NAME¶
pt-upgrade - Execute queries on multiple servers and check for differences.
SYNOPSIS¶
Usage: pt-upgrade [OPTION...] DSN [DSN...] [FILE]
pt-upgrade compares query execution on two hosts by executing queries in the
given file (or STDIN if no file given) and examining the results, errors,
warnings, etc.produced on each.
Execute and compare all queries in slow.log on host1 to host2:
pt-upgrade slow.log h=host1 h=host2
Use pt-query-digest to get, execute and compare queries from tcpdump:
tcpdump -i eth0 port 3306 -s 65535 -x -n -q -tttt > tcpdump.txt
pt-query-digest tcpdump.txt --type tcpdump --no-report --print > digest.txt
pt-upgrade digest.txt h=host1 h=host2
Compare only query times on host1 to host2 and host3:
pt-upgrade slow.log h=host1 h=host2 h=host3 --compare query_times
Compare a single query, no slowlog needed:
pt-upgrade h=host1 h=host2 --query 'SELECT * FROM db.tbl'
RISKS¶
The following section is included to inform users about the potential risks,
whether known or unknown, of using this tool. The two main categories of risks
are those created by the nature of the tool (e.g. read-only tools vs.
read-write tools) and those created by bugs.
pt-upgrade is a read-only tool that is meant to be used on non-production
servers. It executes the SQL that you give it as input, which could cause
undesired load on a production server.
At the time of this release, there is a bug that causes the tool to crash, and a
bug that causes a deadlock.
The authoritative source for updated information is always the online issue
tracking system. Issues that affect this tool will be marked as such. You can
see a list of such issues at the following URL:
http://www.percona.com/bugs/pt-upgrade
<
http://www.percona.com/bugs/pt-upgrade>.
See also "BUGS" for more information on filing bugs and getting help.
DESCRIPTION¶
pt-upgrade executes queries from slowlogs on one or more MySQL server to find
differences in query time, warnings, results, and other aspects of the
queries' execution. This helps evaluate upgrades, migrations and configuration
changes. The comparisons specified by "--compare" determine what
differences can be found. A report is printed which outlines all the
differences found; see "OUTPUT" below.
The first DSN (host) specified on the command line is authoritative; it defines
the results to which the other DSNs are compared. You can "compare"
only one host, in which case there will be no differences but the output can
be saved to be diffed later against the output of another single host
"comparison".
At present, pt-upgrade only reads slowlogs. Use "pt-query-digest
--print" to transform other log formats to slowlog.
DSNs and slowlog files can be specified in any order. pt-upgrade will
automatically determine if an argument is a DSN or a slowlog file. If no
slowlog files are given and "--query" is not specified then
pt-upgrade will read from "STDIN".
OUTPUT¶
Queries are group by fingerprints and any with differences are printed. The
first part of a query report is a summary of differences. In the example
below, the query returns a different number of rows ("row counts")
on each server. The second part is the side-by-side comparison of values
obtained from the query on each server. Then a sample of the query is printed,
preceded by its ID which can be used to locate more information in the
sub-report at the end. There are sub-reports for various types of differences.
# Query 1: ID 0x3C830E3839B916D7 at byte 0 _______________________________
# Found 1 differences in 1 samples:
# column counts 0
# column types 0
# column values 0
# row counts 1
# warning counts 0
# warning levels 0
# warnings 0
# 127.1:12345 127.1:12348
# Errors 0 0
# Warnings 0 0
# Query_time
# sum 0 0
# min 0 0
# max 0 0
# avg 0 0
# pct_95 0 0
# stddev 0 0
# median 0 0
# row_count
# sum 4 3
# min 4 3
# max 4 3
# avg 4 3
# pct_95 4 3
# stddev 0 0
# median 4 3
use `test`;
select i from t where i is not null
/* 3C830E3839B916D7-1 */ select i from t where i is not null
# Row count differences
# Query ID 127.1:12345 127.1:12348
# ================== =========== ===========
# 3C830E3839B916D7-1 4 3
The output will vary slightly depending on which options are specified.
OPTIONS¶
This tool accepts additional command-line arguments. Refer to the
"SYNOPSIS" and usage information for details.
- --ask-pass
- Prompt for a password when connecting to MySQL.
- --base-dir
- type: string; default: /tmp
Save outfiles for the "rows" comparison method in this directory.
See the "rows" "--compare-results-method".
- --charset
- short form: -A; type: string
Default character set. If the value is utf8, sets Perl's binmode on STDOUT
to utf8, passes the mysql_enable_utf8 option to DBD::mysql, and runs SET
NAMES UTF8 after connecting to MySQL. Any other value sets binmode on
STDOUT without the utf8 layer, and runs SET NAMES after connecting to
MySQL.
- --[no]clear-warnings
- default: yes
Clear warnings before each warnings comparison.
