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<div class="section" id="execution-profiles">
<h1>Execution Profiles<a class="headerlink" href="#execution-profiles" title="Permalink to this headline">¶</a></h1>
<p>Execution profiles aim at making it easier to execute requests in different ways within
a single connected <code class="docutils literal"><span class="pre">Session</span></code>. Execution profiles are being introduced to deal with the exploding number of
configuration options, especially as the database platform evolves more complex workloads.</p>
<p>The legacy configuration remains intact, but legacy and Execution Profile APIs
cannot be used simultaneously on the same client <code class="docutils literal"><span class="pre">Cluster</span></code>. Legacy configuration
will be removed in the next major release (4.0).</p>
<p>This document explains how Execution Profiles relate to existing settings, and shows how to use the new profiles for
request execution.</p>
<div class="section" id="mapping-legacy-parameters-to-profiles">
<h2>Mapping Legacy Parameters to Profiles<a class="headerlink" href="#mapping-legacy-parameters-to-profiles" title="Permalink to this headline">¶</a></h2>
<p>Execution profiles can inherit from <a class="reference internal" href="api/cassandra/cluster.html#cassandra.cluster.ExecutionProfile" title="cassandra.cluster.ExecutionProfile"><code class="xref py py-class docutils literal"><span class="pre">cluster.ExecutionProfile</span></code></a>, and currently provide the following options,
previously input from the noted attributes:</p>
<ul class="simple">
<li>load_balancing_policy - <a class="reference internal" href="api/cassandra/cluster.html#cassandra.cluster.Cluster.load_balancing_policy" title="cassandra.cluster.Cluster.load_balancing_policy"><code class="xref py py-attr docutils literal"><span class="pre">Cluster.load_balancing_policy</span></code></a></li>
<li>request_timeout - <a class="reference internal" href="api/cassandra/cluster.html#cassandra.cluster.Session.default_timeout" title="cassandra.cluster.Session.default_timeout"><code class="xref py py-attr docutils literal"><span class="pre">Session.default_timeout</span></code></a>, optional <a class="reference internal" href="api/cassandra/cluster.html#cassandra.cluster.Session.execute" title="cassandra.cluster.Session.execute"><code class="xref py py-meth docutils literal"><span class="pre">Session.execute()</span></code></a> parameter</li>
<li>retry_policy - <a class="reference internal" href="api/cassandra/cluster.html#cassandra.cluster.Cluster.default_retry_policy" title="cassandra.cluster.Cluster.default_retry_policy"><code class="xref py py-attr docutils literal"><span class="pre">Cluster.default_retry_policy</span></code></a>, optional <a class="reference internal" href="api/cassandra/query.html#cassandra.query.Statement.retry_policy" title="cassandra.query.Statement.retry_policy"><code class="xref py py-attr docutils literal"><span class="pre">Statement.retry_policy</span></code></a> attribute</li>
<li>consistency_level - <a class="reference internal" href="api/cassandra/cluster.html#cassandra.cluster.Session.default_consistency_level" title="cassandra.cluster.Session.default_consistency_level"><code class="xref py py-attr docutils literal"><span class="pre">Session.default_consistency_level</span></code></a>, optional <a class="reference internal" href="api/cassandra/query.html#cassandra.query.Statement.consistency_level" title="cassandra.query.Statement.consistency_level"><code class="xref py py-attr docutils literal"><span class="pre">Statement.consistency_level</span></code></a> attribute</li>
<li>serial_consistency_level - <a class="reference internal" href="api/cassandra/cluster.html#cassandra.cluster.Session.default_serial_consistency_level" title="cassandra.cluster.Session.default_serial_consistency_level"><code class="xref py py-attr docutils literal"><span class="pre">Session.default_serial_consistency_level</span></code></a>, optional <a class="reference internal" href="api/cassandra/query.html#cassandra.query.Statement.serial_consistency_level" title="cassandra.query.Statement.serial_consistency_level"><code class="xref py py-attr docutils literal"><span class="pre">Statement.serial_consistency_level</span></code></a> attribute</li>
<li>row_factory - <a class="reference internal" href="api/cassandra/cluster.html#cassandra.cluster.Session.row_factory" title="cassandra.cluster.Session.row_factory"><code class="xref py py-attr docutils literal"><span class="pre">Session.row_factory</span></code></a> attribute</li>
