<div id="docs-body">
 <div class="section">
  <div class="titlepage">
   <div>
    <div>
     <h4 class="title">
      <a name="myisamchk-table-info">
      </a>
      6.6.4.5 Obtaining Table Information with myisamchk
     </h4>
    </div>
   </div>
  </div>
  <a class="indexterm" name="idm46045306792704">
  </a>
  <a class="indexterm" name="idm46045306791248">
  </a>
  <a class="indexterm" name="idm46045306789760">
  </a>
  <a class="indexterm" name="idm46045306788272">
  </a>
  <p>
   To obtain a description of a
   <code class="literal">
    MyISAM
   </code>
   table or
        statistics about it, use the commands shown here. The output
        from these commands is explained later in this section.
  </p>
  <div class="itemizedlist">
   <ul class="itemizedlist" style="list-style-type: disc; ">
    <li class="listitem">
     <p>
      <a class="link" href="myisamchk.html" title="6.6.4 myisamchk — MyISAM Table-Maintenance Utility">
       <span class="command">
        <strong>
         myisamchk -d
         <em class="replaceable">
          <code>
           tbl_name
          </code>
         </em>
        </strong>
       </span>
      </a>
     </p>
     <p>
      Runs
      <a class="link" href="myisamchk.html" title="6.6.4 myisamchk — MyISAM Table-Maintenance Utility">
       <span class="command">
        <strong>
         myisamchk
        </strong>
       </span>
      </a>
      in
      <span class="quote">
       “
       <span class="quote">
        describe
            mode
       </span>
       ”
      </span>
      to produce a description of your table. If you
            start the MySQL server with external locking disabled,
      <a class="link" href="myisamchk.html" title="6.6.4 myisamchk — MyISAM Table-Maintenance Utility">
       <span class="command">
        <strong>
         myisamchk
        </strong>
       </span>
      </a>
      may report an error for a table
            that is updated while it runs. However, because
      <a class="link" href="myisamchk.html" title="6.6.4 myisamchk — MyISAM Table-Maintenance Utility">
       <span class="command">
        <strong>
         myisamchk
        </strong>
       </span>
      </a>
      does not change the table in
            describe mode, there is no risk of destroying data.
     </p>
    </li>
    <li class="listitem">
     <p>
      <a class="link" href="myisamchk.html" title="6.6.4 myisamchk — MyISAM Table-Maintenance Utility">
       <span class="command">
        <strong>
         myisamchk -dv
         <em class="replaceable">
          <code>
           tbl_name
          </code>
         </em>
        </strong>
       </span>
      </a>
     </p>
     <p>
      Adding
      <code class="option">
       -v
      </code>
      runs
      <a class="link" href="myisamchk.html" title="6.6.4 myisamchk — MyISAM Table-Maintenance Utility">
       <span class="command">
        <strong>
         myisamchk
        </strong>
       </span>
      </a>
      in verbose mode so that it produces more information about
            the table. Adding
      <code class="option">
       -v
      </code>
      a second time produces
            even more information.
     </p>
    </li>
    <li class="listitem">
     <p>
      <a class="link" href="myisamchk.html" title="6.6.4 myisamchk — MyISAM Table-Maintenance Utility">
       <span class="command">
        <strong>
         myisamchk -eis
         <em class="replaceable">
          <code>
           tbl_name
          </code>
         </em>
        </strong>
       </span>
      </a>
     </p>
     <p>
      Shows only the most important information from a table. This
            operation is slow because it must read the entire table.
     </p>
    </li>
    <li class="listitem">
     <p>
      <a class="link" href="myisamchk.html" title="6.6.4 myisamchk — MyISAM Table-Maintenance Utility">
       <span class="command">
        <strong>
         myisamchk -eiv
         <em class="replaceable">
          <code>
           tbl_name
          </code>
         </em>
        </strong>
       </span>
      </a>
     </p>
     <p>
      This is like
      <code class="option">
       -eis
      </code>
      , but tells you what is
            being done.
     </p>
    </li>
   </ul>
  </div>
  <p>
   The
   <em class="replaceable">
    <code>
     tbl_name
    </code>
   </em>
   argument can be either
        the name of a
   <code class="literal">
    MyISAM
   </code>
   table or the name of its
        index file, as described in
   <a class="xref" href="myisamchk.html" title="6.6.4 myisamchk — MyISAM Table-Maintenance Utility">
    Section 6.6.4, “myisamchk — MyISAM Table-Maintenance Utility”
   </a>
   .
