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# gpudb::AlterWalRequest

> gpudb::AlterWalRequest — Kinetica C++ API

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    <p>A set of parameters for <a className="el" href="/content/api/cpp/classgpudb_1_1GPUdb#a982dab90baf6bd12035b69342f8187a3">GPUdb::alterWal</a>. <a href="#details">More...</a></p>
    <p><code>#include \<<a className="el" href="/content/api/cpp/alter__wal_8h_source">gpudb/protocol/alter\_wal.h</a>></code></p>

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          <h2 className="groupheader"> Public Member Functions</h2>
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        <td className="memItemLeft" align="right" valign="top"> </td>
        <td className="memItemRight" valign="bottom"><a className="el" href="#af9baf98c13eecd0539a5e90015f472db">AlterWalRequest</a> ()</td>
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        <td className="mdescLeft"> </td>
        <td className="mdescRight">Constructs an <a className="el" href="/content/api/cpp/structgpudb_1_1AlterWalRequest" title="A set of parameters for GPUdb::alterWal.">AlterWalRequest</a> object with default parameters. <br /></td>
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        <td className="memItemRight" valign="bottom"><a className="el" href="#a64f2a6f742445fd458c61e78b634f0fc">AlterWalRequest</a> (const std::vector\< std::string > \&tableNames\_, const std::map\< std::string, std::string > \&options\_)</td>
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        <td className="mdescLeft"> </td>
        <td className="mdescRight">Constructs an <a className="el" href="/content/api/cpp/structgpudb_1_1AlterWalRequest" title="A set of parameters for GPUdb::alterWal.">AlterWalRequest</a> object with the specified parameters. <br /></td>
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          <h2 className="groupheader"> Public Attributes</h2>
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        <td className="memItemLeft" align="right" valign="top">std::vector\< std::string > </td>
        <td className="memItemRight" valign="bottom"><a className="el" href="#a8bbab25afd11baa41dfc2e82be943944">tableNames</a></td>
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        <td className="mdescRight">List of tables to modify. <br /></td>
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        <td className="memItemLeft" align="right" valign="top">std::map\< std::string, std::string > </td>
        <td className="memItemRight" valign="bottom"><a className="el" href="#ab733a6c494d72fbbef357762d5fd5328">options</a></td>
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        <td className="mdescLeft"> </td>
        <td className="mdescRight">Optional parameters. <br /></td>
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    <h2 className="groupheader">Detailed Description</h2>

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      <p>A set of parameters for <a className="el" href="/content/api/cpp/classgpudb_1_1GPUdb#a982dab90baf6bd12035b69342f8187a3">GPUdb::alterWal</a>. </p>
      <p>Alters table write-ahead log (WAL) settings. Returns information about the requested table WAL modifications. </p>
      <p className="definition">Definition at line <a className="el" href="/content/api/cpp/alter__wal_8h_source#l00018">18</a> of file <a className="el" href="/content/api/cpp/alter__wal_8h_source">alter\_wal.h</a>.</p>
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    <h2 className="groupheader">Constructor & Destructor Documentation</h2>
    <h2 className="memtitle"><span className="permalink"><a href="#af9baf98c13eecd0539a5e90015f472db">◆ </a></span>AlterWalRequest() <span className="overload">\[1/2]</span></h2>

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                  <td className="memname">gpudb::AlterWalRequest::AlterWalRequest </td>
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        <p>Constructs an <a className="el" href="/content/api/cpp/structgpudb_1_1AlterWalRequest" title="A set of parameters for GPUdb::alterWal.">AlterWalRequest</a> object with default parameters. </p>
        <p className="definition">Definition at line <a className="el" href="/content/api/cpp/alter__wal_8h_source#l00023">23</a> of file <a className="el" href="/content/api/cpp/alter__wal_8h_source">alter\_wal.h</a>.</p>
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    <h2 className="memtitle"><span className="permalink"><a href="#a64f2a6f742445fd458c61e78b634f0fc">◆ </a></span>AlterWalRequest() <span className="overload">\[2/2]</span></h2>

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                  <td className="memname">gpudb::AlterWalRequest::AlterWalRequest </td>
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                  <td className="paramtype">const std::vector\< std::string > &</td>
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                  <td className="paramtype">const std::map\< std::string, std::string > &</td>
                  <td className="paramname"><span className="paramname"><span className="em">options\_</span></span> )</td>
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        <p>Constructs an <a className="el" href="/content/api/cpp/structgpudb_1_1AlterWalRequest" title="A set of parameters for GPUdb::alterWal.">AlterWalRequest</a> object with the specified parameters. </p>

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          <div className="dt">Parameters</div>

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                <td className="paramdir">\[in]</td>
                <td className="paramname">tableNames\_</td>
                <td>List of tables to modify. An asterisk changes the system settings. </td>
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                <td className="paramdir">\[in]</td>
                <td className="paramname">options\_</td>

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                  Optional parameters.

