XML SQL Optimization needed - sql-server

Question

Hi I been trying to insert into two tables (groups and fields) from XML in SQL. But the solution either doesn't fix my problem or performance is slow as Groups and Fields can number in hundreds of thousands.
A sample of the XML:
<?xml version="1.0" encoding="utf-16"?>
<FB_Flow
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:xsd="http://www.w3.org/2001/XMLSchema" id="1">
<groups>
<FB_FlowGroup counter="1125" position="2" positionparent="0" id="0">
<fields>
<FB_FlowField>
<value>TEST1</value>
<counter>111</counter>
<lineposition>1</lineposition>
</FB_FlowField>
<FB_FlowField>
<value>TEST2</value>
<counter>222</counter>
<lineposition>2</lineposition>
<groupid>0</groupid>
</FB_FlowField>
<FB_FlowField>
<value>TEST3</value>
<counter>333</counter>
<lineposition>3</lineposition>
</FB_FlowField>
</fields>
</FB_FlowGroup>
<FB_FlowGroup counter="1126" position="3" positionparent="2" id="0">
<fields>
<FB_FlowField>
<value>TEST1</value>
<counter>18</counter>
<lineposition>1</lineposition>
</FB_FlowField>
</fields>
</FB_FlowGroup>
</groups>
</FB_Flow>
The first part works fine (To get a list of all groups)
insert into #Groups (intGroupCounter,intGroupPosition,intGroupPositionParent)
SELECT
gcounter = Groups.value('#counter[1]', 'int'),
gposition = Groups.value('#position[1]', 'int'),
gpositionparent = Groups.value('#positionparent[1]', 'int')
FROM
#FlowXML.nodes('/FB_Flow/groups/FB_FlowGroup') AS XTbl(Groups)
This second part fails for the most part (To get all fields with the parent group position):
insert into #Fields (intGroupPosition,vFieldValue,intFieldCounter,intFieldPosition)
SELECT
gposition = XTbl.Groups.value('#position', 'int'),
fValue = XTbl2.Fields.value('value[1]', 'varchar(max)'),
fcounter = XTbl2.Fields.value('counter[1]', 'int'),
fposition = XTbl2.Fields.value('lineposition[1]', 'int')
FROM
#FlowXML.nodes('/FB_Flow/groups/FB_FlowGroup') AS XTbl(Groups)
cross APPLY
Groups.nodes('fields/FB_FlowField') AS XTbl2(Fields)
I have been getting around this by using a cursor and selecting the group by the position attribute but the performance is very poor.
DECLARE #GroupCounter int,
#GroupPosition int,
#GroupPositionParent int,
#GroupID int
DECLARE #Groups table
(
intGroupCounter int not null,
intGroupPosition int not null,
intGroupPositionParent int null default 0
)
insert into #Groups (intGroupCounter,intGroupPosition,intGroupPositionParent)
SELECT
gcounter = Groups.value('#counter[1]', 'int'),
gposition = Groups.value('#position[1]', 'int'),
gpositionparent = Groups.value('#positionparent[1]', 'int')
FROM
#FlowXML.nodes('/FB_Flow/groups/FB_FlowGroup') AS XTbl(Groups)
DECLARE cur cursor for
SELECT
intGroupCounter,
intGroupPosition,
intGroupPositionParent
FROM
#Groups
OPEN cur
FETCH NEXT FROM cur INTO #GroupCounter, #GroupPosition, #GroupPositionParent
WHILE ##FETCH_STATUS = 0
BEGIN
insert into FB_T_FlowGroups (FH_ID,DTC_GroupCounter,Position,PositionParent)
values (#FlowHeaderID,#GroupCounter,#GroupPosition,#GroupPositionParent)
select #GroupID = ##IDENTITY
--declare #Path varchar(max) = '/FB_Flow/groups/FB_FlowGroup[#position="sql:variable("#GroupPosition")"]/fields/FB_FlowField'
insert into FB_T_FlowGroupField (FlowGroupID,ItemValue,DTC_ItemCounter)
SELECT
#GroupID,
XTbl.Fields.value('value[1]', 'varchar(max)'),
XTbl.Fields.value('counter[1]', 'int')
FROM
#FlowXML.nodes('/FB_Flow/groups/FB_FlowGroup[#position=sql:variable("#GroupPosition")]/fields/FB_FlowField') AS XTbl(Fields)
FETCH NEXT FROM cur INTO #GroupCounter, #GroupPosition, #GroupPositionParent
END
CLOSE cur
DEALLOCATE cur
Any Ideas?

Answer 1

What is your SQL Server version (SELECT ##VERSION;)?
Please try the following approach without a cursor. It should give you a tremendous performance improvement:
XML attributes don't need [1] position. Attributes are always unique.
XML elements need an adjustment in the XPath expression - text().
SQL
DECLARE #FlowXML XML =
N'<FB_Flow xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:xsd="http://www.w3.org/2001/XMLSchema" id="1">
<groups>
<FB_FlowGroup counter="1125" position="2" positionparent="0" id="0">
<fields>
<FB_FlowField>
<value>TEST1</value>
<counter>111</counter>
<lineposition>1</lineposition>
</FB_FlowField>
<FB_FlowField>
<value>TEST2</value>
<counter>222</counter>
<lineposition>2</lineposition>
<groupid>0</groupid>
</FB_FlowField>
<FB_FlowField>
<value>TEST3</value>
<counter>333</counter>
<lineposition>3</lineposition>
</FB_FlowField>
</fields>
</FB_FlowGroup>
<FB_FlowGroup counter="1126" position="3" positionparent="2" id="0">
<fields>
<FB_FlowField>
<value>TEST1</value>
<counter>18</counter>
<lineposition>1</lineposition>
</FB_FlowField>
</fields>
</FB_FlowGroup>
</groups>
</FB_Flow>';
-- insert into #Groups (intGroupCounter,intGroupPosition,intGroupPositionParent)
SELECT gcounter = Groups.value('#counter', 'INT')
, gposition = Groups.value('#position', 'INT')
, gpositionparent = Groups.value('#positionparent', 'INT')
FROM #FlowXML.nodes('/FB_Flow/groups/FB_FlowGroup') AS XTbl(Groups);
--insert into #Fields (intGroupPosition,vFieldValue,intFieldCounter,intFieldPosition)
SELECT gposition = XTbl.Groups.value('#position', 'INT')
, fValue = XTbl2.Fields.value('(value/text())[1]', 'VARCHAR(MAX)')
, fcounter = XTbl2.Fields.value('(counter/text())[1]', 'INT')
, fposition = XTbl2.Fields.value('(lineposition/text())[1]', 'INT')
FROM #FlowXML.nodes('/FB_Flow/groups/FB_FlowGroup') AS XTbl(Groups)
CROSS APPLY Groups.nodes('fields/FB_FlowField') AS XTbl2(Fields);