Double the speed of FbDataReader.GetOrdinal()
---------------------------------------------
Key: DNET-214
URL: http://tracker.firebirdsql.org/browse/DNET-214
Project: .NET Data provider
Issue Type: Improvement
Components: ADO.NET Provider
Environment: N/A
Reporter: Gareth Goslett
Assignee: Jiri Cincura
Priority: Trivial
By creating a hashtable on first access to the GetOrdinal method and populating
it with the fields and indexes we only need to get the hash code of the
requested field name for future lookups.
I did some tests on a table with 10 fields and 1000 records. I read all records
5 times so there were 5 * 1000 * 10 lookups.
CURRENT GetOrdinal
Total ordinal reads: 5000
Result 13
Result 11
Result 11
Result 10
Result 10
Average time 0.011
Total named reads : 5000
Result 33
Result 33
Result 36
Result 32
Average time 0.0268
NEW GetOrdinal
Total ordinal reads: 5000
Result 13
Result 9
Result 10
Result 10
Result 9
Average time 0.0102
Total named reads : 5000
Result 13
Result 16
Result 14
Result 14
Average time 0.0114
Here is the new method:
Hashtable names;
public override int GetOrdinal(string name)
{
this.CheckState();
if (names == null)
{
names = new Hashtable();
for (int i = 0; i < this.fields.Count; i++)
{
names.Add(this.fields[i].Alias.ToLowerInvariant().GetHashCode(), i);
}
}
int hash = name.ToLowerInvariant().GetHashCode();
if (names.ContainsKey(hash) == true)
{
return (Int32)names[hash];
}
throw new IndexOutOfRangeException("Could not find specified column in
results.");
}
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