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.. program:: pt-archiver
========================
:program:`pt-archiver`
========================
.. highlight:: perl
NAME
====
:program:`pt-archiver` - Archive rows from a MySQL table into another table or a file.
SYNOPSIS
========
Usage
-----
::
pt-archiver [OPTION...] --source DSN --where WHERE
:program:`pt-archiver` nibbles records from a MySQL table. The :option:`--source` and :option:`--dest
arguments` use ``DSN`` syntax; if ``COPY`` is yes, :option:`--dest` defaults to the key's value from :option:`--source`.
Examples
--------
Archive all rows from oltp_server to olap_server and to a file:
.. code-block:: perl
pt-archiver --source h=oltp_server,D=test,t=tbl --dest h=olap_server \
--file '/var/log/archive/%Y-%m-%d-%D.%t' \
--where "1=1" --limit 1000 --commit-each
Purge (delete) orphan rows from child table:
.. code-block:: perl
pt-archiver --source h=host,D=db,t=child --purge \
--where 'NOT EXISTS(SELECT * FROM parent WHERE col=child.col)'
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.
:program:`pt-achiver` is a read-write tool. It deletes data from the source by default, so you should test your archiving jobs with the :option:`--dry-run` option if you're not sure about them. It is designed to have as little impact on production systems as possible, but tuning with :option:`--limit`, :option:`--txn-size` and similar options might be a good idea too.
If you write or use :option:`--plugin` modules, you should ensure they are good
quality and well-tested.
At the time of this release there is an unverified bug with
:option:`--bulk-insert` that may cause data loss.
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-archiver <http://www.percona.com/bugs/pt-archiver>`_.
See also ``BUGS`` for more information on filing bugs and getting help.
DESCRIPTION
===========
:program:`pt-archiver` is the tool I use to archive tables as described in
`http://tinyurl.com/mysql-archiving <http://tinyurl.com/mysql-archiving>`_.
The goal is a low-impact, forward-only job to nibble old data out of the table without impacting ``OLTP`` queries much.
You can insert the data into another table, which need not be on the same
server. You can also write it to a file in a format suitable for ``LOAD DATA
INFILE``. Or you can do neither, in which case it's just an incremental ``DELETE``.
:program:`pt-archiver` is extensible via a plugin mechanism. You can inject your own code to add advanced archiving logic that could be useful for archiving
dependent data, applying complex business rules, or building a data warehouse
during the archiving process.
You need to choose values carefully for some options. The most important are
:option:`--limit`, :option:`--retries`, and :option:`--txn-size`.
The strategy is to find the first row(s), then scan some index forward-only to
find more rows efficiently. Each subsequent query should not scan the entire
table; it should seek into the index, then scan until it finds more archivable
rows. Specifying the index with the 'i' part of the :option:`--source` argument can be crucial for this; use :option:`--dry-run` to examine the generated queries and be sure to ``EXPLAIN`` them to see if they are efficient (most of the time you probably want to scan the ``PRIMARY`` key, which is the default). Even better, profile :program:`pt-archiver` with :program:`pt-query-profiler` and make sure it is not scanning the whole
table every query.
You can disable the seek-then-scan optimizations partially or wholly with
:option:`--no-ascend` and :option:`--ascend-first`. Sometimes this may be more efficient for multi-column keys. Be aware that :program:`pt-archiver` is built to start at the beginning of the index it chooses and scan it forward-only. This might result in long table scans if you're trying to nibble from the end of the table by an index other than the one it prefers. See :option:`--source` and read the documentation on the \ ``i``\ part if this applies to you.
OUTPUT
======
If you specify :option:`--progress`, the output is a header row, plus status output at intervals. Each row in the status output lists the current date and time, how many seconds :program:`pt-archiver`; has been running, and how many rows it has
archived.
If you specify :option:`--statistics`, \ ``pt-archiver``\ outputs timing and other information to help you identify which part of your archiving process takes the most time.
ERROR-HANDLING
==============
:program:`pt-archiver` tries to catch signals and exit gracefully; for example, if you send it ``SIGTERM`` (``Ctrl-C`` on UNIX-ish systems), it will catch the signal, print a message about the signal, and exit fairly normally. It will not execute :option:`--analyze` or :option:`--optimize`, because these may take a long time to finish. It will run all other code normally, including calling ``after_finish()`` on any plugins (see "EXTENDING").