                  <ul>
                    <li> <a className="el" href="/content/api/cpp/namespacegpudb#a11243780573269b0188f43086fefd487">alter\_wal\_max\_segment\_size</a>: Maximum size of an individual segment file. </li>
                    <li> <a className="el" href="/content/api/cpp/namespacegpudb#a2cc00dc1d5af908a8cb471d1672a047b">alter\_wal\_segment\_count</a>: Approximate number of segment files to split the WAL across. Must be at least two. </li>

                    <li>
                      <a className="el" href="/content/api/cpp/namespacegpudb#ae521bb194a9ce38e75609142cd93becf">alter\_wal\_sync\_policy</a>: Maximum size of an individual segment file. Supported values:

                      <ul>
                        <li> <a className="el" href="/content/api/cpp/namespacegpudb#a91d162ed444e2e9085c605c28c877e00">alter\_wal\_none</a>: Disables the WAL. </li>
                        <li> <a className="el" href="/content/api/cpp/namespacegpudb#ad2fe01c6f5978e3e7236facab116f4a2">alter\_wal\_background</a>: WAL entries are periodically written instead of immediately after each operation. </li>
                        <li> <a className="el" href="/content/api/cpp/namespacegpudb#ae10a93be3787862b80aab1897fb52e33">alter\_wal\_flush</a>: Protects entries in the event of a database crash. </li>
                        <li> <a className="el" href="/content/api/cpp/namespacegpudb#aae23b82ae4ff72a7ea1a7086fa15a02b">alter\_wal\_fsync</a>: Protects entries in the event of an OS crash. </li>
                      </ul>
                    </li>

                    <li> <a className="el" href="/content/api/cpp/namespacegpudb#ac171e13c8202fc9465715d3b417db8f0">alter\_wal\_flush\_frequency</a>: 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 '\*'. </li>

                    <li>
                      <a className="el" href="/content/api/cpp/namespacegpudb#afda614e8703a8cbfcbd7341c53356a80">alter\_wal\_checksum</a>: If <a className="el" href="/content/api/cpp/namespacegpudb#a05b6ab935abe46b7ad7f3d3be3bee137">true</a> each entry will be checked against a protective checksum. Supported values:

                      <ul>
                        <li> <a className="el" href="/content/api/cpp/namespacegpudb#a05b6ab935abe46b7ad7f3d3be3bee137">alter\_wal\_true</a> </li>
                        <li> <a className="el" href="/content/api/cpp/namespacegpudb#afd2618a1b1b25668ee515a4f44133c9f">alter\_wal\_false</a> </li>
                      </ul>

                      The default value is <a className="el" href="/content/api/cpp/namespacegpudb#a05b6ab935abe46b7ad7f3d3be3bee137">alter\_wal\_true</a>.
                    </li>

                    <li>
                      <a className="el" href="/content/api/cpp/namespacegpudb#a3bf4a86f684e5f72efca3f49eb6606c7">alter\_wal\_override\_non\_default</a>: If <a className="el" href="/content/api/cpp/namespacegpudb#a05b6ab935abe46b7ad7f3d3be3bee137">true</a> tables with unique WAL settings will be overridden when applying a system level change. Supported values:

                      <ul>
                        <li> <a className="el" href="/content/api/cpp/namespacegpudb#a05b6ab935abe46b7ad7f3d3be3bee137">alter\_wal\_true</a> </li>
                        <li> <a className="el" href="/content/api/cpp/namespacegpudb#afd2618a1b1b25668ee515a4f44133c9f">alter\_wal\_false</a> </li>
                      </ul>

                      The default value is <a className="el" href="/content/api/cpp/namespacegpudb#afd2618a1b1b25668ee515a4f44133c9f">alter\_wal\_false</a>.
                    </li>

