1.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     1.2 +++ b/evaluation/src/main/java/org/openrdf/query/algebra/evaluation/impl/SpatioTemporalJoinOptimizer.java	Sun May 12 14:52:16 2013 +0300
     1.3 @@ -0,0 +1,766 @@
     1.4 +/**
     1.5 + * This Source Code Form is subject to the terms of the Mozilla Public
     1.6 + * License, v. 2.0. If a copy of the MPL was not distributed with this
     1.7 + * file, You can obtain one at http://mozilla.org/MPL/2.0/.
     1.8 + * 
     1.9 + * Copyright (C) 2013 Pyravlos Team
    1.10 + * 
    1.11 + * http://www.strabon.di.uoa.gr/
    1.12 + */
    1.13 +package org.openrdf.query.algebra.evaluation.impl;
    1.14 +
    1.15 +import java.util.ArrayList;
    1.16 +import java.util.HashMap;
    1.17 +import java.util.Iterator;
    1.18 +import java.util.LinkedHashSet;
    1.19 +import java.util.List;
    1.20 +import java.util.Map;
    1.21 +import java.util.Set;
    1.22 +
    1.23 +import org.openrdf.query.BindingSet;
    1.24 +import org.openrdf.query.Dataset;
    1.25 +import org.openrdf.query.algebra.Compare;
    1.26 +import org.openrdf.query.algebra.Extension;
    1.27 +import org.openrdf.query.algebra.Filter;
    1.28 +import org.openrdf.query.algebra.FunctionCall;
    1.29 +import org.openrdf.query.algebra.Join;
    1.30 +import org.openrdf.query.algebra.LeftJoin;
    1.31 +import org.openrdf.query.algebra.MathExpr;
    1.32 +import org.openrdf.query.algebra.Or;
    1.33 +import org.openrdf.query.algebra.QueryModelNode;
    1.34 +import org.openrdf.query.algebra.StatementPattern;
    1.35 +import org.openrdf.query.algebra.StatementPattern.Scope;
    1.36 +import org.openrdf.query.algebra.TupleExpr;
    1.37 +import org.openrdf.query.algebra.ValueExpr;
    1.38 +import org.openrdf.query.algebra.Var;
    1.39 +import org.openrdf.query.algebra.evaluation.function.Function;
    1.40 +import org.openrdf.query.algebra.evaluation.function.FunctionRegistry;
    1.41 +import org.openrdf.query.algebra.evaluation.function.spatial.SpatialConstructFunc;
    1.42 +import org.openrdf.query.algebra.evaluation.function.spatial.SpatialMetricFunc;
    1.43 +import org.openrdf.query.algebra.evaluation.function.spatial.SpatialPropertyFunc;
    1.44 +import org.openrdf.query.algebra.evaluation.function.spatial.SpatialRelationshipFunc;
    1.45 +import org.openrdf.query.algebra.evaluation.function.temporal.stsparql.relation.TemporalRelationFunc;
    1.46 +import org.openrdf.query.algebra.helpers.QueryModelVisitorBase;
    1.47 +import org.openrdf.query.algebra.helpers.StatementPatternCollector;
    1.48 +
    1.49 +/**
    1.50 + * A query optimizer that re-orders nested Joins.
    1.51 + * 
    1.52 + * @author Konstantina Bereta <Konstantina.Bereta@di.uoa.gr>
    1.53 + * 
    1.54 + * This is an abstract class of an optimizer that eliminates the production of cross joins in 
    1.55 + * the SQL query. It generalizes the behaviour of the SpatialJoinOptimizer by @author manolee. 
    1.56 + * The SpatialJoinOptimizer and the TemporalJoinOptimizer are now extension of this class.
    1.57 + */
    1.58 +
    1.59 +public abstract class SpatioTemporalJoinOptimizer 
    1.60 +//implements QueryOptimizer //Removed it consciously 
    1.61 +{
    1.62 +
    1.63 +
    1.64 +	//private Set<String> existingVars = new TreeSet<String>();
    1.65 +	/**
    1.66 +	 * Applies generally applicable optimizations: path expressions are sorted
    1.67 +	 * from more to less specific.
