You are viewing a plain text version of this content. The canonical link for it is here.
Posted to commits@lucene.apache.org by va...@apache.org on 2017/05/10 15:57:46 UTC
lucene-solr:branch_6_6: SOLR-9527: Improve distribution of replicas
when restoring a collection
Repository: lucene-solr
Updated Branches:
refs/heads/branch_6_6 7d164a1db -> 201e2125f
SOLR-9527: Improve distribution of replicas when restoring a collection
Project: http://git-wip-us.apache.org/repos/asf/lucene-solr/repo
Commit: http://git-wip-us.apache.org/repos/asf/lucene-solr/commit/201e2125
Tree: http://git-wip-us.apache.org/repos/asf/lucene-solr/tree/201e2125
Diff: http://git-wip-us.apache.org/repos/asf/lucene-solr/diff/201e2125
Branch: refs/heads/branch_6_6
Commit: 201e2125f4db3b4fd1ecfe5ddef5471f305fc1f0
Parents: 7d164a1
Author: Varun Thacker <va...@apache.org>
Authored: Wed May 10 13:34:04 2017 +0100
Committer: Varun Thacker <va...@apache.org>
Committed: Wed May 10 16:57:24 2017 +0100
----------------------------------------------------------------------
solr/CHANGES.txt | 3 +
.../cloud/OverseerCollectionMessageHandler.java | 5 +-
.../java/org/apache/solr/cloud/RestoreCmd.java | 62 +++++++++++++++++++-
.../solr/handler/admin/CollectionsHandler.java | 12 +++-
.../AbstractCloudBackupRestoreTestCase.java | 27 +++++++++
.../core/snapshots/TestSolrCloudSnapshots.java | 5 ++
.../solrj/request/CollectionAdminRequest.java | 32 +++++++++-
.../common/params/CollectionAdminParams.java | 10 ++++
8 files changed, 148 insertions(+), 8 deletions(-)
----------------------------------------------------------------------
http://git-wip-us.apache.org/repos/asf/lucene-solr/blob/201e2125/solr/CHANGES.txt
----------------------------------------------------------------------
diff --git a/solr/CHANGES.txt b/solr/CHANGES.txt
index c642a98..dee3df5 100644
--- a/solr/CHANGES.txt
+++ b/solr/CHANGES.txt
@@ -229,6 +229,9 @@ Bug Fixes
* SOLR-10631: Metric reporters leak on 6x. (ab)
+* SOLR-9527: Improve distribution of replicas when restoring a collection
+ (Hrishikesh Gadre, Stephen Lewis, Rohit, Varun Thacker)
+
Other Changes
----------------------
http://git-wip-us.apache.org/repos/asf/lucene-solr/blob/201e2125/solr/core/src/java/org/apache/solr/cloud/OverseerCollectionMessageHandler.java
----------------------------------------------------------------------
diff --git a/solr/core/src/java/org/apache/solr/cloud/OverseerCollectionMessageHandler.java b/solr/core/src/java/org/apache/solr/cloud/OverseerCollectionMessageHandler.java
index 655bd99..b8e940b 100644
--- a/solr/core/src/java/org/apache/solr/cloud/OverseerCollectionMessageHandler.java
+++ b/solr/core/src/java/org/apache/solr/cloud/OverseerCollectionMessageHandler.java
@@ -58,6 +58,7 @@ import org.apache.solr.common.cloud.ZkConfigManager;
import org.apache.solr.common.cloud.ZkCoreNodeProps;
import org.apache.solr.common.cloud.ZkNodeProps;
import org.apache.solr.common.cloud.ZkStateReader;
+import org.apache.solr.common.params.CollectionAdminParams;
import org.apache.solr.common.params.CollectionParams.CollectionAction;
import org.apache.solr.common.params.CoreAdminParams;
import org.apache.solr.common.params.CoreAdminParams.CoreAdminAction;
@@ -104,9 +105,9 @@ public class OverseerCollectionMessageHandler implements OverseerMessageHandler
public static final String NUM_SLICES = "numShards";
static final boolean CREATE_NODE_SET_SHUFFLE_DEFAULT = true;
- public static final String CREATE_NODE_SET_SHUFFLE = "createNodeSet.shuffle";