                    <li>
                      <a className="el" href="/content/api/cpp/namespacegpudb#ae1945c992a9ac4f5a9e6d7182ad084f5">alter\_wal\_restore\_system\_settings</a>: If <a className="el" href="/content/api/cpp/namespacegpudb#a05b6ab935abe46b7ad7f3d3be3bee137">true</a> tables with unique WAL settings will be reverted to the current global settings. Cannot be used in conjunction with any other option. Supported values:

                      <ul>
                        <li> <a className="el" href="/content/api/cpp/namespacegpudb#a05b6ab935abe46b7ad7f3d3be3bee137">alter\_wal\_true</a> </li>
                        <li> <a className="el" href="/content/api/cpp/namespacegpudb#afd2618a1b1b25668ee515a4f44133c9f">alter\_wal\_false</a> </li>
                      </ul>

                      The default value is <a className="el" href="/content/api/cpp/namespacegpudb#afd2618a1b1b25668ee515a4f44133c9f">alter\_wal\_false</a>.
                    </li>

                    <li>
                      <a className="el" href="/content/api/cpp/namespacegpudb#af6747739be3b5833037159b5e848e54e">alter\_wal\_persist</a>: If <a className="el" href="/content/api/cpp/namespacegpudb#a05b6ab935abe46b7ad7f3d3be3bee137">true</a> 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. Supported values:

                      <ul>
                        <li> <a className="el" href="/content/api/cpp/namespacegpudb#a05b6ab935abe46b7ad7f3d3be3bee137">alter\_wal\_true</a> </li>
                        <li> <a className="el" href="/content/api/cpp/namespacegpudb#afd2618a1b1b25668ee515a4f44133c9f">alter\_wal\_false</a> </li>
                      </ul>

                      The default value is <a className="el" href="/content/api/cpp/namespacegpudb#a05b6ab935abe46b7ad7f3d3be3bee137">alter\_wal\_true</a>.
                    </li>
                  </ul>

                  The default value is an empty map.
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        <p className="definition">Definition at line <a className="el" href="/content/api/cpp/alter__wal_8h_source#l00143">143</a> of file <a className="el" href="/content/api/cpp/alter__wal_8h_source">alter\_wal.h</a>.</p>
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    <h2 className="groupheader">Member Data Documentation</h2>
    <h2 className="memtitle"><span className="permalink"><a href="#ab733a6c494d72fbbef357762d5fd5328">◆ </a></span>options</h2>

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            <td className="memname">std::map\<std::string, std::string> gpudb::AlterWalRequest::options</td>
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        <p>Optional parameters. </p>

        <ul>
          <li> <a className="el" href="/content/api/cpp/namespacegpudb#a11243780573269b0188f43086fefd487">alter\_wal\_max\_segment\_size</a>: Maximum size of an individual segment file. </li>
          <li> <a className="el" href="/content/api/cpp/namespacegpudb#a2cc00dc1d5af908a8cb471d1672a047b">alter\_wal\_segment\_count</a>: Approximate number of segment files to split the WAL across. Must be at least two. </li>

          <li>
            <a className="el" href="/content/api/cpp/namespacegpudb#ae521bb194a9ce38e75609142cd93becf">alter\_wal\_sync\_policy</a>: Maximum size of an individual segment file. Supported values:

            <ul>
              <li> <a className="el" href="/content/api/cpp/namespacegpudb#a91d162ed444e2e9085c605c28c877e00">alter\_wal\_none</a>: Disables the WAL. </li>
              <li> <a className="el" href="/content/api/cpp/namespacegpudb#ad2fe01c6f5978e3e7236facab116f4a2">alter\_wal\_background</a>: WAL entries are periodically written instead of immediately after each operation. </li>
              <li> <a className="el" href="/content/api/cpp/namespacegpudb#ae10a93be3787862b80aab1897fb52e33">alter\_wal\_flush</a>: Protects entries in the event of a database crash. </li>
              <li> <a className="el" href="/content/api/cpp/namespacegpudb#aae23b82ae4ff72a7ea1a7086fa15a02b">alter\_wal\_fsync</a>: Protects entries in the event of an OS crash. </li>
            </ul>
          </li>

          <li> <a className="el" href="/content/api/cpp/namespacegpudb#ac171e13c8202fc9465715d3b417db8f0">alter\_wal\_flush\_frequency</a>: 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 '\*'. </li>

          <li>
            <a className="el" href="/content/api/cpp/namespacegpudb#afda614e8703a8cbfcbd7341c53356a80">alter\_wal\_checksum</a>: If <a className="el" href="/content/api/cpp/namespacegpudb#a05b6ab935abe46b7ad7f3d3be3bee137">true</a> each entry will be checked against a protective checksum. Supported values:

