Performance to copy blob from SqlDataReader

  • Thread starter Thread starter Roy
  • Start date Start date
R

Roy

I have a SqlDataReader dr returned from a SqlCommand. dr contains only one
column of 2000 varbinary(max) records (contains 24 bytes in my testing
case). The following code takes 1 second to
run. I would like to improve the performance. Any suggestions

while (dr.Read())
{
list.Add(dr[0] as byte[]);
}

where list is of List<byte[]>.
 
I don't think it is the List.Add(...). I have tested by replacing the list
with an array and it does not affect. I think the bottleneck is the copy of
the bytes from data reader to a local. I don't know which is the way for best
performance for a data reader column with underlining varbinary(max) type.

Mary Chipman said:
I don't know where the bottleneck is -- possibly the list? This topic
describes different coding techniques for retrieving varbinary(max)
data:

http://msdn.microsoft.com/en-us/library/a1904w6t(VS.80).aspx

--Mary

I have a SqlDataReader dr returned from a SqlCommand. dr contains only one
column of 2000 varbinary(max) records (contains 24 bytes in my testing
case). The following code takes 1 second to
run. I would like to improve the performance. Any suggestions

while (dr.Read())
{
list.Add(dr[0] as byte[]);
}

where list is of List<byte[]>.
Click to expand...
Click to expand...
 
Roy,
I don't think it is the List.Add(...). I have tested by replacing the list
with an array and it does not affect. I think the bottleneck is the copy
of
the bytes from data reader to a local. I don't know which is the way for
best
performance for a data reader column with underlining varbinary(max) type.
Click to expand...

If that would be the case, then why not with an integer, however in my idea
can reading blobs as they have a little bit large size be terible slow.

Cor
 
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