    1.68 +	 * 
    1.69 +	 * @param tupleExpr
    1.70 +	 */
    1.71 +	
    1.72 +	public  abstract String getClassName();
    1.73 +
    1.74 +	public void optimize(TupleExpr tupleExpr, Dataset dataset, BindingSet bindings, List<TupleExpr> spatialJoins) {
    1.75 +		tupleExpr.visit(new JoinVisitor(spatialJoins));
    1.76 +	}
    1.77 +
    1.78 +	protected class JoinVisitor extends QueryModelVisitorBase<RuntimeException> {
    1.79 +		
    1.80 +		
    1.81 +		
    1.82 +		public JoinVisitor(List<TupleExpr> spatialJoins) {
    1.83 +			super();
    1.84 +			this.spatialJoins = spatialJoins;
    1.85 +		}
    1.86 +
    1.87 +		
    1.88 +		private List<TupleExpr> spatialJoins;
    1.89 +		//buffer with a var as a second argument
    1.90 +		private boolean problematicBuffer = false;
    1.91 +
    1.92 +		//indicates whether a metric expression contains a spatial function call	
    1.93 +		private boolean containsSpatial = false;
    1.94 +		private boolean optimizableMetricOrProperty = true;
    1.95 +
    1.96 +		private int thematicJoinsSize = 0;
    1.97 +
    1.98 +		//List<SpatialFilterInfo> allSFilters = new ArrayList<SpatialFilterInfo>();
    1.99 +		Map<TupleExpr, List<Var>> allSFilters = new HashMap<TupleExpr, List<Var>>();
   1.100 +
   1.101 +		@Override
   1.102 +		public void meet(Join node) {
   1.103 +
   1.104 +			//XXX NOTE: NOT OPTIMIZING CONTENTS OF OPTIONAL CLAUSE!!!
   1.105 +			//Reason1: Errors occurred in the condition of the LeftJoin containing the optional subgraph
   1.106 +
   1.107 +			//Not as successful as I hoped. Some OPTIONAL clauses may pass
   1.108 +			if(parentIsOptional(node))
   1.109 +			{
   1.110 +				return;
   1.111 +			}
   1.112 +			//			if(node.getParentNode() instanceof LeftJoin)
   1.113 +			//			{
   1.114 +			//				return;
   1.115 +			//			}
   1.116 +
   1.117 +			// Recursively get the join arguments
   1.118 +			List<TupleExpr> joinArgs = getJoinArgs(node, new ArrayList<TupleExpr>());
   1.119 +
   1.120 +			if(joinArgs == null)
   1.121 +			{
   1.122 +				//2nd mechanism to avoid OPTIONAL clauses from passing
   1.123 +				return;
   1.124 +			}
   1.125 +
   1.126 +
   1.127 +			Map<TupleExpr, List<Var>> varsMap = new /*Linked*/HashMap<TupleExpr, List<Var>>();
   1.128 +
   1.129 +			for (TupleExpr tupleExpr : joinArgs) {
   1.130 +				varsMap.put(tupleExpr, getStatementPatternVars(tupleExpr));
   1.131 +
   1.132 +			}
   1.133 +
   1.134 +			//Now I have all the info I need. Just need to structure it efficiently
   1.135 +			int allNodes = varsMap.size() + allSFilters.size();
   1.136 +			thematicJoinsSize = varsMap.size();
   1.137 +			//careful with positions on the diagonal! Do not utilize them!
