Reindex max_docs parameter name (#41894)

Previously, a reindex request had two different size specifications in the body:
* Outer level, determining the maximum documents to process
* Inside the source element, determining the scroll/batch size.

The outer level size has now been renamed to max_docs to
avoid confusion and clarify its semantics, with backwards compatibility and
deprecation warnings for using size.
Similarly, the size parameter has been renamed to max_docs for
update/delete-by-query to keep the 3 interfaces consistent.

Finally, all 3 endpoints now support max_docs in both body and URL.

Relates #24344

client/rest-high-level/src/main/java/org/elasticsearch/client/RequestConverters.java

@@ -584,8 +584,8 @@ final class RequestConverters {
         if (updateByQueryRequest.getScrollTime() != AbstractBulkByScrollRequest.DEFAULT_SCROLL_TIMEOUT) {
             params.putParam("scroll", updateByQueryRequest.getScrollTime());
         }
-        if (updateByQueryRequest.getSize() > 0) {
-            params.putParam("size", Integer.toString(updateByQueryRequest.getSize()));
+        if (updateByQueryRequest.getMaxDocs() > 0) {
+            params.putParam("max_docs", Integer.toString(updateByQueryRequest.getMaxDocs()));
         }
         request.addParameters(params.asMap());
         request.setEntity(createEntity(updateByQueryRequest, REQUEST_BODY_CONTENT_TYPE));
@@ -611,8 +611,8 @@ final class RequestConverters {
         if (deleteByQueryRequest.getScrollTime() != AbstractBulkByScrollRequest.DEFAULT_SCROLL_TIMEOUT) {
             params.putParam("scroll", deleteByQueryRequest.getScrollTime());
         }
-        if (deleteByQueryRequest.getSize() > 0) {
-            params.putParam("size", Integer.toString(deleteByQueryRequest.getSize()));
+        if (deleteByQueryRequest.getMaxDocs() > 0) {
+            params.putParam("max_docs", Integer.toString(deleteByQueryRequest.getMaxDocs()));
         }
         request.addParameters(params.asMap());
         request.setEntity(createEntity(deleteByQueryRequest, REQUEST_BODY_CONTENT_TYPE));

client/rest-high-level/src/test/java/org/elasticsearch/client/RequestConvertersTests.java

@@ -427,7 +427,11 @@ public class RequestConvertersTests extends ESTestCase {
             reindexRequest.setDestRouting("=cat");
         }
         if (randomBoolean()) {
-            reindexRequest.setSize(randomIntBetween(100, 1000));
+            if (randomBoolean()) {
+                reindexRequest.setMaxDocs(randomIntBetween(100, 1000));
+            } else {
+                reindexRequest.setSize(randomIntBetween(100, 1000));
+            }
         }
         if (randomBoolean()) {
             reindexRequest.setAbortOnVersionConflict(false);
@@ -476,8 +480,12 @@ public class RequestConvertersTests extends ESTestCase {
         }
         if (randomBoolean()) {
             int size = randomIntBetween(100, 1000);
-            updateByQueryRequest.setSize(size);
-            expectedParams.put("size", Integer.toString(size));
+            if (randomBoolean()) {
+                updateByQueryRequest.setMaxDocs(size);
+            } else {
+                updateByQueryRequest.setSize(size);
+            }
+            expectedParams.put("max_docs", Integer.toString(size));
         }
         if (randomBoolean()) {
             updateByQueryRequest.setAbortOnVersionConflict(false);
@@ -521,8 +529,12 @@ public class RequestConvertersTests extends ESTestCase {
         }
         if (randomBoolean()) {
             int size = randomIntBetween(100, 1000);
-            deleteByQueryRequest.setSize(size);
-            expectedParams.put("size", Integer.toString(size));
+            if (randomBoolean()) {
+                deleteByQueryRequest.setMaxDocs(size);
+            } else {
+                deleteByQueryRequest.setSize(size);
+            }
+            expectedParams.put("max_docs", Integer.toString(size));
         }
         if (randomBoolean()) {
             deleteByQueryRequest.setAbortOnVersionConflict(false);

client/rest-high-level/src/test/java/org/elasticsearch/client/documentation/CRUDDocumentationIT.java

@@ -824,9 +824,9 @@ public class CRUDDocumentationIT extends ESRestHighLevelClientTestCase {
             // tag::reindex-request-conflicts
             request.setConflicts("proceed"); // <1>
             // end::reindex-request-conflicts
-            // tag::reindex-request-size
-            request.setSize(10); // <1>
-            // end::reindex-request-size
+            // tag::reindex-request-maxDocs
+            request.setMaxDocs(10); // <1>
+            // end::reindex-request-maxDocs
             // tag::reindex-request-sourceSize
             request.setSourceBatchSize(100); // <1>
             // end::reindex-request-sourceSize
@@ -1026,9 +1026,9 @@ public class CRUDDocumentationIT extends ESRestHighLevelClientTestCase {
             // tag::update-by-query-request-query
             request.setQuery(new TermQueryBuilder("user", "kimchy")); // <1>
             // end::update-by-query-request-query
-            // tag::update-by-query-request-size
-            request.setSize(10); // <1>
-            // end::update-by-query-request-size
+            // tag::update-by-query-request-maxDocs
+            request.setMaxDocs(10); // <1>
+            // end::update-by-query-request-maxDocs
             // tag::update-by-query-request-scrollSize
             request.setBatchSize(100); // <1>
             // end::update-by-query-request-scrollSize
@@ -1148,9 +1148,9 @@ public class CRUDDocumentationIT extends ESRestHighLevelClientTestCase {
             // tag::delete-by-query-request-query
             request.setQuery(new TermQueryBuilder("user", "kimchy")); // <1>
             // end::delete-by-query-request-query
-            // tag::delete-by-query-request-size
-            request.setSize(10); // <1>
-            // end::delete-by-query-request-size
+            // tag::delete-by-query-request-maxDocs
+            request.setMaxDocs(10); // <1>
+            // end::delete-by-query-request-maxDocs
             // tag::delete-by-query-request-scrollSize
             request.setBatchSize(100); // <1>
             // end::delete-by-query-request-scrollSize

docs/java-rest/high-level/document/delete-by-query.asciidoc

@@ -39,11 +39,11 @@ include-tagged::{doc-tests-file}[{api}-request-query]
 --------------------------------------------------
 <1> Only copy documents which have field `user` set to `kimchy`
 
-It’s also possible to limit the number of processed documents by setting size.
+It’s also possible to limit the number of processed documents by setting `maxDocs`.
 