+ public static final String CREATE_NODE_SET_SHUFFLE = CollectionAdminParams.CREATE_NODE_SET_SHUFFLE_PARAM;
public static final String CREATE_NODE_SET_EMPTY = "EMPTY";
- public static final String CREATE_NODE_SET = "createNodeSet";
+ public static final String CREATE_NODE_SET = CollectionAdminParams.CREATE_NODE_SET_PARAM;
public static final String ROUTER = "router";
http://git-wip-us.apache.org/repos/asf/lucene-solr/blob/201e2125/solr/core/src/java/org/apache/solr/cloud/RestoreCmd.java
----------------------------------------------------------------------
diff --git a/solr/core/src/java/org/apache/solr/cloud/RestoreCmd.java b/solr/core/src/java/org/apache/solr/cloud/RestoreCmd.java
index 4e7fb58..23b2fb5 100644
--- a/solr/core/src/java/org/apache/solr/cloud/RestoreCmd.java
+++ b/solr/core/src/java/org/apache/solr/cloud/RestoreCmd.java
@@ -20,16 +20,22 @@ package org.apache.solr.cloud;
import java.lang.invoke.MethodHandles;
import java.net.URI;
+import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Locale;
import java.util.Map;
import java.util.Optional;
import java.util.Properties;
import java.util.Set;
import org.apache.solr.cloud.overseer.OverseerAction;
+import org.apache.solr.cloud.rule.ReplicaAssigner;
+import org.apache.solr.common.SolrException;
+import org.apache.solr.common.SolrException.ErrorCode;
import org.apache.solr.common.cloud.ClusterState;
import org.apache.solr.common.cloud.DocCollection;
import org.apache.solr.common.cloud.ImplicitDocRouter;
@@ -53,6 +59,7 @@ import static org.apache.solr.cloud.OverseerCollectionMessageHandler.COLL_PROPS;
import static org.apache.solr.cloud.OverseerCollectionMessageHandler.CREATE_NODE_SET;
import static org.apache.solr.cloud.OverseerCollectionMessageHandler.CREATE_NODE_SET_EMPTY;
import static org.apache.solr.cloud.OverseerCollectionMessageHandler.NUM_SLICES;
+import static org.apache.solr.cloud.OverseerCollectionMessageHandler.RANDOM;
import static org.apache.solr.cloud.OverseerCollectionMessageHandler.SHARDS_PROP;
import static org.apache.solr.common.cloud.ZkStateReader.COLLECTION_PROP;
import static org.apache.solr.common.cloud.ZkStateReader.SHARD_ID_PROP;
@@ -60,7 +67,8 @@ import static org.apache.solr.common.params.CollectionParams.CollectionAction.CR
import static org.apache.solr.common.params.CollectionParams.CollectionAction.CREATESHARD;
import static org.apache.solr.common.params.CommonAdminParams.ASYNC;
import static org.apache.solr.common.params.CommonParams.NAME;
-
+import static org.apache.solr.common.cloud.ZkStateReader.REPLICATION_FACTOR;
+import static org.apache.solr.common.cloud.ZkStateReader.MAX_SHARDS_PER_NODE;
public class RestoreCmd implements OverseerCollectionMessageHandler.Cmd {
private static final Logger log = LoggerFactory.getLogger(MethodHandles.lookup().lookupClass());
@@ -74,6 +82,7 @@ public class RestoreCmd implements OverseerCollectionMessageHandler.Cmd {
@Override
public void call(ClusterState state, ZkNodeProps message, NamedList results) throws Exception {
// TODO maybe we can inherit createCollection's options/code
+
String restoreCollectionName = message.getStr(COLLECTION_PROP);
String backupName = message.getStr(NAME); // of backup
ShardHandler shardHandler = ocmh.shardHandlerFactory.getShardHandler();
@@ -93,6 +102,22 @@ public class RestoreCmd implements OverseerCollectionMessageHandler.Cmd {
String backupCollection = properties.getProperty(BackupManager.COLLECTION_NAME_PROP);
DocCollection backupCollectionState = backupMgr.readCollectionState(location, backupName, backupCollection);
+ // Get the Solr nodes to restore a collection.