            <ul>
              <li> <a className="el" href="/content/api/cpp/namespacegpudb#a05b6ab935abe46b7ad7f3d3be3bee137">alter\_wal\_true</a> </li>
              <li> <a className="el" href="/content/api/cpp/namespacegpudb#afd2618a1b1b25668ee515a4f44133c9f">alter\_wal\_false</a> </li>
            </ul>

            The default value is <a className="el" href="/content/api/cpp/namespacegpudb#a05b6ab935abe46b7ad7f3d3be3bee137">alter\_wal\_true</a>.
          </li>

          <li>
            <a className="el" href="/content/api/cpp/namespacegpudb#a3bf4a86f684e5f72efca3f49eb6606c7">alter\_wal\_override\_non\_default</a>: If <a className="el" href="/content/api/cpp/namespacegpudb#a05b6ab935abe46b7ad7f3d3be3bee137">true</a> tables with unique WAL settings will be overridden when applying a system level change. Supported values:

            <ul>
              <li> <a className="el" href="/content/api/cpp/namespacegpudb#a05b6ab935abe46b7ad7f3d3be3bee137">alter\_wal\_true</a> </li>
              <li> <a className="el" href="/content/api/cpp/namespacegpudb#afd2618a1b1b25668ee515a4f44133c9f">alter\_wal\_false</a> </li>
            </ul>

            The default value is <a className="el" href="/content/api/cpp/namespacegpudb#afd2618a1b1b25668ee515a4f44133c9f">alter\_wal\_false</a>.
          </li>

          <li>
            <a className="el" href="/content/api/cpp/namespacegpudb#ae1945c992a9ac4f5a9e6d7182ad084f5">alter\_wal\_restore\_system\_settings</a>: If <a className="el" href="/content/api/cpp/namespacegpudb#a05b6ab935abe46b7ad7f3d3be3bee137">true</a> tables with unique WAL settings will be reverted to the current global settings. Cannot be used in conjunction with any other option. Supported values:

            <ul>
              <li> <a className="el" href="/content/api/cpp/namespacegpudb#a05b6ab935abe46b7ad7f3d3be3bee137">alter\_wal\_true</a> </li>
              <li> <a className="el" href="/content/api/cpp/namespacegpudb#afd2618a1b1b25668ee515a4f44133c9f">alter\_wal\_false</a> </li>
            </ul>

            The default value is <a className="el" href="/content/api/cpp/namespacegpudb#afd2618a1b1b25668ee515a4f44133c9f">alter\_wal\_false</a>.
          </li>

          <li>
            <a className="el" href="/content/api/cpp/namespacegpudb#af6747739be3b5833037159b5e848e54e">alter\_wal\_persist</a>: If <a className="el" href="/content/api/cpp/namespacegpudb#a05b6ab935abe46b7ad7f3d3be3bee137">true</a> 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. Supported values:

            <ul>
              <li> <a className="el" href="/content/api/cpp/namespacegpudb#a05b6ab935abe46b7ad7f3d3be3bee137">alter\_wal\_true</a> </li>
              <li> <a className="el" href="/content/api/cpp/namespacegpudb#afd2618a1b1b25668ee515a4f44133c9f">alter\_wal\_false</a> </li>
            </ul>

            The default value is <a className="el" href="/content/api/cpp/namespacegpudb#a05b6ab935abe46b7ad7f3d3be3bee137">alter\_wal\_true</a>.
          </li>
        </ul>

        <p>The default value is an empty map. </p>
        <p className="definition">Definition at line <a className="el" href="/content/api/cpp/alter__wal_8h_source#l00231">231</a> of file <a className="el" href="/content/api/cpp/alter__wal_8h_source">alter\_wal.h</a>.</p>
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        <p>List of tables to modify. </p>
        <p>An asterisk changes the system settings. </p>
        <p className="definition">Definition at line <a className="el" href="/content/api/cpp/alter__wal_8h_source#l00152">152</a> of file <a className="el" href="/content/api/cpp/alter__wal_8h_source">alter\_wal.h</a>.</p>
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    <hr />

    The documentation for this struct was generated from the following file:

    <ul>
      <li>gpudb/protocol/<a className="el" href="/content/api/cpp/alter__wal_8h_source">alter\_wal.h</a></li>
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