///////////////////////////////////////////////////////////////////////
/// <summary>
/// See the <see cref="ISQLiteManagedModule.BestIndex" /> method.
/// </summary>
/// <param name="table">
/// See the <see cref="ISQLiteManagedModule.BestIndex" /> method.
/// </param>
/// <param name="index">
/// See the <see cref="ISQLiteManagedModule.BestIndex" /> method.
/// </param>
/// <returns>
/// See the <see cref="ISQLiteManagedModule.BestIndex" /> method.
/// </returns>
public override SQLiteErrorCode BestIndex(
SQLiteVirtualTable table,
SQLiteIndex index
)
{
CheckDisposed();
return GetMethodResultCode("BestIndex");
}
///////////////////////////////////////////////////////////////////////
/// <summary>
/// Modifies the specified <see cref="SQLiteIndex" /> object instance
/// to contain the default estimated rows.
/// </summary>
/// <param name="index">
/// The <see cref="SQLiteIndex" /> object instance to modify.
/// </param>
/// <returns>
/// Non-zero upon success.
/// </returns>
protected virtual bool SetEstimatedRows(
SQLiteIndex index
)
{
return SetEstimatedRows(index, null);
}
///////////////////////////////////////////////////////////////////////
/// <summary>
/// This method is called in response to the
/// <see cref="ISQLiteNativeModule.xBestIndex" /> method.
/// </summary>
/// <param name="table">
/// The <see cref="SQLiteVirtualTable" /> object instance associated
/// with this virtual table.
/// </param>
/// <param name="index">
/// The <see cref="SQLiteIndex" /> object instance containing all the
/// data for the inputs and outputs relating to index selection.
/// </param>
/// <returns>
/// A standard SQLite return code.
/// </returns>
public abstract SQLiteErrorCode BestIndex(
SQLiteVirtualTable table,
SQLiteIndex index
);
///////////////////////////////////////////////////////////////////////
/// <summary>
/// Modifies the specified <see cref="SQLiteIndex" /> object instance
/// to contain the specified estimated rows.
/// </summary>
/// <param name="index">
/// The <see cref="SQLiteIndex" /> object instance to modify.
/// </param>
/// <param name="estimatedRows">
/// The estimated rows value to use. Using a null value means that the
/// default value provided by the SQLite core library should be used.
/// </param>
/// <returns>
/// Non-zero upon success.
/// </returns>
protected virtual bool SetEstimatedRows(
SQLiteIndex index,
long? estimatedRows
)
{
if ((index == null) || (index.Outputs == null))
return false;
index.Outputs.EstimatedRows = estimatedRows;
return true;
}
///////////////////////////////////////////////////////////////////////
#region Index Handling Helper Methods
/// <summary>
/// Modifies the specified <see cref="SQLiteIndex" /> object instance
/// to contain the specified estimated cost.
/// </summary>
/// <param name="index">
/// The <see cref="SQLiteIndex" /> object instance to modify.
/// </param>
/// <param name="estimatedCost">
/// The estimated cost value to use. Using a null value means that the
/// default value provided by the SQLite core library should be used.
/// </param>
/// <returns>
/// Non-zero upon success.
/// </returns>
protected virtual bool SetEstimatedCost(
SQLiteIndex index,
double? estimatedCost
)
{
if ((index == null) || (index.Outputs == null))
return false;
index.Outputs.EstimatedCost = estimatedCost;
return true;
}
///////////////////////////////////////////////////////////////////////
#region Public Methods
/// <summary>
/// This method should normally be used by the
/// <see cref="ISQLiteManagedModule.BestIndex" /> method in order to
/// perform index selection based on the constraints provided by the
/// SQLite core library.
/// </summary>
/// <param name="index">
/// The <see cref="SQLiteIndex" /> object instance containing all the
/// data for the inputs and outputs relating to index selection.
/// </param>
/// <returns>
/// Non-zero upon success.
/// </returns>
public virtual bool BestIndex(
SQLiteIndex index
)
{
CheckDisposed();
this.index = index;
return true;
}
///////////////////////////////////////////////////////////////////////
/// <summary>
/// Populates the outputs of a pre-allocated native sqlite3_index_info
/// structure using an existing <see cref="SQLiteIndex" /> object
/// instance.
/// </summary>
/// <param name="index">
/// The existing <see cref="SQLiteIndex" /> object instance containing
/// the output data to use.
/// </param>
/// <param name="pIndex">
/// The native pointer to the pre-allocated native sqlite3_index_info
/// structure.
