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copied!<p>In PL/PgSQL parser, assignment operator is defined as </p> <pre><code>assign_operator : '=' | COLON_EQUALS ; </code></pre> <p>This is a legacy feature, present in source code since 1998, when it was introduced - as we can see in the <a href="http://git.postgresql.org/gitweb/?p=postgresql.git;a=commit;h=863a62064cfc2b706dd6ab45487d15cc33cedb35" rel="nofollow noreferrer">PostgreSQL Git repo</a>.</p> <p>Starting from version 9.4 it is <a href="https://www.postgresql.org/docs/9.4/static/plpgsql-statements.html" rel="nofollow noreferrer">oficially documented</a>.</p> <p>This idiosyncrasy - of having two operators for same thing - was raised on pgsql users list, and some people requested it to be removed, but it's still kept in the core because fair corpus of legacy code relies on it.</p> <p>See this <a href="http://archives.postgresql.org/pgsql-bugs/2011-08/msg00140.php" rel="nofollow noreferrer">message from Tom Lane (core Pg developer)</a>.</p> <p>So, to answer your questions straight:</p> <blockquote> <p>Didn't I find some section in the docs which mention and/or explains this?</p> </blockquote> <p>You did not find it because it was undocumented, which is fixed as of version 9.4.</p> <blockquote> <p>Are there any known consequences using = instead of :=.</p> </blockquote> <p>There are no side consequences of using <strong>=</strong>, but you should use <strong>:=</strong> for assignment to make your code more readable, and (as a side effect) more compatible with PL/SQL.</p> <p>Update: there may be a side consequence in rare scenarios (see Erwin's answer) </p> <hr> <p>UPDATE: answer updated thanks to input from Daniel, Sandy & others. </p>

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