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  <div class="section" id="lock-acquire">
<h1><span class="section-number">7.3.26. </span><code class="docutils literal notranslate"><span class="pre">lock_acquire</span></code><a class="headerlink" href="#lock-acquire" title="Permalink to this headline">¶</a></h1>
<div class="section" id="summary">
<h2><span class="section-number">7.3.26.1. </span>Summary<a class="headerlink" href="#summary" title="Permalink to this headline">¶</a></h2>
<div class="versionadded">
<p><span class="versionmodified added">New in version 5.1.2.</span></p>
</div>
<p><code class="docutils literal notranslate"><span class="pre">lock_acquire</span></code> command acquires the lock of the target object. The
target object is one of database, table and column.</p>
<div class="admonition note">
<p class="admonition-title">Note</p>
<p>This is a dangerous command. You must release locks by
<a class="reference internal" href="lock_release.html"><span class="doc">lock_release</span></a> that you acquire when these locks are no longer
needed. If you forget to release these locks, your database may be
broken.</p>
</div>
</div>
<div class="section" id="syntax">
<h2><span class="section-number">7.3.26.2. </span>Syntax<a class="headerlink" href="#syntax" title="Permalink to this headline">¶</a></h2>
<p>This command takes only one optional parameter:</p>
<div class="highlight-none notranslate"><div class="highlight"><pre><span></span>lock_acquire [target_name=null]
</pre></div>
</div>
<p>If <code class="docutils literal notranslate"><span class="pre">target_name</span></code> parameters is omitted, database is used for the
target object.</p>
</div>
<div class="section" id="usage">
<h2><span class="section-number">7.3.26.3. </span>Usage<a class="headerlink" href="#usage" title="Permalink to this headline">¶</a></h2>
<p>Here is an example to acquire the lock of the database:</p>
<p>Execution example:</p>
<div class="highlight-none notranslate"><div class="highlight"><pre><span></span>lock_acquire
# [[0, 1337566253.89858, 0.000355720520019531], true]
</pre></div>
</div>
<p>If the database is locked, you can’t create a new table and
column. Release the lock of the database to show another examples.</p>
<p>Execution example:</p>
<div class="highlight-none notranslate"><div class="highlight"><pre><span></span>lock_release
# [[0, 1337566253.89858, 0.000355720520019531], true]
</pre></div>
</div>
<p>Here is an example to acquire the lock of <code class="docutils literal notranslate"><span class="pre">Entries</span></code> table:</p>
<p>Execution example:</p>
<div class="highlight-none notranslate"><div class="highlight"><pre><span></span>table_create Entries TABLE_NO_KEY
# [[0, 1337566253.89858, 0.000355720520019531], true]
lock_acquire Entries
# [[0, 1337566253.89858, 0.000355720520019531], true]
</pre></div>
</div>
<p>Here is an example to acquire the lock of <code class="docutils literal notranslate"><span class="pre">Sites.title</span></code> column:</p>
<p>Execution example:</p>
<div class="highlight-none notranslate"><div class="highlight"><pre><span></span>table_create Sites TABLE_HASH_KEY ShortText
# [[0, 1337566253.89858, 0.000355720520019531], true]
column_create Sites title COLUMN_SCALAR ShortText
# [[0, 1337566253.89858, 0.000355720520019531], true]
lock_acquire Sites.title
# [[0, 1337566253.89858, 0.000355720520019531], true]
</pre></div>
</div>
</div>
<div class="section" id="parameters">
<h2><span class="section-number">7.3.26.4. </span>Parameters<a class="headerlink" href="#parameters" title="Permalink to this headline">¶</a></h2>
<p>This section describes all parameters.</p>
<div class="section" id="target-name">
<h3><span class="section-number">7.3.26.4.1. </span><code class="docutils literal notranslate"><span class="pre">target_name</span></code><a class="headerlink" href="#target-name" title="Permalink to this headline">¶</a></h3>
<p>Specifies the name of table or column.</p>
<p>If you don’t specify it, database is used for the target object.</p>
<p>The default is none. It means that the target object is database.</p>
</div>
</div>
<div class="section" id="return-value">
<h2><span class="section-number">7.3.26.5. </span>Return value<a class="headerlink" href="#return-value" title="Permalink to this headline">¶</a></h2>
<p><code class="docutils literal notranslate"><span class="pre">lock_acquire</span></code> command returns whether lock is acquired or not:</p>
<div class="highlight-none notranslate"><div class="highlight"><pre><span></span>[HEADER, SUCCEEDED_OR_NOT]
</pre></div>
</div>
<div class="section" id="header">
<h3><span class="section-number">7.3.26.5.1. </span><code class="docutils literal notranslate"><span class="pre">HEADER</span></code><a class="headerlink" href="#header" title="Permalink to this headline">¶</a></h3>
<p>See <a class="reference internal" href="../command/output_format.html"><span class="doc">Output format</span></a> about <code class="docutils literal notranslate"><span class="pre">HEADER</span></code>.</p>
</div>
<div class="section" id="succeeded-or-not">
<h3><span class="section-number">7.3.26.5.2. </span><code class="docutils literal notranslate"><span class="pre">SUCCEEDED_OR_NOT</span></code><a class="headerlink" href="#succeeded-or-not" title="Permalink to this headline">¶</a></h3>
<p>If command succeeded, it returns true, otherwise it returns false on error.</p>
</div>
</div>
<div class="section" id="see-also">
<h2><span class="section-number">7.3.26.6. </span>See also<a class="headerlink" href="#see-also" title="Permalink to this headline">¶</a></h2>
<blockquote>
<div><ul class="simple">
<li><p><a class="reference internal" href="lock_release.html"><span class="doc">lock_release</span></a></p></li>
<li><p><a class="reference internal" href="lock_clear.html"><span class="doc">lock_clear</span></a></p></li>
</ul>
</div></blockquote>
</div>
</div>


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  <ul>
<li><a class="reference internal" href="#">7.3.26. <code class="docutils literal notranslate"><span class="pre">lock_acquire</span></code></a><ul>
<li><a class="reference internal" href="#summary">7.3.26.1. Summary</a></li>
<li><a class="reference internal" href="#syntax">7.3.26.2. Syntax</a></li>
<li><a class="reference internal" href="#usage">7.3.26.3. Usage</a></li>
<li><a class="reference internal" href="#parameters">7.3.26.4. Parameters</a><ul>
<li><a class="reference internal" href="#target-name">7.3.26.4.1. <code class="docutils literal notranslate"><span class="pre">target_name</span></code></a></li>
</ul>
</li>
<li><a class="reference internal" href="#return-value">7.3.26.5. Return value</a><ul>
<li><a class="reference internal" href="#header">7.3.26.5.1. <code class="docutils literal notranslate"><span class="pre">HEADER</span></code></a></li>
<li><a class="reference internal" href="#succeeded-or-not">7.3.26.5.2. <code class="docutils literal notranslate"><span class="pre">SUCCEEDED_OR_NOT</span></code></a></li>
</ul>
</li>
<li><a class="reference internal" href="#see-also">7.3.26.6. See also</a></li>
</ul>
</li>
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