Index in Berkeley DB XML - Problems with time

Question

I have some querys that not show a better time after have been indexed.
I saw that this query that show problems with index realize : ordering , substring and empty values or tag.
This query was extracted from benchmark xbench x toxgene
I will post the queryPlan and results before and after add index.
computer configuration : pentim RAM : 2Gb HD : 160
Results
Query 1
dbxml> query 'for $a in collection("container_db_xbench_250Mb.dbxml")/article w
here every $b in $a/body/abstract/p satisfies contains($b, "hockey") return $a
/prolog/title'
Query - Starting query execution
Query - container_db_xbench_250Mb.dbxml - U : [405] 2 3 4 5 6 7 8 9 10 11 1
2 13 14 15 16 17 18 19 20 21 ...
Query - Finished query execution, time taken = 168.522ms
102 objects returned for eager expression 'for $a in collection("container_db_xb
ench_250Mb.dbxml")/article where every $b in $a/body/abstract/p satisfies cont
ains($b, "hockey") return $a/prolog/title'
dbxml> queryPlan 'for $a in collection("container_db_xbench_250Mb.dbxml")/articl
e
where every $b in $a/body/abstract/p satisfies contains($b, "hockey")
return $a/prolog/title'
<XQuery>
<FLWOR>
<ForBinding name="a">
<Navigation>
<QueryPlanFunction result="collection" container="container_db_xbench_25
0Mb.dbxml">
<OQPlan>U</OQPlan>
</QueryPlanFunction>
<Step axis="child" name="article" nodeType="element"/>
</Navigation>
<Where>
<EveryFLWOR>
<ForBinding name="b">
<Navigation>
<Variable name="a"/>
<Step axis="child" name="body" nodeType="element"/>
<Step axis="child" name="abstract" nodeType="element"/>
<Step axis="child" name="p" nodeType="element"/>
</Navigation>
</ForBinding>
<Navigation>
<Variable name="b"/>
<DbXmlContains>
<Sequence>
<AnyAtomicTypeConstructor value="hockey" typeuri="http://www.w3.
org/2001/XMLSchema" typename="string"/>
</Sequence>
</DbXmlContains>
</Navigation>
</EveryFLWOR>
</Where>
</ForBinding>
<Navigation>
<Variable name="a"/>
<Step axis="child" name="prolog" nodeType="element"/>
<Step axis="child" name="title" nodeType="element">
<OQPlan>P(node-element-equality-string,prefix,title)</OQPlan>
</Step>
</Navigation>
</FLWOR>
</XQuery>
dbxml>
dbxml> query 'for $a in collection("container_db_xbench_250Mb.dbxml")/article w
here every $b in $a/body/abstract/p satisfies contains($b, "hockey") return $a
/prolog/title'
Query - Starting query execution
Query - container_db_xbench_250Mb.dbxml - U : [405] 2 3 4 5 6 7 8 9 10 11 1
2 13 14 15 16 17 18 19 20 21 ...
Query - container_db_xbench_250Mb.dbxml - P(title) : [405] 2(0x04020204) 3(
0x04020204) 4(0x04020204) 5(0x04020204) 6(0x04020204) 7(0x04020204) 8(0x04020204
) 9(0x04020204) 10(0x04020204) 11(0x04020204) ...
Query - Finished query execution, time taken = 710.093ms
102 objects returned for eager expression 'for $a in collection("container_db_xb
ench_250Mb.dbxml")/article where every $b in $a/body/abstract/p satisfies cont
ains($b, "hockey") return $a/prolog/title'
Query 2
dbxml> query 'for $a in collection("container_db_xbench_250Mb.dbxml")/article/pr
olog order by $a/dateline/country return <Output> {$a/title} {$a/dateline/
country} </Output>'
Query - Starting query execution
Query - container_db_xbench_250Mb.dbxml - U : [405] 2 3 4 5 6 7 8 9 10 11 1
2 13 14 15 16 17 18 19 20 21 ...