 ["source","java",subs="attributes,callouts,macros"]
 --------------------------------------------------
-include-tagged::{doc-tests-file}[{api}-request-size]
+include-tagged::{doc-tests-file}[{api}-request-maxDocs]
 --------------------------------------------------
 <1> Only copy 10 documents
 

docs/java-rest/high-level/document/reindex.asciidoc

@@ -65,11 +65,11 @@ include-tagged::{doc-tests-file}[{api}-request-query]
 --------------------------------------------------
 <1> Only copy documents which have field `user` set to `kimchy`
 
-It’s also possible to limit the number of processed documents by setting size.
+It’s also possible to limit the number of processed documents by setting `maxDocs`.
 
 ["source","java",subs="attributes,callouts,macros"]
 --------------------------------------------------
-include-tagged::{doc-tests-file}[{api}-request-size]
+include-tagged::{doc-tests-file}[{api}-request-maxDocs]
 --------------------------------------------------
 <1> Only copy 10 documents
 
@@ -90,7 +90,7 @@ include-tagged::{doc-tests-file}[{api}-request-pipeline]
 <1> set pipeline to `my_pipeline`
 
 If you want a particular set of documents from the source index you’ll need to use sort. If possible, prefer a more
-selective query to size and sort.
+selective query to maxDocs and sort.
 
 ["source","java",subs="attributes,callouts,macros"]
 --------------------------------------------------

docs/java-rest/high-level/document/update-by-query.asciidoc

@@ -40,11 +40,11 @@ include-tagged::{doc-tests-file}[{api}-request-query]
 --------------------------------------------------
 <1> Only copy documents which have field `user` set to `kimchy`
 
-It’s also possible to limit the number of processed documents by setting size.
+It’s also possible to limit the number of processed documents by setting `maxDocs`.
 
 ["source","java",subs="attributes,callouts,macros"]
 --------------------------------------------------
-include-tagged::{doc-tests-file}[{api}-request-size]
+include-tagged::{doc-tests-file}[{api}-request-maxDocs]
 --------------------------------------------------
 <1> Only copy 10 documents
 

docs/reference/docs/delete-by-query.asciidoc

@@ -571,11 +571,11 @@ sub-request proportionally.
 * Due to the nature of `slices` each sub-request won't get a perfectly even
 portion of the documents. All documents will be addressed, but some slices may
 be larger than others. Expect larger slices to have a more even distribution.
-* Parameters like `requests_per_second` and `size` on a request with `slices`
-are distributed proportionally to each sub-request. Combine that with the point
-above about distribution being uneven and you should conclude that the using
-`size` with `slices` might not result in exactly `size` documents being
-deleted.
+* Parameters like `requests_per_second` and `max_docs` on a request with
+slices` are distributed proportionally to each sub-request. Combine that with
+the point above about distribution being uneven and you should conclude that
+using `max_docs` with `slices` might not result in exactly `max_docs` documents
+being deleted.
 * Each sub-request gets a slightly different snapshot of the source index
 though these are all taken at approximately the same time.
 

docs/reference/docs/reindex.asciidoc

@@ -190,14 +190,14 @@ not a good idea to rely on this behavior. Instead, make sure that IDs are unique
 using a script.
 
 It's also possible to limit the number of processed documents by setting
-`size`. This will only copy a single document from `twitter` to
+`max_docs`. This will only copy a single document from `twitter` to
 `new_twitter`:
 
 [source,js]
 --------------------------------------------------
 POST _reindex
 {
-  "size": 1,
+  "max_docs": 1,
   "source": {
     "index": "twitter"
   },
@@ -211,14 +211,14 @@ POST _reindex
 
 If you want a particular set of documents from the `twitter` index you'll
 need to use `sort`. Sorting makes the scroll less efficient but in some contexts
-it's worth it. If possible, prefer a more selective query to `size` and `sort`.
+it's worth it. If possible, prefer a more selective query to `max_docs` and `sort`.
 This will copy 10000 documents from `twitter` into `new_twitter`:
 
 [source,js]
 --------------------------------------------------
 POST _reindex
 {
-  "size": 10000,
+  "max_docs": 10000,
   "source": {
     "index": "twitter",
     "sort": { "date": "desc" }
@@ -1115,11 +1115,11 @@ sub-request proportionally.
 * Due to the nature of `slices` each sub-request won't get a perfectly even
 portion of the documents. All documents will be addressed, but some slices may
 be larger than others. Expect larger slices to have a more even distribution.
-* Parameters like `requests_per_second` and `size` on a request with `slices`
-are distributed proportionally to each sub-request. Combine that with the point
-above about distribution being uneven and you should conclude that the using
-`size` with `slices` might not result in exactly `size` documents being
-reindexed.
+* Parameters like `requests_per_second` and `max_docs` on a request with
+`slices` are distributed proportionally to each sub-request. Combine that with
+the point above about distribution being uneven and you should conclude that
+using `max_docs` with `slices` might not result in exactly `max_docs` documents
+being reindexed.
 * Each sub-request gets a slightly different snapshot of the source index,
 though these are all taken at approximately the same time.
 
@@ -1236,7 +1236,7 @@ to load only the existing data into the new index and rename any fields if neede
 ----------------------------------------------------------------
 POST _reindex
 {
-  "size": 10,
+  "max_docs": 10,
   "source": {
     "index": "twitter",
     "query": {

docs/reference/docs/update-by-query.asciidoc

@@ -602,11 +602,11 @@ sub-request proportionally.
 * Due to the nature of `slices` each sub-request won't get a perfectly even
 portion of the documents. All documents will be addressed, but some slices may
 be larger than others. Expect larger slices to have a more even distribution.
-* Parameters like `requests_per_second` and `size` on a request with `slices`
-are distributed proportionally to each sub-request. Combine that with the point
-above about distribution being uneven and you should conclude that the using
-`size` with `slices` might not result in exactly `size` documents being
-updated.
+* Parameters like `requests_per_second` and `max_docs` on a request with
+`slices` are distributed proportionally to each sub-request. Combine that with
+the point above about distribution being uneven and you should conclude that
+using `max_docs` with `slices` might not result in exactly `max_docs` documents
+being updated.
 * Each sub-request gets a slightly different snapshot of the source index
 though these are all taken at approximately the same time.
 

modules/reindex/src/main/java/org/elasticsearch/index/reindex/AbstractAsyncBulkByScrollAction.java

