[jira] [Commented] (GEODE-333) Indexes sometimes are no longer used after a rebalance

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    [ https://issues.apache.org/jira/browse/GEODE-333?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14791223#comment-14791223 ] 

ASF subversion and git services commented on GEODE-333:
-------------------------------------------------------

Commit 2c99b9e6dbbae1f7fa169f43b3708328cb4d0ebf in incubator-geode's branch refs/heads/develop from [~barry.oglesby]
[ https://git-wip-us.apache.org/repos/asf?p=incubator-geode.git;h=2c99b9e ]

GEODE-333: Indexes sometimes are no longer used after a rebalance

Incorporated changes from GemFire


> Indexes sometimes are no longer used after a rebalance
> ------------------------------------------------------
>
>                 Key: GEODE-333
>                 URL: https://issues.apache.org/jira/browse/GEODE-333
>             Project: Geode
>          Issue Type: Bug
>          Components: querying
>            Reporter: Barry Oglesby
>            Assignee: Barry Oglesby
>
> My test defines the following index:
> {noformat}
> <index name="customer_displayName" from-clause="/customer" expression="displayName"/>
> {noformat}
> And the following query:
> {noformat}
> select * from /customer where displayName='some-display-name'
> {noformat}
> Query execution uses the index during execution before a rebalance takes place. In some cases (see below) the index is no longer used after a rebalance.
> When the issue occurs, the {{IndexManager getBestMatchIndex}} method returns no indexes for the {{index_iter1.displayName}} expression even though there is one.
> Here is some debugging that shows null being returned:
> {noformat}
> IndexManager getBestMatchIndex FUNCTIONAL index for index_iter1.displayName found null from [Index [ Name=customer_displayName Type =FUNCTIONAL IdxExp=displayName From=/customer Proj=*]imports : null]
> {noformat}
> This is due to this clause in the getBestMatchIndex method:
> {noformat}
> index = prIndex.getBucketIndex();
> if (index == null) {
> 	continue;
> }
> {noformat}
> The {{getBucketIndex}} method asks the first value in the {{bucketIndexes}} Map for its indexes. If the first value is empty, null is returned.
> In this case, the first value is empty because the index at that bucket ({{\_B__customer_47}}) was removed during the rebalance.
> Here is some debugging that shows it. The first value in the {{bucketIndexes}} Map is for {{\_B__customer_47}}. This bucket is removed during the rebalance, so its List of indexes initially contains an index, then it doesn't. This causes {{getBucketIndex}} to return null and causes {{getBestMatchIndex}} to short-circuit.
> {noformat}
> PartitionedIndex Bucket Indexes size=113; first entry=BucketRegion[path='/__PR/_B__customer_47;serial=149;primary=false;indexUpdater=null]=[Index [ Name=customer_displayName Type =FUNCTIONAL IdxExp=displayName From=/customer Proj=*]]
> PartitionedIndex removeFromBucketIndexes /__PR/_B__customer_47->Index [ Name=customer_displayName Type =FUNCTIONAL IdxExp=displayName From=/customer Proj=*]
> PartitionedIndex Bucket Indexes size=113; first entry=BucketRegion[path='/__PR/_B__customer_47;serial=149;primary=false;indexUpdater=null]=[]
> {noformat}
> A potential fix is to remove any entries from the {{bucketIndexes}} Map that are empty in the {{removeFromBucketIndexes}} method like:
> {noformat}
> public void removeFromBucketIndexes(Region r, Index index)
> {
> 	synchronized(this.bucketIndexes) {
> 		List<Index> indexes = this.bucketIndexes.get(r);
> 		if(indexes != null) {
> 			indexes.remove(index);
> 			if (indexes.isEmpty()) {
> 				this.bucketIndexes.remove(r);
> 			}
> 		}
> 	}
> }
> {noformat}
> Here is some debugging that shows the first value in the {{bucketIndexes}} Map is initially for {{\_B\_\_customer_68}}. Then {{\_B\_\_customer_68}} is removed and {{\_B\_\_customer\_46}} takes over as first in the value in the {{bucketIndexes}} Map.
> {noformat}
> PartitionedIndex Bucket Indexes size=113; first entry=BucketRegion[path='/__PR/_B__customer_68;serial=209;primary=true;indexUpdater=null]=[Index [ Name=customer_displayName Type =FUNCTIONAL IdxExp=displayName From=/customer Proj=*]]
> PartitionedIndex removeFromBucketIndexes removing entry for /__PR/_B__customer_68
> PartitionedIndex Bucket Indexes size=95; first entry=BucketRegion[path='/__PR/_B__customer_46;serial=229;primary=false;indexUpdater=null]=[Index [ Name=customer_displayName Type =FUNCTIONAL IdxExp=displayName From=/customer Proj=*]]
> {noformat}



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