A name the engine already defines takes the prefix of the class or base type of its argument, and functions that belong together take the same prefix: spanLowerInc goes with spanLower, geoCumulativeLength with geoLength. Spark and Flink use the same names, so a query written for one runs on the other, and round(1.23456, 2) keeps meaning the engine's own rounding of a number. The names that change are the following.

The names a raster and a raquet share take the prefix of their type too, even where the engine defines no such name: both travel as WKB, so an engine holding one function per name cannot tell a raster given to width from a raquet.

PostgreSQL reads and writes a value through the four functions its type declares, and calls them for you: a typed literal, a cast from text and a text COPY go through the input function, the text a client displays through the output function, and a binary COPY or a driver in binary mode through the receive and send functions. Spark and Flink call none of them. A value travels between them as its Well-Known Binary (WKB) bytes, and each conversion is a function the query calls, each with its inverse, as the following table shows.

Every type has the functions of the table that apply to it: the E forms when it carries an SRID its plain text and binary forms omit, and MF-JSON when it is temporal. This includes the types PostgreSQL reads and writes only through its four functions: the set, span and span set types of integers, big integers, floats, dates and timestamps, textset and jsonbset, tbox and stbox, tbool, tint, tbigint, tfloat and ttext, and quadbin, s2cell, nsegment and tpcbox.

The text of a raquet is its hexadecimal WKB, so it is read with raquetFromHexWKB and written with asHexWKB, as a PostGIS raster is with ST_RastFromHexWKB and ST_AsHexWKB. A box, stbox or tpcbox, writes its SRID in both its text and its WKB, and so has no E form. Every WKB output takes the byte order endian, and every text output of a value with floats or coordinates the number of decimal digits maxdecimaldigits. A column of WKB bytes, such as a TemporalParquet column, is read in every engine with the binary constructor of its type, as in tgeompointFromBinary(col).

A function returning several rows, such as timeSplit or unnest, is called in PostgreSQL as a table in the FROM clause. In Spark and Flink the same function, unnest under the names setUnnest and temporalUnnest, returns an array with one element per row, an array of records when it returns several columns. Flink turns the array into rows with CROSS JOIN UNNEST, and Spark with LATERAL VIEW explode, or inline for an array of records.

The query

SELECT vehicle, round(length(trip)::numeric, 1), lower(timeSpan(trip))
FROM Trips
WHERE trip && stbox 'SRID=3857;STBOX X((0,0),(1000,1000))';

is written, in Spark and Flink,

SELECT vehicle, round(geoLength(trip), 1), spanLower(timeSpan(trip))
FROM Trips
WHERE stboxOverlaps(trip, stboxFromText('SRID=3857;STBOX X((0,0),(1000,1000))'));

Here round applies to a number, so it is the engine's own function and keeps its name.