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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<div class="title">Dump Formats </div> </div>
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<div class="textblock"><p>The <a class="el" href="command_line.html#util_dump">wt dump</a> command produces a flat-text representation of a table that can be loaded by <a class="el" href="command_line.html#util_load">wt load</a>. This page describes the output formats of the <a class="el" href="command_line.html#util_dump">wt dump</a> command.</p>
<h1><a class="anchor" id="dump_formats_json"></a>
JSON dump format</h1>
<p>JSON (<a href="http://www.json.org">JavaScript Object Notation</a>) dump files use the standard JSON data-interchange format to specify the objects, and may be interpreted by any JSON reader.</p>
<p>The format is a JSON object where each key is the URI passed to <a class="el" href="struct_w_t___s_e_s_s_i_o_n.html#a358ca4141d59c345f401c58501276bbb" title="Create a table, column group, index or file. ">WT_SESSION::create</a> and the corresponding value is a JSON array of two entries. The first entry in this array is a JSON object composed of configuration information: the "config" key has the configuration string used with <a class="el" href="struct_w_t___s_e_s_s_i_o_n.html#a358ca4141d59c345f401c58501276bbb" title="Create a table, column group, index or file. ">WT_SESSION::create</a>, the "colgroups" and "indices" keys have values that are arrays of objects that are in turn composed of configuration information. The second entry is a JSON array, with each entry an object representing a row of data. If the columns were named in the configuration string used with <a class="el" href="struct_w_t___s_e_s_s_i_o_n.html#a358ca4141d59c345f401c58501276bbb" title="Create a table, column group, index or file. ">WT_SESSION::create</a>, those names are used for keys, otherwise predictable names (for example, "key0", "value0", "value1") are generated. The values in this object are the values for each column in the record.</p>
<p>Here is some sample output:</p>
<div class="fragment"><div class="line">{</div>
<div class="line"> <span class="stringliteral">"table:planets"</span> : [</div>
<div class="line"> {</div>
<div class="line"> <span class="stringliteral">"config"</span> : <span class="stringliteral">"columns=(id,name,distance),key_format=i,value_format=Si"</span>,</div>
<div class="line"> <span class="stringliteral">"colgroups"</span> : [],</div>
<div class="line"> <span class="stringliteral">"indices"</span> : [</div>
<div class="line"> {</div>
<div class="line"> <span class="stringliteral">"uri"</span> : <span class="stringliteral">"index:planets:names"</span>,</div>
<div class="line"> <span class="stringliteral">"config"</span> : <span class="stringliteral">"columns=(name),key_format=Si,source=\"file:astronomy.wt\",type=file"</span></div>
<div class="line"> }</div>
<div class="line"> ]</div>
<div class="line"> },</div>
<div class="line"> [</div>
<div class="line"> {</div>
<div class="line"><span class="stringliteral">"id"</span> : 1,</div>
<div class="line"><span class="stringliteral">"name"</span> : <span class="stringliteral">"Mercury"</span>,</div>
<div class="line"><span class="stringliteral">"distance"</span> : 57910000</div>
<div class="line"> },</div>
<div class="line"> {</div>
<div class="line"><span class="stringliteral">"id"</span> : 2,</div>
<div class="line"><span class="stringliteral">"name"</span> : <span class="stringliteral">"Venus"</span>,</div>
<div class="line"><span class="stringliteral">"distance"</span> : 108200000</div>
<div class="line"> },</div>
<div class="line"> ...</div>
<div class="line"> ]</div>
<div class="line"> ]</div>
<div class="line">}</div>
</div><!-- fragment --><h1><a class="anchor" id="dump_formats_text"></a>
Text dump format</h1>
<p>Text dump files have three parts, a prefix, a header and a body.</p>
<p>The dump prefix includes basic information about the dump including the WiredTiger version that created the dump and the dump format. The dump format consists of a line beginning with <code>"Format="</code>, and contains the following information:</p>
<table class="doxtable">
<tr>
<th>String</th><th>Meaning </th></tr>
<tr>
<td>hex</td><td>the dumped data is in a hexadecimal dump format </td></tr>
<tr>
<td>print</td><td>the dumped data is in a printable format </td></tr>
</table>
<p>The dump header follows a single <code>"Header"</code> line in the file and consists of paired key and value lines, where the key is the URI passed to <a class="el" href="struct_w_t___s_e_s_s_i_o_n.html#a358ca4141d59c345f401c58501276bbb" title="Create a table, column group, index or file. ">WT_SESSION::create</a> and the value is corresponding configuration string. The table or file can be recreated by calling <a class="el" href="struct_w_t___s_e_s_s_i_o_n.html#a358ca4141d59c345f401c58501276bbb" title="Create a table, column group, index or file. ">WT_SESSION::create</a> for each pair of lines in the header.</p>
<p>The dump body follows a single <code>"Data"</code> line in the file and consists of a text representation of the records in the table. Each record is a represented by a pair of lines: the first line is the key and the second line is the value. These lines are encoded in one of two formats: a printable format and a hexadecimal format.</p>
<p>The printable format consists of literal printable characters, and hexadecimal encoded non-printable characters. Encoded characters are written as three separate characters: a backslash character followed by two hexadecimal characters (first the high nibble and then the low nibble). For example, a newline character in the ASCII character set would be encoded as <code>"\0a"</code> and an escape character would be encoded as <code>"\1b"</code>. Backslash characters which do not precede a hexadecimal encoding are paired, that is, the characters <code>"\\"</code> should be interpreted as a single backslash character.</p>
<p>The hexadecimal format consists of encoded characters, where each literal character is written as a pair of characters (first the high-nibble and then the low-nibble). For example, "0a" would be an ASCII newline character and "1b" would be an ASCII escape character.</p>
<p>Because the definition of "printable" may depend on the application's locale, dump files in the printable output format may be less portable than dump files in the hexadecimal output format. </p>
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