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Hence the hash is constant even if the database file +is modified by: + +</p><ul> +<li> <a href="lang_vacuum.html">VACUUM</a> +</li><li> <a href="pragma.html#pragma_page_size">PRAGMA page_size</a> +</li><li> <a href="pragma.html#pragma_journal_mode">PRAGMA journal_mode</a> +</li><li> <a href="lang_reindex.html">REINDEX</a> +</li><li> <a href="lang_analyze.html">ANALYZE</a> +</li><li> copied via the <a href="backup.html">backup API</a> +</li><li> ... and so forth +</li></ul> + +<p>The operations above can potentially cause vast changes the raw database file, +and hence cause very different SHA1 hashes at the file level. +But since the content represented in the database file is unchanged by these +operations, the hash computed by dbhash is also unchanged. + +</p><p>Dbhash can be used to compare two databases to confirm that they +are equivalent, even though their representation on disk is quite different. +Dbhash might also be used to verify the content of a remote database without having +to transmit the entire content of the remote database over a slow link. + +</p><h1 id="usage"><span>2. </span>Usage</h1> + +<p>Dbhash is a command-line utility. +To run it, type "dbhash" on a command-line prompt followed by the names of +one or more SQLite database files that are to be hashed. +The database hashes will be displayed on standard output. +For example: + +</p><div class="codeblock"><pre>drh@bella:~/sqlite/bld$ dbhash ~/Fossils/sqlite.fossil +8d3da9ff87196312aaa33076627ccb7943ef79e3 /home/drh/Fossils/sqlite.fossil +</pre></div> + +<p>Dbhash supports command-line options that can restrict the tables of the +database file that are hashed, or restrict the hash to only content or only +the schema. Run "dbhash --help" for further information. + +</p><h1 id="building"><span>3. </span>Building</h1> + +<p>To build a copy of the dbhash utility program on unix, get a copy of the +canonical SQLite source code and enter: + +</p><div class="codeblock"><pre>./configure +make dbhash +</pre></div> + +<p>On Windows, enter: + +</p><div class="codeblock"><pre>nmake /f makefile.msc dbhash.exe +</pre></div> + +<p>The dbhash program is implemented by a single file of C-code +called <a href="https://www.sqlite.org/src/artifact?ci=trunk&filename=tool/dbhash.c">dbhash.c</a>. +To build the dbhash program manually, simply compile the dbhash.c source file +and link it against the SQLite library. +</p><p align="center"><small><i>This page last modified on <a href="https://sqlite.org/docsrc/honeypot" id="mtimelink" data-href="https://sqlite.org/docsrc/finfo/pages/dbhash.in?m=e56508811fb75e69b">2016-07-13 13:57:06</a> UTC </small></i></p> + |