Sql Server Xml Column query performance?
I'm trying to query an xml column in sql server. I've created a primary index on the column and query it using:
SELECT *
FROM MyTable
where Doc.exist('/xml/root/propertyx/text()[. = "something"]') = 1
In a table with 60 000 entries , this query takes some 100 ms on my local dev machine. Is it possible to optimize this somehow to increase performance of the qu开发者_C百科ery?
You can optimize for fast query times with a calculated column. A calculated column can't use the XML functions directly, so you have to wrap them in a function:
go
create function dbo.GetSomethingExists(
@Doc xml)
returns bit
with schemabinding
as begin return (
select @Doc.exist('/xml/root/property/text()[. = "something"]')
) end
go
create table TestTable (
Doc xml,
SomethingExists as dbo.GetSomethingExists(Doc) persisted
)
go
If you declare the function with schemabinding
, you can create an index on SomethingExists:
create index IX_TestTable_SomethingExists on TestTable(SomethingExists)
This should make the query much faster.
Creating a Secondary XML Index of Path
type might speed things up for you.
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