Dear Christian, Thanks for your suggestion.

With the function-lookup, my essential requirement is to process an incoming XML message containing a UUID and execute a particular function based on that UUID. As I would ideally like to be able to manage the associations between UUID and function names dynamically, I do not see immediately how to apply your suggestion.

There is a work-around along the lines of: let $function_name := local:lookup-function-name($uuid) let $def := concat( "import module namespace ‘blah’ at ‘blah.xml’; declare variable $a external; declare variable $b external; ”, $function_name , “($a,$b)”) return xquery:evalulate($def)

Although this is not particularly ideal as it uses an eval/evaluate statement (evil [1]). Moreover, I was trying to replace an eval/evaluate statements with a function-lookup, as I assumed that this would be a more proper way to handle it, when I ran into the performance issue.

Besides reverting back to the eval statements, only one other option comes to mind: for a given set of pairs ($uuid,$function_name) generate the needed xquery to invoke the functions with a switch statement. If I wanted to maintain at least a dynamic nature, I suppose I could write this generated xquery to a file and use the repository module [2]. There are some immediate drawbacks that I see to this though.

So maybe my question is, how evil is evil? If the eval’ed code is largely just calling existing functions, will there be a big performance impact? If there are plans for optimize function-lookup in the future, I suppose I could live with a bit of short-term evil.

Cheers, -carl

[1] https://mailman.uni-konstanz.de/pipermail/basex-talk/2013-November/005707.ht... [2] http://docs.basex.org/wiki/Repository_Module

On Feb 22, 2014, at 11:24 AM, Christian Grün christian.gruen@gmail.com wrote:

Hi Carl,

it would be generally possible to optimize the current implementation of function-lookup and related reflective functions, but I think it will take us some more time.

Instead, I rather recommend you to use function items, because these will always give you better performance and are less error-prone (they can be optimized much better than function calls based on string references).

I'm not sure how your complete code looks like (and it would probably be too complex to serve as example here), but the following code might give you a hint how this could look like:

let $add := function($a) { $a + $a } let $multiply := function($a) { $a * 2 } for $f in ($add, $multiply) return $f(2)

If you have already worked with function items... Sorry for teaching ;)

Christian

On Fri, Feb 21, 2014 at 5:06 PM, Carl Leitner litlfred@ibiblio.org wrote:

...

Hi, I noticed a significant performance degradation in the function-lookup method introduced at: https://github.com/BaseXdb/basex/commit/4aeb4bdc74d980b4c8f2e27546d21fdc1eba...

Where as at: b8b3dd2bee205303aeab3e8a0967b371a2ad7ef7 I have:

...

xquery import module namespace csd_bsq = "https://github.com/his-interop/openinfoman/csd_bsq" at "/Users/litlfred/pulsar_cats/openinfoman/repo/csd_base_stored_queries.xqm"; let $r:= function-lookup(xs:QName('csd_bsq:facility_search'),2) return ()

Query executed in 22.57 ms.

At 4aeb4bdc74d980b4c8f2e27546d21fdc1ebaeb77 I have:

...

xquery import module namespace csd_bsq = "https://github.com/his-interop/openinfoman/csd_bsq" at "/Users/litlfred/pulsar_cats/openinfoman/repo/csd_base_stored_queries.xqm"; ()

Query executed in 17.48 ms.

...

xquery import module namespace csd_bsq = "https://github.com/his-interop/openinfoman/csd_bsq" at "/Users/litlfred/pulsar_cats/openinfoman/repo/csd_base_stored_queries.xqm"; let $r:= xs:QName('csd_bsq:facility_search') return ()

Query executed in 20.44 ms.

...

xquery import module namespace csd_bsq = "https://github.com/his-interop/openinfoman/csd_bsq" at "/Users/litlfred/pulsar_cats/openinfoman/repo/csd_base_stored_queries.xqm"; let $r:= function-lookup(xs:QName('csd_bsq:facility_search'),2) return ()

Query executed in 716.18 ms.

Any suggestions on how to avoid this?

Thanks so much.

