid any issues. (See SSC-EWI-0009, SC-FDM-0032, SSC-FDM- PG0011).

REPEAT

REPEAT

REPLACE

REPLACE

REVERSE

REVERSE

SPLIT_PART

SPLIT_PART

Notes: Snowflake and PostgreSQL handle SPLIT_PART differently with case-insensitive collations.

STRPOS (string, substring )

POSITION ( <expr1> IN <expr> )

SUBSTRING

SUBSTRING

Notes: Snowflake partially supports this function. PostgreSQL’s SUBSTRING, with a non-positive start_position, calculates start_position + number_characters (returning ‘’ if the result is non-positive). Snowflake’s behavior differs.

TRANSLATE

TRANSLATE

TRIM

TRIM

Notes: PostgreSQL uses keywords (BOTH, LEADING, TRAILING) for trim; Snowflake uses TRIM, LTRIM, RTRIM.

UPPER

UPPER

Window functions

PostgreSQL

Snowflake

AVG

AVG

Notes: AVG rounding/formatting can vary by data type between PostgreSQL and Snowflake.

COUNT

COUNT

DENSE_RANK

DENSE_RANK

Notes: ORDER BY is mandatory in Snowflake; missing clauses are replaced with ORDER BY 1.

FIRST_VALUE

FIRST_VALUE

Notes: Snowflake needs ORDER BY; missing clauses get ORDER BY <expr>.

LAG

LAG

LAST_VALUE

LAST_VALUE

Notes: Snowflake needs ORDER BY; missing clauses get ORDER BY <expr>.

LEAD

LEAD

Notes: PostgreSQL allows constant or expression offsets; Snowflake allows only constant offsets.

NTH_VALUE

NTH_VALUE

Notes: ORDER BY is mandatory in Snowflake; missing clauses are replaced with ORDER BY 1.

NTILE

NTILE

Notes: ORDER BY is mandatory in Snowflake; missing clauses are replaced with ORDER BY 1. (See SSC-FDM-PG0013).

PERCENT_RANK

PERCENT_RANK

Notes: ORDER BY is mandatory in Snowflake; missing clauses are replaced with ORDER BY 1.

PERCENTILE_CONT

PERCENTILE_CONT

Notes: Rounding varies between platforms.

PERCENTILE_DISC

PERCENTILE_DISC

RANK

RANK

ROW_NUMBER

ROW_NUMBER

Notes: ORDER BY is mandatory in Snowflake; missing clauses are replaced with ORDER BY 1.