/// </param>
internal static void ToIntPtr(
SQLiteIndex index,
IntPtr pIndex
)
{
if ((index == null) || (index.Inputs == null) ||
(index.Inputs.Constraints == null) ||
(index.Outputs == null) ||
(index.Outputs.ConstraintUsages == null))
{
return;
}
if (pIndex == IntPtr.Zero)
return;
int offset = 0;
int nConstraint = SQLiteMarshal.ReadInt32(pIndex, offset);
if (nConstraint != index.Inputs.Constraints.Length)
return;
if (nConstraint != index.Outputs.ConstraintUsages.Length)
return;
offset = SQLiteMarshal.NextOffsetOf(offset, sizeof(int),
IntPtr.Size);
offset = SQLiteMarshal.NextOffsetOf(offset, IntPtr.Size,
sizeof(int));
offset = SQLiteMarshal.NextOffsetOf(offset, sizeof(int),
IntPtr.Size);
offset = SQLiteMarshal.NextOffsetOf(offset, IntPtr.Size,
sizeof(int));
IntPtr pConstraintUsage = SQLiteMarshal.ReadIntPtr(pIndex, offset);
int sizeOfConstraintUsageType = Marshal.SizeOf(typeof(
UnsafeNativeMethods.sqlite3_index_constraint_usage));
for (int iConstraint = 0; iConstraint < nConstraint; iConstraint++)
{
UnsafeNativeMethods.sqlite3_index_constraint_usage constraintUsage =
new UnsafeNativeMethods.sqlite3_index_constraint_usage(
index.Outputs.ConstraintUsages[iConstraint]);
Marshal.StructureToPtr(
constraintUsage, SQLiteMarshal.IntPtrForOffset(
pConstraintUsage, iConstraint * sizeOfConstraintUsageType),
false);
}
offset = SQLiteMarshal.NextOffsetOf(offset, IntPtr.Size,
sizeof(int));
SQLiteMarshal.WriteInt32(pIndex, offset,
index.Outputs.IndexNumber);
offset = SQLiteMarshal.NextOffsetOf(offset, sizeof(int),
IntPtr.Size);
SQLiteMarshal.WriteIntPtr(pIndex, offset,
SQLiteString.Utf8IntPtrFromString(index.Outputs.IndexString));
offset = SQLiteMarshal.NextOffsetOf(offset, IntPtr.Size,
sizeof(int));
//
// NOTE: We just allocated the IndexString field; therefore, we
// need to set the NeedToFreeIndexString field to non-zero.
//
SQLiteMarshal.WriteInt32(pIndex, offset, 1);
offset = SQLiteMarshal.NextOffsetOf(offset, sizeof(int),
sizeof(int));
SQLiteMarshal.WriteInt32(pIndex, offset,
index.Outputs.OrderByConsumed);
offset = SQLiteMarshal.NextOffsetOf(offset, sizeof(int),
sizeof(double));
if (index.Outputs.EstimatedCost.HasValue)
{
SQLiteMarshal.WriteDouble(pIndex, offset,
index.Outputs.EstimatedCost.GetValueOrDefault());
}
if (index.Outputs.CanUseEstimatedRows() &&
index.Outputs.EstimatedRows.HasValue)
{
SQLiteMarshal.WriteInt64(pIndex, offset,
index.Outputs.EstimatedRows.GetValueOrDefault());
}
}
///////////////////////////////////////////////////////////////////////
#region Internal Marshal Helper Methods
/// <summary>
/// Converts a native pointer to a native sqlite3_index_info structure
/// into a new <see cref="SQLiteIndex" /> object instance.
/// </summary>
/// <param name="pIndex">
/// The native pointer to the native sqlite3_index_info structure to
/// convert.
/// </param>
/// <param name="index">
/// Upon success, this parameter will be modified to contain the newly
/// created <see cref="SQLiteIndex" /> object instance.
/// </param>
internal static void FromIntPtr(
IntPtr pIndex,
ref SQLiteIndex index
)
{
if (pIndex == IntPtr.Zero)
return;
int offset = 0;
int nConstraint = SQLiteMarshal.ReadInt32(pIndex, offset);
offset = SQLiteMarshal.NextOffsetOf(offset, sizeof(int),
IntPtr.Size);
IntPtr pConstraint = SQLiteMarshal.ReadIntPtr(pIndex, offset);
offset = SQLiteMarshal.NextOffsetOf(offset, IntPtr.Size,
sizeof(int));
int nOrderBy = SQLiteMarshal.ReadInt32(pIndex, offset);
offset = SQLiteMarshal.NextOffsetOf(offset, sizeof(int),
IntPtr.Size);
IntPtr pOrderBy = SQLiteMarshal.ReadIntPtr(pIndex, offset);
index = new SQLiteIndex(nConstraint, nOrderBy);
Type indexConstraintType = typeof(
UnsafeNativeMethods.sqlite3_index_constraint);
int sizeOfConstraintType = Marshal.SizeOf(indexConstraintType);
for (int iConstraint = 0; iConstraint < nConstraint; iConstraint++)
{
IntPtr pOffset = SQLiteMarshal.IntPtrForOffset(
pConstraint, iConstraint * sizeOfConstraintType);
UnsafeNativeMethods.sqlite3_index_constraint constraint =
(UnsafeNativeMethods.sqlite3_index_constraint)
Marshal.PtrToStructure(pOffset, indexConstraintType);
index.Inputs.Constraints[iConstraint] =
new SQLiteIndexConstraint(constraint);
}
Type indexOrderByType = typeof(
UnsafeNativeMethods.sqlite3_index_orderby);
int sizeOfOrderByType = Marshal.SizeOf(indexOrderByType);
for (int iOrderBy = 0; iOrderBy < nOrderBy; iOrderBy++)
{
IntPtr pOffset = SQLiteMarshal.IntPtrForOffset(
pOrderBy, iOrderBy * sizeOfOrderByType);
UnsafeNativeMethods.sqlite3_index_orderby orderBy =
(UnsafeNativeMethods.sqlite3_index_orderby)
Marshal.PtrToStructure(pOffset, indexOrderByType);
index.Inputs.OrderBys[iOrderBy] =
new SQLiteIndexOrderBy(orderBy);
}
}
