> ## Documentation Index
> Fetch the complete documentation index at: https://docs.kinetica.com/llms.txt
> Use this file to discover all available pages before exploring further.

# alter_wal

<div className="kinetica-pydoc">
  <div className="dl py method">
    <div className="dt sig sig-object py" id="gpudb.GPUdb.alter_wal"> <span className="sig-name descname"><span className="pre">alter\_wal</span></span><span className="sig-paren">(</span><span className="em sig-param"><span className="n"><span className="pre">table\_names</span></span><span className="o"><span className="pre">=</span></span><span className="default_value"><span className="pre">None</span></span></span>, <span className="em sig-param"><span className="n"><span className="pre">options</span></span><span className="o"><span className="pre">=</span></span><span className="default_value"><span className="pre">{"{"}{"}"}</span></span></span><span className="sig-paren">)</span><a href="https://github.com/kineticadb/kinetica-api-python/blob/master/gpudb/gpudb.py#L20870"><span className="viewcode-link"><span className="pre">\[source]</span></span></a></div>

    <div className="dd">
      <p>Alters table write-ahead log (WAL) settings. Returns information about the requested table WAL modifications.</p>
      <p><strong>Parameters</strong></p>

      <div className="blockquote">
        <div>
          <div className="dl">
            <div className="dt">table\_names (<span className="em">list of str</span>) –</div>

            <div className="dd">
              <p>List of tables to modify. An asterisk changes the system settings. The user can provide a single element (which will be automatically promoted to a list internally) or a list.</p>
            </div>

            <div className="dt">options (<span className="em">dict of str to str</span>) –</div>

            <div className="dd">
              <p>Optional parameters. Allowed keys are:</p>

              <ul>
                <li>
                  <p><strong>max\_segment\_size</strong> – Maximum size of an individual segment file.</p>
                </li>

                <li>
                  <p><strong>segment\_count</strong> – Approximate number of segment files to split the WAL across. Must be at least two.</p>
                </li>

                <li>
                  <p><strong>sync\_policy</strong> – Maximum size of an individual segment file. Allowed values are:</p>

                  <ul className="simple">
                    <li>
                      <p><strong>none</strong> – Disables the WAL.</p>
                    </li>

                    <li>
                      <p><strong>background</strong> – WAL entries are periodically written instead of immediately after each operation.</p>
                    </li>

                    <li>
                      <p><strong>flush</strong> – Protects entries in the event of a database crash.</p>
                    </li>

                    <li>
                      <p><strong>fsync</strong> – Protects entries in the event of an OS crash.</p>
                    </li>
                  </ul>
                </li>

                <li>
                  <p><strong>flush\_frequency</strong> – Specifies how frequently WAL entries are written with background sync. This is a global setting and can only be used with the system {"{"}options.table\_names{"}"} specifier ‘\*’.</p>
                </li>

                <li>
                  <p><strong>checksum</strong> – If <span className="em">true</span> each entry will be checked against a protective checksum. Allowed values are:</p>

                  <ul className="simple">
                    <li>
                      <p>true</p>
                    </li>

                    <li>
                      <p>false</p>
                    </li>
                  </ul>

                  <p>The default value is ‘true’.</p>
                </li>

                <li>
                  <p><strong>override\_non\_default</strong> – If <span className="em">true</span> tables with unique WAL settings will be overridden when applying a system level change. Allowed values are:</p>

                  <ul className="simple">
                    <li>
                      <p>true</p>
                    </li>

                    <li>
                      <p>false</p>
                    </li>
                  </ul>

                  <p>The default value is ‘false’.</p>
                </li>

                <li>
                  <p><strong>restore\_system\_settings</strong> – If <span className="em">true</span> tables with unique WAL settings will be reverted to the current global settings. Cannot be used in conjunction with any other option. Allowed values are:</p>

                  <ul className="simple">
                    <li>
                      <p>true</p>
                    </li>

                    <li>
                      <p>false</p>
                    </li>
                  </ul>

                  <p>The default value is ‘false’.</p>
                </li>

                <li>
                  <p><strong>persist</strong> – If <span className="em">true</span> and a system-level change was requested, the system configuration will be written to disk upon successful application of this request. This will commit the changes from this request and any additional in-memory modifications. Allowed values are:</p>

                  <ul className="simple">
                    <li>
                      <p>true</p>
                    </li>

                    <li>
                      <p>false</p>
                    </li>
                  </ul>

                  <p>The default value is ‘true’.</p>
                </li>
              </ul>

              <p>The default value is an empty dict ( {"{"}{"}"} ).</p>
            </div>
          </div>
        </div>
      </div>

      <p><strong>Returns</strong></p>

      <div className="blockquote">
        <div>
          <p>A dict with the following entries–</p>

          <div className="dl simple">
            <div className="dt">info (<span className="em">dict of str to str</span>) –</div>

            <div className="dd">
              <p>Additional information.</p>
            </div>
          </div>
        </div>
      </div>
    </div>
  </div>
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