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| <h1 class="title topictitle1" id="ariaid-title1">Impala Transactions</h1> |
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| <p class="p"> |
| 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. |
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| <p class="p"> |
| 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. |
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| 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. |
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| For insert-only transactional tables, you can perform the following statements: |
| <code class="ph codeph">CREATE TABLE</code>, <code class="ph codeph">DROP TABLE</code>, <code class="ph codeph">TRUNCATE</code>, |
| <code class="ph codeph">INSERT</code>, <code class="ph codeph">SELECT</code> |
| </p> |
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| <p class="p"> |
| All transactions in Impala automatically commit at the end of the statement. Currently, |
| Impala does not support multi-statement transactions. |
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| <p class="p"> |
| Insert-only tables must be the managed and file-format based tables, such as Parquet, |
| Avro, and text. |
| </p> |
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| <div class="note note"><span class="notetitle">Note:</span> |
| Impala does not support changing transactional properties of tables. For example, you |
| cannot alter a transactional table to a non-transactional table. |
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| <div class="parentlink"><strong>Parent topic:</strong> <a class="link" href="../topics/impala_langref.html">Impala SQL Language Reference</a></div> |
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