Query - Finished query execution, time taken = 248.939ms
405 objects returned for eager expression 'for $a in collection("container_db_xb
ench_250Mb.dbxml")/article/prolog order by $a/dateline/country return <Outpu
t> {$a/title} {$a/dateline/country} </Output>'
dbxml> queryPlan 'for $a in collection("container_db_xbench_250Mb.dbxml")/articl
e/prolog order by $a/dateline/country return <Output> {$a/title} {$a/datel
ine/country} </Output>'
<XQuery>
<FLWOR>
<ForBinding name="a">
<Navigation>
<QueryPlanFunction result="collection" container="container_db_xbench_25
0Mb.dbxml">
<OQPlan>U</OQPlan>
</QueryPlanFunction>
<Step axis="child" name="article" nodeType="element"/>
<Step axis="child" name="prolog" nodeType="element"/>
</Navigation>
</ForBinding>
<Sort>
<Specification modifier="ascending|empty_least">
<Navigation>
<Variable name="a"/>
<Step axis="child" name="dateline" nodeType="element"/>
<Step axis="child" name="country" nodeType="element">
<OQPlan>P(node-element-equality-string,prefix,country)</OQPlan>
</Step>
</Navigation>
</Specification>
</Sort>
<DOMConstructor type="element">
<Name>
<Sequence>
<AnyAtomicTypeConstructor value="Output" typeuri="http://www.w3.org/20
01/XMLSchema" typename="string"/>
</Sequence>
</Name>
<Children>
<Navigation>
<Variable name="a"/>
<Step axis="child" name="title" nodeType="element"/>
</Navigation>
<Navigation>
<Variable name="a"/>
<Step axis="child" name="dateline" nodeType="element"/>
<Step axis="child" name="country" nodeType="element">
<OQPlan>P(node-element-equality-string,prefix,country)</OQPlan>
</Step>
</Navigation>
</Children>
</DOMConstructor>
</FLWOR>
</XQuery>
dbxml>
Query - container_db_xbench_250Mb.dbxml - P(country) : NONE
Query - container_db_xbench_250Mb.dbxml - P(country) : NONE
Query - Finished query execution, time taken = 1573.17ms
405 objects returned for eager expression 'for $a in collection("container_db_xb
ench_250Mb.dbxml")/article/prolog order by $a/dateline/country return <Outpu
t> {$a/title} {$a/dateline/country} </Output>'
Query 3
dbxml> query 'for $a in collection("container_db_xbench_250Mb.dbxml")/article/pr
olog where empty ($a/genre) return <NoGenre> {$a/title} </N
oGenre>'
Query - Starting query execution
Query - container_db_xbench_250Mb.dbxml - U : [405] 2 3 4 5 6 7 8 9 10 11 1
2 13 14 15 16 17 18 19 20 21 ...
Query - Finished query execution, time taken = 207.782ms
170 objects returned for eager expression 'for $a in collection("container_db_xb
ench_250Mb.dbxml")/article/prolog where empty ($a/genre) return <NoGenre>
{$a/title} </NoGenre>'
dbxml> queryPlan 'for $a in collection("container_db_xbench_250Mb.dbxml")/articl
e/prolog where empty ($a/genre) return <NoGenre> {$a/title}
</NoGenre>'
<XQuery>
<FLWOR>
<ForBinding name="a">
<Navigation>
<QueryPlanFunction result="collection" container="container_db_xbench_25
0Mb.dbxml">
<OQPlan>U</OQPlan>
</QueryPlanFunction>
<Step axis="child" name="article" nodeType="element"/>
<Step axis="child" name="prolog" nodeType="element"/>
</Navigation>
<Where>
<Function name="{http://www.w3.org/2005/04/xpath-functions}:empty">
<Navigation>
<Variable name="a"/>
<Step axis="child" name="genre" nodeType="element">
<OQPlan>P(node-element-presence-none,=,genre)</OQPlan>
</Step>
</Navigation>
</Function>
</Where>
</ForBinding>
<DOMConstructor type="element">
<Name>
<Sequence>
<AnyAtomicTypeConstructor value="NoGenre" typeuri="http://www.w3.org/2
001/XMLSchema" typename="string"/>
</Sequence>
</Name>
<Children>
<Navigation>
<Variable name="a"/>
<Step axis="child" name="title" nodeType="element"/>
</Navigation>
</Children>
</DOMConstructor>
</FLWOR>
</XQuery>
dbxml>
0x0402025E) 9(0x040202D0) 10(0x0402023F) 11(0x0402020F) 14(0x0402020F) 15(0x0402
0253) 17(0x0402025E) 20(0x040202EE) 23(0x040202C0) ...
Query - container_db_xbench_250Mb.dbxml - P(genre) : [235] 4(0x0402024G) 5(
0x0402025E) 9(0x040202D0) 10(0x0402023F) 11(0x0402020F) 14(0x0402020F) 15(0x0402
0253) 17(0x0402025E) 20(0x040202EE) 23(0x040202C0) ...
Query - Finished query execution, time taken = 2362.08ms
170 objects returned for eager expression 'for $a in collection("container_db_xb
ench_250Mb.dbxml")/article/prolog where empty ($a/genre) return <NoGenre>
{$a/title} </NoGenre>'
Query 4
dbxml> query 'for $a in collection("container_db_xbench_250Mb.dbxml")/article/pr
olog/authors/author where empty($a/contact/text()) return <NoContact> {
$a/name} </NoContact>'
Query - Starting query execution
Query - container_db_xbench_250Mb.dbxml - U : [405] 2 3 4 5 6 7 8 9 10 11 1
2 13 14 15 16 17 18 19 20 21 ...