+ final List<String> nodeList = OverseerCollectionMessageHandler.getLiveOrLiveAndCreateNodeSetList(
+ zkStateReader.getClusterState().getLiveNodes(), message, RANDOM);
+
+ int numShards = backupCollectionState.getActiveSlices().size();
+ int repFactor = message.getInt(REPLICATION_FACTOR, backupCollectionState.getReplicationFactor());
+ int maxShardsPerNode = message.getInt(MAX_SHARDS_PER_NODE, backupCollectionState.getMaxShardsPerNode());
+ int availableNodeCount = nodeList.size();
+ if ((numShards * repFactor) > (availableNodeCount * maxShardsPerNode)) {
+ throw new SolrException(ErrorCode.BAD_REQUEST,
+ String.format(Locale.ROOT, "Solr cloud with available number of nodes:%d is insufficient for"
+ + " restoring a collection with %d shards, replication factor %d and maxShardsPerNode %d."
+ + " Consider increasing maxShardsPerNode value OR number of available nodes.",
+ availableNodeCount, numShards, repFactor, maxShardsPerNode));
+ }
+
//Upload the configs
String configName = (String) properties.get(COLL_CONF);
String restoreConfigName = message.getStr(COLL_CONF, configName);
@@ -168,9 +193,16 @@ public class RestoreCmd implements OverseerCollectionMessageHandler.Cmd {
inQueue.offer(Utils.toJSON(new ZkNodeProps(propMap)));
}
- // TODO how do we leverage the CREATE_NODE_SET / RULE / SNITCH logic in createCollection?
+ // TODO how do we leverage the RULE / SNITCH logic in createCollection?
ClusterState clusterState = zkStateReader.getClusterState();
+
+ List<String> sliceNames = new ArrayList<>();
+ restoreCollection.getSlices().forEach(x -> sliceNames.add(x.getName()));
+
+ Map<ReplicaAssigner.Position, String> positionVsNodes = ocmh.identifyNodes(clusterState, nodeList,
+ message, sliceNames, repFactor);
+
//Create one replica per shard and copy backed up data to it
for (Slice slice : restoreCollection.getSlices()) {
log.debug("Adding replica for shard={} collection={} ", slice.getName(), restoreCollection);
@@ -178,6 +210,19 @@ public class RestoreCmd implements OverseerCollectionMessageHandler.Cmd {
propMap.put(Overseer.QUEUE_OPERATION, CREATESHARD);
propMap.put(COLLECTION_PROP, restoreCollectionName);
propMap.put(SHARD_ID_PROP, slice.getName());
+
+ // Get the first node matching the shard to restore in
+ String node;
+ for (Map.Entry<ReplicaAssigner.Position, String> pvn : positionVsNodes.entrySet()) {
+ ReplicaAssigner.Position position = pvn.getKey();
+ if (position.shard == slice.getName()) {
+ node = pvn.getValue();
+ propMap.put(CoreAdminParams.NODE, node);
+ positionVsNodes.remove(position);
+ break;
+ }
+ }
+
// add async param
if (asyncId != null) {
propMap.put(ASYNC, asyncId);
@@ -227,6 +272,19 @@ public class RestoreCmd implements OverseerCollectionMessageHandler.Cmd {
HashMap<String, Object> propMap = new HashMap<>();
propMap.put(COLLECTION_PROP, restoreCollectionName);
propMap.put(SHARD_ID_PROP, slice.getName());
+
+ // Get the first node matching the shard to restore in
+ String node;
+ for (Map.Entry<ReplicaAssigner.Position, String> pvn : positionVsNodes.entrySet()) {
+ ReplicaAssigner.Position position = pvn.getKey();
+ if (position.shard == slice.getName()) {
+ node = pvn.getValue();
+ propMap.put(CoreAdminParams.NODE, node);
+ positionVsNodes.remove(position);
+ break;
+ }
+ }
+
// add async param
if (asyncId != null) {
propMap.put(ASYNC, asyncId);
http://git-wip-us.apache.org/repos/asf/lucene-solr/blob/201e2125/solr/core/src/java/org/apache/solr/handler/admin/CollectionsHandler.java
----------------------------------------------------------------------
diff --git a/solr/core/src/java/org/apache/solr/handler/admin/CollectionsHandler.java b/solr/core/src/java/org/apache/solr/handler/admin/CollectionsHandler.java
index 9420f99..3384005 100644
--- a/solr/core/src/java/org/apache/solr/handler/admin/CollectionsHandler.java