In other words, a signal, if caught, will break out of the main archiving
loop and skip optimize/analyze.
OPTIONS
=======
Specify at least one of :option:`--dest`, :option:`--file`, or :option:`--purge`.
* :option:`--ignore` and :option:`--replace` are mutually exclusive.
* :option:`--txn-size` and :option:`--commit-each` are mutually exclusive.
* :option:`--low-priority-insert` and :option:`--delayed-insert` are mutually exclusive.
* :option:`--share-lock` and :option:`--for-update` are mutually exclusive.
* :option:`--analyze` and :option:`--optimize` are mutually exclusive.
* :option:`--no-ascend` and :option:`--no-delete` are mutually exclusive.
DSN values in "--dest" default to values from "--source" if COPY is yes.
.. option:: --analyze
* Type:
``STRING``
Run ANALYZE TABLE afterwards on "--source" and/or "--dest".
Runs ANALYZE TABLE after finishing. The argument is an arbitrary string. If it contains the letter 's', the source will be analyzed. If it contains 'd', the destination will be analyzed. You can specify either or both. For example, the following will analyze both:
.. code-block:: perl
--analyze=ds
See `http://dev.mysql.com/doc/en/analyze-table.html <http://dev.mysql.com/doc/en/analyze-table.html>`_ for details on ANALYZE
TABLE.
.. option:: --ascend-first
Ascend only first column of index.
If you do want to use the ascending index optimization (see :option:`--no-ascend`), but do not want to incur the overhead of ascending a large multi-column index, you can use this option to tell pt-archiver to ascend only the leftmost column of the index. This can provide a significant performance boost over not ascending the index at all, while avoiding the cost of ascending the whole index.
See "EXTENDING" for a discussion of how this interacts with plugins.
.. option:: --ask-pass
Prompt for a password when connecting to |MySQL|.
.. option:: --buffer
Buffer output to :option:`--file` and flush at commit.
Disables autoflushing to :option:`--file` and flushes :option:`--file` to disk only when a transaction commits. This typically means the file is block-flushed by the operating system, so there may be some implicit flushes to disk between commits as well. The default is to flush :option:`--file` to disk after every row.
The danger is that a crash might cause lost data.
The performance increase I have seen from using :option:`--buffer` is around 5 to 15 percent. Your mileage may vary.
.. option:: --bulk-delete
Delete each chunk with a single statement (implies :option:`--commit-each`).
Delete each chunk of rows in bulk with a single ``DELETE`` statement. The
statement deletes every row between the first and last row of the chunk,
inclusive. It implies :option:`--commit-each`, since it would be a bad idea to
``INSERT`` rows one at a time and commit them before the bulk ``DELETE``.
The normal method is to delete every row by its primary key. Bulk deletes might be a lot faster. **They also might not be faster** if you have a complex
``WHERE`` clause.
This option completely defers all ``DELETE`` processing until the chunk of rows is finished. If you have a plugin on the source, its ``before_delete`` method will not be called. Instead, its ``before_bulk_delete`` method is called later.
**WARNING**: if you have a plugin on the source that sometimes doesn't return
true from ``is_archivable()``, you should use this option only if you understand what it does. If the plugin instructs ``pt-archiver`` not to archive a row, it will still be deleted by the bulk delete!
.. option:: --[no]bulk-delete-limit
Default: yes
Add :option:`--limit` to :option:`--bulk-delete` statement.
This is an advanced option and you should not disable it unless you know what
you are doing and why! By default, :option:`--bulk-delete` appends a "--limit" clause to the bulk delete SQL statement. In certain cases, this clause can be omitted by specifying ``--no-bulk-delete-limit``. :option:`--limit` must still be specified.
.. option:: --bulk-insert
Insert each chunk with ``LOAD DATA INFILE`` (implies :option:`--bulk-delete` :option:`--commit-each`).
Insert each chunk of rows with ``LOAD DATA LOCAL INFILE``. This may be much faster than inserting a row at a time with ``INSERT`` statements. It is implemented by creating a temporary file for each chunk of rows, and writing the rows to this file instead of inserting them. When the chunk is finished, it uploads the rows.
To protect the safety of your data, this option forces bulk deletes to be used. It would be unsafe to delete each row as it is found, before inserting the rows into the destination first. Forcing bulk deletes guarantees that the deletion waits until the insertion is successful.