</ul>
<p>When using the new API, these parameters can be defined by instances of <a class="reference internal" href="api/cassandra/cluster.html#cassandra.cluster.ExecutionProfile" title="cassandra.cluster.ExecutionProfile"><code class="xref py py-class docutils literal"><span class="pre">cluster.ExecutionProfile</span></code></a>.</p>
</div>
<div class="section" id="using-execution-profiles">
<h2>Using Execution Profiles<a class="headerlink" href="#using-execution-profiles" title="Permalink to this headline">¶</a></h2>
<div class="section" id="default">
<h3>Default<a class="headerlink" href="#default" title="Permalink to this headline">¶</a></h3>
<div class="code python highlight-default"><div class="highlight"><pre><span></span><span class="kn">from</span> <span class="nn">cassandra.cluster</span> <span class="k">import</span> <span class="n">Cluster</span>
<span class="n">cluster</span> <span class="o">=</span> <span class="n">Cluster</span><span class="p">()</span>
<span class="n">session</span> <span class="o">=</span> <span class="n">cluster</span><span class="o">.</span><span class="n">connect</span><span class="p">()</span>
<span class="n">local_query</span> <span class="o">=</span> <span class="s1">'SELECT rpc_address FROM system.local'</span>
<span class="k">for</span> <span class="n">_</span> <span class="ow">in</span> <span class="n">cluster</span><span class="o">.</span><span class="n">metadata</span><span class="o">.</span><span class="n">all_hosts</span><span class="p">():</span>
<span class="nb">print</span> <span class="n">session</span><span class="o">.</span><span class="n">execute</span><span class="p">(</span><span class="n">local_query</span><span class="p">)[</span><span class="mi">0</span><span class="p">]</span>
</pre></div>
</div>
<div class="highlight-default"><div class="highlight"><pre><span></span><span class="n">Row</span><span class="p">(</span><span class="n">rpc_address</span><span class="o">=</span><span class="s1">'127.0.0.2'</span><span class="p">)</span>
<span class="n">Row</span><span class="p">(</span><span class="n">rpc_address</span><span class="o">=</span><span class="s1">'127.0.0.1'</span><span class="p">)</span>
</pre></div>
</div>
<p>The default execution profile is built from Cluster parameters and default Session attributes. This profile matches existing default
parameters.</p>
</div>
<div class="section" id="initializing-cluster-with-profiles">
<h3>Initializing cluster with profiles<a class="headerlink" href="#initializing-cluster-with-profiles" title="Permalink to this headline">¶</a></h3>
<div class="code python highlight-default"><div class="highlight"><pre><span></span><span class="kn">from</span> <span class="nn">cassandra.cluster</span> <span class="k">import</span> <span class="n">ExecutionProfile</span>
<span class="kn">from</span> <span class="nn">cassandra.policies</span> <span class="k">import</span> <span class="n">WhiteListRoundRobinPolicy</span>
<span class="n">node1_profile</span> <span class="o">=</span> <span class="n">ExecutionProfile</span><span class="p">(</span><span class="n">load_balancing_policy</span><span class="o">=</span><span class="n">WhiteListRoundRobinPolicy</span><span class="p">([</span><span class="s1">'127.0.0.1'</span><span class="p">]))</span>
<span class="n">node2_profile</span> <span class="o">=</span> <span class="n">ExecutionProfile</span><span class="p">(</span><span class="n">load_balancing_policy</span><span class="o">=</span><span class="n">WhiteListRoundRobinPolicy</span><span class="p">([</span><span class="s1">'127.0.0.2'</span><span class="p">]))</span>
<span class="n">profiles</span> <span class="o">=</span> <span class="p">{</span><span class="s1">'node1'</span><span class="p">:</span> <span class="n">node1_profile</span><span class="p">,</span> <span class="s1">'node2'</span><span class="p">:</span> <span class="n">node2_profile</span><span class="p">}</span>
<span class="n">session</span> <span class="o">=</span> <span class="n">Cluster</span><span class="p">(</span><span class="n">execution_profiles</span><span class="o">=</span><span class="n">profiles</span><span class="p">)</span><span class="o">.</span><span class="n">connect</span><span class="p">()</span>
<span class="k">for</span> <span class="n">_</span> <span class="ow">in</span> <span class="n">cluster</span><span class="o">.</span><span class="n">metadata</span><span class="o">.</span><span class="n">all_hosts</span><span class="p">():</span>