@@ -75,7 +75,7 @@ import static java.util.Collections.emptyList;
 import static java.util.Collections.unmodifiableList;
 import static org.elasticsearch.action.bulk.BackoffPolicy.exponentialBackoff;
 import static org.elasticsearch.common.unit.TimeValue.timeValueNanos;
-import static org.elasticsearch.index.reindex.AbstractBulkByScrollRequest.SIZE_ALL_MATCHES;
+import static org.elasticsearch.index.reindex.AbstractBulkByScrollRequest.MAX_DOCS_ALL_MATCHES;
 import static org.elasticsearch.rest.RestStatus.CONFLICT;
 import static org.elasticsearch.search.sort.SortBuilders.fieldSort;
 
@@ -263,8 +263,8 @@ public abstract class AbstractAsyncBulkByScrollAction<Request extends AbstractBu
             return;
         }
         long total = response.getTotalHits();
-        if (mainRequest.getSize() > 0) {
-            total = min(total, mainRequest.getSize());
+        if (mainRequest.getMaxDocs() > 0) {
+            total = min(total, mainRequest.getMaxDocs());
         }
         worker.setTotal(total);
         AbstractRunnable prepareBulkRequestRunnable = new AbstractRunnable() {
@@ -304,9 +304,9 @@ public abstract class AbstractAsyncBulkByScrollAction<Request extends AbstractBu
         }
         worker.countBatch();
         List<? extends ScrollableHitSource.Hit> hits = response.getHits();
-        if (mainRequest.getSize() != SIZE_ALL_MATCHES) {
-            // Truncate the hits if we have more than the request size
-            long remaining = max(0, mainRequest.getSize() - worker.getSuccessfullyProcessed());
+        if (mainRequest.getMaxDocs() != MAX_DOCS_ALL_MATCHES) {
+            // Truncate the hits if we have more than the request max docs
+            long remaining = max(0, mainRequest.getMaxDocs() - worker.getSuccessfullyProcessed());
             if (remaining < hits.size()) {
                 hits = hits.subList(0, (int) remaining);
             }
@@ -395,7 +395,7 @@ public abstract class AbstractAsyncBulkByScrollAction<Request extends AbstractBu
                 return;
             }
 
-            if (mainRequest.getSize() != SIZE_ALL_MATCHES && worker.getSuccessfullyProcessed() >= mainRequest.getSize()) {
+            if (mainRequest.getMaxDocs() != MAX_DOCS_ALL_MATCHES && worker.getSuccessfullyProcessed() >= mainRequest.getMaxDocs()) {
                 // We've processed all the requested docs.
                 refreshAndFinish(emptyList(), emptyList(), false);
                 return;

modules/reindex/src/main/java/org/elasticsearch/index/reindex/AbstractBaseReindexRestHandler.java

@@ -19,8 +19,8 @@
 
 package org.elasticsearch.index.reindex;
 
-import org.elasticsearch.action.ActionRequestValidationException;
 import org.elasticsearch.action.Action;
+import org.elasticsearch.action.ActionRequestValidationException;
 import org.elasticsearch.action.support.ActiveShardCount;
 import org.elasticsearch.client.node.NodeClient;
 import org.elasticsearch.common.settings.Settings;
@@ -105,6 +105,11 @@ public abstract class AbstractBaseReindexRestHandler<
         if (requestsPerSecond != null) {
             request.setRequestsPerSecond(requestsPerSecond);
         }
+
+        if (restRequest.hasParam("max_docs")) {
+            setMaxDocsValidateIdentical(request, restRequest.paramAsInt("max_docs", -1));
+        }
+
         return request;
     }
 
@@ -170,4 +175,13 @@ public abstract class AbstractBaseReindexRestHandler<
         }
         return requestsPerSecond;
     }
+
+    static void setMaxDocsValidateIdentical(AbstractBulkByScrollRequest<?> request, int maxDocs) {
+        if (request.getMaxDocs() != AbstractBulkByScrollRequest.MAX_DOCS_ALL_MATCHES && request.getMaxDocs() != maxDocs) {
+            throw new IllegalArgumentException("[max_docs] set to two different values [" + request.getMaxDocs() + "]" +
+                " and [" + maxDocs + "]");
+        } else {
+            request.setMaxDocs(maxDocs);
+        }
+    }
 }

modules/reindex/src/main/java/org/elasticsearch/index/reindex/AbstractBulkByQueryRestHandler.java

@@ -23,6 +23,7 @@ import org.elasticsearch.action.Action;
 import org.elasticsearch.action.search.SearchRequest;
 import org.elasticsearch.common.bytes.BytesReference;
 import org.elasticsearch.common.settings.Settings;
+import org.elasticsearch.common.xcontent.LoggingDeprecationHandler;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.common.xcontent.XContentFactory;
 import org.elasticsearch.common.xcontent.XContentParser;
@@ -52,7 +53,7 @@ public abstract class AbstractBulkByQueryRestHandler<
         SearchRequest searchRequest = internal.getSearchRequest();
 
         try (XContentParser parser = extractRequestSpecificFields(restRequest, bodyConsumers)) {
-            RestSearchAction.parseSearchRequest(searchRequest, restRequest, parser, internal::setSize);
+            RestSearchAction.parseSearchRequest(searchRequest, restRequest, parser, size -> setMaxDocsFromSearchSize(internal, size));
         }
 
         searchRequest.source().size(restRequest.paramAsInt("scroll_size", searchRequest.source().size()));
@@ -94,4 +95,9 @@ public abstract class AbstractBulkByQueryRestHandler<
                 parser.getDeprecationHandler(), BytesReference.bytes(builder.map(body)).streamInput());
         }
     }
+
+    private void setMaxDocsFromSearchSize(Request request, int size) {
+        LoggingDeprecationHandler.INSTANCE.usedDeprecatedName("size", "max_docs");
+        setMaxDocsValidateIdentical(request, size);
+    }
 }

modules/reindex/src/main/java/org/elasticsearch/index/reindex/RestDeleteByQueryAction.java

@@ -58,6 +58,7 @@ public class RestDeleteByQueryAction extends AbstractBulkByQueryRestHandler<Dele
 
         Map<String, Consumer<Object>> consumers = new HashMap<>();
         consumers.put("conflicts", o -> internal.setConflicts((String) o));
+        consumers.put("max_docs", s -> setMaxDocsValidateIdentical(internal, ((Number) s).intValue()));
 
         parseInternalRequest(internal, request, consumers);
 

modules/reindex/src/main/java/org/elasticsearch/index/reindex/RestReindexAction.java

@@ -92,7 +92,7 @@ public class RestReindexAction extends AbstractBaseReindexRestHandler<ReindexReq
 