   1.138 +			int joinsGraph[][] = new int[allNodes][allNodes];
   1.139 +
   1.140 +			//prints for debug
   1.141 +			//			Set<TupleExpr> allExprs = varsMap.keySet();
   1.142 +			//			System.out.println(allExprs.toString());
   1.143 +			//			
   1.144 +			//			Set<TupleExpr> allFilters = allSFilters.keySet();
   1.145 +			//			System.out.println(allFilters.toString());
   1.146 +
   1.147 +			//Thematic part first
   1.148 +			int i = 0;
   1.149 +
   1.150 +			for(List<Var> listHorizontal : varsMap.values())
   1.151 +			{
   1.152 +				int j = 0;
   1.153 +				int k = 0;
   1.154 +
   1.155 +				//Other thematics
   1.156 +				for(List<Var> listVertical : varsMap.values())
   1.157 +				{
   1.158 +					if(i==j)
   1.159 +					{
   1.160 +						j++;
   1.161 +						continue;
   1.162 +					}
   1.163 +
   1.164 +
   1.165 +					joinsGraph[i][j] = sameVar(listHorizontal, listVertical);
   1.166 +
   1.167 +					j++;
   1.168 +				}
   1.169 +
   1.170 +				//Spatials
   1.171 +				for(List<Var> listVertical : allSFilters.values())
   1.172 +				{
   1.173 +
   1.174 +					joinsGraph[i][k+varsMap.size()] = sameVar(listHorizontal, listVertical);
   1.175 +
   1.176 +					k++;
   1.177 +				}
   1.178 +
   1.179 +				i++;
   1.180 +			}
   1.181 +
   1.182 +			//Now for the spatial horizontal nodes
   1.183 +			i = varsMap.size();
   1.184 +			for(List<Var> listHorizontal : allSFilters.values())
   1.185 +			{
   1.186 +				int j = 0;
   1.187 +				int k = 0;
   1.188 +
   1.189 +				//Other thematics
   1.190 +				for(List<Var> listVertical : varsMap.values())
   1.191 +				{
   1.192 +
   1.193 +					joinsGraph[i][j] = sameVar(listHorizontal, listVertical);
   1.194 +
   1.195 +					j++;
   1.196 +				}
   1.197 +
   1.198 +				//Spatials
   1.199 +				for(List<Var> listVertical : allSFilters.values())
   1.200 +				{
   1.201 +					if(i==k+varsMap.size())
   1.202 +					{
   1.203 +						k++;
   1.204 +						continue;
   1.205 +					}
   1.206 +
   1.207 +					joinsGraph[i][k+varsMap.size()] =sameVar(listHorizontal, listVertical);
   1.208 +
   1.209 +					k++;
   1.210 +				}
   1.211 +
   1.212 +				i++;
   1.213 +			}
   1.214 +
   1.215 +			//Checking graph to be sure
   1.216 +			/*
   1.217 +			for(int a = 0; a < allNodes; a++)
   1.218 +			{
   1.219 +				for(int b = 0; b < allNodes; b++)
   1.220 +				{
   1.221 +					System.out.print(joinsGraph[a][b]+" ");
   1.222 +
   1.223 +				}
   1.224 +				System.out.println("");
   1.225 +			}
   1.226 +			*/
   1.227 +
   1.228 +			//Time to construct ordered sequence of joins + filters
   1.229 +			List<TupleExpr> orderedJoinArgs = new ArrayList<TupleExpr>(allNodes);
   1.230 +			//maybe I won't need all the positions -> some spatial joins may not be utilized
   1.231 +			List<Integer> tempList = new ArrayList<Integer>(allNodes);
   1.232 +			List<Integer> pathList = new ArrayList<Integer>();
   1.233 +			List<Integer> finalList = new ArrayList<Integer>();
   1.234 +			Set<Var> varsTillNow = new LinkedHashSet<Var>();
   1.235 +			for(int row = 0 ; row < allNodes ; row++)
   1.236 +			{
   1.237 +				tempList.add(row);
   1.238 +				createOrderedJoins(joinsGraph, row, row, 1, varsTillNow, tempList, pathList, finalList);
   1.239 +				pathList.clear();
   1.240 +				if(finalList.size() == allNodes)
   1.241 +				{
   1.242 +					break;
   1.243 +				}
   1.244 +
   1.245 +			}
   1.246 +
   1.247 +			/*
   1.248 +			System.out.println("*--REWRITTEN TREE--**");
   1.249 +			System.out.println(finalList.toString());
   1.250 +			*/
   1.251 +
   1.252 +			int varsMapSize = varsMap.size();
   1.253 +			for(Integer position : finalList)
   1.254 +			{
   1.255 +				if(position<varsMapSize)//thematic!
   1.256 +				{
   1.257 +					int count = 0;
   1.258 +					Iterator it = varsMap.entrySet().iterator();
   1.259 +
   1.260 +					while (it.hasNext())
   1.261 +					{
   1.262 +						{
   1.263 +							Map.Entry entry = (Map.Entry)it.next();
   1.264 +							if(count == position)
   1.265 +							{
   1.266 +								orderedJoinArgs.add((TupleExpr) entry.getKey());
   1.267 +
   1.268 +								it.remove();
   1.269 +								varsMapSize--;
   1.270 +
   1.271 +								for(int fix = 0 ; fix < finalList.size(); fix++)
   1.272 +								{
   1.273 +									if(finalList.get(fix) > position)
   1.274 +									{
   1.275 +										int reduced = finalList.get(fix) - 1;
   1.276 +										finalList.set(fix, reduced);
   1.277 +
   1.278 +									}
   1.279 +								}
   1.280 +								break;
   1.281 +							}
   1.282 +							count++;
   1.283 +						}
   1.284 +					}
   1.285 +				}
   1.286 +				else//spatial!