<span class="nb">print</span> <span class="n">session</span><span class="o">.</span><span class="n">execute</span><span class="p">(</span><span class="n">local_query</span><span class="p">,</span> <span class="n">execution_profile</span><span class="o">=</span><span class="s1">'node1'</span><span class="p">)[</span><span class="mi">0</span><span class="p">]</span>
</pre></div>
</div>
<div class="highlight-default"><div class="highlight"><pre><span></span><span class="n">Row</span><span class="p">(</span><span class="n">rpc_address</span><span class="o">=</span><span class="s1">'127.0.0.1'</span><span class="p">)</span>
<span class="n">Row</span><span class="p">(</span><span class="n">rpc_address</span><span class="o">=</span><span class="s1">'127.0.0.1'</span><span class="p">)</span>
</pre></div>
</div>
<div class="code python highlight-default"><div class="highlight"><pre><span></span><span class="k">for</span> <span class="n">_</span> <span class="ow">in</span> <span class="n">cluster</span><span class="o">.</span><span class="n">metadata</span><span class="o">.</span><span class="n">all_hosts</span><span class="p">():</span>
<span class="nb">print</span> <span class="n">session</span><span class="o">.</span><span class="n">execute</span><span class="p">(</span><span class="n">local_query</span><span class="p">,</span> <span class="n">execution_profile</span><span class="o">=</span><span class="s1">'node2'</span><span class="p">)[</span><span class="mi">0</span><span class="p">]</span>
</pre></div>
</div>
<div class="highlight-default"><div class="highlight"><pre><span></span><span class="n">Row</span><span class="p">(</span><span class="n">rpc_address</span><span class="o">=</span><span class="s1">'127.0.0.2'</span><span class="p">)</span>
<span class="n">Row</span><span class="p">(</span><span class="n">rpc_address</span><span class="o">=</span><span class="s1">'127.0.0.2'</span><span class="p">)</span>
</pre></div>
</div>
<div class="code python highlight-default"><div class="highlight"><pre><span></span><span class="k">for</span> <span class="n">_</span> <span class="ow">in</span> <span class="n">cluster</span><span class="o">.</span><span class="n">metadata</span><span class="o">.</span><span class="n">all_hosts</span><span class="p">():</span>
<span class="nb">print</span> <span class="n">session</span><span class="o">.</span><span class="n">execute</span><span class="p">(</span><span class="n">local_query</span><span class="p">)[</span><span class="mi">0</span><span class="p">]</span>
</pre></div>
</div>
<div class="highlight-default"><div class="highlight"><pre><span></span><span class="n">Row</span><span class="p">(</span><span class="n">rpc_address</span><span class="o">=</span><span class="s1">'127.0.0.2'</span><span class="p">)</span>
<span class="n">Row</span><span class="p">(</span><span class="n">rpc_address</span><span class="o">=</span><span class="s1">'127.0.0.1'</span><span class="p">)</span>
</pre></div>
</div>
<p>Note that, even when custom profiles are injected, the default <code class="docutils literal"><span class="pre">TokenAwarePolicy(DCAwareRoundRobinPolicy())</span></code> is still
present. To override the default, specify a policy with the <a class="reference internal" href="api/cassandra/cluster.html#cassandra.cluster.EXEC_PROFILE_DEFAULT" title="cassandra.cluster.EXEC_PROFILE_DEFAULT"><code class="xref py py-data docutils literal"><span class="pre">EXEC_PROFILE_DEFAULT</span></code></a> key.</p>
<div class="code python highlight-default"><div class="highlight"><pre><span></span><span class="kn">from</span> <span class="nn">cassandra.cluster</span> <span class="k">import</span> <span class="n">EXEC_PROFILE_DEFAULT</span>
<span class="n">profile</span> <span class="o">=</span> <span class="n">ExecutionProfile</span><span class="p">(</span><span class="n">request_timeout</span><span class="o">=</span><span class="mi">30</span><span class="p">)</span>
<span class="n">cluster</span> <span class="o">=</span> <span class="n">Cluster</span><span class="p">(</span><span class="n">execution_profiles</span><span class="o">=</span><span class="p">{</span><span class="n">EXEC_PROFILE_DEFAULT</span><span class="p">:</span> <span class="n">profile</span><span class="p">})</span>
</pre></div>
</div>
</div>
<div class="section" id="adding-named-profiles">
<h3>Adding named profiles<a class="headerlink" href="#adding-named-profiles" title="Permalink to this headline">¶</a></h3>
<p>New profiles can be added constructing from scratch, or deriving from default:</p>