If comparing warnings ("--compare" includes "warnings"),
this option causes pt-upgrade to execute a successful "SELECT"
statement which clears any warnings left over from previous queries. This
requires a current database that pt-upgrade usually detects automatically,
but in some cases it might be necessary to specify
"--temp-database". If pt-upgrade can't auto-detect the current
database, it will create a temporary table in the
"--temp-database" called
"mk_upgrade_clear_warnings".
- --clear-warnings-table
- type: string
Execute "SELECT * FROM ... LIMIT 1" from this table to clear
warnings.
- --compare
- type: Hash; default: query_times,results,warnings
What to compare for each query executed on each host.
Comparisons determine differences when the queries are executed on the
hosts. More comparisons enable more differences to be detected. The
following comparisons are available:
- query_times
- Compare query execution times. If this comparison is
disabled, the queries are still executed so that other comparisons will
work, but the query time attributes are removed from the events.
- results
- Compare result sets to find differences in rows, columns,
etc.
What differences can be found depends on the
"--compare-results-method" used.
- warnings
- Compare warnings from "SHOW WARNINGS". Requires
at least MySQL 4.1.
- --compare-results-method
- type: string; default: CHECKSUM; group: Comparisons
Method to use for "--compare" "results". This option has
no effect if "--no-compare-results" is given.
Available compare methods (case-insensitive):
- CHECKSUM
- Do "CREATE TEMPORARY TABLE `mk_upgrade` AS query"
then "CHECKSUM TABLE `mk_upgrade`". This method is fast and
simple but in rare cases might it be inaccurate because the MySQL manual
says:
[The] fact that two tables produce the same checksum does I<not> mean that
the tables are identical.
Requires at least MySQL 4.1.
- rows
- Compare rows one-by-one to find differences. This method
has advantages and disadvantages. Its disadvantages are that it may be
slower and it requires writing and reading outfiles from disk. Its
advantages are that it is universal (works for all versions of MySQL), it
doesn't alter the query in any way, and it can find column value
differences.
The "rows" method works as follows:
1. Rows from each host are compared one-by-one.
2. If no differences are found, comparison stops, else...
3. All remain rows (after the point where they begin to differ)
are written to outfiles.
4. The outfiles are loaded into temporary tables with
C<LOAD DATA LOCAL INFILE>.
5. The temporary tables are analyzed to determine the differences.
The outfiles are written to the "--base-dir".
- --config
- type: Array
Read this comma-separated list of config files; if specified, this must be
the first option on the command line.
- --continue-on-error
- Continue working even if there is an error.
- --convert-to-select
- Convert non-SELECT statements to SELECTs and compare.
By default non-SELECT statements are not allowed. This option causes
non-SELECT statements (like UPDATE, INSERT and DELETE) to be converted to
SELECT statements, executed and compared.
For example, "DELETE col FROM tbl WHERE id=1" is converted to
"SELECT col FROM tbl WHERE id=1".
- --daemonize
- Fork to the background and detach from the shell. POSIX
operating systems only.
- --explain-hosts
- Print connection information and exit.
- --filter
- type: string
Discard events for which this Perl code doesn't return true.
This option is a string of Perl code or a file containing Perl code that
gets compiled into a subroutine with one argument: $event. This is a
hashref. If the given value is a readable file, then pt-upgrade reads the
entire file and uses its contents as the code. The file should not contain
a shebang (#!/usr/bin/perl) line.
If the code returns true, the chain of callbacks continues; otherwise it
ends. The code is the last statement in the subroutine other than
"return $event". The subroutine template is:
sub { $event = shift; filter && return $event; }
Filters given on the command line are wrapped inside parentheses like like
"( filter )". For complex, multi-line filters, you must put the
code inside a file so it will not be wrapped inside parentheses. Either
way, the filter must produce syntactically valid code given the template.
For example, an if-else branch given on the command line would not be
valid:
--filter 'if () { } else { }' # WRONG
Since it's given on the command line, the if-else branch would be wrapped
inside parentheses which is not syntactically valid. So to accomplish
something more complex like this would require putting the code in a file,
for example filter.txt:
my $event_ok; if (...) { $event_ok=1; } else { $event_ok=0; } $event_ok
Then specify "--filter filter.txt" to read the code from
filter.txt.
If the filter code won't compile, pt-upgrade will die with an error. If the
filter code does compile, an error may still occur at runtime if the code
tries to do something wrong (like pattern match an undefined value).
pt-upgrade does not provide any safeguards so code carefully!
An example filter that discards everything but SELECT statements:
--filter '$event->{arg} =~ m/^select/i'
This is compiled into a subroutine like the following:
sub { $event = shift; ( $event->{arg} =~ m/^select/i ) && return $event; }
It is permissible for the code to have side effects (to alter $event).
You can find an explanation of the structure of $event at
<http://code.google.com/p/maatkit/wiki/EventAttributes>.