         PARSER.declareField(sourceParser::parse, new ParseField("source"), ValueType.OBJECT);
         PARSER.declareField((p, v, c) -> destParser.parse(p, v.getDestination(), c), new ParseField("dest"), ValueType.OBJECT);
-        PARSER.declareInt(ReindexRequest::setSize, new ParseField("size"));
+        PARSER.declareInt(RestReindexAction::setMaxDocsValidateIdentical, new ParseField("max_docs", "size"));
         PARSER.declareField((p, v, c) -> v.setScript(Script.parse(p)), new ParseField("script"),
                 ValueType.OBJECT);
         PARSER.declareString(ReindexRequest::setConflicts, new ParseField("conflicts"));

modules/reindex/src/main/java/org/elasticsearch/index/reindex/RestUpdateByQueryAction.java

@@ -66,6 +66,7 @@ public class RestUpdateByQueryAction extends AbstractBulkByQueryRestHandler<Upda
         Map<String, Consumer<Object>> consumers = new HashMap<>();
         consumers.put("conflicts", o -> internal.setConflicts((String) o));
         consumers.put("script", o -> internal.setScript(parseScript(o)));
+        consumers.put("max_docs", s -> setMaxDocsValidateIdentical(internal, ((Number) s).intValue()));
 
         parseInternalRequest(internal, request, consumers);
 

modules/reindex/src/test/java/org/elasticsearch/client/documentation/ReindexDocumentationIT.java

@@ -116,7 +116,7 @@ public class ReindexDocumentationIT extends ESIntegTestCase {
               new UpdateByQueryRequestBuilder(client, UpdateByQueryAction.INSTANCE);
             updateByQuery.source("source_index")
                 .filter(QueryBuilders.termQuery("level", "awesome"))
-                .size(1000)
+                .maxDocs(1000)
                 .script(new Script(ScriptType.INLINE,
                     "ctx._source.awesome = 'absolutely'",
                     "painless",
@@ -139,7 +139,7 @@ public class ReindexDocumentationIT extends ESIntegTestCase {
             UpdateByQueryRequestBuilder updateByQuery =
                new UpdateByQueryRequestBuilder(client, UpdateByQueryAction.INSTANCE);
             updateByQuery.source("source_index")
-                .size(100)
+                .maxDocs(100)
                 .source()
                 .addSort("cat", SortOrder.DESC);
             BulkByScrollResponse response = updateByQuery.get();

modules/reindex/src/test/java/org/elasticsearch/index/reindex/ReindexBasicTests.java

@@ -58,8 +58,8 @@ public class ReindexBasicTests extends ReindexTestCase {
         assertThat(copy.get(), matcher().created(2));
         assertHitCount(client().prepareSearch("dest_half").setSize(0).get(), 2);
 
-        // Limit with size
-        copy = reindex().source("source").destination("dest_size_one", "type").size(1).refresh(true);
+        // Limit with maxDocs
+        copy = reindex().source("source").destination("dest_size_one", "type").maxDocs(1).refresh(true);
         assertThat(copy.get(), matcher().created(1));
         assertHitCount(client().prepareSearch("dest_size_one").setSize(0).get(), 1);
     }
@@ -86,7 +86,7 @@ public class ReindexBasicTests extends ReindexTestCase {
         copy = reindex().source("source").destination("dest_half", "type").refresh(true);
         // Use a small batch size so we have to use more than one batch
         copy.source().setSize(5);
-        copy.size(half); // The real "size" of the request.
+        copy.maxDocs(half);
         assertThat(copy.get(), matcher().created(half).batches(half, 5));
         assertHitCount(client().prepareSearch("dest_half").setSize(0).get(), half);
     }
@@ -116,7 +116,7 @@ public class ReindexBasicTests extends ReindexTestCase {
         copy = reindex().source("source").destination("dest_half", "type").refresh(true).setSlices(slices);
         // Use a small batch size so we have to use more than one batch
         copy.source().setSize(5);
-        copy.size(half); // The real "size" of the request.
+        copy.maxDocs(half);
         BulkByScrollResponse response = copy.get();
         assertThat(response, matcher().created(lessThanOrEqualTo((long) half)).slices(hasSize(expectedSlices)));
         assertHitCount(client().prepareSearch("dest_half").setSize(0).get(), response.getCreated());

modules/reindex/src/test/java/org/elasticsearch/index/reindex/RoundTripTests.java

@@ -107,7 +107,11 @@ public class RoundTripTests extends ESTestCase {
         request.getSearchRequest().indices("test");
         request.getSearchRequest().source().size(between(1, 1000));
         if (randomBoolean()) {
-            request.setSize(between(1, Integer.MAX_VALUE));
+            if (randomBoolean()) {
+                request.setMaxDocs(between(1, Integer.MAX_VALUE));
+            } else {
+                request.setSize(between(1, Integer.MAX_VALUE));
+            }
         }
         request.setAbortOnVersionConflict(random().nextBoolean());
         request.setRefresh(rarely());

modules/reindex/src/test/resources/rest-api-spec/test/delete_by_query/10_basic.yml

@@ -281,6 +281,56 @@
 
 ---
 "Limit by size":
+  - skip:
+      version: " - 7.1.99"
+      reason: "deprecation warnings only emitted on 7.2+"
+      features: warnings
+
+  - do:
+      index:
+        index:  twitter
+        id:     1
+        body:   { "user": "kimchy" }
+  - do:
+      index:
+        index:  twitter
+        id:     2
+        body:   { "user": "kimchy" }
+  - do:
+      indices.refresh: {}
+
+  - do:
+      warnings:
+        - Deprecated field [size] used, expected [max_docs] instead
+      delete_by_query:
+        index: twitter
+        size: 1
+        body:
+          query:
+            match_all: {}
+
+  - match: {deleted: 1}
+  - match: {version_conflicts: 0}
+  - match: {batches: 1}
+  - match: {failures: []}
+  - match: {throttled_millis: 0}
+  - gte: { took: 0 }
+
+  - do:
+      indices.refresh: {}
+
+  - do:
+      count:
+        index: twitter
+
+  - match: {count: 1}
+
+---
+"Limit by size pre 7.2":
+  - skip:
+      version: "7.2.0 - "
+      reason: "7.2 should use max_docs or get deprecation warning"
+
   - do:
       index:
         index:  twitter
@@ -318,6 +368,93 @@
 