        Multiple
   <em class="replaceable">
    <code>
     tbl_name
    </code>
   </em>
   arguments can be
        given.
  </p>
  <p>
   Suppose that a table named
   <code class="literal">
    person
   </code>
   has the
        following structure. (The
   <code class="literal">
    MAX_ROWS
   </code>
   table
        option is included so that in the example output from
   <a class="link" href="myisamchk.html" title="6.6.4 myisamchk — MyISAM Table-Maintenance Utility">
    <span class="command">
     <strong>
      myisamchk
     </strong>
    </span>
   </a>
   shown later, some values are
        smaller and fit the output format more easily.)
  </p>
  <div class="copytoclipboard-wrapper">
   <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa85707746"><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> person
<span class="token punctuation">(</span>
  id         <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span> <span class="token keyword">AUTO_INCREMENT</span><span class="token punctuation">,</span>
  last_name  <span class="token datatype">VARCHAR</span><span class="token punctuation">(</span><span class="token number">20</span><span class="token punctuation">)</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span>
  first_name <span class="token datatype">VARCHAR</span><span class="token punctuation">(</span><span class="token number">20</span><span class="token punctuation">)</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span>
  birth      <span class="token datatype">DATE</span><span class="token punctuation">,</span>
  death      <span class="token datatype">DATE</span><span class="token punctuation">,</span>
  <span class="token keyword">PRIMARY</span> <span class="token keyword">KEY</span> <span class="token punctuation">(</span>id<span class="token punctuation">)</span><span class="token punctuation">,</span>
  <span class="token keyword">INDEX</span> <span class="token punctuation">(</span>last_name<span class="token punctuation">,</span> first_name<span class="token punctuation">)</span><span class="token punctuation">,</span>
  <span class="token keyword">INDEX</span> <span class="token punctuation">(</span>birth<span class="token punctuation">)</span>
<span class="token punctuation">)</span> <span class="token keyword">MAX_ROWS</span> <span class="token operator">=</span> <span class="token number">1000000</span> <span class="token keyword">ENGINE</span><span class="token operator">=</span>MYISAM<span class="token punctuation">;</span></code></pre>
  </div>
  <p>
   Suppose also that the table has these data and index file sizes:
  </p>
  <div class="copytoclipboard-wrapper">
   <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa26195996"><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-terminal"><span class="token property">-rw-rw----</span>  1 mysql  mysql  9347072 Aug 19 11<span class="token punctuation">:</span>47 person<span class="token punctuation">.</span>MYD
<span class="token property">-rw-rw----</span>  1 mysql  mysql  6066176 Aug 19 11<span class="token punctuation">:</span>47 person<span class="token punctuation">.</span>MYI</code></pre>
  </div>
  <p>
   Example of
   <a class="link" href="myisamchk.html" title="6.6.4 myisamchk — MyISAM Table-Maintenance Utility">
    <span class="command">
     <strong>
      myisamchk -dvv
     </strong>
    </span>
   </a>
   output:
  </p>
  <div class="copytoclipboard-wrapper">
   <pre class="programlisting language-none"><div class="docs-select-all right" id="sa99661820"><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-none">MyISAM file:         person
Record format:       Packed
Character set:       utf8mb4_0900_ai_ci (255)
File-version:        1
Creation time:       2017-03-30 21:21:30
Status:              checked,analyzed,optimized keys,sorted index pages
Auto increment key:              1  Last value:                306688
Data records:               306688  Deleted blocks:                 0
Datafile parts:             306688  Deleted data:                   0
Datafile pointer (bytes):        4  Keyfile pointer (bytes):        3
Datafile length:           9347072  Keyfile length:           6066176
Max datafile length:    4294967294  Max keyfile length:   17179868159
Recordlength:                   54

table description:
Key Start Len Index   Type                     Rec/key         Root  Blocksize
1   2     4   unique  long                           1                    1024
2   6     80  multip. varchar prefix                 0                    1024
    87    80          varchar                        0
3   168   3   multip. uint24 NULL                    0                    1024

Field Start Length Nullpos Nullbit Type
1     1     1
2     2     4                      no zeros
3     6     81                     varchar
4     87    81                     varchar
5     168   3      1       1       no zeros
6     171   3      1       2       no zeros</code></pre>
  </div>
  <p>
   Explanations for the types of information
   <a class="link" href="myisamchk.html" title="6.6.4 myisamchk — MyISAM Table-Maintenance Utility">
    <span class="command">
     <strong>
      myisamchk
     </strong>
    </span>
   </a>
   produces are given here.
