fn:concat and op:concatenate are indeed different.
The first is a function that accepts two strings as argument and creates
a *string* that is a string-concatenation of the two strings.
op:concatenate on the other hand is used to create a sequence of items.
Say A and B are two strings. Then:
fn:string-join(op:concatenate(A, B)) == fn:concat(A, B)
The string-join creates the new string that is a concatenation of string
A and string B. The op:concatenate only creates a sequence containing
two items, A and B.
Vinayak
On 6/6/12 9:04 PM, Eldon Carman wrote:
Below are example queries and their plans. The first two are just
string literals. The remaining queries are examples from the "XQuery
1.0 and XPath 2.0 Functions and Operators (Second Edition)" webpage
(http://www.w3.org/TR/xquery-operators/#func-string-join) for the "7.4
Functions on String Values". The list of query plans are fairly
straight forward after looking at the math functions.
Questions
- In the plans, two similar activities happen with two different
commands: a function concat and an operator concatenate. Is the
difference on the output returned from concat and concatenate? A
string or sequence, respectively.
- Can a sequence be used as a string? In "string-join" concatenate is
used to pass in a string.
String Queries
--------------
"a"
assign [$$1]<- [{http://www.w3.org/2001/XMLSchema}string
QUANT_ONE(a)] -- |UNPARTITIONED|
empty-tuple-source -- |UNPARTITIONED|
"abc"
assign [$$1]<- [{http://www.w3.org/2001/XMLSchema}string
QUANT_ONE(abc)] -- |UNPARTITIONED|
empty-tuple-source -- |UNPARTITIONED|
concat('un', 'grateful')
assign [$$3]<- [function-call:
vxquery:{http://www.w3.org/2005/xpath-functions}concat,
Args:[function-call:
vxquery:{urn:org.apache.vxquery.operators-ext}promote,
Args:[function-call:
vxquery:{http://www.w3.org/2005/xpath-functions}data, Args:[$$1],
{http://www.w3.org/2001/XMLSchema-extensions}type
QUANT_ONE({http://www.w3.org/2001/XMLSchema}anyAtomicType
QUANT_QUESTION)], function-call:
vxquery:{urn:org.apache.vxquery.operators-ext}promote,
Args:[function-call:
vxquery:{http://www.w3.org/2005/xpath-functions}data, Args:[$$2],
{http://www.w3.org/2001/XMLSchema-extensions}type
QUANT_ONE({http://www.w3.org/2001/XMLSchema}anyAtomicType
QUANT_QUESTION)]]] -- |UNPARTITIONED|
assign [$$2]<- [{http://www.w3.org/2001/XMLSchema}string
QUANT_ONE(grateful)] -- |UNPARTITIONED|
assign [$$1]<- [{http://www.w3.org/2001/XMLSchema}string
QUANT_ONE(un)] -- |UNPARTITIONED|
empty-tuple-source -- |UNPARTITIONED|
string-join(('Now', 'is', 'the', 'time', '...'), ' ')
assign [$$8]<- [function-call:
vxquery:{http://www.w3.org/2005/xpath-functions}string-join,
Args:[function-call:
vxquery:{urn:org.apache.vxquery.operators-ext}promote,
Args:[function-call:
vxquery:{http://www.w3.org/2005/xpath-functions}data, Args:[$$6],
{http://www.w3.org/2001/XMLSchema-extensions}type
QUANT_ONE({http://www.w3.org/2001/XMLSchema}string QUANT_STAR)],
function-call: vxquery:{urn:org.apache.vxquery.operators-ext}promote,
Args:[function-call:
vxquery:{http://www.w3.org/2005/xpath-functions}data, Args:[$$7],
{http://www.w3.org/2001/XMLSchema-extensions}type
QUANT_ONE({http://www.w3.org/2001/XMLSchema}string QUANT_ONE)]]] --
|UNPARTITIONED|
assign [$$7]<- [{http://www.w3.org/2001/XMLSchema}string QUANT_ONE(
)] -- |UNPARTITIONED|
assign [$$6]<- [function-call:
vxquery:{urn:org.apache.vxquery.operators}concatenate, Args:[$$1, $$2,
$$3, $$4, $$5]] -- |UNPARTITIONED|
assign [$$5]<- [{http://www.w3.org/2001/XMLSchema}string
QUANT_ONE(...)] -- |UNPARTITIONED|
assign [$$4]<- [{http://www.w3.org/2001/XMLSchema}string
QUANT_ONE(time)] -- |UNPARTITIONED|
assign [$$3]<- [{http://www.w3.org/2001/XMLSchema}string
QUANT_ONE(the)] -- |UNPARTITIONED|
assign [$$2]<- [{http://www.w3.org/2001/XMLSchema}string
QUANT_ONE(is)] -- |UNPARTITIONED|
assign [$$1]<-
[{http://www.w3.org/2001/XMLSchema}string QUANT_ONE(Now)] --
|UNPARTITIONED|
empty-tuple-source -- |UNPARTITIONED|