   - match: {count: 1}
 
+---
+"Limit by max_docs in URL":
+  - skip:
+      version: " - 7.1.99"
+      reason: "max_docs introduced in 7.2.0"
+
+  - do:
+      index:
+        index:  twitter
+        id:     1
+        body:   { "user": "kimchy" }
+  - do:
+      index:
+        index:  twitter
+        id:     2
+        body:   { "user": "kimchy" }
+  - do:
+      indices.refresh: {}
+
+  - do:
+      delete_by_query:
+        index: twitter
+        max_docs: 1
+        body:
+          query:
+            match_all: {}
+
+  - match: {deleted: 1}
+  - match: {version_conflicts: 0}
+  - match: {batches: 1}
+  - match: {failures: []}
+  - match: {throttled_millis: 0}
+  - gte: { took: 0 }
+
+  - do:
+      indices.refresh: {}
+
+  - do:
+      count:
+        index: twitter
+
+  - match: {count: 1}
+
+---
+"Limit by max_docs in body":
+  - skip:
+      version: " - 7.1.99"
+      reason: "max_docs introduced in 7.2.0"
+
+  - do:
+      index:
+        index:  twitter
+        id:     1
+        body:   { "user": "kimchy" }
+  - do:
+      index:
+        index:  twitter
+        id:     2
+        body:   { "user": "kimchy" }
+  - do:
+      indices.refresh: {}
+
+  - do:
+      delete_by_query:
+        index: twitter
+        body:
+          max_docs: 1
+          query:
+            match:
+              user: "kimchy"
+
+  - match: {deleted: 1}
+  - match: {version_conflicts: 0}
+  - match: {batches: 1}
+  - match: {failures: []}
+  - match: {throttled_millis: 0}
+  - gte: { took: 0 }
+
+  - do:
+      indices.refresh: {}
+
+  - do:
+      count:
+        index: twitter
+
+  - match: {count: 1}
+
 ---
 "Can override scroll_size":
   - do:

modules/reindex/src/test/resources/rest-api-spec/test/delete_by_query/20_validation.yml

@@ -38,7 +38,7 @@
         id:      1
         body:    { "text": "test" }
   - do:
-      catch: /\[size\] parameter cannot be negative, found \[-4\]/
+      catch: /\[max_docs\] parameter cannot be negative, found \[-4\]/
       delete_by_query:
         index: test
         size: -4
@@ -46,6 +46,47 @@
           query:
             match_all: {}
 
+---
+"invalid max_docs fails":
+  - skip:
+      version: " - 7.1.99"
+      reason: "max_docs introduced in 7.2.0"
+
+  - do:
+      index:
+        index:   test
+        id:      1
+        body:    { "text": "test" }
+  - do:
+      catch: /\[max_docs\] parameter cannot be negative, found \[-4\]/
+      delete_by_query:
+        index: test
+        max_docs: -4
+        body:
+          query:
+            match_all: {}
+
+---
+"both max_docs and size fails":
+  - skip:
+      version: " - 7.1.99"
+      reason: "max_docs introduced in 7.2.0"
+
+  - do:
+      index:
+        index:   test
+        id:      1
+        body:    { "text": "test" }
+  - do:
+      catch: /\[max_docs\] set to two different values \[4\] and \[5\]/
+      delete_by_query:
+        index: test
+        size: 4
+        max_docs: 5
+        body:
+          query:
+            match_all: {}
+
 ---
 "invalid scroll_size fails":
   - do:

modules/reindex/src/test/resources/rest-api-spec/test/reindex/20_validation.yml

@@ -102,7 +102,7 @@
         id:      1
         body:    { "text": "test" }
   - do:
-      catch: /\[size\] parameter cannot be negative, found \[-4\]/
+      catch: /\[max_docs\] parameter cannot be negative, found \[-4\]/
       reindex:
         body:
           source:
@@ -111,6 +111,92 @@
             index: dest
           size: -4
 
+---
+"invalid max_docs in body fails":
+  - skip:
+      version: " - 7.1.99"
+      reason: "max_docs introduced in 7.2.0"
+
+  - do:
+      index:
+        index:   test
+        id:      1
+        body:    { "text": "test" }
+  - do:
+      catch: /\[max_docs\] parameter cannot be negative, found \[-4\]/
+      reindex:
+        body:
+          source:
+            index: test
+          dest:
+            index: dest
+          max_docs: -4
+
+---
+"invalid max_docs in URL fails":
+  - skip:
+      version: " - 7.1.99"
+      reason: "max_docs introduced in 7.2.0"
+
+  - do:
+      index:
+        index:   test
+        id:      1
+        body:    { "text": "test" }
+  - do:
+      catch: /\[max_docs\] parameter cannot be negative, found \[-4\]/
+      reindex:
+        max_docs: -4
+        body:
+          source:
+            index: test
+          dest:
+            index: dest
+
+---
+"inconsistent max_docs and size fails":
+  - skip:
+      version: " - 7.1.99"
+      reason: "max_docs introduced in 7.2.0"
+
+  - do:
+      index:
+        index:   test
+        id:      1
+        body:    { "text": "test" }
+  - do:
+      catch: /\[max_docs\] set to two different values \[4\] and \[5\]/
+      reindex:
+        body:
+          source:
+            index: test
+          dest:
+            index: dest
+          size: 4
+          max_docs: 5
+
+---
+"inconsistent max_docs in body and max_docs in URL fails":
+  - skip:
+      version: " - 7.1.99"
+      reason: "max_docs introduced in 7.2.0"
+
+  - do:
+      index:
+        index:   test
+        id:      1
+        body:    { "text": "test" }
+  - do:
+      catch: /\[max_docs\] set to two different values \[4\] and \[5\]/
+      reindex:
+        max_docs: 5
+        body:
+          source:
+            index: test
+          dest:
+            index: dest
+          max_docs: 4
+
 ---
 "requests_per_second cannot be an empty string":
   - do:

modules/reindex/src/test/resources/rest-api-spec/test/reindex/30_search.yml

@@ -33,6 +33,11 @@
 
 ---
 "Sorting and size combined":
+  - skip:
+      version: " - 7.1.99"
+      reason: "deprecation warnings only emitted on 7.2+"
+      features: warnings
+
   - do:
       index:
         index:  test
@@ -47,6 +52,8 @@
       indices.refresh: {}
 
