Function Support

Function Support (C# to ksqlDB)

This page lists the C# methods and properties that the LINQ-to-ksql translator maps to ksqlDB functions. Only query-usable mappings are included.

String

C#	ksqlDB	Notes
s.Substring(start, length)	SUBSTRING(s, start, length)
s.Replace(oldValue, newValue)	REPLACE(s, oldValue, newValue)
string.Concat(a, b, ...)	CONCAT(a, b, ...)
s.IndexOf(sub)	INSTR(s, sub)
s.Trim()	TRIM(s)
s.Split(delim)	SPLIT(s, delim)
s.PadLeft(len, pad)	LPAD(s, len, pad)
s.PadRight(len, pad)	RPAD(s, len, pad)
s.ToUpper()	UPPER(s)
s.ToLower()	LOWER(s)
Left(s, n)	SUBSTRING(s, 1, n)	helper
Right(s, n)	SUBSTRING(s, LEN(s)-n+1, n)	helper; implementation clamps lower bound to 1

Math

C#	ksqlDB	Notes
Math.Round(x, p)	ROUND(x, p)
Math.Floor(x)	FLOOR(x)
Math.Ceiling(x)	CEIL(x)
Math.Abs(x)	ABS(x)
Math.Log(x)	LOG(x)
Math.Exp(x)	EXP(x)
Math.Pow(x, y)	POWER(x, y)
Math.Sqrt(x)	SQRT(x)

Date/Time (TIMESTAMP inputs)

C#	ksqlDB	Notes
dt.Year	EXTRACT(YEAR FROM dt)
dt.Month	EXTRACT(MONTH FROM dt)
dt.Day	DAYOFMONTH(dt)
dt.Hour	EXTRACT(HOUR FROM dt)
dt.Minute	EXTRACT(MINUTE FROM dt)
dt.Second	EXTRACT(SECOND FROM dt)
dt.DayOfWeek	DAYOFWEEK(dt)
dt.DayOfYear	DAYOFYEAR(dt)
WeekOfYear(dt)	CAST(FORMAT_TIMESTAMP(dt, 'w', 'UTC') AS INT)

Aggregates (LINQ)

C#	ksqlDB	Notes
query.Sum(x => x.F)	SUM(F)
query.Average(x => x.F)	AVG(F)
query.Min(x => x.F)	MIN(F)
query.Max(x => x.F)	MAX(F)
query.Count()	COUNT(*)
query.Count(x => cond)	SUM(CASE WHEN cond THEN 1 ELSE 0 END)	conditional count emulation
query.EarliestByOffset(x => x.F)	EARLIEST_BY_OFFSET(F)	first value by Kafka offset within group/window
query.LatestByOffset(x => x.F)	LATEST_BY_OFFSET(F)	last value by Kafka offset within group/window