1. 问题背景
目前项目中所使用的Elasticsearch(一下简称ES)的服务器版本是6.8.1，但将来有升级到7.8.1版本的计划。这样对于相同的应用软件版本而言，可能会在有的地方搭配6.8.1版本使用，有的地方搭配7.8.1版本使用。
对于应用软件而言，作为ES服务器的JAVA客户端，需要使用一套代码来兼容6.8.1版本和7.8.1版本的ES服务器。
2. 设计思路
Java High Level REST Client（以下简称High Level）是ES官方推荐的JAVA客户端，具有即时同步ES服务器版本，功能特性齐全等特点，因此项目选用High Level作为视信通应用服务的ES客户端。
根据High Level的官方文档，对于兼容性有如下说明：
图1
由官方文档可以看到，High Level具有向前兼容的特性，即老的High Level客户端可以被新版本的服务器兼容。
根据这一特性，应用软件决定使用6.8.1版本的6.8.1客户端来兼容6.8.1和7.8.1的服务器。
分析ES服务器6和7版本之间的差别，最大差别在于6中每个索引存储数据时需要指定Type,而7中不需要指定Type，即一个索引对应一个Mapping。
目前项目的应用软件中使用6的客户端索引建立规则为:一个索引对应一个Type, 索引名与Type名相同，在升级ES的服务器版本到7之后，目前的这种索引创建模式需要修改，否则在服务器版本升级到7之后无法运行。
3. 设计方案
3.1. 索引模型兼容
为兼容6.8.1与7.8.1的ES服务器，应用软件在创建索引时不指定Type。目前High Level 6.8.1的API中创建索引可以不指定Type参数，创建的索引默认Type为“_doc”,而7.8.1的服务器支持对于Type为“_doc”的DSL查询。
应用软件的JAVA客户端使用High Level 6.8.1在创建索引时不指定Type，对于查询、聚合的API需要填入Type的情况，使用默认Type值“_doc”。
3.2. 封装ES操作
为避免应用软件不同的服务使用High Level出现姿势不一样的情况。视信通将对ES的操作封装到一个公共工具类中，对于各应用服务而言，不再关注ES的实现细节，运行方式也都一致，更便于扩展与维护。
3.3. 使用High Level与LOW Level结合的方式兼容ES操作
尽管官方宣称High Level的向前兼容性，但是在语法格式上还有一些细微差别。如对于查询返回结果的总数字段(Total)：
在6.8.1服务器中，查询返回命中结果如下：
{
"took": 0,
"timed_out": false,
"_shards": {
"total": 5,
"successful": 5,
"skipped": 0,
"failed": 0
},
"hits": {
"total": 0,
"max_score": null,
"hits": []
}
}
请注意，这里total字段为一个整型。
但在7.8.1的服务器中，查询返回命中结果如下：
{
"took": 6,
"timed_out": false,
"_shards": {
"total": 1,
"successful": 1,
"skipped": 0,
"failed": 0
},
"hits": {
"total": {
"value": 0,
"relation": "eq"
},
"max_score": null,
"hits": []
}
}
若使用6.8.1的High Level去查询7.8.1的服务器，会出现API解析total字段不正确的情况(始终返回为0)。
针对这种情况，在视信通的ES封装函数中首先使用Java Low Level REST Client执行该查询，然后针对返回的结果JSON解析total字段是一个整型还是JSON对象来获取正确的total值。
3.4. 数据迁移
由于老的应用软件版本中ES索引模式为ES索引名与Type名相同，这种方式不适用于兼容方案。
因而在使用ES兼容方案后，应用软件升级时需要重新创建索引（兼容索引），可使用ES的reindex命令，示例如下：
POST http://172.16.249.177:9200/_reindex
{
"source": {
"index": "vline_event_recorder_exception",
"type":"vline_event_recorder_exception"
},
"dest": {
"index": "vline_event_recorder_exception_test",
"type": "_doc"
}
}
附录：ES客户端封装函数
import lombok.extern.slf4j.Slf4j;
import org.apache.http.HttpHost;
import org.apache.http.util.EntityUtils;
import org.elasticsearch.action.DocWriteResponse;
import org.elasticsearch.action.admin.indices.settings.put.UpdateSettingsRequest;
import org.elasticsearch.action.bulk.BulkRequest;
import org.elasticsearch.action.bulk.BulkResponse;
import org.elasticsearch.action.index.IndexRequest;
import org.elasticsearch.action.index.IndexResponse;
import org.elasticsearch.action.search.SearchRequest;
import org.elasticsearch.action.search.SearchResponse;
import org.elasticsearch.action.search.SearchScrollRequest;
import org.elasticsearch.action.support.master.AcknowledgedResponse;
import org.elasticsearch.action.update.UpdateRequest;
import org.elasticsearch.action.update.UpdateResponse;
import org.elasticsearch.client.Request;
import org.elasticsearch.client.RequestOptions;
import org.elasticsearch.client.Response;
import org.elasticsearch.client.RestClient;
import org.elasticsearch.client.RestClientBuilder;
import org.elasticsearch.client.RestHighLevelClient;
import org.elasticsearch.client.indices.CreateIndexRequest;
import org.elasticsearch.client.indices.CreateIndexResponse;
import org.elasticsearch.client.indices.GetIndexRequest;
import org.elasticsearch.client.indices.PutMappingRequest;
import org.elasticsearch.common.unit.TimeValue;
import org.elasticsearch.common.xcontent.XContentBuilder;
import org.elasticsearch.common.xcontent.XContentType;
import org.elasticsearch.index.query.QueryBuilder;
import org.elasticsearch.index.reindex.BulkByScrollResponse;
import org.elasticsearch.index.reindex.DeleteByQueryRequest;
import org.elasticsearch.rest.RestStatus;
import org.elasticsearch.search.SearchHit;
