<div id="docs-body">
 <div class="section">
  <div class="titlepage">
   <div>
    <div>
     <h3 class="title">
      <a name="index-page-merge-threshold">
      </a>
      17.8.11 Configuring the Merge Threshold for Index Pages
     </h3>
    </div>
   </div>
  </div>
  <p>
   You can configure the
   <code class="literal">
    MERGE_THRESHOLD
   </code>
   value for
      index pages. If the
   <span class="quote">
    “
    <span class="quote">
     page-full
    </span>
    ”
   </span>
   percentage for an
      index page falls below the
   <code class="literal">
    MERGE_THRESHOLD
   </code>
   value when a row is deleted or when a row is shortened by an
   <a class="link" href="update.html" title="15.2.17 UPDATE Statement">
    <code class="literal">
     UPDATE
    </code>
   </a>
   operation,
   <code class="literal">
    InnoDB
   </code>
   attempts to merge the index page with a
      neighboring index page. The default
   <code class="literal">
    MERGE_THRESHOLD
   </code>
   value is 50, which is the
      previously hardcoded value. The minimum
   <code class="literal">
    MERGE_THRESHOLD
   </code>
   value is 1 and the maximum
      value is 50.
  </p>
  <p>
   When the
   <span class="quote">
    “
    <span class="quote">
     page-full
    </span>
    ”
   </span>
   percentage for an index page
      falls below 50%, which is the default
   <code class="literal">
    MERGE_THRESHOLD
   </code>
   setting,
   <code class="literal">
    InnoDB
   </code>
   attempts to merge the index page with a
      neighboring page. If both pages are close to 50% full, a page
      split can occur soon after the pages are merged. If this
      merge-split behavior occurs frequently, it can have an adverse
      affect on performance. To avoid frequent merge-splits, you can
      lower the
   <code class="literal">
    MERGE_THRESHOLD
   </code>
   value so that
   <code class="literal">
    InnoDB
   </code>
   attempts page merges at a lower
   <span class="quote">
    “
    <span class="quote">
     page-full
    </span>
    ”
   </span>
   percentage. Merging pages at a lower
      page-full percentage leaves more room in index pages and helps
      reduce merge-split behavior.
  </p>
  <p>
   The
   <code class="literal">
    MERGE_THRESHOLD
   </code>
   for index pages can be
      defined for a table or for individual indexes. A
   <code class="literal">
    MERGE_THRESHOLD
   </code>
   value defined for an individual
      index takes priority over a
   <code class="literal">
    MERGE_THRESHOLD
   </code>
   value defined for the table. If undefined, the
   <code class="literal">
    MERGE_THRESHOLD
   </code>
   value defaults to 50.
  </p>
  <h4>
   <a name="idm46045161921136">
   </a>
   Setting MERGE_THRESHOLD for a Table
  </h4>
  <p>
   You can set the
   <code class="literal">
    MERGE_THRESHOLD
   </code>
   value for a
      table using the
   <em class="replaceable">
    <code>
     table_option
    </code>
   </em>
   <code class="literal">
    COMMENT
   </code>
   clause of the
   <a class="link" href="create-table.html" title="15.1.20 CREATE TABLE Statement">
    <code class="literal">
     CREATE TABLE
    </code>
   </a>
   statement. For
      example:
  </p>
  <div class="copytoclipboard-wrapper">
   <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa44551888"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> t1 <span class="token punctuation">(</span>
   id <span class="token datatype">INT</span><span class="token punctuation">,</span>
  <span class="token keyword">KEY</span> id_index <span class="token punctuation">(</span>id<span class="token punctuation">)</span>
<span class="token punctuation">)</span> <span class="token keyword">COMMENT</span><span class="token operator">=</span><span class="token string">'MERGE_THRESHOLD=45'</span><span class="token punctuation">;</span></code></pre>
  </div>
  <p>
   You can also set the
   <code class="literal">
    MERGE_THRESHOLD
   </code>
   value for
      an existing table using the
   <em class="replaceable">
    <code>
     table_option
    </code>
   </em>
   <code class="literal">
    COMMENT
   </code>
   clause with
   <a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement">
    <code class="literal">
     ALTER TABLE
    </code>
   </a>
   :
  </p>
  <div class="copytoclipboard-wrapper">
   <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa77746136"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> t1 <span class="token punctuation">(</span>
   id <span class="token datatype">INT</span><span class="token punctuation">,</span>
  <span class="token keyword">KEY</span> id_index <span class="token punctuation">(</span>id<span class="token punctuation">)</span>
<span class="token punctuation">)</span><span class="token punctuation">;</span>

<span class="token keyword">ALTER</span> <span class="token keyword">TABLE</span> t1 <span class="token keyword">COMMENT</span><span class="token operator">=</span><span class="token string">'MERGE_THRESHOLD=40'</span><span class="token punctuation">;</span></code></pre>
  </div>
  <h4>
   <a name="idm46045161911328">
   </a>
