At times like this it's useful to take a quick look at what other
systems do, if they have such functions - e.g., are there precedents we
should base our answer on? (In Java, Postgres, MySQL, ...)
On 9/28/15 6:03 PM, Jianfeng Jia wrote:
Hi Devs,
Another question about the string functions.
The example code on the
http://asterixdb.ics.uci.edu/documentation/aql/functions.html#StringFunctions
<http://asterixdb.ics.uci.edu/documentation/aql/functions.html#StringFunctions>
shows that these two function are suppose to be called after contains(). I wonder
what is the expected behavior if the they can't find the match pattern?
The current result is confusing.
e.g.
let $x := "substring"
return [ substring-before($x, "subx"), substring-after($x, “subx”)]
it will return
[ [ "subst", "" ]
]
Should we always return an empty string in such case, or throw an exception
like “you shall filter the result by contain() first” ?
IMHO, I’d like to return a null string. Any opinion?
Best,
Jianfeng Jia
PhD Candidate of Computer Science
University of California, Irvine