import org.elasticsearch.search.SearchHits;
import org.elasticsearch.search.builder.SearchSourceBuilder;
import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONObject;
import com.alibaba.fastjson.serializer.SerializerFeature;
import com.kedacom.microservice.pojo.AbstractCommonIndex;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
/**
* @author zhang.kai
*
*/
@Slf4j
public class ESDataUtils {
private static final int SCROLL_PAGE_SIZE = 1000; // 每次scroll的页面大小
private static final String DEFAULT_TYPE = "_doc";
// lowLevelClient客户端
public static RestClient restClient;
// RestHighLevelClient客户端
public static RestHighLevelClient highLevelClient;
// 索引创建时的分片值，如为-1则使用系统默认值
public static int numberOfShards = -1;
// 索引创建时的分片复制因子，如为-1则使用系统默认值
public static int numberOfReplicas = -1;
public static SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss:SSS");
public static SimpleDateFormat sdfForLog = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSS");
public static SimpleDateFormat sdfForName = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
// 内部类，返回分页查询结果
public static class EsSearchResult {
public List<String> recorders; // 查询到的记录
public SearchResponse sr; // 执行查询的结果对象，可能包含聚合指标
public long total; // 文档总数
}
/**
* 根据配置中心获取的es服务器地址与端口初始化RestClient与RestHighLevelClient
*
* @param esHost es服务器地址
* @param esPort es服务器端口
*/
public static void initClient(String esHost, int esPort) {
RestClientBuilder restClientBuilder = RestClient.builder(new HttpHost(esHost, esPort, "http"));
ESDataUtils.restClient = restClientBuilder.build();
ESDataUtils.highLevelClient = new RestHighLevelClient(restClientBuilder);
}
/**
* 判断索引是否存在
*
* @param indexName
* @return
* @throws IOException
*/
public static boolean ifIndexExists(String indexName) throws IOException {
GetIndexRequest request = new GetIndexRequest(indexName);
return highLevelClient.indices().exists(request, RequestOptions.DEFAULT);
}
/**
* 创建ES索引,参数为索引配置包装类，此方法适用于已经创建索引配置类
*
* @param index
* @return
* @throws IOException
*/
public static boolean createIndex(AbstractCommonIndex index) throws IOException {
String indexName = index.getIndexName();
CreateIndexRequest request = new CreateIndexRequest(indexName);
if (!ifIndexExists(indexName)) {
if (null != index.getSettings()) {
String settings = index.getSettings();
JSONObject settingsJo = JSON.parseObject(settings);
if (numberOfShards > 0) {
settingsJo.put("index.number_of_shards", numberOfShards);
}
if (numberOfReplicas > 0) {
settingsJo.put("index.number_of_replicas", numberOfReplicas);
}
request.settings(JSON.toJSONString(settingsJo, SerializerFeature.WriteMapNullValue), XContentType.JSON);
}
request.mapping(index.getMapping());
log.info("createIndex {}:{}", indexName, request.toString());
CreateIndexResponse createIndexResponse = highLevelClient.indices().create(request, RequestOptions.DEFAULT);
if (!createIndexResponse.isAcknowledged()) {
log.error("createIndex fail:{}", createIndexResponse);
}
return createIndexResponse.isAcknowledged();
}
log.info("{} has created!", indexName);
return false;
}
/**
* 创建ES索引,参数为字符串形式，此方法适用于未创建索引配置类，直接适用json字符串作为参数
*
* @param indexName
* @param mappingStr
* @param settingsStr
* @return
* @throws IOException
*/
public static boolean createIndex(String indexName, String mappingStr, String settingsStr) throws IOException {
CreateIndexRequest request = new CreateIndexRequest(indexName);
if (!ifIndexExists(indexName)) {
if (null != settingsStr) {
JSONObject settingsJo = JSON.parseObject(settingsStr);
if (numberOfShards > 0) {
settingsJo.put("index.number_of_shards", numberOfShards);
}
if (numberOfReplicas > 0) {
settingsJo.put("index.number_of_replicas", numberOfReplicas);
}
request.settings(JSON.toJSONString(settingsJo, SerializerFeature.WriteMapNullValue), XContentType.JSON);