<div class="code python highlight-default"><div class="highlight"><pre><span></span><span class="n">locked_execution</span> <span class="o">=</span> <span class="n">ExecutionProfile</span><span class="p">(</span><span class="n">load_balancing_policy</span><span class="o">=</span><span class="n">WhiteListRoundRobinPolicy</span><span class="p">([</span><span class="s1">'127.0.0.1'</span><span class="p">]))</span>
<span class="n">node1_profile</span> <span class="o">=</span> <span class="s1">'node1_whitelist'</span>
<span class="n">cluster</span><span class="o">.</span><span class="n">add_execution_profile</span><span class="p">(</span><span class="n">node1_profile</span><span class="p">,</span> <span class="n">locked_execution</span><span class="p">)</span>
<span class="k">for</span> <span class="n">_</span> <span class="ow">in</span> <span class="n">cluster</span><span class="o">.</span><span class="n">metadata</span><span class="o">.</span><span class="n">all_hosts</span><span class="p">():</span>
<span class="nb">print</span> <span class="n">session</span><span class="o">.</span><span class="n">execute</span><span class="p">(</span><span class="n">local_query</span><span class="p">,</span> <span class="n">execution_profile</span><span class="o">=</span><span class="n">node1_profile</span><span class="p">)[</span><span class="mi">0</span><span class="p">]</span>
</pre></div>
</div>
<div class="highlight-default"><div class="highlight"><pre><span></span><span class="n">Row</span><span class="p">(</span><span class="n">rpc_address</span><span class="o">=</span><span class="s1">'127.0.0.1'</span><span class="p">)</span>
<span class="n">Row</span><span class="p">(</span><span class="n">rpc_address</span><span class="o">=</span><span class="s1">'127.0.0.1'</span><span class="p">)</span>
</pre></div>
</div>
<p>See <a class="reference internal" href="api/cassandra/cluster.html#cassandra.cluster.Cluster.add_execution_profile" title="cassandra.cluster.Cluster.add_execution_profile"><code class="xref py py-meth docutils literal"><span class="pre">Cluster.add_execution_profile()</span></code></a> for details and optional parameters.</p>
</div>
<div class="section" id="passing-a-profile-instance-without-mapping">
<h3>Passing a profile instance without mapping<a class="headerlink" href="#passing-a-profile-instance-without-mapping" title="Permalink to this headline">¶</a></h3>
<p>We also have the ability to pass profile instances to be used for execution, but not added to the mapping:</p>
<div class="code python highlight-default"><div class="highlight"><pre><span></span><span class="kn">from</span> <span class="nn">cassandra.query</span> <span class="k">import</span> <span class="n">tuple_factory</span>
<span class="n">tmp</span> <span class="o">=</span> <span class="n">session</span><span class="o">.</span><span class="n">execution_profile_clone_update</span><span class="p">(</span><span class="s1">'node1'</span><span class="p">,</span> <span class="n">request_timeout</span><span class="o">=</span><span class="mi">100</span><span class="p">,</span> <span class="n">row_factory</span><span class="o">=</span><span class="n">tuple_factory</span><span class="p">)</span>
<span class="nb">print</span> <span class="n">session</span><span class="o">.</span><span class="n">execute</span><span class="p">(</span><span class="n">local_query</span><span class="p">,</span> <span class="n">execution_profile</span><span class="o">=</span><span class="n">tmp</span><span class="p">)[</span><span class="mi">0</span><span class="p">]</span>
<span class="nb">print</span> <span class="n">session</span><span class="o">.</span><span class="n">execute</span><span class="p">(</span><span class="n">local_query</span><span class="p">,</span> <span class="n">execution_profile</span><span class="o">=</span><span class="s1">'node1'</span><span class="p">)[</span><span class="mi">0</span><span class="p">]</span>
</pre></div>
</div>
<div class="highlight-default"><div class="highlight"><pre><span></span><span class="p">(</span><span class="s1">'127.0.0.1'</span><span class="p">,)</span>
<span class="n">Row</span><span class="p">(</span><span class="n">rpc_address</span><span class="o">=</span><span class="s1">'127.0.0.1'</span><span class="p">)</span>
</pre></div>
</div>
<p>The new profile is a shallow copy, so the <code class="docutils literal"><span class="pre">tmp</span></code> profile shares a load balancing policy with one managed by the cluster.
If reference objects are to be updated in the clone, one would typically set those attributes to a new instance.</p>
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