Don't know why the patch didn't get through, sending again...
===
diff -ur a\System.Data.SQLite\SQLiteDataReader.cs
b\System.Data.SQLite\SQLiteDataReader.cs
--- a\System.Data.SQLite\SQLiteDataReader.cs Sat Aug 11 16:40:46 2012
+++ b\System.Data.SQLite\SQLiteDataReader.cs Fri Oct 05 13:47:16 2012
@@ -48,6 +48,10 @@
/// </summary>
private int _fieldCount;
/// <summary>
+ /// Names of fields (columns) in the row-returning statement currently
being processed
+ /// </summary>
+ private string[] _fieldNames;
+ /// <summary>
/// Datatypes of active fields (columns) in the current statement, used
for type-restricting data
/// </summary>
private SQLiteType[] _fieldTypeArray;
@@ -208,6 +212,7 @@
_command = null;
_activeStatement = null;
_fieldTypeArray = null;
+ _fieldNames = null;
}
finally
{
@@ -643,7 +648,13 @@
CheckClosed();
SQLiteCommand.Check(_command);
- int r = _activeStatement._sql.ColumnIndex(_activeStatement, name);
+ int r = -1;
+#if !PLATFORM_COMPACTFRAMEWORK
+ if (_fieldNames != null)
+ r = Array.FindIndex(_fieldNames, delegate(string x) { return
x.Equals(name, StringComparison.OrdinalIgnoreCase); });
+ if (r == -1)
+#endif
+ r = _activeStatement._sql.ColumnIndex(_activeStatement, name);
if (r == -1 && _keyInfo != null)
{
r = _keyInfo.GetOrdinal(name);
@@ -1191,6 +1202,7 @@
_activeStatementIndex++;
fieldCount = stmt._sql.ColumnCount(stmt);
+ _fieldNames = null;
// If the statement is not a select statement or we're not retrieving schema only, then perform the initial step
if ((_commandBehavior & CommandBehavior.SchemaOnly) == 0 || fieldCount
== 0)
@@ -1216,6 +1228,9 @@
_activeStatement = stmt;
_fieldCount = fieldCount;
_fieldTypeArray = null;
+ _fieldNames = new string[fieldCount];
+ for (int i=0; i<fieldCount; i++)
+ _fieldNames[i] = GetName(i);
if ((_commandBehavior & CommandBehavior.KeyInfo) != 0)
LoadKeyInfo();
===
Ashish Kulkarni wrote:
Hello,
I've attached a patch which caches the column names in SQLiteDataReader.
During profiling a scenario where more than 100-200 records are read and
columns are accessed by name and not by index -- well over 50% of the time
was spent in System.Data.SQLite.SQLite3.ColumnIndex(). The attached patch
caches the field names in the data reader (using the same semantics) which
speeds up retrieval of records by a large margin.
Thanks,
Ashish
diff -ur a\System.Data.SQLite\SQLiteDataReader.cs
b\System.Data.SQLite\SQLiteDataReader.cs
--- a\System.Data.SQLite\SQLiteDataReader.cs Sat Aug 11 16:40:46 2012
+++ b\System.Data.SQLite\SQLiteDataReader.cs Fri Oct 05 13:47:16 2012
@@ -48,6 +48,10 @@
/// </summary>
private int _fieldCount;
/// <summary>
+ /// Names of fields (columns) in the row-returning statement currently
being processed
+ /// </summary>
+ private string[] _fieldNames;
+ /// <summary>
/// Datatypes of active fields (columns) in the current statement, used
for type-restricting data
/// </summary>
private SQLiteType[] _fieldTypeArray;
@@ -208,6 +212,7 @@
_command = null;
_activeStatement = null;
_fieldTypeArray = null;
+ _fieldNames = null;
}
finally
{
@@ -643,7 +648,13 @@
CheckClosed();
SQLiteCommand.Check(_command);
- int r = _activeStatement._sql.ColumnIndex(_activeStatement, name);
+ int r = -1;
+#if !PLATFORM_COMPACTFRAMEWORK
+ if (_fieldNames != null)
+ r = Array.FindIndex(_fieldNames, delegate(string x) { return
x.Equals(name, StringComparison.OrdinalIgnoreCase); });
+ if (r == -1)
+#endif
+ r = _activeStatement._sql.ColumnIndex(_activeStatement, name);
if (r == -1 && _keyInfo != null)
{
r = _keyInfo.GetOrdinal(name);
@@ -1191,6 +1202,7 @@
_activeStatementIndex++;
fieldCount = stmt._sql.ColumnCount(stmt);
+ _fieldNames = null;
// If the statement is not a select statement or we're not retrieving
schema only, then perform the initial step
if ((_commandBehavior & CommandBehavior.SchemaOnly) == 0 || fieldCount
== 0)
@@ -1216,6 +1228,9 @@
_activeStatement = stmt;
_fieldCount = fieldCount;
_fieldTypeArray = null;
+ _fieldNames = new string[fieldCount];
+ for (int i=0; i<fieldCount; i++)
+ _fieldNames[i] = GetName(i);
if ((_commandBehavior & CommandBehavior.KeyInfo) != 0)
LoadKeyInfo();
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