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https://issues.apache.org/jira/browse/OAK-4887?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16253245#comment-16253245
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Thomas Mueller commented on OAK-4887:
-------------------------------------
Actually I found Lucene returns all plans. It is true that right now, the order
doesn't affect the cost. The following patch (not test yet) should resolve this
issue:
{noformat}
--- src/main/java/org/apache/jackrabbit/oak/query/QueryImpl.java
(revision 1814727)
+++ src/main/java/org/apache/jackrabbit/oak/query/QueryImpl.java
(working copy)
@@ -1004,8 +1004,12 @@
if (p.getSupportsPathRestriction()) {
entryCount = scaleEntryCount(rootState, filter,
entryCount);
}
-
- entryCount = Math.min(maxEntryCount, entryCount);
+ if (sortOrder == null || p.getSortOrder() != null) {
+ // if the query is unordered, or
+ // if the query contains "order by" and the index can
sort on that,
+ // then we don't need to read all entries from the
index
+ entryCount = Math.min(maxEntryCount, entryCount);
+ }
double c = p.getCostPerExecution() + entryCount *
p.getCostPerEntry();
if (LOG.isDebugEnabled()) {
{noformat}
> Query cost estimation: ordering by an unindexed property not reflected
> ----------------------------------------------------------------------
>
> Key: OAK-4887
> URL: https://issues.apache.org/jira/browse/OAK-4887
> Project: Jackrabbit Oak
> Issue Type: Improvement
> Components: query
> Affects Versions: 1.4.2
> Reporter: Alexander Klimetschek
> Assignee: Thomas Mueller
> Fix For: 1.8
>
>
> A query that orders by an unindexed property seems to have no effect on the
> cost estimation, compared to the same query without the order by, although it
> has a big impact on the execution performance for larger results/indexes.
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