+++ b/solr/core/src/java/org/apache/solr/handler/admin/CollectionsHandler.java
@@ -101,6 +101,7 @@ import static org.apache.solr.cloud.Overseer.QUEUE_OPERATION;
import static org.apache.solr.cloud.OverseerCollectionMessageHandler.COLL_CONF;
import static org.apache.solr.cloud.OverseerCollectionMessageHandler.COLL_PROP_PREFIX;
import static org.apache.solr.cloud.OverseerCollectionMessageHandler.CREATE_NODE_SET;
+import static org.apache.solr.cloud.OverseerCollectionMessageHandler.CREATE_NODE_SET_EMPTY;
import static org.apache.solr.cloud.OverseerCollectionMessageHandler.CREATE_NODE_SET_SHUFFLE;
import static org.apache.solr.cloud.OverseerCollectionMessageHandler.NUM_SLICES;
import static org.apache.solr.cloud.OverseerCollectionMessageHandler.ONLY_ACTIVE_NODES;
@@ -812,10 +813,19 @@ public class CollectionsHandler extends RequestHandlerBase implements Permission
throw new SolrException(ErrorCode.SERVER_ERROR, "Failed to check the existance of " + uri + ". Is it valid?", ex);
}
+ String createNodeArg = req.getParams().get(CREATE_NODE_SET);
+ if (CREATE_NODE_SET_EMPTY.equals(createNodeArg)) {
+ throw new SolrException(
+ SolrException.ErrorCode.BAD_REQUEST,
+ "Cannot restore with a CREATE_NODE_SET of CREATE_NODE_SET_EMPTY."
+ );
+ }
+
Map<String, Object> params = req.getParams().getAll(null, NAME, COLLECTION_PROP);
params.put(CoreAdminParams.BACKUP_LOCATION, location);
// from CREATE_OP:
- req.getParams().getAll(params, COLL_CONF, REPLICATION_FACTOR, MAX_SHARDS_PER_NODE, STATE_FORMAT, AUTO_ADD_REPLICAS);
+ req.getParams().getAll(params, COLL_CONF, REPLICATION_FACTOR, MAX_SHARDS_PER_NODE, STATE_FORMAT,
+ AUTO_ADD_REPLICAS, CREATE_NODE_SET, CREATE_NODE_SET_SHUFFLE);
copyPropertiesWithPrefix(req.getParams(), params, COLL_PROP_PREFIX);
return params;
}),
http://git-wip-us.apache.org/repos/asf/lucene-solr/blob/201e2125/solr/core/src/test/org/apache/solr/cloud/AbstractCloudBackupRestoreTestCase.java
----------------------------------------------------------------------
diff --git a/solr/core/src/test/org/apache/solr/cloud/AbstractCloudBackupRestoreTestCase.java b/solr/core/src/test/org/apache/solr/cloud/AbstractCloudBackupRestoreTestCase.java
index f39cfed..3414759 100644
--- a/solr/core/src/test/org/apache/solr/cloud/AbstractCloudBackupRestoreTestCase.java
+++ b/solr/core/src/test/org/apache/solr/cloud/AbstractCloudBackupRestoreTestCase.java
@@ -19,6 +19,8 @@ package org.apache.solr.cloud;
import java.io.IOException;
import java.lang.invoke.MethodHandles;
import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Properties;
@@ -28,6 +30,7 @@ import java.util.TreeMap;
import org.apache.lucene.util.TestUtil;
import org.apache.solr.client.solrj.SolrQuery;
import org.apache.solr.client.solrj.SolrServerException;
+import org.apache.solr.client.solrj.embedded.JettySolrRunner;
import org.apache.solr.client.solrj.impl.CloudSolrClient;
import org.apache.solr.client.solrj.request.CollectionAdminRequest;
import org.apache.solr.client.solrj.request.CollectionAdminRequest.ClusterProp;
@@ -236,9 +239,24 @@ public abstract class AbstractCloudBackupRestoreTestCase extends SolrCloudTestCa
// may need to increase maxShardsPerNode (e.g. if it was shard split, then now we need more)
restore.setMaxShardsPerNode(origShardToDocCount.size());
}
+
+ if (rarely()) { // Try with createNodeSet configuration
+ int nodeSetSize = cluster.getJettySolrRunners().size() / 2;
+ List<String> nodeStrs = new ArrayList<>(nodeSetSize);
+ Iterator<JettySolrRunner> iter = cluster.getJettySolrRunners().iterator();
+ for (int i = 0; i < nodeSetSize ; i++) {
+ nodeStrs.add(iter.next().getNodeName());
+ }
+ restore.setCreateNodeSet(String.join(",", nodeStrs));
+ restore.setCreateNodeSetShuffle(usually());
+ // we need to double maxShardsPerNode value since we reduced number of available nodes by half.
