This fix is to correct issue AG-252 which is due to FieldSelect
expressions that are unexpected.
The original shortest path algorithm appears to have not anticipated the
cases where the source/target expressions might be something other than a
Param expression. To fix this issue, logic needed to be added to allow
FieldSelect expressions in source/target nodes.
The following is done to correct the issue -
The Hash2SideState structure had the following fields added to support
the fix.
bool isFieldSelect; To flag a FieldSelect node.
Param *correctedParam; To hold the corrected Param node.
HeapTuple vertexRow; To hold the vertexRow for reuse;
TupleDesc tupleDesc; To hold a tuple descriptor for reuse.
The support function replace_vertexRow_graphid is added to allow reusing
a vertexRow by replacing its contained graphid value.
The ExecReScanShortestpath function is fixed to use the correct Param
node.
The ExecShortestpathRescanOuterNode function is fixed to use the
correct Param node and logic is added to pass a reused vertexRow with
the correct graphid when the expression node is a FieldSelect.
The ExecInitShortestpath function is modified to initialize the new
fields in the Hash2SideState structure. Additionally, it creates a
tuple descriptor and vertexRow as needed. These are freed in the end
function.
The ExecEndShortestpath function is modified to clean up both the
vertexRow and tuple descriptor allocated in the init function.
Note: It appears like the Dijkstra path algorithm uses similar logic
and may have similar issues.
This fix is to correct issue AG-252 which is due to FieldSelect expressions that are unexpected.
The original shortest path algorithm appears to have not anticipated the cases where the source/target expressions might be something other than a Param expression. To fix this issue, logic needed to be added to allow FieldSelect expressions in source/target nodes.
The following is done to correct the issue -
The Hash2SideState structure had the following fields added to support the fix.
The support function
replace_vertexRow_graphidis added to allow reusing a vertexRow by replacing its contained graphid value.The
ExecReScanShortestpathfunction is fixed to use the correct Param node.The
ExecShortestpathRescanOuterNodefunction is fixed to use the correct Param node and logic is added to pass a reused vertexRow with the correct graphid when the expression node is a FieldSelect.The
ExecInitShortestpathfunction is modified to initialize the new fields in the Hash2SideState structure. Additionally, it creates a tuple descriptor and vertexRow as needed. These are freed in the end function.The
ExecEndShortestpathfunction is modified to clean up both the vertexRow and tuple descriptor allocated in the init function.Note: It appears like the Dijkstra path algorithm uses similar logic and may have similar issues.
-jrg