Pushdown with outer joins

Question

I'm implementing ALDSP 2.1 using the BEA best practice with 4 layers (physical, canonical, logical and application). The result of the logical layer is comparable with the example at http://e-docs.bea.com/aldsp/docs21/xquery/sql_pushdown.html#1131036
In the application layer I have defined a function findCustomerByOrderId($p_id as xs:string), searching on $c_order/ORDER_ID. I would have expected that the argument OrderId is pushed down to the final database query, but it is not. Can anyone tell me, if possible, how I get the argument pushed down and get the required result?

Answer 1

Looks like I outsmarted myself with the optimization on RX_Addresses.
Looking at the query plan, I see a 'where' operator - drill into it and you will eventually find $fxxx eq $fparam0 (the $postalCode). So the engine decided it would be more effective to get all the Addresses from the database (and put them in our variable), and then look if any of them have a matching postalCode.
Since all the addresses (even those with a postalCode that do not match) when at least one postalCode matches, DSP does the selection in memory. If you go directly to the database table for the postalCode (instead of using the addresses in the variable), the selection does get pushed.
Strictly speaking, I don't think it is impossible for the optimizer to figure out what we just figured out. But the format of your output hides this inference somewhat from the optimizer.
declare function tns:getCompanyProfiles() as element(ns0:company)* {
for $RXS_Org in (ns1:RXS_OrganizationObject())
let $RXS_AddressList := for $RXS_Addresses in ns2:RXS_Addresses()
where $RXS_Addresses/g_id eq $RXS_Org/g_org_id
return $RXS_Addresses
where $RXS_Org/u_relation_type eq "B"
return
<ns0:company>
<ns0:companySpecific? source?="{xs:string("REEDXS")}" reliability?="" registrationState?="" recordDate?="" changeDate?="" validationDate?="">
<ns0:companyIdentifier?>{fn:data($RXS_Org/g_org_id)}</ns0:companyIdentifier>
<ns0:companyName?>{fn:data($RXS_Org/u_Name)}</ns0:companyName>
<ns0:vatNumber?>{fn:data($RXS_Org/u_btw_number)}</ns0:vatNumber>
<ns0:employementClass?>{fn:data($RXS_Org/u_company_size)}</ns0:employementClass>
{   if (fn:string-length(xs:string($RXS_Org/i_branch))>0) then
<ns0:brancheCode?>{xs:string($RXS_Org/i_branch)}</ns0:brancheCode>
else
<ns0:brancheCode?>{xs:string($RXS_Org/i_branch_group)}</ns0:brancheCode>
</ns0:companySpecific>
<ns0:communication?>
{   for $RXS_Addresses in ns2:RXS_Addresses()
where $RXS_Addresses/g_id eq $RXS_Org/g_org_id
return
<ns0:address>
<ns0:country>{fn:data($RXS_Addresses/u_country_name)}</ns0:country>
{   if ($RXS_Addresses/u_address_line1/text()  eq "Postbus") then
<ns0:poBox>{fn:data($RXS_Addresses/u_address_line2)}</ns0:poBox>
else ()
{   if ($RXS_Addresses/u_address_line1/text() != "Postbus") then
<ns0:houseNumber>{fn:data($RXS_Addresses/u_address_line2)}</ns0:houseNumber>
else ()
<ns0:postalCode?>{fn:data($RXS_Addresses/u_postal_code)}</ns0:postalCode>
<ns0:street>{fn:data($RXS_Addresses/u_address_line1)}</ns0:street>
<ns0:city>{fn:data($RXS_Addresses/u_city)}</ns0:city>
<ns0:addressIdentifier>{fn:data($RXS_Addresses/g_address_id)}</ns0:addressIdentifier>
<ns0:addressCategory>{"B"}</ns0:addressCategory>
</ns0:address>
{   for $RXS_Addresses in $RXS_AddressList
return
<ns0:phoneNumber?>
{ if (fn:string-length($RXS_Addresses/u_tel_number) > 0) then
( <ns0:phoneNumberCategory>{"V"}</ns0:phoneNumberCategory>
, <ns0:phoneNumberContent?>{fn:data($RXS_Addresses/u_tel_number)}</ns0:phoneNumberContent>
else ()
</ns0:phoneNumber>
{   for $RXS_Addresses in $RXS_AddressList
return
<ns0:phoneNumber?>
{ if (fn:string-length($RXS_Addresses/u_fax_number) > 0) then
( <ns0:phoneNumberCategory>{"F"}</ns0:phoneNumberCategory>
, <ns0:phoneNumberContent?>{fn:data($RXS_Addresses/u_fax_number)}</ns0:phoneNumberContent>
else ()
</ns0:phoneNumber>
{   for $RXS_Addresses in $RXS_AddressList
return
<ns0:phoneNumber?>
{ if (fn:string-length($RXS_Addresses/u_mobile_tel_number) > 0) then
( <ns0:phoneNumberCategory>{"M"}</ns0:phoneNumberCategory>
, <ns0:phoneNumberContent?>{fn:data($RXS_Addresses/u_mobile_tel_number)}</ns0:phoneNumberContent>
else ()
</ns0:phoneNumber>
<ns0:webAddress?>{fn:data($RXS_Org/u_internet_url)}</ns0:webAddress>
</ns0:communication>
</ns0:company>