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authorBrian S. O'Neill <bronee@gmail.com>2006-09-06 01:34:09 +0000
committerBrian S. O'Neill <bronee@gmail.com>2006-09-06 01:34:09 +0000
commit7cd5f147ea63fbead8d53927d52e144ff0e2e1a5 (patch)
tree9a5fa603ab07a6d5919e1dc9dbb572515e605cf2 /src/main/java/com
parent0c7b8f94b8a1f61db66f32561483a7f192486183 (diff)
Resolve orderings with unspecified direction.
Diffstat (limited to 'src/main/java/com')
-rw-r--r--src/main/java/com/amazon/carbonado/qe/UnionQueryAnalyzer.java75
1 files changed, 60 insertions, 15 deletions
diff --git a/src/main/java/com/amazon/carbonado/qe/UnionQueryAnalyzer.java b/src/main/java/com/amazon/carbonado/qe/UnionQueryAnalyzer.java
index 2906c8a..2f467eb 100644
--- a/src/main/java/com/amazon/carbonado/qe/UnionQueryAnalyzer.java
+++ b/src/main/java/com/amazon/carbonado/qe/UnionQueryAnalyzer.java
@@ -84,9 +84,34 @@ public class UnionQueryAnalyzer<S extends Storable> {
return new Result(subResults);
}
- // FIXME: If any orderings have an unspecified direction, switch to
- // ASCENDING or DESCENDING, depending on which is more popular. Then
- // build new sub-results.
+ boolean canMutateOrderings = false;
+
+ // If any orderings have an unspecified direction, switch to ASCENDING
+ // or DESCENDING, depending on which is more popular. Then build new
+ // sub-results.
+ for (int pos = 0; pos < orderings.size(); pos++) {
+ OrderedProperty<S> ordering = orderings.get(pos);
+ if (ordering.getDirection() != Direction.UNSPECIFIED) {
+ continue;
+ }
+
+ // Find out which direction is most popular for this property.
+ Tally tally = new Tally(ordering.getChainedProperty());
+ for (IndexedQueryAnalyzer<S>.Result result : subResults) {
+ tally.increment(findHandledDirection(result, ordering));
+ }
+
+ if (!canMutateOrderings) {
+ orderings = new ArrayList<OrderedProperty<S>>(orderings);
+ canMutateOrderings = true;
+ }
+
+ orderings.set(pos, ordering.direction(tally.getBestDirection()));
+
+ // Re-calc with specified direction. Only do one property at a time
+ // since one simple change might alter the query plan.
+ subResults = splitIntoSubResults(filter, orderings);
+ }
// Gather all the keys available. As ordering properties touch key
// properties, they are removed from all key sets. When a key set size
@@ -119,7 +144,10 @@ public class UnionQueryAnalyzer<S extends Storable> {
}
// Prepare to augment orderings to ensure a total ordering.
- orderings = new ArrayList<OrderedProperty<S>>(orderings);
+ if (!canMutateOrderings) {
+ orderings = new ArrayList<OrderedProperty<S>>(orderings);
+ canMutateOrderings = true;
+ }
// Keep looping until total ordering achieved.
while (true) {
@@ -143,14 +171,7 @@ public class UnionQueryAnalyzer<S extends Storable> {
}
}
- // Find the best tally.
- Tally best = null;
- for (Tally tally : superKey.values()) {
- if (best == null || tally.compareTo(best) < 0) {
- best = tally;
- }
- }
-
+ Tally best = bestTally(superKey.values());
ChainedProperty<S> bestProperty = best.getProperty();
// Now augment the orderings and create new sub-results.
@@ -217,6 +238,30 @@ public class UnionQueryAnalyzer<S extends Storable> {
return result;
}
+ private Tally bestTally(Iterable<Tally> tallies) {
+ Tally best = null;
+ for (Tally tally : tallies) {
+ if (best == null || tally.compareTo(best) < 0) {
+ best = tally;
+ }
+ }
+ return best;
+ }
+
+ private Direction findHandledDirection(IndexedQueryAnalyzer<S>.Result result,
+ OrderedProperty unspecified)
+ {
+ ChainedProperty<S> chained = unspecified.getChainedProperty();
+ OrderingScore<S> score = result.getCompositeScore().getOrderingScore();
+ List<OrderedProperty<S>> handled = score.getHandledOrderings();
+ for (OrderedProperty<S> property : handled) {
+ if (chained.equals(property)) {
+ return property.getDirection();
+ }
+ }
+ return Direction.UNSPECIFIED;
+ }
+
private List<IndexedQueryAnalyzer<S>.Result>
splitIntoSubResults(Filter<S> filter, List<OrderedProperty<S>> orderings)
{
@@ -316,7 +361,7 @@ public class UnionQueryAnalyzer<S extends Storable> {
}
/**
- * Used to track which properties should be augmented to create a total ordering.
+ * Used to track which property direction is most popular.
*/
private class Tally implements Comparable<Tally> {
private final ChainedProperty<S> mProperty;
@@ -353,14 +398,14 @@ public class UnionQueryAnalyzer<S extends Storable> {
* Only returns ASCENDING or DESCENDING.
*/
Direction getBestDirection() {
- if (mAscendingCount > mDescendingCount) {
+ if (mAscendingCount >= mDescendingCount) {
return Direction.ASCENDING;
}
return Direction.DESCENDING;
}
int getBestCount() {
- if (mAscendingCount > mDescendingCount) {
+ if (mAscendingCount >= mDescendingCount) {
return mAscendingCount;
}
return mDescendingCount;