+ restore.setMaxShardsPerNode(origShardToDocCount.size() * 2);
+ }
+
Properties props = new Properties();
props.setProperty("customKey", "customVal");
restore.setProperties(props);
+
if (sameConfig==false) {
restore.setConfigName("customConfigName");
}
@@ -268,6 +286,15 @@ public abstract class AbstractCloudBackupRestoreTestCase extends SolrCloudTestCa
assertEquals(sameConfig ? "conf1" : "customConfigName",
cluster.getSolrClient().getZkStateReader().readConfigName(restoreCollectionName));
+ Map<String, Integer> numReplicasByNodeName = new HashMap<>();
+ restoreCollection.getReplicas().forEach(x -> {
+ numReplicasByNodeName.put(x.getNodeName(), numReplicasByNodeName.getOrDefault(x.getNodeName(), 0) + 1);
+ });
+ numReplicasByNodeName.forEach((k, v) -> {
+ assertTrue("Node " + k + " has " + v + " replicas. Expected num replicas : " + restoreCollection.getMaxShardsPerNode() ,
+ v <= restoreCollection.getMaxShardsPerNode());
+ });
+
// assert added core properties:
// DWS: did via manual inspection.
// TODO Find the applicable core.properties on the file system but how?
http://git-wip-us.apache.org/repos/asf/lucene-solr/blob/201e2125/solr/core/src/test/org/apache/solr/core/snapshots/TestSolrCloudSnapshots.java
----------------------------------------------------------------------
diff --git a/solr/core/src/test/org/apache/solr/core/snapshots/TestSolrCloudSnapshots.java b/solr/core/src/test/org/apache/solr/core/snapshots/TestSolrCloudSnapshots.java
index 9503ee4..592200d 100644
--- a/solr/core/src/test/org/apache/solr/core/snapshots/TestSolrCloudSnapshots.java
+++ b/solr/core/src/test/org/apache/solr/core/snapshots/TestSolrCloudSnapshots.java
@@ -178,6 +178,11 @@ public class TestSolrCloudSnapshots extends SolrCloudTestCase {
{
CollectionAdminRequest.Restore restore = CollectionAdminRequest.restoreCollection(restoreCollectionName, backupName)
.setLocation(backupLocation);
+ if (replicaFailures) {
+ // In this case one of the Solr servers would be down. Hence we need to increase
+ // max_shards_per_node property for restore command to succeed.
+ restore.setMaxShardsPerNode(2);
+ }
if (random().nextBoolean()) {
assertEquals(0, restore.process(solrClient).getStatus());
} else {
http://git-wip-us.apache.org/repos/asf/lucene-solr/blob/201e2125/solr/solrj/src/java/org/apache/solr/client/solrj/request/CollectionAdminRequest.java
----------------------------------------------------------------------
diff --git a/solr/solrj/src/java/org/apache/solr/client/solrj/request/CollectionAdminRequest.java b/solr/solrj/src/java/org/apache/solr/client/solrj/request/CollectionAdminRequest.java
index 8a59feb..ad5d045 100644
--- a/solr/solrj/src/java/org/apache/solr/client/solrj/request/CollectionAdminRequest.java
+++ b/solr/solrj/src/java/org/apache/solr/client/solrj/request/CollectionAdminRequest.java
@@ -46,6 +46,8 @@ import org.apache.solr.common.util.ContentStream;
import org.apache.solr.common.util.NamedList;
import static org.apache.solr.common.params.CollectionAdminParams.COUNT_PROP;
+import static org.apache.solr.common.params.CollectionAdminParams.CREATE_NODE_SET_PARAM;
+import static org.apache.solr.common.params.CollectionAdminParams.CREATE_NODE_SET_SHUFFLE_PARAM;
/**
* This class is experimental and subject to change.
