1

I have a table which I'm only Insert, Delete and Select (no Updates)

on Insert, Sometimes it used a session lock (WITH (TABLOCKX))

I have a program using ADO which Select from the table using the RecordSet::Open command to open a simple sequential query.

like:

Select * from t1 where id >= @from_id And >= @to_id`  

Or:

Select top(10) * from t1 where id >= @id Order by id 

The id column is an Identity column.

When I'm open the query, sometimes I'm getting a deadlock. (the table is locked by the Insert query and the id column's index is locked by the Select)

I'm trying to prevent the deadlocks.

Should I open the select queries WITH(NOLOCK)? may it prevent the deadlocks?

  • 8
    WITH (NODEADLOCK) – Philᵀᴹ Aug 13 at 17:30
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    Are you ok with the possibility of reading the same rows twice, skipping rows, seeing data never committed, and having your query fail with error? Reference 1, Reference 2 – scsimon Aug 13 at 17:50
  • @Philᵀᴹ so using WITH (NODEADLOCK) is safe enough? – SHR Aug 13 at 19:52
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    @shr - Phil was being facetious. There is no such hint named NODEADLOCK – Max Vernon Aug 13 at 20:33
5

A better idea would be to enable snapshot isolation: https://docs.microsoft.com/en-us/dotnet/framework/data/adonet/sql/snapshot-isolation-in-sql-server

This will enable each transaction to have its own snapshot of data and will not lock, or block other transactions.

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