}
if (null != mappingStr) {
request.mapping(mappingStr, XContentType.JSON);
}
log.info("createIndex {}:{}", indexName, request.toString());
CreateIndexResponse createIndexResponse = highLevelClient.indices().create(request, RequestOptions.DEFAULT);
if (!createIndexResponse.isAcknowledged()) {
log.error("createIndex fail:{}", createIndexResponse);
}
return createIndexResponse.isAcknowledged();
}
log.info("{} has created!", indexName);
return false;
}
/**
* 修改索引映射，参数为XContentBuilder
*
* @param indexName
* @param mappingStr
* @return
* @throws IOException
*/
public static boolean updateMapping(String indexName, XContentBuilder mapBuilder) throws IOException {
PutMappingRequest request = new PutMappingRequest(indexName);
request.source(mapBuilder);
log.info("putMapping:{},{}", indexName, request.source());
AcknowledgedResponse putMappingResponse = highLevelClient.indices().putMapping(request, RequestOptions.DEFAULT);
if (!putMappingResponse.isAcknowledged()) {
log.error("updateMapping fail:{}", putMappingResponse.toString());
}
return putMappingResponse.isAcknowledged();
}
/**
* 修改索引映射，参数为String
*
* @param indexName
* @param mappingStr
* @return
* @throws IOException
*/
public static boolean updateMapping(String indexName, String mappingStr) throws IOException {
PutMappingRequest request = new PutMappingRequest(indexName);
request.source(mappingStr, XContentType.JSON);
log.info("putMapping:{},{}", indexName, request.source());
AcknowledgedResponse putMappingResponse = highLevelClient.indices().putMapping(request, RequestOptions.DEFAULT);
if (!putMappingResponse.isAcknowledged()) {
log.error("updateMapping fail:{}", putMappingResponse.toString());
}
return putMappingResponse.isAcknowledged();
}
/**
* 修改索引的设置,参数为Map
*
* @param indexName
* @param settingsMap
* @return
* @throws IOException
*/
public static boolean updateSettings(String indexName, Map<String, Object> settingsMap) throws IOException {
UpdateSettingsRequest request = new UpdateSettingsRequest(indexName);
request.settings(settingsMap);
log.info("updateSettings {}:{}", indexName, settingsMap);
AcknowledgedResponse updateSettingsResponse = highLevelClient.indices().putSettings(request,
RequestOptions.DEFAULT);
if (!updateSettingsResponse.isAcknowledged()) {
log.error("updateSettings fail:{}", updateSettingsResponse);
}
return updateSettingsResponse.isAcknowledged();
}
/**
* 修改索引的设置,参数为String
*
* @param indexName
* @param settingsMap
* @return
* @throws IOException
*/
public static boolean updateSettings(String indexName, String settingsStr) throws IOException {
UpdateSettingsRequest request = new UpdateSettingsRequest(indexName);
request.settings(settingsStr, XContentType.JSON);
log.info("updateSettings {}:{}", indexName, settingsStr);
AcknowledgedResponse updateSettingsResponse = highLevelClient.indices().putSettings(request,
RequestOptions.DEFAULT);
if (!updateSettingsResponse.isAcknowledged()) {
log.error("updateSettings fail:{}", updateSettingsResponse);
}
return updateSettingsResponse.isAcknowledged();
}
/**
* 向索引插入单条记录
*
* @param indexName
* @param docId
* @param docSource
* @return
* @throws IOException
*/
public static boolean insertDoc(String indexName, String docId, String docSource) throws IOException {
IndexRequest request = new IndexRequest(indexName, DEFAULT_TYPE);
if (null != docId) {
request.id(docId);
}
request.source(docSource, XContentType.JSON);
IndexResponse indexResponse = highLevelClient.index(request, RequestOptions.DEFAULT);
if ((indexResponse.status() == RestStatus.CREATED) || (indexResponse.status() == RestStatus.OK)) {
return true;
} else {
log.error("insertDoc fail status:{} => {}", indexResponse.status(), indexResponse.toString());
return false;
}
}
/**
* 向索引插入批量记录
*
* @param indexName
