NAME¶
pt-fingerprint - Convert queries into fingerprints.
SYNOPSIS¶
Usage: pt-fingerprint [OPTIONS] [FILES]
pt-fingerprint converts queries into fingerprints. With the --query option,
converts the option's value into a fingerprint. With no options, treats
command-line arguments as FILEs and reads and converts semicolon-separated
queries from the FILEs. When FILE is -, it read standard input.
Convert a single query:
pt-fingerprint --query "select a, b, c from users where id = 500"
Convert a file full of queries:
pt-fingerprint /path/to/file.txt
RISKS¶
Percona Toolkit is mature, proven in the real world, and well tested, but all
database tools can pose a risk to the system and the database server. Before
using this tool, please:
- •
- Read the tool's documentation
- •
- Review the tool's known "BUGS"
- •
- Test the tool on a non-production server
- •
- Backup your production server and verify the backups
DESCRIPTION¶
A query fingerprint is the abstracted form of a query, which makes it possible
to group similar queries together. Abstracting a query removes literal values,
normalizes whitespace, and so on. For example, consider these two queries:
SELECT name, password FROM user WHERE id='12823';
select name, password from user
where id=5;
Both of those queries will fingerprint to
select name, password from user where id=?
Once the query's fingerprint is known, we can then talk about a query as though
it represents all similar queries.
Query fingerprinting accommodates a great many special cases, which have proven
necessary in the real world. For example, an IN list with 5 literals is really
equivalent to one with 4 literals, so lists of literals are collapsed to a
single one. If you want to understand more about how and why all of these
cases are handled, please review the test cases in the Subversion repository.
If you find something that is not fingerprinted properly, please submit a bug
report with a reproducible test case. Here is a list of transformations during
fingerprinting, which might not be exhaustive:
- •
- Group all SELECT queries from mysqldump together, even if they are against
different tables. Ditto for all of pt-table-checksum's checksum
queries.
- •
- Shorten multi-value INSERT statements to a single VALUES()
list.
- •
- Strip comments.
- •
- Abstract the databases in USE statements, so all USE statements are
grouped together.
- •
- Replace all literals, such as quoted strings. For efficiency, the code
that replaces literal numbers is somewhat non-selective, and might replace
some things as numbers when they really are not. Hexadecimal literals are
also replaced. NULL is treated as a literal. Numbers embedded in
identifiers are also replaced, so tables named similarly will be
fingerprinted to the same values (e.g. users_2009 and users_2010 will
fingerprint identically).
- •
- Collapse all whitespace into a single space.
- •
- Lowercase the entire query.
- •
- Replace all literals inside of IN() and VALUES() lists with
a single placeholder, regardless of cardinality.
- •
- Collapse multiple identical UNION queries into a single one.
OPTIONS¶
This tool accepts additional command-line arguments. Refer to the
"SYNOPSIS" and usage information for details.
- --config
- type: Array
Read this comma-separated list of config files; if specified, this must be
the first option on the command line.
- --help
- Show help and exit.
- --match-embedded-numbers
- Match numbers embedded in words and replace as single values. This option
causes the tool to be more careful about matching numbers so that words
with numbers, like "catch22" are matched and replaced as a
single "?" placeholder. Otherwise the default number matching
pattern will replace "catch22" as "catch?".
This is helpful if database or table names contain numbers.
- --match-md5-checksums
- Match MD5 checksums and replace as single values. This option causes the
tool to be more careful about matching numbers so that MD5 checksums like
"fbc5e685a5d3d45aa1d0347fdb7c4d35" are matched and replaced as a
single "?" placeholder. Otherwise, the default number matching
pattern will replace "fbc5e685a5d3d45aa1d0347fdb7c4d35" as
"fbc?".
- --query
- type: string
The query to convert into a fingerprint.
- --version
- Show version and exit.
ENVIRONMENT¶
The environment variable "PTDEBUG" enables verbose debugging output to
STDERR. To enable debugging and capture all output to a file, run the tool
like:
PTDEBUG=1 pt-fingerprint ... > FILE 2>&1
Be careful: debugging output is voluminous and can generate several megabytes of
output.
SYSTEM REQUIREMENTS¶
You need Perl, DBI, DBD::mysql, and some core packages that ought to be
installed in any reasonably new version of Perl.
BUGS¶
For a list of known bugs, see
<
http://www.percona.com/bugs/pt-fingerprint>.
Please report bugs at <
https://bugs.launchpad.net/percona-toolkit>.
Include the following information in your bug report:
- •
- Complete command-line used to run the tool
- •
- Tool "--version"
- •
- MySQL version of all servers involved
- •
- Output from the tool including STDERR
- •
- Input files (log/dump/config files, etc.)
If possible, include debugging output by running the tool with
"PTDEBUG"; see "ENVIRONMENT".
DOWNLOADING¶
Visit <
http://www.percona.com/software/percona-toolkit/> to download the
latest release of Percona Toolkit. Or, get the latest release from the command
line:
wget percona.com/get/percona-toolkit.tar.gz
wget percona.com/get/percona-toolkit.rpm
wget percona.com/get/percona-toolkit.deb
You can also get individual tools from the latest release:
wget percona.com/get/TOOL
Replace "TOOL" with the name of any tool.
AUTHORS¶
Baron Schwartz and Daniel Nichter
This tool is part of Percona Toolkit, a collection of advanced command-line
tools for MySQL developed by Percona. Percona Toolkit was forked from two
projects in June, 2011: Maatkit and Aspersa. Those projects were created by
Baron Schwartz and primarily developed by him and Daniel Nichter. Visit
<
http://www.percona.com/software/> to learn about other free,
open-source software from Percona.
COPYRIGHT, LICENSE, AND WARRANTY¶
This program is copyright 2011-2014 Percona LLC and/or its affiliates.
THIS PROGRAM IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR IMPLIED
WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
This program is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free Software
Foundation, version 2; OR the Perl Artistic License. On UNIX and similar
systems, you can issue `man perlgpl' or `man perlartistic' to read these
licenses.
You should have received a copy of the GNU General Public License along with
this program; if not, write to the Free Software Foundation, Inc., 59 Temple
Place, Suite 330, Boston, MA 02111-1307 USA.
VERSION¶
pt-fingerprint 2.2.11