Cheers, -carl

---

BaseX-Talk mailing list BaseX-Talk@mailman.uni-konstanz.de https://mailman.uni-konstanz.de/mailman/listinfo/basex-talk

Dear Christian, Thanks for the suggestion, the map is certainly cleaner looking than the switch statement.

Is support for updating statements in an eval something that would be considered for the future, for example by postponing the application of the updates to after the calling function finishes?

Cheers, -carl

On Feb 22, 2014, at 4:12 PM, Christian Grün christian.gruen@gmail.com wrote:

Hi Carl,

...

As I would ideally like to be able to manage the associations between UUID and function names dynamically, I do not see immediately how to apply your suggestion.

Would sth. like the following code help?

declare variable $FUNCTIONS := map { '69bfbe73-23ac-4033-b60b-6672fd67b937': function() { 12345 }, '0d22d6a8-035b-46bf-a396-00471c840a08': function() { 67890 } };

let $uuid := '69bfbe73-23ac-4033-b60b-6672fd67b937' return $FUNCTIONS($uuid)()

You could as well move this map, or the functions declared inside, into another module, etc.

...

So maybe my question is, how evil is evil?

One drawback of using xquery:eval (and xquery:evaluate) is that your code will only be evaluated at runtime, which is why the compiler has no chance to detect syntax and type errors at compile time. This is also the reason why updates operations are not allowed inside xquery:eval, because an updating eval query may change nodes that are referenced in the calling query.

However, if you know exactly what your code is doing, the xquery:eval function won't cause any trouble (this is also the reason why we are offering the functions at all... And it may even be officially introduced with XQuery 3.1).

Christian

...

On Feb 22, 2014, at 11:24 AM, Christian Grün christian.gruen@gmail.com wrote:

Hi Carl,

it would be generally possible to optimize the current implementation of function-lookup and related reflective functions, but I think it will take us some more time.

Instead, I rather recommend you to use function items, because these will always give you better performance and are less error-prone (they can be optimized much better than function calls based on string references).

I'm not sure how your complete code looks like (and it would probably be too complex to serve as example here), but the following code might give you a hint how this could look like:

let $add := function($a) { $a + $a } let $multiply := function($a) { $a * 2 } for $f in ($add, $multiply) return $f(2)

If you have already worked with function items... Sorry for teaching ;)

Christian

On Fri, Feb 21, 2014 at 5:06 PM, Carl Leitner litlfred@ibiblio.org wrote:

Hi, I noticed a significant performance degradation in the function-lookup method introduced at:

https://github.com/BaseXdb/basex/commit/4aeb4bdc74d980b4c8f2e27546d21fdc1eba...

Where as at: b8b3dd2bee205303aeab3e8a0967b371a2ad7ef7 I have:

xquery import module namespace csd_bsq = "https://github.com/his-interop/openinfoman/csd_bsq" at "/Users/litlfred/pulsar_cats/openinfoman/repo/csd_base_stored_queries.xqm"; let $r:= function-lookup(xs:QName('csd_bsq:facility_search'),2) return ()

Query executed in 22.57 ms.

At 4aeb4bdc74d980b4c8f2e27546d21fdc1ebaeb77 I have:

xquery import module namespace csd_bsq = "https://github.com/his-interop/openinfoman/csd_bsq" at "/Users/litlfred/pulsar_cats/openinfoman/repo/csd_base_stored_queries.xqm"; ()

Query executed in 17.48 ms.

xquery import module namespace csd_bsq = "https://github.com/his-interop/openinfoman/csd_bsq" at "/Users/litlfred/pulsar_cats/openinfoman/repo/csd_base_stored_queries.xqm"; let $r:= xs:QName('csd_bsq:facility_search') return ()

Query executed in 20.44 ms.

xquery import module namespace csd_bsq = "https://github.com/his-interop/openinfoman/csd_bsq" at "/Users/litlfred/pulsar_cats/openinfoman/repo/csd_base_stored_queries.xqm"; let $r:= function-lookup(xs:QName('csd_bsq:facility_search'),2) return ()

Query executed in 716.18 ms.

Any suggestions on how to avoid this?

Thanks so much.