   1.287 +				{
   1.288 +					int count = 0;
   1.289 +					Iterator it = allSFilters.entrySet().iterator();
   1.290 +					while (it.hasNext())
   1.291 +					{
   1.292 +						{
   1.293 +							Map.Entry entry = (Map.Entry)it.next();
   1.294 +							if(count == position - varsMapSize)
   1.295 +							{
   1.296 +								//If I keep record of this entry, I can use the info later to avoid duplicate filters
   1.297 +								spatialJoins.add((TupleExpr) entry.getKey());
   1.298 +								//
   1.299 +								orderedJoinArgs.add((TupleExpr) entry.getKey());
   1.300 +								it.remove();
   1.301 +								for(int fix = 0 ; fix < finalList.size(); fix++)
   1.302 +								{
   1.303 +									if(finalList.get(fix) > position)
   1.304 +									{
   1.305 +										int reduced = finalList.get(fix) - 1;
   1.306 +										finalList.set(fix, reduced);
   1.307 +									}
   1.308 +								}
   1.309 +								break;
   1.310 +							}
   1.311 +							count++;
   1.312 +						}
   1.313 +					}
   1.314 +				}
   1.315 +
   1.316 +			}
   1.317 +			//Must take care of the remainders as well!
   1.318 +			Iterator it = varsMap.entrySet().iterator();
   1.319 +			while (it.hasNext())
   1.320 +			{
   1.321 +				Map.Entry entry = (Map.Entry)it.next();
   1.322 +				orderedJoinArgs.add((TupleExpr) entry.getKey());
   1.323 +				it.remove();
   1.324 +			}
   1.325 +
   1.326 +			TupleExpr replacement = orderedJoinArgs.get(0);
   1.327 +			for (int ii = 1; ii < orderedJoinArgs.size(); ii++) {
   1.328 +				replacement = new Join(replacement, orderedJoinArgs.get(ii));
   1.329 +			}
   1.330 +
   1.331 +			// Replace old join hierarchy
   1.332 +			node.replaceWith(replacement);
   1.333 +
   1.334 +		}
   1.335 +
   1.336 +
   1.337 +		public boolean parentIsOptional(QueryModelNode node)
   1.338 +		{
   1.339 +			if(node.getParentNode() == null)
   1.340 +			{
   1.341 +				return false;
   1.342 +			}
   1.343 +			else if(node.getParentNode() instanceof LeftJoin)
   1.344 +			{
   1.345 +				return true;
   1.346 +			}
   1.347 +			else
   1.348 +			{
   1.349 +				return parentIsOptional(node.getParentNode());
   1.350 +			}
   1.351 +		}
   1.352 +
   1.353 +		/**
   1.354 +		 * General Comment: If more than one function exists in the query and can be used to perform the join, no preference is shown 
   1.355 +		 * on which function will actually be used for this purpose. This could cause an issue if ST_Disjoint is the one finally used, 
   1.356 +		 * as the index won't be used for the evaluation in this case. Perhaps I should include some 'priority'
   1.357 +		 */
   1.358 +		@Override
   1.359 +		public void meet(Filter node) {
   1.360 +
   1.361 +			/**
   1.362 +			 * Filter node must not be in OPTIONAL clause!