   Setting MERGE_THRESHOLD for Individual Indexes
  </h4>
  <p>
   To set the
   <code class="literal">
    MERGE_THRESHOLD
   </code>
   value for an
      individual index, you can use the
   <em class="replaceable">
    <code>
     index_option
    </code>
   </em>
   <code class="literal">
    COMMENT
   </code>
   clause with
   <a class="link" href="create-table.html" title="15.1.20 CREATE TABLE Statement">
    <code class="literal">
     CREATE TABLE
    </code>
   </a>
   ,
   <a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement">
    <code class="literal">
     ALTER TABLE
    </code>
   </a>
   , or
   <a class="link" href="create-index.html" title="15.1.15 CREATE INDEX Statement">
    <code class="literal">
     CREATE INDEX
    </code>
   </a>
   , as shown in the
      following examples:
  </p>
  <div class="itemizedlist">
   <ul class="itemizedlist" style="list-style-type: disc; ">
    <li class="listitem">
     <p>
      Setting
      <code class="literal">
       MERGE_THRESHOLD
      </code>
      for an individual
          index using
      <a class="link" href="create-table.html" title="15.1.20 CREATE TABLE Statement">
       <code class="literal">
        CREATE TABLE
       </code>
      </a>
      :
     </p>
     <div class="copytoclipboard-wrapper">
      <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa60266295"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> t1 <span class="token punctuation">(</span>
   id <span class="token datatype">INT</span><span class="token punctuation">,</span>
  <span class="token keyword">KEY</span> id_index <span class="token punctuation">(</span>id<span class="token punctuation">)</span> <span class="token keyword">COMMENT</span> <span class="token string">'MERGE_THRESHOLD=40'</span>
<span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre>
     </div>
    </li>
    <li class="listitem">
     <p>
      Setting
      <code class="literal">
       MERGE_THRESHOLD
      </code>
      for an individual
          index using
      <a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement">
       <code class="literal">
        ALTER TABLE
       </code>
      </a>
      :
     </p>
     <div class="copytoclipboard-wrapper">
      <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa31890012"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> t1 <span class="token punctuation">(</span>
   id <span class="token datatype">INT</span><span class="token punctuation">,</span>
  <span class="token keyword">KEY</span> id_index <span class="token punctuation">(</span>id<span class="token punctuation">)</span>
<span class="token punctuation">)</span><span class="token punctuation">;</span>

<span class="token keyword">ALTER</span> <span class="token keyword">TABLE</span> t1 <span class="token keyword">DROP</span> <span class="token keyword">KEY</span> id_index<span class="token punctuation">;</span>
<span class="token keyword">ALTER</span> <span class="token keyword">TABLE</span> t1 <span class="token keyword">ADD</span> <span class="token keyword">KEY</span> id_index <span class="token punctuation">(</span>id<span class="token punctuation">)</span> <span class="token keyword">COMMENT</span> <span class="token string">'MERGE_THRESHOLD=40'</span><span class="token punctuation">;</span></code></pre>
     </div>
    </li>
    <li class="listitem">
     <p>
      Setting
      <code class="literal">
       MERGE_THRESHOLD
      </code>
      for an individual
          index using
      <a class="link" href="create-index.html" title="15.1.15 CREATE INDEX Statement">
       <code class="literal">
        CREATE INDEX
       </code>
      </a>
      :
     </p>
     <div class="copytoclipboard-wrapper">
      <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa92262354"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> t1 <span class="token punctuation">(</span>id <span class="token datatype">INT</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">CREATE</span> <span class="token keyword">INDEX</span> id_index <span class="token keyword">ON</span> t1 <span class="token punctuation">(</span>id<span class="token punctuation">)</span> <span class="token keyword">COMMENT</span> <span class="token string">'MERGE_THRESHOLD=40'</span><span class="token punctuation">;</span></code></pre>
     </div>
    </li>
   </ul>
  </div>
  <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
   <div class="admon-title">
    Note
   </div>
   <p>
    You cannot modify the
    <code class="literal">
     MERGE_THRESHOLD
    </code>
    value
        at the index level for
    <code class="literal">
     GEN_CLUST_INDEX
    </code>
    , which
        is the clustered index created by
    <code class="literal">
     InnoDB
    </code>
    when
        an
    <code class="literal">
     InnoDB
    </code>
    table is created without a primary
        key or unique key index. You can only modify the
    <code class="literal">
     MERGE_THRESHOLD
    </code>
    value for
    <code class="literal">
     GEN_CLUST_INDEX
    </code>
    by setting
    <code class="literal">
     MERGE_THRESHOLD
    </code>
    for the table.
