Should the client/server interface support the declaration of external variables?
Right now, consider an XQuery such as this one (simplified form shown)
declare variable *$entry* as xs:anyAtomicType external; return insert node <entry> <title>Copy of { *$entry*//atom:title/text() }</title> { *$entry*/libx:module | *$entry*/libx:package | *$entry*/libx:libapp } </entry> into $feed
Suppose "entry" is an element rendered into a blob of XML of 1000 characters and markup. Before we can send above XQuery to the BaseX server, we have to replace all instances of '$entry' with the actual XML (as per the previous discussion that XQJ is deprecated and the client/server interface is the preferred way to communicate with BaseX).
This means that we're sending roughly 4x the amount of data (note that $entry is used four times above), just to be able to say "$entry//atom:title/text()". This can easily lead to unexpected performance as queries become more complicated; in addition and more importantly, it makes it really tough to debug the expanded XQuery if there is a need.
Why not extend the protocol so that a client can define the external variables in an XQuery first?
- Godmar
ps: I understand that I could work around this by introducing additional variables with let, as in let $dummy = $entry ... and then using $dummy//atom:title/text() etc. Awkward.
Dear Godmar,
as i understand you could probably use the following... For Example in the php binding:
$external = "<xml>test</xml>"; $query = 'xquery declare variable $entry as xs:anyAtomicType := '.$external.'; for $i in 1 to 2 return $entry';
So the xml snippet is just send once to the server.
Kind regards, Andreas
Godmar Back schrieb:
Should the client/server interface support the declaration of external variables?
Right now, consider an XQuery such as this one (simplified form shown)
declare variable *$entry* as xs:anyAtomicType external; return insert node
<entry> <title>Copy of { *$entry*//atom:title/text() }</title> { *$entry*/libx:module | *$entry*/libx:package | *$entry*/libx:libapp } </entry> into $feed
Suppose "entry" is an element rendered into a blob of XML of 1000 characters and markup. Before we can send above XQuery to the BaseX server, we have to replace all instances of '$entry' with the actual XML (as per the previous discussion that XQJ is deprecated and the client/server interface is the preferred way to communicate with BaseX).
This means that we're sending roughly 4x the amount of data (note that $entry is used four times above), just to be able to say "$entry//atom:title/text()". This can easily lead to unexpected performance as queries become more complicated; in addition and more importantly, it makes it really tough to debug the expanded XQuery if there is a need.
Why not extend the protocol so that a client can define the external variables in an XQuery first?
- Godmar
ps: I understand that I could work around this by introducing additional variables with let, as in let $dummy = $entry ... and then using $dummy//atom:title/text() etc. Awkward.
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Andreas Weiler -
Godmar Back