   1.363 +			 * After all, unneeded check. If an optional exists, the 'Filter' tuple expression
   1.364 +			 * is removed and only the Function Calls remain
   1.365 +			 */
   1.366 +			if(!withinHaving(node))
   1.367 +			{
   1.368 +				//if(!(node.getParentNode() instanceof LeftJoin))
   1.369 +				//{
   1.370 +				//XXX Ignore OR in Filters for now! (perhaps permanently)
   1.371 +				if(!(node.getCondition() instanceof Or))
   1.372 +				{
   1.373 +					if(node.getCondition() instanceof FunctionCall)
   1.374 +					{
   1.375 +						//Only interested in spatial ones
   1.376 +						if(isRelevantSTFunc((FunctionCall) node.getCondition()))
   1.377 +						{
   1.378 +							//Have to retrieve all nested variables and other info
   1.379 +
   1.380 +							//1.Retrieve varNames
   1.381 +							List<Var> varList = getFunctionCallVars((FunctionCall) node.getCondition());
   1.382 +
   1.383 +							//Cannot optimize buffer constructs when their 2nd argument is a 
   1.384 +							//thematic var, because I can't manipulate the order of the 
   1.385 +							//numeric_values table
   1.386 +							if(!problematicBuffer)
   1.387 +							{
   1.388 +								//XXX I cannot process cases involving more than 2 arguments in the spatial join!
   1.389 +								// They transcend the theta join level!
   1.390 +								//							if(varList.size()<3)
   1.391 +
   1.392 +								//if the arguments are not 2, I am essentially doing a selection!
   1.393 +								//No reason to push into optimizer then
   1.394 +								if(varList.size()==2)
   1.395 +								{
   1.396 +									//Add all important info about this spatial relationship to the appropriate structure
   1.397 +									//allSFilters.add(new SpatialFilterInfo(varList, (FunctionCall) node.getCondition()));
   1.398 +									Filter toEnter = node.clone();
   1.399 +
   1.400 +									/**
   1.401 +									 * VERY CAREFUL HERE! 
   1.402 +									 * Reason I did this: If not, I would carry a copy of the whole expression for
   1.403 +									 * every extra filter of my query!
   1.404 +									 * -DUMMY-!!!
   1.405 +									 */
   1.406 +
   1.407 +									StatementPattern t = new StatementPattern();
   1.408 +									String className = getClassName();
   1.409 +									if(className.equals("org.openrdf.query.algebra.evaluation.impl.SpatialJoinOptimizer"))
   1.410 +									{
   1.411 +										t.setSubjectVar(new Var("-dummy-"));
   1.412 +										t.setPredicateVar(new Var("-dummy-"));
   1.413 +										t.setObjectVar(new Var("-dummy-"));
   1.414 +									}
   1.415 +									else //TemporalJoinOptimizer case
   1.416 +									{
   1.417 +										t.setSubjectVar(new Var("-dummy-temporal"));
   1.418 +										t.setPredicateVar(new Var("-dummy-temporal"));
   1.419 +										t.setObjectVar(new Var("-dummy-temporal"));
   1.420 +									}
   1.421 +									
   1.422 +									t.setScope(Scope.DEFAULT_CONTEXTS);
   1.423 +									toEnter.setArg(t);
   1.424 +
   1.425 +									if(!allSFilters.containsKey(toEnter))
   1.426 +									{
   1.427 +										allSFilters.put(toEnter,varList);
   1.428 +									}
   1.429 +								}
   1.430 +								problematicBuffer = false;
   1.431 +							}
   1.432 +						}
   1.433 +					}
   1.434 +					//Metrics
   1.435 +					//I have a similar problematic case with the one occurring in Buffer! 
   1.436 +					//Cannot manipulate the join order when I am dealing with numerics!
   1.437 +					//Therefore, I cannot use a numeric field (a numeric var) to alter the join sequence
   1.438 +					else if(node.getCondition() instanceof Compare)
   1.439 +					{
   1.440 +						containsSpatial = false;
   1.441 +						List<Var> allVars = new ArrayList<Var>(getVarsInMetricOrProperty(node.getCondition()));
   1.442 +						if(containsSpatial&&optimizableMetricOrProperty)
   1.443 +						{
   1.444 +							//if the arguments are not 2, I am essentially doing a selection!
