Zen

Source string Source string

216/10000 · 216
English Actions
Variation: ``EXPLAIN QUERY PLAN statement;`` shows the steps of a search.
Statements for transactions
START TRANSACTION
:samp:`START TRANSACTION;`
Start a transaction. After ``START TRANSACTION;``, a transaction is "active". If a transaction is already active, then ``START TRANSACTION;`` is illegal.
Transactions should be active for fairly short periods of time, to avoid concurrency issues. To end a transaction, say :ref:`COMMIT; <sql_commit>` or :ref:`ROLLBACK; <sql_rollback>`.
Just as in NoSQL, transaction control statements are subject to limitations set by the :ref:`storage engine <engines-chapter>` involved: |br| * For the memtx storage engine, if a yield happens within an active transaction, the transaction is rolled back. |br| * For the vinyl engine, yields are allowed. |br| Also, although CREATE AND DROP and ALTER statements are legal in transactions, there are a few exceptions. For example, :samp:`CREATE INDEX ON {table_name} ...` will fail within a multi-statement transaction if the table is not empty.
However, transaction control statements still may not work as you expect when run over a network connection: a transaction is associated with a fiber, not a network connection, and different transaction control statements sent via the same network connection may be executed by different fibers from the fiber pool.
In order to ensure that all statements are part of the intended transaction, put all of them between ``START TRANSACTION;`` and ``COMMIT;`` or ``ROLLBACK;`` then send as a single batch. For example:
Enclose each separate SQL statement in a :ref:`box.execute() <box-sql_box_execute>` function.
Pass all the ``box.execute()`` functions to the server in a single message.
If you are using a console, you can do this by writing everything on a single line.
If you are using :ref:`net.box <net_box-module>`, you can do this by putting all the function calls in a single string and calling :ref:`eval(string) <net_box-eval>`.
START TRANSACTION;
Example of a whole transaction sent to a server on ``localhost:3301`` with ``eval(string)``:
net_box = require('net.box')
conn = net_box.new('localhost', 3301)
s = 'box.execute([[START TRANSACTION;]]) '
s = s .. 'box.execute([[INSERT INTO t VALUES (1);]]) '
s = s .. 'box.execute([[ROLLBACK;]]) '
conn:eval(s)
COMMIT
:samp:`COMMIT;`
Commit an active transaction, so all changes are made permanent and the transaction ends.
COMMIT is illegal unless a transaction is active. If a transaction is not active then SQL statements are committed automatically.
COMMIT;
SAVEPOINT
:samp:`SAVEPOINT {savepoint-name};`
Set a savepoint, so that :ref:`ROLLBACK TO savepoint-name <sql_rollback>` is possible.
SAVEPOINT is illegal unless a transaction is active.
If a savepoint with the same name already exists, it is released before the new savepoint is set.
SAVEPOINT x;
RELEASE SAVEPOINT
:samp:`RELEASE SAVEPOINT {savepoint-name};`
Release (destroy) a savepoint created by a :ref:`SAVEPOINT statement <sql_savepoint>`.
RELEASE is illegal unless a transaction is active.

Loading…

User avatar None

New source string

testing_project / Documentation: reference/reference_sql/sql_statements_and_clauses — English

net_box = require('net.box')
conn = net_box.new('localhost', 3301)
s = 'box.execute([[START TRANSACTION;]]) '
s = s .. 'box.execute([[INSERT INTO t VALUES (1);]]) '
s = s .. 'box.execute([[ROLLBACK;]]) '
conn:eval(s)
a year ago
Browse all string changes

Things to check

Unpluralised

The string is used as plural, but not using plural forms

Reset

Glossary

English English
No related strings found in the glossary.

String information

Flags
read-only
String age
a year ago
Last updated
a year ago
Source string age
a year ago
Translation file
string 704