Updating docs

docs/querying/math-expr.md

@@ -82,7 +82,7 @@ The following built-in functions are available.
 |concat|concat(expr, expr...) concatenate a list of strings|
 |format|format(pattern[, args...]) returns a string formatted in the manner of Java's [String.format](https://docs.oracle.com/javase/8/docs/api/java/lang/String.html#format-java.lang.String-java.lang.Object...-).|
 |like|like(expr, pattern[, escape]) is equivalent to SQL `expr LIKE pattern`|
-|lookup|lookup(expr, lookup-name) looks up expr in a registered [query-time lookup](../querying/lookups.md)|
+|lookup|lookup(expr, lookup-name[,replaceMissingValueWith]) looks up expr in a registered [query-time lookup](../querying/lookups.md)|
 |parse_long|parse_long(string[, radix]) parses a string as a long with the given radix, or 10 (decimal) if a radix is not provided.|
 |regexp_extract|regexp_extract(expr, pattern[, index]) applies a regular expression pattern and extracts a capture group index, or null if there is no match. If index is unspecified or zero, returns the substring that matched the pattern. The pattern may match anywhere inside `expr`; if you want to match the entire string instead, use the `^` and `$` markers at the start and end of your pattern.|
 |regexp_like|regexp_like(expr, pattern) returns whether `expr` matches regular expression `pattern`. The pattern may match anywhere inside `expr`; if you want to match the entire string instead, use the `^` and `$` markers at the start and end of your pattern. |

docs/querying/sql-functions.md

@@ -885,7 +885,7 @@ Calculates the base-10 of the numeric expression.
 
 ## LOOKUP
 
-`LOOKUP(<CHARACTER>, <CHARACTER>)`
+`LOOKUP(<CHARACTER>, <CHARACTER>, [<CHARACTER>])`
 
 **Function type:** [Scalar, string](sql-scalar.md#string-functions)
 

docs/querying/sql-scalar.md

@@ -98,7 +98,7 @@ String functions accept strings, and return a type appropriate to the function.
 |`CHAR_LENGTH(expr)`|Alias for `LENGTH`.|
 |`CHARACTER_LENGTH(expr)`|Alias for `LENGTH`.|
 |`STRLEN(expr)`|Alias for `LENGTH`.|
-|`LOOKUP(expr, lookupName)`|Look up `expr` in a registered [query-time lookup table](lookups.md). Note that lookups can also be queried directly using the [`lookup` schema](sql.md#from).|
+|`LOOKUP(expr, lookupName, [replaceMissingValueWith])`|Look up `expr` in a registered [query-time lookup table](lookups.md). Note that lookups can also be queried directly using the [`lookup` schema](sql.md#from).|
 |`LOWER(expr)`|Returns `expr` in all lowercase.|
 |`UPPER(expr)`|Returns `expr` in all uppercase.|
 |`PARSE_LONG(string, [radix])`|Parses a string into a long (BIGINT) with the given radix, or 10 (decimal) if a radix is not provided.|