   1.445 +							//No reason to push into optimizer then
   1.446 +							if(allVars.size()==2)
   1.447 +								//if(allVars.size()<3)
   1.448 +							{
   1.449 +								//Add all important info about this spatial relationship to the appropriate structure
   1.450 +								//allSFilters.add(new SpatialFilterInfo(varList, (FunctionCall) node.getCondition()));
   1.451 +								Filter toEnter = node.clone();
   1.452 +
   1.453 +								StatementPattern t = new StatementPattern();
   1.454 +								t.setSubjectVar(new Var("-dummy-"));
   1.455 +								t.setPredicateVar(new Var("-dummy-"));
   1.456 +								t.setObjectVar(new Var("-dummy-"));
   1.457 +								t.setScope(Scope.DEFAULT_CONTEXTS);
   1.458 +								toEnter.setArg(t);
   1.459 +
   1.460 +								if(!allSFilters.containsKey(toEnter))
   1.461 +								{
   1.462 +									allSFilters.put(toEnter,allVars);
   1.463 +								}
   1.464 +							}
   1.465 +							containsSpatial = false;
   1.466 +						}
   1.467 +						optimizableMetricOrProperty = true;
   1.468 +					}
   1.469 +
   1.470 +				}
   1.471 +				//}
   1.472 +			}
   1.473 +
   1.474 +			//Last thing to do is ensuring the entire tree is traversed
   1.475 +			node.visitChildren(this);
   1.476 +
   1.477 +		}
   1.478 +
   1.479 +
   1.480 +		/**
   1.481 +		 * Helper Functions
   1.482 +		 */
   1.483 +
   1.484 +		/**
   1.485 +		 * Used to find out whether the Filter expr we are currently visiting is located inside
   1.486 +		 * a HAVING clause.
   1.487 +		 * 
   1.488 +		 * From what I have seen so far, it seems that if this is the case, its arg (or one of the following FILTER args in 
   1.489 +		 * the case of disjunction/conjunction) will be an Extension expr followed by a GROUP expr
   1.490 +		 */
   1.491 +		private boolean withinHaving(Filter expr)
   1.492 +		{
   1.493 +			if(expr.getArg() instanceof Extension)
   1.494 +			{
   1.495 +				return true;
   1.496 +			}
   1.497 +			else if(expr.getArg() instanceof Filter)
   1.498 +			{
   1.499 +				return withinHaving((Filter) expr.getArg());
   1.500 +			}
   1.501 +			else
   1.502 +			{
   1.503 +				return false;
   1.504 +			}
   1.505 +		}
   1.506 +
   1.507 +		private <L extends List<TupleExpr>> L getJoinArgs(TupleExpr tupleExpr, L joinArgs) {
   1.508 +			if (tupleExpr instanceof Join) {
   1.509 +				Join join = (Join)tupleExpr;
   1.510 +				if(getJoinArgs(join.getLeftArg(), joinArgs) == null)
   1.511 +					return null;
   1.512 +				if(getJoinArgs(join.getRightArg(), joinArgs) == null)
   1.513 +					return null;
   1.514 +			}
   1.515 +			else if(tupleExpr instanceof LeftJoin) 
   1.516 +			{
   1.517 +				//Trying to avoid OPTIONAL clauses from passing
   1.518 +				return null;
   1.519 +			}
   1.520 +			else 
   1.521 +			{
   1.522 +				joinArgs.add(tupleExpr);
   1.523 +			}
   1.524 +
   1.525 +			return joinArgs;
   1.526 +		}
   1.527 +
   1.528 +		private List<Var> getStatementPatternVars(TupleExpr tupleExpr) {
   1.529 +			List<StatementPattern> stPatterns = StatementPatternCollector.process(tupleExpr);
   1.530 +			List<Var> varList = new ArrayList<Var>(stPatterns.size() * 4);
   1.531 +			for (StatementPattern sp : stPatterns) {
   1.532 +				sp.getVars(varList);
   1.533 +			}
   1.534 +			return varList;
   1.535 +		}
   1.536 +
   1.537 +		/**
   1.538 +		 * spatialContent: Used to declare that this expression does include some spatial 
   1.539 +		 * content and an attempt should be made to use it in the joins' optimization process
   1.540 +		 */
   1.541 +		private Set<Var> getVarsInMetricOrProperty(ValueExpr expr)
   1.542 +		{
   1.543 +			Set<Var> allVars = new LinkedHashSet<Var>();
   1.544 +
   1.545 +			if(expr instanceof Compare)
   1.546 +			{
   1.547 +				allVars.addAll(getVarsInMetricOrProperty(((Compare) expr).getLeftArg()));
   1.548 +				allVars.addAll(getVarsInMetricOrProperty(((Compare) expr).getRightArg()));
   1.549 +			}
   1.550 +			else if(expr instanceof MathExpr)
   1.551 +			{
   1.552 +				allVars.addAll(getVarsInMetricOrProperty(((MathExpr) expr).getLeftArg()));
   1.553 +				allVars.addAll(getVarsInMetricOrProperty(((MathExpr) expr).getRightArg()));
   1.554 +			}
   1.555 +			else if(expr instanceof FunctionCall )
   1.556 +			{
   1.557 +				if(isRelevantSTFunc((FunctionCall) expr))
   1.558 +				{
   1.559 +					/**
   1.560 +					 * There is a point in continuing the search recursively ONLY 
   1.561 +					 * if I reach this case. Otherwise, the function call
   1.562 +					 * may not refer to a spatial function
   1.563 +					 */
   1.564 +					this.containsSpatial = true;
   1.565 +					allVars.addAll(getFunctionCallVars((FunctionCall) expr));
   1.566 +
   1.567 +				}
   1.568 +			}
   1.569 +			else if(expr instanceof Var)
   1.570 +			{
   1.571 +				if(!(expr.getParentNode() instanceof FunctionCall))
   1.572 +				{
   1.573 +					//Cannot manipulate the join order when I am dealing with numerics!