* @param docId
* @param docSource
* @return
* @throws IOException
*/
public static boolean insertDocBulk(String indexName, List<String> docIds, List<String> docSources)
throws IOException {
if (null == docSources) {
log.error("insertDocBulk docSources are null!");
return false;
}
BulkRequest bulkRequest = new BulkRequest();
for (int i = 0; i < docSources.size(); i++) {
IndexRequest request = new IndexRequest(indexName, DEFAULT_TYPE);
if ((null != docIds) && (null != docIds.get(i))) {
request.id(docIds.get(i));
}
request.source(docSources.get(i), XContentType.JSON);
bulkRequest.add(request);
}
if (bulkRequest.numberOfActions() > 0) {
BulkResponse bulkResponse = highLevelClient.bulk(bulkRequest, RequestOptions.DEFAULT);
if (!bulkResponse.hasFailures()) {
return true;
} else {
log.error("insertDocBulk fail status:{} => {}", bulkResponse.status(),
bulkResponse.buildFailureMessage());
return false;
}
}
return true;
}
/**
* 修改es文档中的某些字段值，docId必须存在
*
* @param indexName
* @param docId
* @param updateFields
* @return
* @throws IOException
*/
public static boolean updateDoc(String indexName, String docId, String updateFields) throws IOException {
if (null == docId) {
log.info("updateDoc {} fail cause docId is null:{}", indexName, updateFields);
return false;
}
UpdateRequest request = new UpdateRequest(indexName, DEFAULT_TYPE, docId);
request.doc(updateFields, XContentType.JSON);
UpdateResponse updateResponse = highLevelClient.update(request, RequestOptions.DEFAULT);
if (updateResponse.getResult() == DocWriteResponse.Result.UPDATED) {
return true;
} else {
log.error("updateDoc {} fail by {} :{}", indexName, docId, updateResponse.toString());
return false;
}
}
/**
* 执行ES查询并支持分页(超过10000条限制的分页)
*
* @param ssb
* @param from
* @param size
* @param indexName
* @return
* @throws IOException
*/
public static EsSearchResult executeEsSearch(SearchSourceBuilder ssb, int from, int size, String indexName)
throws IOException {
if (null == ssb) {
log.error("executeEsSearch args is error!");
return null;
}
EsSearchResult esr = new EsSearchResult();
SearchResponse searchResponse = null;
SearchRequest searchRequest = new SearchRequest(indexName);
if (from + size <= 10000) { // 10000以内，正常执行查询
esr.total = getEsSearchTotal(ssb, indexName);
ssb.from(from).size(size);
log.info("executble es search dsl for {} is:{}", indexName, ssb.toString());
searchRequest.source(ssb);
searchResponse = highLevelClient.search(searchRequest, RequestOptions.DEFAULT);
SearchHits hits = searchResponse.getHits();
List<String> docList = new ArrayList<String>();
for (SearchHit hit : hits.getHits()) {
docList.add(hit.getSourceAsString());
}
esr.recorders = docList;
esr.sr = searchResponse;
} else {// 超过10000，使用scrollid
esr.total = getEsSearchTotal(ssb, indexName);
ssb.size(SCROLL_PAGE_SIZE);
log.info("executble es search dsl for {} is:{}", indexName, ssb.toString());
searchRequest.source(ssb);
searchRequest.scroll(TimeValue.timeValueMinutes(3L));
searchResponse = highLevelClient.search(searchRequest, RequestOptions.DEFAULT);
SearchHits hits = searchResponse.getHits();
esr.sr = searchResponse;
// 如果所有记录数小于等于请求起始数，返回null
if ((null != searchResponse) && (esr.total <= from)) {
log.info("total:{} is less than from:{}", esr.total, from);
return esr;
}
int unFetchedIndex = 0; // 未取到的索引
while ((null != searchResponse) && (searchResponse.status() == RestStatus.OK)) {
List<String> curPageList = new ArrayList<String>();
for (SearchHit hit : hits.getHits()) {
curPageList.add(hit.getSourceAsString());
}
unFetchedIndex += SCROLL_PAGE_SIZE;
log.info("current unFetchedIndex is :{}->{}", unFetchedIndex, curPageList.get(0));
if (unFetchedIndex > from) {
int startIndex = from % SCROLL_PAGE_SIZE;
// 只在本页内取，由程序约束：比如一次scroll的size是1000,取得页大小未10，20，50