@@ -487,7 +489,7 @@ public abstract class CollectionAdminRequest<T extends CollectionAdminResponse>
if (configName != null)
params.set("collection.configName", configName);
if (createNodeSet != null)
- params.set("createNodeSet", createNodeSet);
+ params.set(CREATE_NODE_SET_PARAM, createNodeSet);
if (numShards != null) {
params.set( ZkStateReader.NUM_SHARDS_PROP, numShards);
}
@@ -846,6 +848,8 @@ public abstract class CollectionAdminRequest<T extends CollectionAdminResponse>
protected Integer maxShardsPerNode;
protected Integer replicationFactor;
protected Boolean autoAddReplicas;
+ protected Optional<String> createNodeSet = Optional.empty();
+ protected Optional<Boolean> createNodeSetShuffle = Optional.empty();
protected Properties properties;
public Restore(String collection, String backupName) {
@@ -883,6 +887,22 @@ public abstract class CollectionAdminRequest<T extends CollectionAdminResponse>
return this;
}
+ public void setCreateNodeSet(String createNodeSet) {
+ this.createNodeSet = Optional.of(createNodeSet);
+ }
+
+ public Optional<String> getCreateNodeSet() {
+ return createNodeSet;
+ }
+
+ public Optional<Boolean> getCreateNodeSetShuffle() {
+ return createNodeSetShuffle;
+ }
+
+ public void setCreateNodeSetShuffle(boolean createNodeSetShuffle) {
+ this.createNodeSetShuffle = Optional.of(createNodeSetShuffle);
+ }
+
// Collection creation params in common:
public Restore setConfigName(String config) { this.configName = config; return this; }
public String getConfigName() { return configName; }
@@ -901,7 +921,7 @@ public abstract class CollectionAdminRequest<T extends CollectionAdminResponse>
}
public Restore setProperties(Properties properties) { this.properties = properties; return this;}
- // TODO support createNodeSet, rule, snitch
+ // TODO support rule, snitch
@Override
public SolrParams getParams() {
@@ -925,6 +945,12 @@ public abstract class CollectionAdminRequest<T extends CollectionAdminResponse>
if (repositoryName.isPresent()) {
params.set(CoreAdminParams.BACKUP_REPOSITORY, repositoryName.get());
}
+ if (createNodeSet.isPresent()) {
+ params.set(CREATE_NODE_SET_PARAM, createNodeSet.get());
+ }
+ if (createNodeSetShuffle.isPresent()) {
+ params.set(CREATE_NODE_SET_SHUFFLE_PARAM, createNodeSetShuffle.get());
+ }
return params;
}
@@ -1105,7 +1131,7 @@ public abstract class CollectionAdminRequest<T extends CollectionAdminResponse>
public SolrParams getParams() {
ModifiableSolrParams params = (ModifiableSolrParams) super.getParams();
if (nodeSet != null) {
- params.set("createNodeSet", nodeSet);
+ params.set(CREATE_NODE_SET_PARAM, nodeSet);
}
if (properties != null) {
addProperties(params, properties);
http://git-wip-us.apache.org/repos/asf/lucene-solr/blob/201e2125/solr/solrj/src/java/org/apache/solr/common/params/CollectionAdminParams.java
----------------------------------------------------------------------
diff --git a/solr/solrj/src/java/org/apache/solr/common/params/CollectionAdminParams.java b/solr/solrj/src/java/org/apache/solr/common/params/CollectionAdminParams.java
index 98ae292..ffc373b 100644
--- a/solr/solrj/src/java/org/apache/solr/common/params/CollectionAdminParams.java
+++ b/solr/solrj/src/java/org/apache/solr/common/params/CollectionAdminParams.java
@@ -28,6 +28,16 @@ public interface CollectionAdminParams {
String COUNT_PROP = "count";
+ /**
+ * A parameter to specify list of Solr nodes to be used (e.g. for collection creation or restore operation).
+ */
+ public static final String CREATE_NODE_SET_PARAM = "createNodeSet";
+
+ /**
+ * A parameter which specifies if the provided list of Solr nodes (via {@linkplain #CREATE_NODE_SET_PARAM})
+ * should be shuffled before being used.
+ */
+ public static final String CREATE_NODE_SET_SHUFFLE_PARAM = "createNodeSet.shuffle";
/**
* A parameter to specify the name of the index backup strategy to be used.