   1.574 +					//Therefore, I cannot use a numeric field (a numeric var) to alter the join sequence
   1.575 +					this.optimizableMetricOrProperty = false;
   1.576 +				}
   1.577 +				if(!allVars.contains(expr))
   1.578 +				{
   1.579 +					allVars.add((Var) expr);
   1.580 +				}
   1.581 +			}
   1.582 +
   1.583 +			return allVars;
   1.584 +		}
   1.585 +
   1.586 +		
   1.587 +
   1.588 +		private List<Var> getFunctionCallVars(FunctionCall functionCall) {
   1.589 +			List<Var> varList = new ArrayList<Var>();
   1.590 +			int argList = 0;
   1.591 +			for(ValueExpr expr : functionCall.getArgs())
   1.592 +			{
   1.593 +				argList++;
   1.594 +				if(expr instanceof Var)
   1.595 +				{
   1.596 +					//					if(!existingVars.contains(((Var) expr).getName()))
   1.597 +					//					{
   1.598 +					//						existingVars.add(((Var) expr).getName());
   1.599 +					//					}
   1.600 +
   1.601 +					if(!varList.contains(expr))
   1.602 +					{
   1.603 +						//Was using this code when I tried to incorporate the Buffer case buffer(?Spatial,?thematic)
   1.604 +						if(argList == 2 && functionCall.getURI().equals("http://strdf.di.uoa.gr/ontology#buffer"))
   1.605 +						{
   1.606 +							problematicBuffer = true;
   1.607 +						}
   1.608 +						varList.add((Var) expr);
   1.609 +					}
   1.610 +
   1.611 +				}
   1.612 +				else if(expr instanceof FunctionCall)
   1.613 +				{
   1.614 +					varList.addAll(getFunctionCallVars((FunctionCall) expr));
   1.615 +				}
   1.616 +				//TODO Should I add any additional cases? I don't think so
   1.617 +				else
   1.618 +				{
   1.619 +					continue;
   1.620 +				}
   1.621 +			}
   1.622 +			return varList;
   1.623 +		}
   1.624 +
   1.625 +		/**
   1.626 +		 * Both lists belong to either a thematic node (St.Pattern) or a spatial node (Filter)
   1.627 +		 * Comparing the vars with each other to discover links of the query graph
   1.628 +		 * @param list1 
   1.629 +		 * @param list2
   1.630 +		 * @return
   1.631 +		 */
   1.632 +		private int sameVar(List<Var> list1, List<Var> list2)
   1.633 +		{
   1.634 +			for(Var var : list1)
   1.635 +			{
   1.636 +				if(list2.contains(var))
   1.637 +				{
   1.638 +					return 1;
   1.639 +				}
   1.640 +			}
   1.641 +
   1.642 +			return 0;
   1.643 +		}
   1.644 +
   1.645 +
   1.646 +
   1.647 +
   1.648 +
   1.649 +		//Input: a single line of the table
   1.650 +		//NOTE: NO LOOPS! CAREFUL!!