Cheers, -carl

---

BaseX-Talk mailing list BaseX-Talk@mailman.uni-konstanz.de https://mailman.uni-konstanz.de/mailman/listinfo/basex-talk

Dear Christian, Thanks for your suggestion.

With the function-lookup, my essential requirement is to process an incoming XML message containing a UUID and execute a particular function based on that UUID. As I would ideally like to be able to manage the associations between UUID and function names dynamically, I do not see immediately how to apply your suggestion.

There is a work-around along the lines of: let $function_name := local:lookup-function-name($uuid) let $def := concat( "import module namespace ‘blah’ at ‘blah.xml’; declare variable $a external; declare variable $b external; ”, $function_name , “($a,$b)”) return xquery:evalulate($def)

Although this is not particularly ideal as it uses an eval/evaluate statement (evil [1]). Moreover, I was trying to replace an eval/evaluate statements with a function-lookup, as I assumed that this would be a more proper way to handle it, when I ran into the performance issue.

Besides reverting back to the eval statements, only one other option comes to mind: for a given set of pairs ($uuid,$function_name) generate the needed xquery to invoke the functions with a switch statement. If I wanted to maintain at least a dynamic nature, I suppose I could write this generated xquery to a file and use the repository module [2]. There are some immediate drawbacks that I see to this though.

So maybe my question is, how evil is evil? If the eval’ed code is largely just calling existing functions, will there be a big performance impact? If there are plans for optimize function-lookup in the future, I suppose I could live with a bit of short-term evil.

Cheers, -carl

[1] https://mailman.uni-konstanz.de/pipermail/basex-talk/2013-November/005707.ht... [2] http://docs.basex.org/wiki/Repository_Module

On Feb 22, 2014, at 11:24 AM, Christian Grün christian.gruen@gmail.com wrote:

Hi Carl,

it would be generally possible to optimize the current implementation of function-lookup and related reflective functions, but I think it will take us some more time.

Instead, I rather recommend you to use function items, because these will always give you better performance and are less error-prone (they can be optimized much better than function calls based on string references).

I'm not sure how your complete code looks like (and it would probably be too complex to serve as example here), but the following code might give you a hint how this could look like:

let $add := function($a) { $a + $a } let $multiply := function($a) { $a * 2 } for $f in ($add, $multiply) return $f(2)

If you have already worked with function items... Sorry for teaching ;)

Christian

On Fri, Feb 21, 2014 at 5:06 PM, Carl Leitner litlfred@ibiblio.org wrote:

...

Hi, I noticed a significant performance degradation in the function-lookup method introduced at: https://github.com/BaseXdb/basex/commit/4aeb4bdc74d980b4c8f2e27546d21fdc1eba...

Where as at: b8b3dd2bee205303aeab3e8a0967b371a2ad7ef7 I have:

...

xquery import module namespace csd_bsq = "https://github.com/his-interop/openinfoman/csd_bsq" at "/Users/litlfred/pulsar_cats/openinfoman/repo/csd_base_stored_queries.xqm"; let $r:= function-lookup(xs:QName('csd_bsq:facility_search'),2) return ()

Query executed in 22.57 ms.

At 4aeb4bdc74d980b4c8f2e27546d21fdc1ebaeb77 I have:

...

xquery import module namespace csd_bsq = "https://github.com/his-interop/openinfoman/csd_bsq" at "/Users/litlfred/pulsar_cats/openinfoman/repo/csd_base_stored_queries.xqm"; ()

Query executed in 17.48 ms.

...

xquery import module namespace csd_bsq = "https://github.com/his-interop/openinfoman/csd_bsq" at "/Users/litlfred/pulsar_cats/openinfoman/repo/csd_base_stored_queries.xqm"; let $r:= xs:QName('csd_bsq:facility_search') return ()

Query executed in 20.44 ms.

...

xquery import module namespace csd_bsq = "https://github.com/his-interop/openinfoman/csd_bsq" at "/Users/litlfred/pulsar_cats/openinfoman/repo/csd_base_stored_queries.xqm"; let $r:= function-lookup(xs:QName('csd_bsq:facility_search'),2) return ()

Query executed in 716.18 ms.

Any suggestions on how to avoid this?

Thanks so much.

Cheers, -carl

---

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