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POSlow SQL Updates within a Cursor
 

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    <p>I've added a new column, <code>packageNo</code>, to my table:</p> <pre><code> create table Packages( id varchar(20) primary key, -- ok, I know :) orderNo uniqueIdentifier not null, orderlineNo int not null, packageNo int not null default(0) ) </code></pre> <p>Now I want to generate the <code>packageNo</code> with the following rules: <ul>reset it for each order</ul> <ul>ascendantfor order, orderline</ul></p> <p>My problem is that the script I wrote uses 15 minutes for 26500 rows on my testServer. Here it is:</p> <pre><code>set NoCount ON declare @Counter int declare @handledCounter int declare @currentorder uniqueIdentifier declare @fetchedOrder uniqueIdentifier declare @fetchedId varchar(20) -- will using PK speed up things? declare PackageNo_Cursor cursor for select orderNo, id from packages order by orderNo, orderlineNo for update of packageNo open PackageNo_Cursor fetch next from PackageNo_Cursor into @fetchedOrder, @fetchedId set @currentOrder = @fetchedOrder set @counter = 0 set @handledCounter = 0 while @@fetch_status = 0 begin if (@currentOrder &lt;&gt; @fetchedOrder) begin -- reset counter for each order set @currentOrder = @fetchedOrder set @counter = 0 end set @counter = @counter + 1 set @handledCounter = @handledCounter +1 if (@handledCounter % 50 = 0) begin print 'handled = ' + cast(@handledCounter as varchar) end update packages set packageNo = @counter where current of PackageNo_Cursor fetch next from PackageNo_Cursor into @fetchedOrder, @fetchedId end close PackageNo_Cursor deallocate PackageNo_Cursor </code></pre> <p>This should result in:</p> <pre><code>id - orderno - lineNo - packageNo (what I need to set) ean1 - guid1 - 1 - 1 ean2 - guid1 - 2 - 2 ean3 - guid2 - 1 - 1 ean15- guid2 - 3 - 2 ean15- guid2 - 4 - 3 </code></pre> <p>Can I make this run any faster?</p>
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    1. USDom Ribaut
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    1. COAre you especially concerned about printing out every 50th package you've handled?
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      1. USPaul Alan Taylor
    2. COnot really, I used it to check that something was happening and to see that the time consumption was linear.
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      1. USDom Ribaut
 

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