Changes between Version 7 and Version 8 of MapGuideRfc123

Timestamp:

11/03/11 20:37:25 (13 years ago)

Author:

jng

Comment:

--

MapGuideRfc123

@@ -101 +101 @@
 === The FDO join feature reader ===
 
-The existing MgServerFeatureReader will be modified to incorporate iteration logic to handle forcing 1:1 in the resulting FDO feature reader.
+We will include a custom server-only implementation of FdoIFeatureReader (MgFdoForcedOneToOneFeatureReader) which wraps an existing FdoIFeatureReader to incorporate iteration logic to handle forcing 1:1 cardinality on the iterated results.
 
-When 1:1 cardinality is not being forced, this reader behaves like a normal feature reader.
+This reader behaves like a normal feature reader. All FdoIFeatureReader calls pass through to the underlying reader, except for ReadNext()
 
-In the case of the forcing of 1:1 cardinality, we take a different path and employ the following logic for ReadNext():
+To force 1:1 cardinality, the ReadNext() method employs the following logic:
 
  1. Read the current identity property values. Hash these values into a string and check if this hashed string exists in an internal std::set.
@@ -111 +111 @@
  3. Store this hashed string into the internal set for future comparisons.
 
-Iteration logic for the normal case (not 1:1), is simply to pass over to the underlying reader's ReadNext() method. Tracking of identity property values is not required for this case.
+Depending on whether 1:1 cardinality is forced, the final reader that is returned to the web tier will either be:
+
+{{{
+MgServerFeatureReader (containing...)
+    FdoIFeatureReader (from FdoIExtendedSelect::Execute())
+}}}
+
+Or if 1:1 is forced
+
+{{{
+MgServerFeatureReader (containing...)
+    MgFdoForcedOneToOneFeatureReader (containing...)
+        FdoIFeatureReader (from FdoIExtendedSelect::Execute())
+}}}
 
 Performance-wise, support for FDO joins has already been implemented in [http://mg-desktop.googlecode.com mg-desktop] and the benefits there are clear. The performance times for a 17000 feature by 16000 feature join (of [http://code.google.com/p/mg-desktop/source/browse/DesktopTestData/ParcelsJoinTest.sqlite this dataset]) are outlined below.
@@ -145 +158 @@
 == Test Plan ==
 
-Add unit tests against some sample SQLite feature sources configured to take advantage of these optimizations. Verify that the FDO join optimization path is taken when selecting from these feature sources.
+Add unit tests against some sample SQLite feature sources configured to take advantage of these optimizations. Verify that the FDO join optimization path is taken when selecting from these feature sources. Also exercise the SpatialExtents() aggregate function against SQLite extended feature classes which can take advantage of this optimization.
 
 == Funding / Resources ==