- --fingerprints
- Add query fingerprints to the standard query analysis
report. This is mostly useful for debugging purposes.
- --float-precision
- type: int
Round float, double and decimal values to this many places.
This option helps eliminate false-positives caused by floating-point
imprecision.
- --help
- Show help and exit.
- --host
- short form: -h; type: string
Connect to host.
- --iterations
- type: int; default: 1
How many times to iterate through the collect-and-report cycle. If 0,
iterate to infinity. See also --run-time.
- --limit
- type: string; default: 95%:20
Limit output to the given percentage or count.
If the argument is an integer, report only the top N worst queries. If the
argument is an integer followed by the "%" sign, report that
percentage of the worst queries. If the percentage is followed by a colon
and another integer, report the top percentage or the number specified by
that integer, whichever comes first.
- --log
- type: string
Print all output to this file when daemonized.
- --max-different-rows
- type: int; default: 10
Stop comparing rows for "--compare-results-method rows" after this
many differences are found.
- --order-by
- type: string; default: differences:sum
Sort events by this attribute and aggregate function.
- --password
- short form: -p; type: string
Password to use when connecting.
- --pid
- type: string
Create the given PID file when daemonized. The file contains the process ID
of the daemonized instance. The PID file is removed when the daemonized
instance exits. The program checks for the existence of the PID file when
starting; if it exists and the process with the matching PID exists, the
program exits.
- --port
- short form: -P; type: int
Port number to use for connection.
- --query
- type: string
Execute and compare this single query; ignores files on command line.
This option allows you to supply a single query on the command line. Any
slowlogs also specified on the command line are ignored.
- --reports
- type: Hash; default: queries,differences,errors,statistics
Print these reports. Valid reports are queries, differences, errors, and
statistics.
See "OUTPUT" for more information on the various parts of the
report.
- --run-time
- type: time
How long to run before exiting. The default is to run forever (you can
interrupt with CTRL-C).
- --set-vars
- type: string; default:
wait_timeout=10000,query_cache_type=0
Set these MySQL variables. Immediately after connecting to MySQL, this
string will be appended to SET and executed.
- --shorten
- type: int; default: 1024
Shorten long statements in reports.
Shortens long statements, replacing the omitted portion with a "/*...
omitted ...*/" comment. This applies only to the output in reports.
It prevents a large statement from causing difficulty in a report. The
argument is the preferred length of the shortened statement. Not all
statements can be shortened, but very large INSERT and similar statements
often can; and so can IN() lists, although only the first such list
in the statement will be shortened.
If it shortens something beyond recognition, you can find the original
statement in the log, at the offset shown in the report header (see
"OUTPUT").
- --socket
- short form: -S; type: string
Socket file to use for connection.
- --temp-database
- type: string
Use this database for creating temporary tables.
If given, this database is used for creating temporary tables for the
results comparison (see "--compare"). Otherwise, the current
database (from the last event that specified its database) is used.
- --temp-table
- type: string; default: mk_upgrade
Use this table for checksumming results.
- --user
- short form: -u; type: string
User for login if not current user.
- --version
- Show version and exit.
- --zero-query-times
- Zero the query times in the report.
DSN OPTIONS¶
These DSN options are used to create a DSN. Each option is given like
"option=value". The options are case-sensitive, so P and p are not
the same option. There cannot be whitespace before or after the "=",
and if the value contains whitespace it must be quoted. DSN options are
comma-separated. See the percona-toolkit manpage for full details.
- •
- A
dsn: charset; copy: yes
Default character set.
- •
- D
dsn: database; copy: yes
Default database.
- •
- F
dsn: mysql_read_default_file; copy: yes
Only read default options from the given file
- •
- h
dsn: host; copy: yes
Connect to host.
- •
- p
dsn: password; copy: yes
Password to use when connecting.
- •
- P
dsn: port; copy: yes
Port number to use for connection.
- •
- S
dsn: mysql_socket; copy: yes
Socket file to use for connection.
- •
- u
dsn: user; copy: yes
User for login if not current user.
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-upgrade ... > 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-upgrade
<
http://www.percona.com/bugs/pt-upgrade>.
Please report bugs at
https://bugs.launchpad.net/percona-toolkit
<
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/
<
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¶
Daniel Nichter
This tool is part of Percona Toolkit, a collection of advanced command-line
tools developed by Percona for MySQL support and consulting. Percona Toolkit
was forked from two projects in June, 2011: Maatkit and Aspersa. Those
projects were created by Baron Schwartz and developed primarily by him and
Daniel Nichter, both of whom are employed by Percona. Visit
<
http://www.percona.com/software/> for more software developed by
Percona.
COPYRIGHT, LICENSE, AND WARRANTY¶
This program is copyright 2009-2012 Percona Inc. Feedback and improvements are
welcome.
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-upgrade 2.1.2