blob: 45f449261248591e24010ed546d256715ca7e30a [file] [log] [blame]
<?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
Unless required by applicable law or agreed to in writing,
software distributed under the License is distributed on an
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="transactions">
<title>Impala Transactions</title>
<titlealts audience="PDF">
A transaction is a single logical operation on the data. Impala supports transactions that
satisfy a level of consistency that improves the integrity and reliability of the data
before and after a transaction.
Specifically, Impala provides atomicity and isolation of insert operations on
transactional tables. A single table insert is either committed in full or not committed,
and the results of the insert operation are not visible to other query operations until
the operation is committed.
For single table, the inserts are ordered, so if Impala doesn't see a committed insert, it
won't see any insert committed after it.
For insert-only transactional tables, you can perform the following statements:
<codeph>CREATE TABLE</codeph>, <codeph>DROP TABLE</codeph>, <codeph>TRUNCATE</codeph>,
<codeph>INSERT</codeph>, <codeph>SELECT</codeph>
All transactions in Impala automatically commit at the end of the statement. Currently,
Impala does not support multi-statement transactions.
Insert-only tables must be the managed and file-format based tables, such as Parquet,
Avro, and text.
Impala does not support changing transactional properties of tables. For example, you
cannot alter a transactional table to a non-transactional table.