'\" t
.\"     Title: START TRANSACTION
.\"    Author: The PostgreSQL Global Development Group
.\" Generator: DocBook XSL Stylesheets v1.75.2 <http://docbook.sf.net/>
.\"      Date: 2016
.\"    Manual: PostgreSQL 9.5.2 Documentation
.\"    Source: PostgreSQL 9.5.2
.\"  Language: English
.\"
.TH "START TRANSACTION" "5sql" "2016" "PostgreSQL 9.5.2" "PostgreSQL 9.5.2 Documentation"
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.SH "NAME"
START_TRANSACTION \- start a transaction block
.SH "SYNOPSIS"
.sp
.nf
START TRANSACTION [ \fItransaction_mode\fR [, \&.\&.\&.] ]

where \fItransaction_mode\fR is one of:

    ISOLATION LEVEL { SERIALIZABLE | REPEATABLE READ | READ COMMITTED | READ UNCOMMITTED }
    READ WRITE | READ ONLY
    [ NOT ] DEFERRABLE
.fi
.SH "DESCRIPTION"
.PP
This command begins a new transaction block\&. If the isolation level, read/write mode, or deferrable mode is specified, the new transaction has those characteristics, as if
SET TRANSACTION (\fBSET_TRANSACTION\fR(5))
was executed\&. This is the same as the
\fBBEGIN\fR(5)
command\&.
.SH "PARAMETERS"
.PP
Refer to
SET TRANSACTION (\fBSET_TRANSACTION\fR(5))
for information on the meaning of the parameters to this statement\&.
.SH "COMPATIBILITY"
.PP
In the standard, it is not necessary to issue
\fBSTART TRANSACTION\fR
to start a transaction block: any SQL command implicitly begins a block\&.
PostgreSQL\(aqs behavior can be seen as implicitly issuing a
\fBCOMMIT\fR
after each command that does not follow
\fBSTART TRANSACTION\fR
(or
\fBBEGIN\fR), and it is therefore often called
\(lqautocommit\(rq\&. Other relational database systems might offer an autocommit feature as a convenience\&.
.PP
The
DEFERRABLE
\fItransaction_mode\fR
is a
PostgreSQL
language extension\&.
.PP
The SQL standard requires commas between successive
\fItransaction_modes\fR, but for historical reasons
PostgreSQL
allows the commas to be omitted\&.
.PP
See also the compatibility section of
SET TRANSACTION (\fBSET_TRANSACTION\fR(5))\&.
.SH "SEE ALSO"
\fBBEGIN\fR(5), \fBCOMMIT\fR(5), \fBROLLBACK\fR(5), \fBSAVEPOINT\fR(5), SET TRANSACTION (\fBSET_TRANSACTION\fR(5))