   - do:
+      warnings:
+        - Deprecated field [size] used, expected [max_docs] instead
       reindex:
         refresh: true
         body:
@@ -69,3 +76,124 @@
         index: target
         q: order:1
   - match: { hits.total: 1 }
+
+---
+"Sorting and size combined pre 7.2":
+  - skip:
+      version: "7.2.0 - "
+      reason: "7.2 should use max_docs or get deprecation warning"
+
+  - do:
+      index:
+        index:  test
+        id:     1
+        body:   { "order": 1 }
+  - do:
+      index:
+        index:  test
+        id:     2
+        body:   { "order": 2 }
+  - do:
+      indices.refresh: {}
+
+  - do:
+      reindex:
+        refresh: true
+        body:
+          size: 1
+          source:
+            index: test
+            sort: order
+          dest:
+            index: target
+
+  - do:
+      search:
+        rest_total_hits_as_int: true
+        index: target
+  - match: { hits.total: 1 }
+
+  - do:
+      search:
+        rest_total_hits_as_int: true
+        index: target
+        q: order:1
+  - match: { hits.total: 1 }
+
+---
+"Sorting and max_docs in body combined":
+  - skip:
+      version: " - 7.1.99"
+      reason: "max_docs introduced in 7.2.0"
+
+  - do:
+      index:
+        index:  test
+        id:     1
+        body:   { "order": 1 }
+  - do:
+      index:
+        index:  test
+        id:     2
+        body:   { "order": 2 }
+  - do:
+      indices.refresh: {}
+
+  - do:
+      reindex:
+        refresh: true
+        body:
+          max_docs: 1
+          source:
+            index: test
+            sort: order
+          dest:
+            index: target
+
+  - do:
+      search:
+        rest_total_hits_as_int: true
+        index: target
+  - match: { hits.total: 1 }
+
+  - do:
+      search:
+        rest_total_hits_as_int: true
+        index: target
+        q: order:1
+  - match: { hits.total: 1 }
+
+---
+"max_docs in URL":
+  - skip:
+      version: " - 7.1.99"
+      reason: "max_docs introduced in 7.2.0"
+
+  - do:
+      index:
+        index:  test
+        id:     1
+        body:   { "value": 17 }
+  - do:
+      index:
+        index:  test
+        id:     2
+        body:   { "value": 17 }
+  - do:
+      indices.refresh: {}
+
+  - do:
+      reindex:
+        refresh: true
+        max_docs: 1
+        body:
+          source:
+            index: test
+          dest:
+            index: target
+
+  - do:
+      search:
+        rest_total_hits_as_int: true
+        index: target
+  - match: { hits.total: 1 }

modules/reindex/src/test/resources/rest-api-spec/test/reindex/90_remote.yml

@@ -219,6 +219,10 @@
 
 ---
 "Reindex from remote with size":
+  - skip:
+      version: "7.2.0 - "
+      reason: "7.2 should use max_docs or get deprecation warning"
+
   - do:
       index:
         index:   source
@@ -279,6 +283,72 @@
         metric: search
   - match: {indices.source.total.search.open_contexts: 0}
 
+---
+"Reindex from remote with max_docs":
+  - skip:
+      version: " - 7.1.99"
+      reason: "max_docs introduced in 7.2.0"
+
+  - do:
+      index:
+        index:   source
+        id:      1
+        body:    { "text": "test" }
+        refresh: true
+  - do:
+      index:
+        index:   source
+        id:      2
+        body:    { "text": "test" }
+        refresh: true
+
+  # Fetch the http host. We use the host of the master because we know there will always be a master.
+  - do:
+      cluster.state: {}
+  - set: { master_node: master }
+  - do:
+      nodes.info:
+        metric: [ http ]
+  - is_true: nodes.$master.http.publish_address
+  - set: {nodes.$master.http.publish_address: host}
+  - do:
+      reindex:
+        refresh: true
+        body:
+          max_docs: 1
+          source:
+            remote:
+              host: http://${host}
+            index: source
+          dest:
+            index: dest
+  - match: {created: 1}
+  - match: {updated: 0}
+  - match: {version_conflicts: 0}
+  - match: {batches: 1}
+  - match: {failures: []}
+  - match: {throttled_millis: 0}
+  - gte: { took: 0 }
+  - is_false: task
+  - is_false: deleted
+
+  - do:
+      search:
+        rest_total_hits_as_int: true
+        index: dest
+        body:
+          query:
+            match:
+              text: test
+  - match: {hits.total: 1}
+
+  # Make sure reindex closed all the scroll contexts
+  - do:
+      indices.stats:
+        index: source
+        metric: search
+  - match: {indices.source.total.search.open_contexts: 0}
+
 ---
 "Reindex from remote with broken query":
   - do:

modules/reindex/src/test/resources/rest-api-spec/test/update_by_query/10_basic.yml

@@ -219,6 +219,43 @@
 
 ---
 "Limit by size":
+  - skip:
+      version: " - 7.1.99"
+      reason: "deprecation warnings only emitted on 7.2+"
+      features: warnings
+
+  - do:
+      index:
+        index:  twitter
+        id:     1
+        body:   { "user": "kimchy" }
+  - do:
+      index:
+        index:  twitter
+        id:     2
+        body:   { "user": "kimchy" }
+  - do:
+      indices.refresh: {}
+
+  - do:
+      warnings:
+        - Deprecated field [size] used, expected [max_docs] instead
+      update_by_query:
+        index: twitter
+        size: 1
+  - match: {updated: 1}
+  - match: {version_conflicts: 0}
+  - match: {batches: 1}
+  - match: {failures: []}
+  - match: {throttled_millis: 0}
+  - gte: { took: 0 }
+
+---
+"Limit by size pre 7.2":
+  - skip:
+      version: "7.2.0 - "
+      reason: "7.2 should use max_docs or get deprecation warning"
+
   - do:
       index:
         index:  twitter
@@ -243,6 +280,70 @@
   - match: {throttled_millis: 0}
   - gte: { took: 0 }
 
+---
+"Limit by max_docs in URL":
+  - skip:
+      version: " - 7.1.99"
+      reason: "max_docs introduced in 7.2.0"
+
+  - do:
+      index:
+        index:  twitter
+        id:     1
+        body:   { "user": "kimchy" }
+  - do:
+      index:
+        index:  twitter
+        id:     2
+        body:   { "user": "kimchy" }
+  - do:
+      indices.refresh: {}
+
+  - do:
+      update_by_query:
+        index: twitter
+        max_docs: 1
+  - match: {updated: 1}
+  - match: {version_conflicts: 0}
+  - match: {batches: 1}
+  - match: {failures: []}
+  - match: {throttled_millis: 0}
+  - gte: { took: 0 }
+
+---
+"Limit by max_docs in body":
+  - skip:
+      version: " - 7.1.99"
+      reason: "max_docs introduced in 7.2.0"
+
+  - do:
+      index:
+        index:  twitter
+        id:     1
+        body:   { "user": "kimchy" }
+  - do:
+      index:
+        index:  twitter
+        id:     2
+        body:   { "user": "kimchy" }
+  - do:
+      indices.refresh: {}
+
+  - do:
+      update_by_query:
+        index: twitter
+        body:
+          max_docs: 1
+          query:
+            match:
+              user: "kimchy"
+  - match: {updated: 1}
+  - match: {version_conflicts: 0}
+  - match: {batches: 1}
+  - match: {failures: []}
+  - match: {throttled_millis: 0}
+  - gte: { took: 0 }
+
 ---
 "Can override scroll_size":
   - do:

modules/reindex/src/test/resources/rest-api-spec/test/update_by_query/20_validation.yml