Query - Finished query execution, time taken = 680.503ms
212 objects returned for eager expression 'for $a in collection("container_db_xb
ench_250Mb.dbxml")/article/prolog/authors/author where empty($a/contact/text())
return <NoContact> {$a/name} </NoContact>'
dbxml> queryPlan 'for $a in collection("container_db_xbench_250Mb.dbxml")/articl
e/prolog/authors/author where empty($a/contact/text()) return <NoContact>
{$a/name} </NoContact>'
<XQuery>
<FLWOR>
<ForBinding name="a">
<Navigation>
<QueryPlanFunction result="collection" container="container_db_xbench_25
0Mb.dbxml">
<OQPlan>U</OQPlan>
</QueryPlanFunction>
<Step axis="child" name="article" nodeType="element"/>
<Step axis="child" name="prolog" nodeType="element"/>
<Step axis="child" name="authors" nodeType="element"/>
<Step axis="child" name="author" nodeType="element"/>
</Navigation>
<Where>
<Function name="{http://www.w3.org/2005/04/xpath-functions}:empty">
<Navigation>
<Variable name="a"/>
<Step axis="child" name="contact" nodeType="element">
<OQPlan>P(node-element-presence-none,=,contact)</OQPlan>
</Step>
<Step axis="child">
<ItemType testType="text"/>
</Step>
</Navigation>
</Function>
</Where>
</ForBinding>
<DOMConstructor type="element">
<Name>
<Sequence>
<AnyAtomicTypeConstructor value="NoContact" typeuri="http://www.w3.org
/2001/XMLSchema" typename="string"/>
</Sequence>
</Name>
<Children>
<Navigation>
<Variable name="a"/>
<Step axis="child" name="name" nodeType="element">
<OQPlan>P(node-element-equality-string,prefix,name)</OQPlan>
</Step>
</Navigation>
</Children>
</DOMConstructor>
</FLWOR>
</XQuery>
2(0x0402020E) 2(0x04020212) 2(0x04020216) 2(0x0402021B) 2(0x0402021F) 2(0x04020
223) 2(0x04020227) 2(0x0402022C) 2(0x0402022G) ...
Query - Finished query execution, time taken = 48724.8ms
212 objects returned for eager expression 'for $a in collection("container_db_xb
ench_250Mb.dbxml")/article/prolog/authors/author where empty($a/contact/text())
return <NoContact> {$a/name} </NoContact>'
Query 5
dbxml> query 'for $a in collection("container_db_xbench_250Mb.dbxml")/article w
here contains ($a//p, "the hockey") return <Output> {$a/prolog/ti
tle} {$a/body/abstract} </Output>'
Query - Starting query execution
Query - container_db_xbench_250Mb.dbxml - U : [405] 2 3 4 5 6 7 8 9 10 11 1
2 13 14 15 16 17 18 19 20 21 ...
Query - Finished query execution, time taken = 3605.86ms
383 objects returned for eager expression 'for $a in collection("container_db_xb
ench_250Mb.dbxml")/article where contains ($a//p, "the hockey") return <O
utput> {$a/prolog/title} {$a/body/abstract} </Output>'
dbxml> queryPlan 'for $a in collection("container_db_xbench_250Mb.dbxml")/articl
e where contains ($a//p, "the hockey") return <Output> {$a/prolo
g/title} {$a/body/abstract} </Output>'
<XQuery>
<FLWOR>
<ForBinding name="a">
<Navigation>
<QueryPlanFunction result="collection" container="container_db_xbench_25
0Mb.dbxml">
<OQPlan>U</OQPlan>
</QueryPlanFunction>
<Step axis="child" name="article" nodeType="element"/>
<DbXmlFilter>
<Navigation>
<Step axis="descendant" name="p" nodeType="element"/>
<DbXmlContains>
<Sequence>
<AnyAtomicTypeConstructor value="the hockey" typeuri="http://www
.w3.org/2001/XMLSchema" typename="string"/>
</Sequence>
</DbXmlContains>
</Navigation>
</DbXmlFilter>
</Navigation>
</ForBinding>
<DOMConstructor type="element">
<Name>
<Sequence>
<AnyAtomicTypeConstructor value="Output" typeuri="http://www.w3.org/20
01/XMLSchema" typename="string"/>
</Sequence>
</Name>
<Children>
<Navigation>
<Variable name="a"/>
<Step axis="child" name="prolog" nodeType="element"/>
<Step axis="child" name="title" nodeType="element">
<OQPlan>P(node-element-equality-string,prefix,title)</OQPlan>
</Step>
</Navigation>
<Navigation>
<Variable name="a"/>
<Step axis="child" name="body" nodeType="element"/>
<Step axis="child" name="abstract" nodeType="element"/>
</Navigation>
</Children>
</DOMConstructor>
</FLWOR>
</XQuery>
dbxml>
time taken = 6038.12ms

Answer 1

Hi Miriam,
What storage model are you using, and are you using DBXML_INDEX_NODES? What indexes did you try to add to make these queries faster?
John