   <span class="quote">
    “
    <span class="quote">
     Keyfile
    </span>
    ”
   </span>
   refers to the index file.
   <span class="quote">
    “
    <span class="quote">
     Record
    </span>
    ”
   </span>
   and
   <span class="quote">
    “
    <span class="quote">
     row
    </span>
    ”
   </span>
   are synonymous, as
        are
   <span class="quote">
    “
    <span class="quote">
     field
    </span>
    ”
   </span>
   and
   <span class="quote">
    “
    <span class="quote">
     column.
    </span>
    ”
   </span>
  </p>
  <p>
   The initial part of the table description contains these values:
  </p>
  <div class="itemizedlist">
   <ul class="itemizedlist" style="list-style-type: disc; ">
    <li class="listitem">
     <p>
      <code class="literal">
       MyISAM file
      </code>
     </p>
     <p>
      Name of the
      <code class="literal">
       MyISAM
      </code>
      (index) file.
     </p>
    </li>
    <li class="listitem">
     <p>
      <code class="literal">
       Record format
      </code>
     </p>
     <p>
      The format used to store table rows. The preceding examples
            use
      <code class="literal">
       Fixed length
      </code>
      . Other possible values
            are
      <code class="literal">
       Compressed
      </code>
      and
      <code class="literal">
       Packed
      </code>
      . (
      <code class="literal">
       Packed
      </code>
      corresponds to what
      <code class="literal">
       SHOW TABLE STATUS
      </code>
      reports as
      <code class="literal">
       Dynamic
      </code>
      .)
     </p>
    </li>
    <li class="listitem">
     <p>
      <code class="literal">
       Chararacter set
      </code>
     </p>
     <p>
      The table default character set.
     </p>
    </li>
    <li class="listitem">
     <p>
      <code class="literal">
       File-version
      </code>
     </p>
     <p>
      Version of
      <code class="literal">
       MyISAM
      </code>
      format. Always 1.
     </p>
    </li>
    <li class="listitem">
     <p>
      <code class="literal">
       Creation time
      </code>
     </p>
     <p>
      When the data file was created.
     </p>
    </li>
    <li class="listitem">
     <p>
      <code class="literal">
       Recover time
      </code>
     </p>
     <p>
      When the index/data file was last reconstructed.
     </p>
    </li>
    <li class="listitem">
     <p>
      <code class="literal">
       Status
      </code>
     </p>
     <p>
      Table status flags. Possible values are
      <code class="literal">
       crashed
      </code>
      ,
      <code class="literal">
       open
      </code>
      ,
      <code class="literal">
       changed
      </code>
      ,
      <code class="literal">
       analyzed
      </code>
      ,
      <code class="literal">
       optimized keys
      </code>
      , and
      <code class="literal">
       sorted index
            pages
      </code>
      .
     </p>
    </li>
    <li class="listitem">
     <p>
      <code class="literal">
       Auto increment key
      </code>
      ,
      <code class="literal">
       Last
            value
      </code>
     </p>
     <p>
      The key number associated the table's
      <code class="literal">
       AUTO_INCREMENT
      </code>
      column, and the most
            recently generated value for this column. These fields do
            not appear if there is no such column.
     </p>
    </li>
    <li class="listitem">
     <p>
      <code class="literal">
       Data records
      </code>
     </p>
     <p>
      The number of rows in the table.
     </p>
    </li>
    <li class="listitem">
     <p>
      <code class="literal">
       Deleted blocks
      </code>
     </p>
     <p>
      How many deleted blocks still have reserved space. You can
            optimize your table to minimize this space. See
      <a class="xref" href="myisam-optimization.html" title="9.6.4 MyISAM Table Optimization">
       Section 9.6.4, “MyISAM Table Optimization”
      </a>
      .
     </p>
    </li>
    <li class="listitem">
     <p>
      <code class="literal">
       Datafile parts
      </code>
     </p>
     <p>
      For dynamic-row format, this indicates how many data blocks
            there are. For an optimized table without fragmented rows,
            this is the same as
      <code class="literal">
       Data records
      </code>
      .