@@ -19,11 +19,88 @@
         id:      1
         body:    { "text": "test" }
   - do:
-      catch: /\[size\] parameter cannot be negative, found \[-4\]/
+      catch: /\[max_docs\] parameter cannot be negative, found \[-4\]/
       update_by_query:
         index: test
         size: -4
 
+---
+"invalid max_docs in URL fails":
+  - skip:
+      version: " - 7.1.99"
+      reason: "max_docs introduced in 7.2.0"
+
+  - do:
+      index:
+        index:   test
+        id:      1
+        body:    { "text": "test" }
+  - do:
+      catch: /\[max_docs\] parameter cannot be negative, found \[-4\]/
+      update_by_query:
+        index: test
+        max_docs: -4
+
+---
+"invalid max_docs in body fails":
+  - skip:
+      version: " - 7.1.99"
+      reason: "max_docs introduced in 7.2.0"
+
+  - do:
+      index:
+        index:   test
+        id:      1
+        body:    { "text": "test" }
+  - do:
+      catch: /\[max_docs\] parameter cannot be negative, found \[-4\]/
+      update_by_query:
+        index: test
+        body:
+          max_docs: -4
+
+---
+"inconsistent max_docs and size fails":
+  - skip:
+      version: " - 7.1.99"
+      reason: "max_docs introduced in 7.2.0"
+
+  - do:
+      index:
+        index:   test
+        id:      1
+        body:    { "text": "test" }
+  - do:
+      catch: /\[max_docs\] set to two different values \[4\] and \[5\]/
+      delete_by_query:
+        index: test
+        size: 4
+        max_docs: 5
+        body:
+          query:
+            match_all: {}
+
+---
+"inconsistent max_docs in body and max_docs in URL fails":
+  - skip:
+      version: " - 7.1.99"
+      reason: "max_docs introduced in 7.2.0"
+
+  - do:
+      index:
+        index:   test
+        id:      1
+        body:    { "text": "test" }
+  - do:
+      catch: /\[max_docs\] set to two different values \[4\] and \[5\]/
+      delete_by_query:
+        index: test
+        max_docs: 5
+        body:
+          max_docs: 4
+          query:
+            match_all: {}
+
 ---
 "invalid scroll_size fails":
   - do:

rest-api-spec/src/main/resources/rest-api-spec/api/delete_by_query.json

@@ -88,7 +88,11 @@
         },
         "size": {
           "type" : "number",
-          "description" : "Number of hits to return (default: 10)"
+          "description" : "Deprecated, please use `max_docs` instead"
+        },
+        "max_docs": {
+          "type" : "number",
+          "description" : "Maximum number of documents to process (default: all documents)"
         },
         "sort": {
           "type" : "list",

rest-api-spec/src/main/resources/rest-api-spec/api/reindex.json

@@ -39,6 +39,10 @@
           "type": "number",
           "default": 1,
           "description": "The number of slices this task should be divided into. Defaults to 1 meaning the task isn't sliced into subtasks."
+        },
+        "max_docs": {
+          "type" : "number",
+          "description" : "Maximum number of documents to process (default: all documents)"
         }
       }
     },

rest-api-spec/src/main/resources/rest-api-spec/api/update_by_query.json

@@ -92,7 +92,11 @@
         },
         "size": {
           "type" : "number",
-          "description" : "Number of hits to return (default: 10)"
+          "description" : "Deprecated, please use `max_docs` instead"
+        },
+        "max_docs": {
+          "type" : "number",
+          "description" : "Maximum number of documents to process (default: all documents)"
         },
         "sort": {
           "type" : "list",

server/src/main/java/org/elasticsearch/index/reindex/AbstractBulkByScrollRequest.java

@@ -42,7 +42,12 @@ import static org.elasticsearch.common.unit.TimeValue.timeValueMinutes;
 
 public abstract class AbstractBulkByScrollRequest<Self extends AbstractBulkByScrollRequest<Self>> extends ActionRequest {
 
-    public static final int SIZE_ALL_MATCHES = -1;
+    public static final int MAX_DOCS_ALL_MATCHES = -1;
+    /**
+     * @deprecated please use MAX_DOCS_ALL_MATCHES instead.
+     */
+    @Deprecated
+    public static final int SIZE_ALL_MATCHES = MAX_DOCS_ALL_MATCHES;
     public static final TimeValue DEFAULT_SCROLL_TIMEOUT = timeValueMinutes(5);
     public static final int DEFAULT_SCROLL_SIZE = 1000;
 
@@ -59,7 +64,7 @@ public abstract class AbstractBulkByScrollRequest<Self extends AbstractBulkByScr
      * Maximum number of processed documents. Defaults to -1 meaning process all
      * documents.
      */
-    private int size = SIZE_ALL_MATCHES;
+    private int maxDocs = MAX_DOCS_ALL_MATCHES;
 
     /**
      * Should version conflicts cause aborts? Defaults to true.
@@ -151,10 +156,10 @@ public abstract class AbstractBulkByScrollRequest<Self extends AbstractBulkByScr
         if (maxRetries < 0) {
             e = addValidationError("retries cannot be negative", e);
         }
-        if (false == (size == -1 || size > 0)) {
+        if (false == (maxDocs == -1 || maxDocs > 0)) {
             e = addValidationError(
-                    "size should be greater than 0 if the request is limited to some number of documents or -1 if it isn't but it was ["
-                            + size + "]",
+                    "maxDocs should be greater than 0 if the request is limited to some number of documents or -1 if it isn't but it was ["
+                            + maxDocs + "]",
                     e);
         }
         if (searchRequest.source().slice() != null && slices != DEFAULT_SLICES) {
@@ -166,20 +171,41 @@ public abstract class AbstractBulkByScrollRequest<Self extends AbstractBulkByScr
     /**
      * Maximum number of processed documents. Defaults to -1 meaning process all
      * documents.
+     * @deprecated please use getMaxDocs() instead.
      */
+    @Deprecated
     public int getSize() {
-        return size;
+        return getMaxDocs();
     }
 
