Hi Patrick,
in case of two-way-sync the engine always reads
all items of the plugin with a sequence of
ReadNextItem until eof. So the engine knows about
the number of elements.
In case of refresh-from-server and availability
of DeleteSyncSet, reading the items is not
needed, because the elements will be deleted
anyway.
But the number of items is not known for this case.
The difference in performance is marginal if your
implementation of DeleteSyncSet just goes thru
the list of your items and deletes them item by
item, the overhead by returning 20030 and let the
engine delete element by element (but knowing
then how many elements are deleted).
The only difference is mainly reading the sync
set (which must be done for all two-way-syncs
anyway). The performance difference is huge, if
you have just one command to delete all elements,
which is e.g. the case for our iPhone client.
But I'm not even sure if this command would
return the number of deleted elements.
Best Regards,
Beat
On Tue, 2009-07-28 at 13:13 +0100, Beat Forster wrote:
Hello Patrick,
my opinion is that this is not worth an API
change. DeleteSyncSet always expects to remove
all elements of the sync set, a return value
different to this is anyway not allowed and might
be interesting for statistics but in all other
cases very confusing.
Yes, that's also what I thought. My last sentence should have said "API
extension", like DeleteSyncSetCounted(). Do you also think that this is
not necessary?
Usually the engine knows
about the number of elements in the sync set,
therefore no additional information is needed to
get this count.
In case of a refresh-from-server I assume the
sync set will not be read, but the plugin could
return 20030 if no ReadNextItem sequence has been
done before. So the engine will remove element by
element then and get the number of elements this
way.
I'm not sure I follow here. Suppose a database plugin implements the
current DeleteSyncSet(). How does the engine know how many items were
deleted? Is it possible without causing overhead (the main reason for
the existance of DeleteSyncSync(), I suppose)?
--
Best Regards, Patrick Ohly
The content of this message is my personal opinion only and although
I am an employee of Intel, the statements I make here in no way
represent Intel's position on the issue, nor am I authorized to speak
on behalf of Intel on this matter.
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-----------------------------------------------
Beat FORSTER
Dipl. El. Ing. ETH
Dipl. NDS ETHZ in Betriebswissenschaften
Managing Partner
beat.fors...@synthesis.ch
Synthesis AG SyncML Server & Client Solutions
Badenerstrasse 18, CH-8004 Zürich, Switzerland
Tel (direct): +41 44 440 66 02
Fax: +41 44 440 66 04
email: i...@synthesis.ch
web: http://www.synthesis.ch
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