     </p>
    </li>
    <li class="listitem">
     <p>
      <code class="literal">
       Deleted data
      </code>
     </p>
     <p>
      How many bytes of unreclaimed deleted data there are. You
            can optimize your table to minimize this space. See
      <a class="xref" href="myisam-optimization.html" title="9.6.4 MyISAM Table Optimization">
       Section 9.6.4, “MyISAM Table Optimization”
      </a>
      .
     </p>
    </li>
    <li class="listitem">
     <p>
      <code class="literal">
       Datafile pointer
      </code>
     </p>
     <p>
      The size of the data file pointer, in bytes. It is usually
            2, 3, 4, or 5 bytes. Most tables manage with 2 bytes, but
            this cannot be controlled from MySQL yet. For fixed tables,
            this is a row address. For dynamic tables, this is a byte
            address.
     </p>
    </li>
    <li class="listitem">
     <p>
      <code class="literal">
       Keyfile pointer
      </code>
     </p>
     <p>
      The size of the index file pointer, in bytes. It is usually
            1, 2, or 3 bytes. Most tables manage with 2 bytes, but this
            is calculated automatically by MySQL. It is always a block
            address.
     </p>
    </li>
    <li class="listitem">
     <p>
      <code class="literal">
       Max datafile length
      </code>
     </p>
     <p>
      How long the table data file can become, in bytes.
     </p>
    </li>
    <li class="listitem">
     <p>
      <code class="literal">
       Max keyfile length
      </code>
     </p>
     <p>
      How long the table index file can become, in bytes.
     </p>
    </li>
    <li class="listitem">
     <p>
      <code class="literal">
       Recordlength
      </code>
     </p>
     <p>
      How much space each row takes, in bytes.
     </p>
    </li>
   </ul>
  </div>
  <p>
   The
   <code class="literal">
    table description
   </code>
   part of the output
        includes a list of all keys in the table. For each key,
   <a class="link" href="myisamchk.html" title="6.6.4 myisamchk — MyISAM Table-Maintenance Utility">
    <span class="command">
     <strong>
      myisamchk
     </strong>
    </span>
   </a>
   displays some low-level
        information:
  </p>
  <div class="itemizedlist">
   <ul class="itemizedlist" style="list-style-type: disc; ">
    <li class="listitem">
     <p>
      <code class="literal">
       Key
      </code>
     </p>
     <p>
      This key's number. This value is shown only for the first
            column of the key. If this value is missing, the line
            corresponds to the second or later column of a
            multiple-column key. For the table shown in the example,
            there are two
      <code class="literal">
       table description
      </code>
      lines for
            the second index. This indicates that it is a multiple-part
            index with two parts.
     </p>
    </li>
    <li class="listitem">
     <p>
      <code class="literal">
       Start
      </code>
     </p>
     <p>
      Where in the row this portion of the index starts.
     </p>
    </li>
    <li class="listitem">
     <p>
      <code class="literal">
       Len
      </code>
     </p>
     <p>
      How long this portion of the index is. For packed numbers,
            this should always be the full length of the column. For
            strings, it may be shorter than the full length of the
            indexed column, because you can index a prefix of a string
            column. The total length of a multiple-part key is the sum
            of the
      <code class="literal">
       Len
      </code>
      values for all key parts.
     </p>
    </li>
    <li class="listitem">
     <p>
      <code class="literal">
       Index
      </code>
     </p>
     <p>
      Whether a key value can exist multiple times in the index.
            Possible values are
      <code class="literal">
       unique
      </code>
      or
      <code class="literal">
       multip.
      </code>
      (multiple).
     </p>
    </li>
    <li class="listitem">
     <p>
      <code class="literal">
       Type
      </code>
     </p>
     <p>
      What data type this portion of the index has. This is a
      <code class="literal">
       MyISAM
      </code>
      data type with the possible values
      <code class="literal">
       packed
      </code>
      ,
      <code class="literal">
       stripped
      </code>
      , or
      <code class="literal">
       empty
      </code>
      .
     </p>
    </li>
    <li class="listitem">
     <p>
      <code class="literal">
       Root
      </code>
     </p>
     <p>
      Address of the root index block.
