From 0c7b8f94b8a1f61db66f32561483a7f192486183 Mon Sep 17 00:00:00 2001 From: "Brian S. O'Neill" Date: Tue, 5 Sep 2006 06:26:30 +0000 Subject: More progress on total ordering support. --- .../amazon/carbonado/qe/UnionQueryAnalyzer.java | 235 ++++++++++++++++----- 1 file changed, 184 insertions(+), 51 deletions(-) (limited to 'src/main/java/com/amazon/carbonado/qe') diff --git a/src/main/java/com/amazon/carbonado/qe/UnionQueryAnalyzer.java b/src/main/java/com/amazon/carbonado/qe/UnionQueryAnalyzer.java index 81779b0..2906c8a 100644 --- a/src/main/java/com/amazon/carbonado/qe/UnionQueryAnalyzer.java +++ b/src/main/java/com/amazon/carbonado/qe/UnionQueryAnalyzer.java @@ -20,8 +20,10 @@ package com.amazon.carbonado.qe; import java.util.ArrayList; import java.util.Collections; +import java.util.LinkedHashMap; import java.util.HashSet; import java.util.List; +import java.util.Map; import java.util.Set; import com.amazon.carbonado.Storable; @@ -33,6 +35,7 @@ import com.amazon.carbonado.filter.PropertyFilter; import com.amazon.carbonado.filter.Visitor; import com.amazon.carbonado.info.ChainedProperty; +import com.amazon.carbonado.info.Direction; import com.amazon.carbonado.info.OrderedProperty; import com.amazon.carbonado.info.StorableIndex; import com.amazon.carbonado.info.StorableInfo; @@ -76,75 +79,142 @@ public class UnionQueryAnalyzer { List.Result> subResults = splitIntoSubResults(filter, orderings); - if (subResults.size() > 1 && !isTotalOrdering(orderings)) { - // If more than one, then a total ordering is required. + if (subResults.size() < 1) { + // Total ordering not required. + return new Result(subResults); + } - // The approach is to choose an index, and then augment ordering - // properties arranged in accordance with the index. The index is - // chosen from the sub-result that has the worst filtering - // score. Why? The other sub-results are likely to filter and sort - // fewer records than worst one. Imposing a total ordering may - // require a post-sort on the high scoring sub-results which might - // not see many records. Put another way, the worst scoring - // sub-result is already the bottleneck, so avoid making it work - // any harder. + // FIXME: If any orderings have an unspecified direction, switch to + // ASCENDING or DESCENDING, depending on which is more popular. Then + // build new sub-results. - // The properties to augment with are the contents of a primary or - // alternate key. Select the key which most closely matches the - // user's desired ordering. Default to primary key if none. + // Gather all the keys available. As ordering properties touch key + // properties, they are removed from all key sets. When a key set size + // reaches zero, total ordering has been achieved. + List>> keys = getKeys(); - // 1. Results guaranteed to produce one result already have a total ordering. + // Check if current ordering is total. + for (OrderedProperty ordering : orderings) { + ChainedProperty property = ordering.getChainedProperty(); + if (pruneKeys(keys, property)) { + // Found a key which is fully covered, indicating total ordering. + return new Result(subResults); + } + } - // FIXME + // Create a super key which contains all the properties required for + // total ordering. The goal here is to append these properties to the + // ordering in a fashion that takes advantage of each index's natural + // ordering. This in turn should cause any sort operation to operate + // over smaller groups. Smaller groups means smaller sort buffers. + // Smaller sort buffers makes a merge sort happy. + + // Super key could be stored simply in a set, but a map makes it + // convenient for tracking tallies. + Map, Tally> superKey = new LinkedHashMap, Tally>(); + for (Set> key : keys) { + for (ChainedProperty property : key) { + superKey.put(property, new Tally(property)); + } } - return new Result(subResults); - } + // Prepare to augment orderings to ensure a total ordering. + orderings = new ArrayList>(orderings); + + // Keep looping until total ordering achieved. + while (true) { + // For each ordering score, find the next free property. If + // property is in the super key increment a tally associated with + // property direction. Choose the property with the best tally and + // augment the orderings with it and create new sub-results. + // Remove the property from the super key and the key set. If any + // key is now fully covered, a total ordering has been achieved. + + for (IndexedQueryAnalyzer.Result result : subResults) { + OrderingScore score = result.getCompositeScore().getOrderingScore(); + List> free = score.getFreeOrderings(); + if (free.size() > 