   </p>
  </div>
  <h4>
   <a name="idm46045161886736">
   </a>
   Querying the MERGE_THRESHOLD Value for an Index
  </h4>
  <p>
   The current
   <code class="literal">
    MERGE_THRESHOLD
   </code>
   value for an index
      can be obtained by querying the
   <a class="link" href="information-schema-innodb-indexes-table.html" title="28.4.20 The INFORMATION_SCHEMA INNODB_INDEXES Table">
    <code class="literal">
     INNODB_INDEXES
    </code>
   </a>
   table. For example:
  </p>
  <div class="copytoclipboard-wrapper">
   <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa50025705"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql&gt;</span> <span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> INFORMATION_SCHEMA<span class="token punctuation">.</span>INNODB_INDEXES <span class="token keyword">WHERE</span> <span class="token keyword">NAME</span><span class="token operator">=</span><span class="token string">'id_index'</span> \G
<span class="token output"><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span> 1. row <span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span>
       INDEX_ID<span class="token punctuation">:</span> 91
           NAME<span class="token punctuation">:</span> id_index
       TABLE_ID<span class="token punctuation">:</span> 68
           TYPE<span class="token punctuation">:</span> 0
       N_FIELDS<span class="token punctuation">:</span> 1
        PAGE_NO<span class="token punctuation">:</span> 4
          SPACE<span class="token punctuation">:</span> 57
MERGE_THRESHOLD<span class="token punctuation">:</span> 40</span></code></pre>
  </div>
  <p>
   You can use
   <a class="link" href="show-create-table.html" title="15.7.7.11 SHOW CREATE TABLE Statement">
    <code class="literal">
     SHOW CREATE TABLE
    </code>
   </a>
   to
      view the
   <code class="literal">
    MERGE_THRESHOLD
   </code>
   value for a table, if
      explicitly defined using the
   <em class="replaceable">
    <code>
     table_option
    </code>
   </em>
   <code class="literal">
    COMMENT
   </code>
   clause:
  </p>
  <div class="copytoclipboard-wrapper">
   <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa97733350"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql&gt;</span> <span class="token keyword">SHOW</span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> t2 \G
<span class="token output"><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span> 1. row <span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span>
       Table<span class="token punctuation">:</span> t2
Create Table<span class="token punctuation">:</span> CREATE TABLE `t2` (
  `id` int(11) DEFAULT NULL,
  KEY `id_index` (`id`) COMMENT 'MERGE_THRESHOLD=40'
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci</span></code></pre>
  </div>
  <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
   <div class="admon-title">
    Note
   </div>
   <p>
    A
    <code class="literal">
     MERGE_THRESHOLD
    </code>
    value defined at the index
        level takes priority over a
    <code class="literal">
     MERGE_THRESHOLD
    </code>
    value defined for the table. If undefined,
    <code class="literal">
     MERGE_THRESHOLD
    </code>
    defaults to 50%
        (
    <code class="literal">
     MERGE_THRESHOLD=50
    </code>
    , which is the previously
        hardcoded value.