     </p>
    </li>
    <li class="listitem">
     <p>
      <code class="literal">
       Blocksize
      </code>
     </p>
     <p>
      The size of each index block. By default this is 1024, but
            the value may be changed at compile time when MySQL is built
            from source.
     </p>
    </li>
    <li class="listitem">
     <p>
      <code class="literal">
       Rec/key
      </code>
     </p>
     <p>
      This is a statistical value used by the optimizer. It tells
            how many rows there are per value for this index. A unique
            index always has a value of 1. This may be updated after a
            table is loaded (or greatly changed) with
      <a class="link" href="myisamchk.html" title="6.6.4 myisamchk — MyISAM Table-Maintenance Utility">
       <span class="command">
        <strong>
         myisamchk
            -a
        </strong>
       </span>
      </a>
      . If this is not updated at all, a default value
            of 30 is given.
     </p>
    </li>
   </ul>
  </div>
  <p>
   The last part of the output provides information about each
        column:
  </p>
  <div class="itemizedlist">
   <ul class="itemizedlist" style="list-style-type: disc; ">
    <li class="listitem">
     <p>
      <code class="literal">
       Field
      </code>
     </p>
     <p>
      The column number.
     </p>
    </li>
    <li class="listitem">
     <p>
      <code class="literal">
       Start
      </code>
     </p>
     <p>
      The byte position of the column within table rows.
     </p>
    </li>
    <li class="listitem">
     <p>
      <code class="literal">
       Length
      </code>
     </p>
     <p>
      The length of the column in bytes.
     </p>
    </li>
    <li class="listitem">
     <p>
      <code class="literal">
       Nullpos
      </code>
      ,
      <code class="literal">
       Nullbit
      </code>
     </p>
     <p>
      For columns that can be
      <code class="literal">
       NULL
      </code>
      ,
      <code class="literal">
       MyISAM
      </code>
      stores
      <code class="literal">
       NULL
      </code>
      values as a flag in a byte. Depending on how many nullable
            columns there are, there can be one or more bytes used for
            this purpose. The
      <code class="literal">
       Nullpos
      </code>
      and
      <code class="literal">
       Nullbit
      </code>
      values, if nonempty, indicate
            which byte and bit contains that flag indicating whether the
            column is
      <code class="literal">
       NULL
      </code>
      .
     </p>
     <p>
      The position and number of bytes used to store
      <code class="literal">
       NULL
      </code>
      flags is shown in the line for field
            1. This is why there are six
      <code class="literal">
       Field
      </code>
      lines
            for the
      <code class="literal">
       person
      </code>
      table even though it has
            only five columns.
     </p>
    </li>
    <li class="listitem">
     <p>
      <code class="literal">
       Type
      </code>
     </p>
     <p>
      The data type. The value may contain any of the following
            descriptors:
     </p>
     <div class="itemizedlist">
      <ul class="itemizedlist" style="list-style-type: circle; ">
       <li class="listitem">
        <p>
         <code class="literal">
          constant
         </code>
        </p>
        <p>
         All rows have the same value.
        </p>
       </li>
       <li class="listitem">
        <p>
         <code class="literal">
          no endspace
         </code>
        </p>
        <p>
         Do not store endspace.
        </p>
       </li>
       <li class="listitem">
        <p>
         <code class="literal">
          no endspace, not_always
         </code>
        </p>
        <p>
         Do not store endspace and do not do endspace compression
                for all values.
        </p>
       </li>
       <li class="listitem">
        <p>
         <code class="literal">
          no endspace, no empty
         </code>
        </p>
        <p>
         Do not store endspace. Do not store empty values.
        </p>
       </li>
       <li class="listitem">
        <p>
         <code class="literal">
          table-lookup
         </code>
        </p>
        <p>
         The column was converted to an
         <a class="link" href="enum.html" title="13.3.5 The ENUM Type">
          <code class="literal">
           ENUM
          </code>
         </a>
         .
        </p>
       </li>
       <li class="listitem">
        <p>
         <code class="literal">
          zerofill(
          <em class="replaceable">
           <code>
            N
           </code>
          </em>
          )
         </code>
        </p>
        <p>
         The most significant
         <em class="replaceable">
          <code>
           N
          </code>
         </em>
         bytes
                in the value are always 0 and are not stored.
        </p>
       </li>
       <li class="listitem">
        <p>
         <code class="literal">
          no zeros
         </code>
        </p>
        <p>
         Do not store zeros.