0) { + OrderedProperty prop = free.get(0); + ChainedProperty chainedProp = prop.getChainedProperty(); + Tally tally = superKey.get(chainedProp); + if (tally != null) { + tally.increment(prop.getDirection()); + } + } + } - private boolean isTotalOrdering(List> orderings) { - // First strip out directions, since they are not relevant here. - List> properties = new ArrayList>(orderings.size()); - for (OrderedProperty ordering : orderings) { - properties.add(ordering.getChainedProperty()); - } + // Find the best tally. + Tally best = null; + for (Tally tally : superKey.values()) { + if (best == null || tally.compareTo(best) < 0) { + best = tally; + } + } - StorableInfo info = StorableIntrospector.examine(mIndexAnalyzer.getStorableType()); + ChainedProperty bestProperty = best.getProperty(); - if (containsKey(properties, info.getPrimaryKey())) { - return true; - } + // Now augment the orderings and create new sub-results. + orderings.add(OrderedProperty.get(bestProperty, best.getBestDirection())); + subResults = splitIntoSubResults(filter, orderings); - for (StorableKey altKey : info.getAlternateKeys()) { - if (containsKey(properties, altKey)) { - return true; + // Remove property from super key and key set... + superKey.remove(bestProperty); + if (superKey.size() == 0) { + break; + } + if (pruneKeys(keys, bestProperty)) { + break; + } + + // Clear the tallies for the next run. + for (Tally tally : superKey.values()) { + tally.clear(); } } - return false; + return new Result(subResults); } - private boolean containsKey(List> properties, StorableKey key) { - Set> orderedKeyProps = key.getProperties(); + /** + * Returns a list of all primary and alternate keys, stripped of ordering. + */ + private List>> getKeys() { + StorableInfo info = StorableIntrospector.examine(mIndexAnalyzer.getStorableType()); + List>> keys = new ArrayList>>(); + + keys.add(stripOrdering(info.getPrimaryKey().getProperties())); - if (properties.size() < orderedKeyProps.size()) { - // Short-circuit. - return false; + for (StorableKey altKey : info.getAlternateKeys()) { + keys.add(stripOrdering(altKey.getProperties())); } - // Strip out directions, since they are not relevant here. - Set> keyProps = new HashSet>(orderedKeyProps.size()); - for (OrderedProperty ordering : orderedKeyProps) { - keyProps.add(ordering.getChainedProperty()); + return keys; + } + + private Set> stripOrdering(Set> orderedProps) { + Set> props = new HashSet>(orderedProps.size()); + for (OrderedProperty ordering : orderedProps) { + props.add(ordering.getChainedProperty()); } + return props; + } - for (ChainedProperty property : properties) { - keyProps.remove(property); - if (keyProps.size() == 0) { - break; + /** + * Removes the given property from all keys, returning true if any key has + * zero properties as a result. + */ + private boolean pruneKeys(List>> keys, ChainedProperty property) { + boolean result = false; + + for (Set> key : keys) { + key.remove(property); + if (key.size() == 0) { + result = true; + continue; } } - return keyProps.size() == 0; + return result; } private List.Result> @@ -243,14 +313,77 @@ public class UnionQueryAnalyzer { public List.Result> getSubResults() { return mSubResults; } + } + + /** + * Used to track which properties should be augmented to create a total ordering. + */ + private class Tally implements Comparable { + private final ChainedProperty mProperty; + + private int mAscendingCount; + private int mDescendingCount; + + Tally(ChainedProperty property) { + mProperty = property; + } + + ChainedProperty getProperty() { + return mProperty; + } + + void increment(Direction dir) { + switch (dir) { + case UNSPECIFIED: + mAscendingCount++; + mDescendingCount++; + break; + + case ASCENDING: + mAscendingCount++; + break; + + case DESCENDING: + mDescendingCount++; + break; + } + } /** - * If more than one sub-result, then a total ordering is - * imposed. Otherwise, null is returned. + * Only returns ASCENDING or DESCENDING. */ - public List> getTotalOrdering() { - // FIXME - return null; + Direction getBestDirection() { + if (mAscendingCount > mDescendingCount) { + return Direction.ASCENDING; + } + return Direction.DESCENDING; + } + + int getBestCount() { + if (mAscendingCount > mDescendingCount) { + return mAscendingCount; + } + return mDescendingCount; + } + + void clear() { + mAscendingCount = 0; + mDescendingCount = 0; + } + + /** + * Returns -1 if this tally is better. + */ + public int compareTo(Tally other) { + int thisBest = getBestCount(); + int otherBest = other.getBestCount(); + if (thisBest < otherBest) { + return -1; + } + if (thisBest > otherBest) { + return 1; + } + return 0; } } -- cgit v1.2.3