     /**
      * Maximum number of processed documents. Defaults to -1 meaning process all
      * documents.
+     *
+     * @deprecated please use setMaxDocs(int) instead.
      */
+    @Deprecated
     public Self setSize(int size) {
-        if (size < 0) {
-            throw new IllegalArgumentException("[size] parameter cannot be negative, found [" + size + "]");
+        return setMaxDocs(size);
+    }
+
+    /**
+     * Maximum number of processed documents. Defaults to -1 meaning process all
+     * documents.
+     */
+    public int getMaxDocs() {
+        return maxDocs;
+    }
+
+    /**
+     * Maximum number of processed documents. Defaults to -1 meaning process all
+     * documents.
+     */
+    public Self setMaxDocs(int maxDocs) {
+        if (maxDocs < 0) {
+            throw new IllegalArgumentException("[max_docs] parameter cannot be negative, found [" + maxDocs + "]");
         }
-        this.size = size;
+        this.maxDocs = maxDocs;
         return self();
     }
 
@@ -404,10 +430,10 @@ public abstract class AbstractBulkByScrollRequest<Self extends AbstractBulkByScr
                 .setRequestsPerSecond(requestsPerSecond / totalSlices)
                 // Sub requests don't have workers
                 .setSlices(1);
-        if (size != -1) {
-            // Size is split between workers. This means the size might round
+        if (maxDocs != MAX_DOCS_ALL_MATCHES) {
+            // maxDocs is split between workers. This means the maxDocs might round
             // down!
-            request.setSize(size == SIZE_ALL_MATCHES ? SIZE_ALL_MATCHES : size / totalSlices);
+            request.setMaxDocs(maxDocs / totalSlices);
         }
         // Set the parent task so this task is cancelled if we cancel the parent
         request.setParentTask(slicingTask);
@@ -425,7 +451,7 @@ public abstract class AbstractBulkByScrollRequest<Self extends AbstractBulkByScr
         super.readFrom(in);
         searchRequest = new SearchRequest(in);
         abortOnVersionConflict = in.readBoolean();
-        size = in.readVInt();
+        maxDocs = in.readVInt();
         refresh = in.readBoolean();
         timeout = in.readTimeValue();
         activeShardCount = ActiveShardCount.readFrom(in);
@@ -440,7 +466,7 @@ public abstract class AbstractBulkByScrollRequest<Self extends AbstractBulkByScr
         super.writeTo(out);
         searchRequest.writeTo(out);
         out.writeBoolean(abortOnVersionConflict);
-        out.writeVInt(size);
+        out.writeVInt(maxDocs);
         out.writeBoolean(refresh);
         out.writeTimeValue(timeout);
         activeShardCount.writeTo(out);

server/src/main/java/org/elasticsearch/index/reindex/AbstractBulkByScrollRequestBuilder.java

@@ -67,10 +67,22 @@ public abstract class AbstractBulkByScrollRequestBuilder<
     }
 
     /**
-     * The maximum number of documents to attempt.
+     * Maximum number of processed documents. Defaults to processing all
+     * documents.
+     * @deprecated please use maxDocs(int) instead.
      */
+    @Deprecated
     public Self size(int size) {
-        request.setSize(size);
+        return maxDocs(size);
+    }
+
+
+    /**
+     * Maximum number of processed documents. Defaults to processing all
+     * documents.
+     */
+    public Self maxDocs(int maxDocs) {
+        request.setMaxDocs(maxDocs);
         return self();
     }
 

server/src/main/java/org/elasticsearch/index/reindex/ReindexRequest.java

@@ -308,8 +308,8 @@ public class ReindexRequest extends AbstractBulkIndexByScrollRequest<ReindexRequ
         }
         {
             // Other fields
-            if (getSize() != -1 || getSize() > 0) {
-                builder.field("size", getSize());
+            if (getMaxDocs() != -1) {
+                builder.field("max_docs", getMaxDocs());
             }
             if (getScript() != null) {
                 builder.field("script", getScript());

server/src/test/java/org/elasticsearch/index/reindex/AbstractBulkByScrollRequestTestCase.java

@@ -42,7 +42,11 @@ public abstract class AbstractBulkByScrollRequestTestCase<R extends AbstractBulk
         original.setRequestsPerSecond(
                 randomBoolean() ? Float.POSITIVE_INFINITY : randomValueOtherThanMany(r -> r < 0, ESTestCase::randomFloat));
         if (randomBoolean()) {
-            original.setSize(between(0, Integer.MAX_VALUE));
+            if (randomBoolean()) {
+                original.setMaxDocs(between(0, Integer.MAX_VALUE));
+            } else {
+                original.setSize(between(0, Integer.MAX_VALUE));
+            }
         }
 
         // it's not important how many slices there are, we just need a number for forSlice
@@ -64,8 +68,10 @@ public abstract class AbstractBulkByScrollRequestTestCase<R extends AbstractBulk
         assertEquals("slice requests always have a single worker", 1, forSliced.getSlices());
         assertEquals("requests_per_second is split between all workers", original.getRequestsPerSecond() / actualSlices,
                 forSliced.getRequestsPerSecond(), Float.MIN_NORMAL);
-        assertEquals("size is split evenly between all workers", original.getSize() == AbstractBulkByScrollRequest.SIZE_ALL_MATCHES
-                ? AbstractBulkByScrollRequest.SIZE_ALL_MATCHES : original.getSize() / actualSlices, forSliced.getSize());
+        assertEquals("max_docs is split evenly between all workers",
+            original.getMaxDocs() == AbstractBulkByScrollRequest.MAX_DOCS_ALL_MATCHES
+                ? AbstractBulkByScrollRequest.MAX_DOCS_ALL_MATCHES : original.getMaxDocs() / actualSlices,
+            forSliced.getMaxDocs());
         assertEquals(slicingTask, forSliced.getParentTask());
 
         extraForSliceAssertions(original, forSliced);

x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/action/TransportDeleteForecastAction.java

@@ -197,7 +197,7 @@ public class TransportDeleteForecastAction extends HandledTransportAction<Delete
     private DeleteByQueryRequest buildDeleteByQuery(String jobId, List<String> forecastsToDelete) {
         DeleteByQueryRequest request = new DeleteByQueryRequest()
             .setAbortOnVersionConflict(false) //since these documents are not updated, a conflict just means it was deleted previously
-            .setSize(MAX_FORECAST_TO_SEARCH)
+            .setMaxDocs(MAX_FORECAST_TO_SEARCH)
             .setSlices(5);
 
         request.indices(AnomalyDetectorsIndex.jobResultsAliasedName(jobId));