        </p>
       </li>
       <li class="listitem">
        <p>
         <code class="literal">
          always zero
         </code>
        </p>
        <p>
         Zero values are stored using one bit.
        </p>
       </li>
      </ul>
     </div>
    </li>
    <li class="listitem">
     <p>
      <code class="literal">
       Huff tree
      </code>
     </p>
     <p>
      The number of the Huffman tree associated with the column.
     </p>
    </li>
    <li class="listitem">
     <p>
      <code class="literal">
       Bits
      </code>
     </p>
     <p>
      The number of bits used in the Huffman tree.
     </p>
    </li>
   </ul>
  </div>
  <p>
   The
   <code class="literal">
    Huff tree
   </code>
   and
   <code class="literal">
    Bits
   </code>
   fields are displayed if the table has been compressed with
   <a class="link" href="myisampack.html" title="6.6.6 myisampack — Generate Compressed, Read-Only MyISAM Tables">
    <span class="command">
     <strong>
      myisampack
     </strong>
    </span>
   </a>
   . See
   <a class="xref" href="myisampack.html" title="6.6.6 myisampack — Generate Compressed, Read-Only MyISAM Tables">
    Section 6.6.6, “myisampack — Generate Compressed, Read-Only MyISAM Tables”
   </a>
   ,
        for an example of this information.
  </p>
  <p>
   Example of
   <a class="link" href="myisamchk.html" title="6.6.4 myisamchk — MyISAM Table-Maintenance Utility">
    <span class="command">
     <strong>
      myisamchk -eiv
     </strong>
    </span>
   </a>
   output:
  </p>
  <div class="copytoclipboard-wrapper">
   <pre class="programlisting language-none"><div class="docs-select-all right" id="sa98917762"><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-none">Checking MyISAM file: person
Data records:  306688   Deleted blocks:       0
- check file-size
- check record delete-chain
No recordlinks
- check key delete-chain
block_size 1024:
- check index reference
- check data record references index: 1
Key:  1:  Keyblocks used:  98%  Packed:    0%  Max levels:  3
- check data record references index: 2
Key:  2:  Keyblocks used:  99%  Packed:   97%  Max levels:  3
- check data record references index: 3
Key:  3:  Keyblocks used:  98%  Packed:  -14%  Max levels:  3
Total:    Keyblocks used:  98%  Packed:   89%

- check records and index references
<em class="replaceable">*** LOTS OF ROW NUMBERS DELETED ***</em>

Records:            306688  M.recordlength:       25  Packed:            83%
Recordspace used:       97% Empty space:           2% Blocks/Record:   1.00
Record blocks:      306688  Delete blocks:         0
Record data:       7934464  Deleted data:          0
Lost space:         256512  Linkdata:        1156096

User time 43.08, System time 1.68
Maximum resident set size 0, Integral resident set size 0
Non-physical pagefaults 0, Physical pagefaults 0, Swaps 0
Blocks in 0 out 7, Messages in 0 out 0, Signals 0
Voluntary context switches 0, Involuntary context switches 0
Maximum memory usage: 1046926 bytes (1023k)</code></pre>
  </div>
  <p>
   <a class="link" href="myisamchk.html" title="6.6.4 myisamchk — MyISAM Table-Maintenance Utility">
    <span class="command">
     <strong>
      myisamchk -eiv
     </strong>
    </span>
   </a>
   output includes the following
        information:
  </p>
  <div class="itemizedlist">
   <ul class="itemizedlist" style="list-style-type: disc; ">
    <li class="listitem">
     <p>
      <code class="literal">
       Data records
      </code>
     </p>
     <p>
      The number of rows in the table.
     </p>
    </li>
    <li class="listitem">
     <p>
      <code class="literal">
       Deleted blocks
      </code>
     </p>
     <p>
      How many deleted blocks still have reserved space. You can
            optimize your table to minimize this space. See
      <a class="xref" href="myisam-optimization.html" title="9.6.4 MyISAM Table Optimization">
       Section 9.6.4, “MyISAM Table Optimization”
      </a>
      .
     </p>
    </li>
    <li class="listitem">
     <p>
      <code class="literal">
       Key
      </code>
     </p>
     <p>
      The key number.