   </p>
  </div>
  <p>
   Likewise, you can use
   <a class="link" href="show-index.html" title="15.7.7.23 SHOW INDEX Statement">
    <code class="literal">
     SHOW INDEX
    </code>
   </a>
   to
      view the
   <code class="literal">
    MERGE_THRESHOLD
   </code>
   value for an index, if
      explicitly defined using the
   <em class="replaceable">
    <code>
     index_option
    </code>
   </em>
   <code class="literal">
    COMMENT
   </code>
   clause:
  </p>
  <div class="copytoclipboard-wrapper">
   <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa86304780"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql&gt;</span> <span class="token keyword">SHOW</span> <span class="token keyword">INDEX</span> <span class="token keyword">FROM</span> t2 \G
<span class="token output"><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span> 1. row <span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span>
        Table<span class="token punctuation">:</span> t2
   Non_unique<span class="token punctuation">:</span> 1
     Key_name<span class="token punctuation">:</span> id_index
 Seq_in_index<span class="token punctuation">:</span> 1
  Column_name<span class="token punctuation">:</span> id
    Collation<span class="token punctuation">:</span> A
  Cardinality<span class="token punctuation">:</span> 0
     Sub_part<span class="token punctuation">:</span> NULL
       Packed<span class="token punctuation">:</span> NULL
         Null<span class="token punctuation">:</span> YES
   Index_type<span class="token punctuation">:</span> BTREE
      Comment<span class="token punctuation">:</span>
Index_comment<span class="token punctuation">:</span> MERGE_THRESHOLD=40</span></code></pre>
  </div>
  <h4>
   <a name="idm46045161866784">
   </a>
   Measuring the Effect of MERGE_THRESHOLD Settings
  </h4>
  <p>
   The
   <a class="link" href="information-schema-innodb-metrics-table.html" title="28.4.21 The INFORMATION_SCHEMA INNODB_METRICS Table">
    <code class="literal">
     INNODB_METRICS
    </code>
   </a>
   table provides two
      counters that can be used to measure the effect of a
   <code class="literal">
    MERGE_THRESHOLD
   </code>
   setting on index page merges.
  </p>
  <div class="copytoclipboard-wrapper">
   <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa44911639"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql&gt;</span> <span class="token keyword">SELECT</span> <span class="token keyword">NAME</span><span class="token punctuation">,</span> <span class="token keyword">COMMENT</span> <span class="token keyword">FROM</span> INFORMATION_SCHEMA<span class="token punctuation">.</span>INNODB_METRICS
       <span class="token keyword">WHERE</span> <span class="token keyword">NAME</span> <span class="token operator">like</span> <span class="token string">'%index_page_merge%'</span><span class="token punctuation">;</span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> NAME                        <span class="token punctuation">|</span> COMMENT                                <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span>
<span class="token output"><span class="token punctuation">|</span> index_page_merge_attempts   <span class="token punctuation">|</span> Number of index page merge attempts    <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">|</span> index_page_merge_successful <span class="token punctuation">|</span> Number of successful index page merges <span class="token punctuation">|</span></span>
<span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre>
  </div>
  <p>
   When lowering the
   <code class="literal">
    MERGE_THRESHOLD
   </code>
   value, the
      objectives are:
  </p>
  <div class="itemizedlist">
   <ul class="itemizedlist" style="list-style-type: disc; ">
    <li class="listitem">
     <p>
      A smaller number of page merge attempts and successful page
          merges
     </p>
    </li>
    <li class="listitem">
     <p>
      A similar number of page merge attempts and successful page
          merges
     </p>
    </li>
   </ul>
  </div>
  <p>
   A
   <code class="literal">
    MERGE_THRESHOLD
   </code>
   setting that is too small
      could result in large data files due to an excessive amount of
      empty page space.
  </p>
  <p>
   For information about using
   <a class="link" href="information-schema-innodb-metrics-table.html" title="28.4.21 The INFORMATION_SCHEMA INNODB_METRICS Table">
    <code class="literal">
     INNODB_METRICS
    </code>
   </a>
   counters, see
   <a class="xref" href="innodb-information-schema-metrics-table.html" title="17.15.6 InnoDB INFORMATION_SCHEMA Metrics Table">
    Section 17.15.6, “InnoDB INFORMATION_SCHEMA Metrics Table”
   </a>
   .
  </p>
 </div>
 <br/>
</div>