   1.651 +		private boolean createOrderedJoins(int table[][], int lineToScan,int columnToSkip, 
   1.652 +				int pathLen, Set<Var> varsTillNow, List<Integer> tempList, List<Integer> pathList, List<Integer> finalList)
   1.653 +		{
   1.654 +			boolean success = false;
   1.655 +			int dims = table.length;
   1.656 +
   1.657 +			int j;
   1.658 +
   1.659 +			//dims: all arguments
   1.660 +			for(j = 0; j < dims; j++)
   1.661 +			{
   1.662 +				if(j == columnToSkip)
   1.663 +				{
   1.664 +					continue;
   1.665 +				}
   1.666 +
   1.667 +				//A connection exists!
   1.668 +				if(table[lineToScan][j]>0)
   1.669 +				{
   1.670 +					//Don't want my graph to have circles!!!
   1.671 +					if(!tempList.contains(j)&&!pathList.contains(j))
   1.672 +					{
   1.673 +						if(j >= thematicJoinsSize) //aka if(allSFilters.size() > 0)
   1.674 +						{
   1.675 +							List<Var> thisFilterVars = null;
   1.676 +							int count = 0;
   1.677 +							for(List<Var> vars : allSFilters.values())
   1.678 +							{
   1.679 +								if(count == j - thematicJoinsSize)
   1.680 +								{
   1.681 +									thisFilterVars = vars;
   1.682 +									break;
   1.683 +								}
   1.684 +								count++;
   1.685 +							}
   1.686 +							if(!varsTillNow.isEmpty())
   1.687 +							{
   1.688 +								if(varsTillNow.containsAll(thisFilterVars))
   1.689 +								{
   1.690 +									continue;
   1.691 +								}
   1.692 +							}
   1.693 +
   1.694 +							//varsTillNow.add(thisFilterVars.get(1));
   1.695 +							varsTillNow.addAll(thisFilterVars);
   1.696 +
   1.697 +						}
   1.698 +
   1.699 +						tempList.add((Integer)j);
   1.700 +						pathLen++;
   1.701 +						if(pathLen == dims)
   1.702 +						{
   1.703 +							//End of recursion
   1.704 +							pathList.addAll(tempList);
   1.705 +							tempList.clear();
   1.706 +							finalList.clear();
   1.707 +							finalList.addAll(pathList);
   1.708 +
   1.709 +							return true;
   1.710 +						}
   1.711 +
   1.712 +						//Recurse
   1.713 +						success = createOrderedJoins(table, j, lineToScan, pathLen, varsTillNow, tempList, pathList, finalList);
   1.714 +
   1.715 +						//Success = true => recursion ended with pathLen = maxLen
   1.716 +						if(success)
   1.717 +						{
   1.718 +							return true;
   1.719 +						}
   1.720 +						else
   1.721 +						{	
   1.722 +							//end of a path originating from this node was found -> find an additional path (if exists)
   1.723 +							continue;
   1.724 +						}
   1.725 +					}
   1.726 +				}
   1.727 +			}
   1.728 +			//To reach this place means the end of a path was found 
   1.729 +			pathList.addAll(tempList);
   1.730 +			tempList.clear();
   1.731 +			if(pathList.size() > finalList.size())
   1.732 +			{
   1.733 +				finalList.clear();
   1.734 +				finalList.addAll(pathList);
   1.735 +				if(finalList.size() == dims)
   1.736 +				{
   1.737 +					return true;
   1.738 +				}
   1.739 +			}
   1.740 +			return false;			
   1.741 +		}
   1.742 +
   1.743 +	}
   1.744 +
   1.745 +	protected abstract boolean isRelevantSTFunc(FunctionCall functionCall);
   1.746 +	/*{
   1.747 +		Function function = FunctionRegistry.getInstance().get(functionCall.getURI());
   1.748 +		if(function instanceof SpatialConstructFunc)
   1.749 +		{
   1.750 +			//TODO may have to comment this part again
   1.751 +			//uncommented because I use this function in the case of metrics
   1.752 +			return true;
   1.753 +		}
   1.754 +		else if(function instanceof SpatialRelationshipFunc)
   1.755 +		{
   1.756 +			return true;
   1.757 +		}
   1.758 +		else if(function instanceof SpatialPropertyFunc) //1 argument
   1.759 +		{
   1.760 +			return true;
   1.761 +		}
   1.762 +		else if(function instanceof SpatialMetricFunc) //Arguments # depends on the function selected
   1.763 +		{
   1.764 +			return true;
   1.765 +		}
   1.766 +		return false;
   1.767 +	}*/
   1.768 +	
   1.769 +}