     </p>
    </li>
    <li class="listitem">
     <p>
      <code class="literal">
       Keyblocks used
      </code>
     </p>
     <p>
      What percentage of the keyblocks are used. When a table has
            just been reorganized with
      <a class="link" href="myisamchk.html" title="6.6.4 myisamchk — MyISAM Table-Maintenance Utility">
       <span class="command">
        <strong>
         myisamchk
        </strong>
       </span>
      </a>
      , the
            values are very high (very near theoretical maximum).
     </p>
    </li>
    <li class="listitem">
     <p>
      <code class="literal">
       Packed
      </code>
     </p>
     <p>
      MySQL tries to pack key values that have a common suffix.
            This can only be used for indexes on
      <a class="link" href="char.html" title="13.3.2 The CHAR and VARCHAR Types">
       <code class="literal">
        CHAR
       </code>
      </a>
      and
      <a class="link" href="char.html" title="13.3.2 The CHAR and VARCHAR Types">
       <code class="literal">
        VARCHAR
       </code>
      </a>
      columns. For long
            indexed strings that have similar leftmost parts, this can
            significantly reduce the space used. In the preceding
            example, the second key is 40 bytes long and a 97% reduction
            in space is achieved.
     </p>
    </li>
    <li class="listitem">
     <p>
      <code class="literal">
       Max levels
      </code>
     </p>
     <p>
      How deep the B-tree for this key is. Large tables with long
            key values get high values.
     </p>
    </li>
    <li class="listitem">
     <p>
      <code class="literal">
       Records
      </code>
     </p>
     <p>
      How many rows are in the table.
     </p>
    </li>
    <li class="listitem">
     <p>
      <code class="literal">
       M.recordlength
      </code>
     </p>
     <p>
      The average row length. This is the exact row length for
            tables with fixed-length rows, because all rows have the
            same length.
     </p>
    </li>
    <li class="listitem">
     <p>
      <code class="literal">
       Packed
      </code>
     </p>
     <p>
      MySQL strips spaces from the end of strings. The
      <code class="literal">
       Packed
      </code>
      value indicates the percentage of
            savings achieved by doing this.
     </p>
    </li>
    <li class="listitem">
     <p>
      <code class="literal">
       Recordspace used
      </code>
     </p>
     <p>
      What percentage of the data file is used.
     </p>
    </li>
    <li class="listitem">
     <p>
      <code class="literal">
       Empty space
      </code>
     </p>
     <p>
      What percentage of the data file is unused.
     </p>
    </li>
    <li class="listitem">
     <p>
      <code class="literal">
       Blocks/Record
      </code>
     </p>
     <p>
      Average number of blocks per row (that is, how many links a
            fragmented row is composed of). This is always 1.0 for
            fixed-format tables. This value should stay as close to 1.0
            as possible. If it gets too large, you can reorganize the
            table. See
      <a class="xref" href="myisam-optimization.html" title="9.6.4 MyISAM Table Optimization">
       Section 9.6.4, “MyISAM Table Optimization”
      </a>
      .
     </p>
    </li>
    <li class="listitem">
     <p>
      <code class="literal">
       Recordblocks
      </code>
     </p>
     <p>
      How many blocks (links) are used. For fixed-format tables,
            this is the same as the number of rows.
     </p>
    </li>
    <li class="listitem">
     <p>
      <code class="literal">
       Deleteblocks
      </code>
     </p>
     <p>
      How many blocks (links) are deleted.
     </p>
    </li>
    <li class="listitem">
     <p>
      <code class="literal">
       Recorddata
      </code>
     </p>
     <p>
      How many bytes in the data file are used.
     </p>
    </li>
    <li class="listitem">
     <p>
      <code class="literal">
       Deleted data
      </code>
     </p>
     <p>
      How many bytes in the data file are deleted (unused).
     </p>
    </li>
    <li class="listitem">
     <p>
      <code class="literal">
       Lost space
      </code>
     </p>
     <p>
      If a row is updated to a shorter length, some space is lost.
            This is the sum of all such losses, in bytes.
     </p>
    </li>
    <li class="listitem">
     <p>
      <code class="literal">
       Linkdata
      </code>
     </p>
     <p>
      When the dynamic table format is used, row fragments are
            linked with pointers (4 to 7 bytes each).
      <code class="literal">
       Linkdata
      </code>
      is the sum of the amount of
            storage used by all such pointers.
     </p>
    </li>
   </ul>
  </div>
 </div>
 <br/>
</div>
