| <?xml version="1.0" encoding="UTF-8"?> |
| <!-- |
| Licensed to the Apache Software Foundation (ASF) under one |
| or more contributor license agreements. See the NOTICE file |
| distributed with this work for additional information |
| regarding copyright ownership. The ASF licenses this file |
| to you under the Apache License, Version 2.0 (the |
| "License"); you may not use this file except in compliance |
| with the License. You may obtain a copy of the License at |
| |
| http://www.apache.org/licenses/LICENSE-2.0 |
| |
| Unless required by applicable law or agreed to in writing, |
| software distributed under the License is distributed on an |
| "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| KIND, either express or implied. See the License for the |
| specific language governing permissions and limitations |
| under the License. |
| --> |
| <!DOCTYPE concept PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd"> |
| <concept id="max_mem_estimate_for_admission"> |
| |
| <title>MAX_MEM_ESTIMATE_FOR_ADMISSION Query Option</title> |
| |
| <titlealts audience="PDF"> |
| |
| <navtitle>MAX MEM ESTIMATE FOR ADMISSION</navtitle> |
| |
| </titlealts> |
| |
| <prolog> |
| <metadata> |
| <data name="Category" value="Impala"/> |
| <data name="Category" value="Impala Query Options"/> |
| <data name="Category" value="Querying"/> |
| <data name="Category" value="Developers"/> |
| <data name="Category" value="Data Analysts"/> |
| </metadata> |
| </prolog> |
| |
| <conbody> |
| |
| <p> |
| Use the <codeph>MAX_MEM_ESTIMATE_FOR_ADMISSION</codeph> query option to set an upper limit |
| on the memory estimates of a query as a workaround for over-estimates precluding a query |
| from being admitted. |
| </p> |
| |
| <p> |
| The query option takes effect when all of the below conditions are met: |
| </p> |
| |
| <ul> |
| <li> |
| Memory-based admission control is enabled for the pool. |
| </li> |
| |
| <li> |
| The <codeph>MEM_LIMIT</codeph> query option is not set at the query, session, resource |
| pool, or global level. |
| </li> |
| </ul> |
| |
| <p> |
| When the above conditions are met, MIN(<codeph>MAX_MEM_ESTIMATE_FOR_ADMISSION</codeph>, |
| mem_estimate) is used for admission control. |
| </p> |
| |
| <p> |
| Setting the <codeph>MEM_LIMIT</codeph> query option is usually a better option. Use the |
| <codeph>MAX_MEM_ESTIMATE_FOR_ADMISSION</codeph> query option when it is not feasible to |
| set <codeph>MEM_LIMIT</codeph> for each individual query. |
| </p> |
| |
| <p conref="../shared/impala_common.xml#common/type_integer"/> |
| |
| <p conref="../shared/impala_common.xml#common/default_blurb"/> |
| |
| <p> |
| <b>Added in:</b> <keyword keyref="impala31"/> |
| </p> |
| |
| <p conref="../shared/impala_common.xml#common/usage_notes_blurb"/> |
| |
| <p conref="../shared/impala_common.xml#common/related_info"/> |
| |
| </conbody> |
| |
| </concept> |