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Change-Id: Ib457775fab03d7f30430fd7dea6404dfcf0783a8 Reviewed-on: http://gerrit.cloudera.org:8080/14235 Tested-by: Impala Public Jenkins <impala-public-jenkins@cloudera.com> Reviewed-by: Zoltan Borok-Nagy <boroknagyz@cloudera.com>
75 lines
2.5 KiB
XML
75 lines
2.5 KiB
XML
<?xml version="1.0" encoding="UTF-8"?>
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<!--
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Licensed to the Apache Software Foundation (ASF) under one
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or more contributor license agreements. See the NOTICE file
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distributed with this work for additional information
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regarding copyright ownership. The ASF licenses this file
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to you under the Apache License, Version 2.0 (the
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"License"); you may not use this file except in compliance
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with the License. You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing,
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software distributed under the License is distributed on an
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"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
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KIND, either express or implied. See the License for the
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specific language governing permissions and limitations
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under the License.
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-->
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<!DOCTYPE concept PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">
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<concept id="transactions">
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<title>Impala Transactions</title>
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<titlealts audience="PDF">
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<navtitle>Transactions</navtitle>
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</titlealts>
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<conbody>
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<p>
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A transaction is a single logical operation on the data. Impala supports transactions that
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satisfy a level of consistency that improves the integrity and reliability of the data
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before and after a transaction.
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</p>
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<p>
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Specifically, Impala provides atomicity and isolation of insert operations on
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transactional tables. A single table insert is either committed in full or not committed,
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and the results of the insert operation are not visible to other query operations until
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the operation is committed.
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</p>
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<p>
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For single table, the inserts are ordered, so if Impala doesn't see a committed insert, it
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won't see any insert committed after it.
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</p>
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<p>
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For insert-only transactional tables, you can perform the following statements:
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<codeph>CREATE TABLE</codeph>, <codeph>DROP TABLE</codeph>, <codeph>TRUNCATE</codeph>,
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<codeph>INSERT</codeph>, <codeph>SELECT</codeph>
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</p>
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<p>
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All transactions in Impala automatically commit at the end of the statement. Currently,
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Impala does not support multi-statement transactions.
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</p>
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<p>
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Insert-only tables must be the managed and file-format based tables, such as Parquet,
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Avro, and text.
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</p>
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<note>
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Impala does not support changing transactional properties of tables. For example, you
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cannot alter a transactional table to a non-transactional table.
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</note>
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</conbody>
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</concept>
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