substring("motor car", 6)
assign [$$3]<- [function-call:
vxquery:{http://www.w3.org/2005/xpath-functions}substring,
Args:[function-call:
vxquery:{urn:org.apache.vxquery.operators-ext}promote,
Args:[function-call:
vxquery:{http://www.w3.org/2005/xpath-functions}data, Args:[$$1],
{http://www.w3.org/2001/XMLSchema-extensions}type
QUANT_ONE({http://www.w3.org/2001/XMLSchema}string QUANT_QUESTION)],
function-call: vxquery:{urn:org.apache.vxquery.operators-ext}promote,
Args:[function-call:
vxquery:{http://www.w3.org/2005/xpath-functions}data, Args:[$$2],
{http://www.w3.org/2001/XMLSchema-extensions}type
QUANT_ONE({http://www.w3.org/2001/XMLSchema}double QUANT_ONE)]]] --
|UNPARTITIONED|
assign [$$2]<- [{http://www.w3.org/2001/XMLSchema}integer
QUANT_ONE(6)] -- |UNPARTITIONED|
assign [$$1]<- [{http://www.w3.org/2001/XMLSchema}string
QUANT_ONE(motor car)] -- |UNPARTITIONED|
empty-tuple-source -- |UNPARTITIONED|
substring("metadata", 4, 3)
assign [$$4]<- [function-call:
vxquery:{http://www.w3.org/2005/xpath-functions}substring,
Args:[function-call:
vxquery:{urn:org.apache.vxquery.operators-ext}promote,
Args:[function-call:
vxquery:{http://www.w3.org/2005/xpath-functions}data, Args:[$$1],
{http://www.w3.org/2001/XMLSchema-extensions}type
QUANT_ONE({http://www.w3.org/2001/XMLSchema}string QUANT_QUESTION)],
function-call: vxquery:{urn:org.apache.vxquery.operators-ext}promote,
Args:[function-call:
vxquery:{http://www.w3.org/2005/xpath-functions}data, Args:[$$2],
{http://www.w3.org/2001/XMLSchema-extensions}type
QUANT_ONE({http://www.w3.org/2001/XMLSchema}double QUANT_ONE)],
function-call: vxquery:{urn:org.apache.vxquery.operators-ext}promote,
Args:[function-call:
vxquery:{http://www.w3.org/2005/xpath-functions}data, Args:[$$3],
{http://www.w3.org/2001/XMLSchema-extensions}type
QUANT_ONE({http://www.w3.org/2001/XMLSchema}double QUANT_ONE)]]] --
|UNPARTITIONED|
assign [$$3]<- [{http://www.w3.org/2001/XMLSchema}integer
QUANT_ONE(3)] -- |UNPARTITIONED|
assign [$$2]<- [{http://www.w3.org/2001/XMLSchema}integer
QUANT_ONE(4)] -- |UNPARTITIONED|
assign [$$1]<- [{http://www.w3.org/2001/XMLSchema}string
QUANT_ONE(metadata)] -- |UNPARTITIONED|
empty-tuple-source -- |UNPARTITIONED|
string-length("Harp not on that string, madam; that is past.")
assign [$$2]<- [function-call:
vxquery:{http://www.w3.org/2005/xpath-functions}string-length,
Args:[function-call:
vxquery:{urn:org.apache.vxquery.operators-ext}promote,
Args:[function-call:
vxquery:{http://www.w3.org/2005/xpath-functions}data, Args:[$$1],
{http://www.w3.org/2001/XMLSchema-extensions}type
QUANT_ONE({http://www.w3.org/2001/XMLSchema}string QUANT_QUESTION)]]]
-- |UNPARTITIONED|
assign [$$1]<- [{http://www.w3.org/2001/XMLSchema}string
QUANT_ONE(Harp not on that string, madam; that is past.)] --
|UNPARTITIONED|
empty-tuple-source -- |UNPARTITIONED|
upper-case("abCd0")
assign [$$2]<- [function-call:
vxquery:{http://www.w3.org/2005/xpath-functions}upper-case,
Args:[function-call:
vxquery:{urn:org.apache.vxquery.operators-ext}promote,
Args:[function-call:
vxquery:{http://www.w3.org/2005/xpath-functions}data, Args:[$$1],
{http://www.w3.org/2001/XMLSchema-extensions}type
QUANT_ONE({http://www.w3.org/2001/XMLSchema}string QUANT_QUESTION)]]]
-- |UNPARTITIONED|
assign [$$1]<- [{http://www.w3.org/2001/XMLSchema}string
QUANT_ONE(abCd0)] -- |UNPARTITIONED|
empty-tuple-source -- |UNPARTITIONED|
lower-case("ABc!D")
assign [$$2]<- [function-call:
vxquery:{http://www.w3.org/2005/xpath-functions}lower-case,
Args:[function-call:
vxquery:{urn:org.apache.vxquery.operators-ext}promote,
Args:[function-call:
vxquery:{http://www.w3.org/2005/xpath-functions}data, Args:[$$1],
{http://www.w3.org/2001/XMLSchema-extensions}type
QUANT_ONE({http://www.w3.org/2001/XMLSchema}string QUANT_QUESTION)]]]
-- |UNPARTITIONED|
assign [$$1]<- [{http://www.w3.org/2001/XMLSchema}string
QUANT_ONE(ABc!D)] -- |UNPARTITIONED|
empty-tuple-source -- |UNPARTITIONED|