List<String> docList = curPageList.subList(startIndex, startIndex + size);
esr.recorders = docList;
break;
} else {// 继续循环
String scrollId = searchResponse.getScrollId();
SearchScrollRequest scrollRequest = new SearchScrollRequest(scrollId);
scrollRequest.scroll(TimeValue.timeValueSeconds(180));
searchResponse = highLevelClient.scroll(scrollRequest, RequestOptions.DEFAULT);
}
}
}
return esr;
}
/**
* 执行es查询返回所有符合条件的结果
*
* @param jestClient
* @param ssb
* @param indexName
* @return
* @throws IOException
*/
public static EsSearchResult searchAllData(SearchSourceBuilder ssb, String indexName) throws IOException {
if (null == ssb) {
log.error("executeEsSearch args is error!");
return null;
}
log.info("executble es search all data dsl for {} is:{}", indexName, ssb.toString());
EsSearchResult esr = new EsSearchResult();
esr.total = getEsSearchTotal(ssb, indexName);
SearchRequest searchRequest = new SearchRequest(indexName);
searchRequest.source(ssb);
searchRequest.scroll(TimeValue.timeValueMinutes(3L));
// 使用scrollid
ssb.size(SCROLL_PAGE_SIZE);
SearchResponse searchResponse = highLevelClient.search(searchRequest, RequestOptions.DEFAULT);
SearchHits hits = searchResponse.getHits();
esr.sr = searchResponse;
List<String> totalData = new ArrayList<>();
int unFetchedIndex = 0; // 未取到的索引
while ((null != hits) && (hits.getHits().length > 0)) {
List<String> curPageList = new ArrayList<String>();
for (SearchHit hit : hits.getHits()) {
curPageList.add(hit.getSourceAsString());
}
totalData.addAll(curPageList);
unFetchedIndex += SCROLL_PAGE_SIZE;
log.info("current unFetchedIndex is :{}->{}", unFetchedIndex, curPageList.get(0));
String scrollId = searchResponse.getScrollId();
SearchScrollRequest scrollRequest = new SearchScrollRequest(scrollId);
scrollRequest.scroll(TimeValue.timeValueSeconds(180));
searchResponse = highLevelClient.scroll(scrollRequest, RequestOptions.DEFAULT);
hits = searchResponse.getHits();
}
esr.recorders = totalData;
return esr;
}
/**
* 根据请求的时间段删除对应索引中的数据
*
* @param indexName
* @param qb
* @return
* @throws IOException
*/
public static boolean deleteByQuery(String indexName, QueryBuilder qb) throws IOException {
DeleteByQueryRequest request = new DeleteByQueryRequest(indexName);
request.setQuery(qb);
request.setConflicts("proceed");
request.setBatchSize(5000);
// 并行
request.setSlices(5);
// 使用滚动参数来控制“搜索上下文”存活的时间
request.setScroll(TimeValue.timeValueMinutes(10));
// 超时
request.setTimeout(TimeValue.timeValueMinutes(2));
// 刷新索引
request.setRefresh(true);
log.info("***deleteByQuery request uri:{}", request.toString());
log.info("***deleteByQuery request body:{}", qb.toString());
BulkByScrollResponse bulkResponse = highLevelClient.deleteByQuery(request, RequestOptions.DEFAULT);
log.info("***handleEsIndexClean response:{}", bulkResponse.toString());
return true;
}
/**
* 使用low level api获取ES查询的total，需要兼容6.8.1与7.8.1版本
*
* @param ssb
* @param indexName
* @return
* @throws IOException
*/
private static long getEsSearchTotal(SearchSourceBuilder ssb, String indexName) throws IOException {
long total = 0;
ssb.from(0).size(0);
Request request = new Request("GET", "/" + indexName + "/_search");
request.setJsonEntity(ssb.toString());
Response response = restClient.performRequest(request);
int statusCode = response.getStatusLine().getStatusCode();
String responseBody = EntityUtils.toString(response.getEntity());
if (statusCode == 200) {
JSONObject responseJo = (JSONObject) JSON.parse(responseBody);
JSONObject hitsJo = responseJo.getJSONObject("hits");
Object totalJo = hitsJo.get("total");
if (totalJo instanceof Integer) { // 6.8.1版本
total = (long) ((Integer) totalJo);
} else { // 7.8.1版本
total = ((JSONObject) totalJo).getLongValue("value");
}
}
return total;
}
}
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