The "--low-priority-insert", "--replace", and "--ignore" options work
with this option, but "--delayed-insert" does not.
.. option:: --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|.
See also :option:`--[no]check-charset`.
.. option:: --[no]check-charset
Default: yes
Ensure connection and table character sets are the same. Disabling this check may cause text to be erroneously converted from one character set to another (usually from ``utf8`` to ``latin1``) which may cause data loss or mojibake. Disabling this check may be useful or necessary when character set conversions are intended.
.. option:: --[no]check-columns
Default: yes
Ensure :option:`--source` and :option:`--dest` have same columns.
Enabled by default; causes :program:`pt-archiver` to check that the source and destination tables have the same columns. It does not check column order, data type, etc.
It just checks that all columns in the source exist in the destination and vice versa. If there are any differences, :program:`pt-archiver` will exit with an error.
To disable this check, specify :option:`--no-check-columns`.
.. option:: --check-interval
Type: time; Default: 1s
How often to check for slave lag if :option:`--check-slave-lag` is given.
.. option:: --check-slave-lag
type: string
Pause archiving until the specified DSN's slave lag is less than :option:`--max-lag`.
.. option:: --columns
short form: -c; type: array
Comma-separated list of columns to archive.
Specify a comma-separated list of columns to fetch, write to the file, and
insert into the destination table. If specified, pt-archiver ignores other
columns unless it needs to add them to the \ ``SELECT``\ statement for ascending an
index or deleting rows. It fetches and uses these extra columns internally, but
does not write them to the file or to the destination table. It \ *does*\ pass
them to plugins.
See also "--primary-key-only".
.. option:: --commit-each
Commit each set of fetched and archived rows (disables "--txn-size").
Commits transactions and flushes "--file" after each set of rows has been
archived, before fetching the next set of rows, and before sleeping if
"--sleep" is specified. Disables "--txn-size"; use "--limit" to
control the transaction size with "--commit-each".
This option is useful as a shortcut to make "--limit" and "--txn-size" the
same value, but more importantly it avoids transactions being held open while
searching for more rows. For example, imagine you are archiving old rows from
the beginning of a very large table, with "--limit" 1000 and "--txn-size"
1000. After some period of finding and archiving 1000 rows at a time,
pt-archiver finds the last 999 rows and archives them, then executes the next
SELECT to find more rows. This scans the rest of the table, but never finds any
more rows. It has held open a transaction for a very long time, only to
determine it is finished anyway. You can use "--commit-each" to avoid this.
.. option:: --config
type: Array
Read this comma-separated list of config files; if specified, this must be the
first option on the command line.
.. option:: --delayed-insert
Add the DELAYED modifier to INSERT statements.
Adds the DELAYED modifier to INSERT or REPLACE statements. See
`http://dev.mysql.com/doc/en/insert.html <http://dev.mysql.com/doc/en/insert.html>`_ for details.
.. option:: --dest
type: DSN
DSN specifying the table to archive to.
This item specifies a table into which pt-archiver will insert rows
archived from "--source". It uses the same key=val argument format as
"--source". Most missing values default to the same values as
"--source", so you don't have to repeat options that are the same in
"--source" and "--dest". Use the "--help" option to see which values
are copied from "--source".
\ **WARNING**\ : Using a default options file (F) DSN option that defines a
socket for "--source" causes pt-archiver to connect to "--dest" using
that socket unless another socket for "--dest" is specified. This
means that pt-archiver may incorrectly connect to "--source" when it
connects to "--dest". For example:
.. code-block:: perl
--source F=host1.cnf,D=db,t=tbl --dest h=host2
When pt-archiver connects to "--dest", host2, it will connect via the
"--source", host1, socket defined in host1.cnf.
.. option:: --dry-run
Print queries and exit without doing anything.
Causes pt-archiver to exit after printing the filename and SQL statements
it will use.
.. option:: --file
type: string
File to archive to, with DATE_FORMAT()-like formatting.
Filename to write archived rows to. A subset of MySQL's DATE_FORMAT()
formatting codes are allowed in the filename, as follows:
.. code-block:: perl
%d Day of the month, numeric (01..31)
%H Hour (00..23)
%i Minutes, numeric (00..59)
%m Month, numeric (01..12)
%s Seconds (00..59)
%Y Year, numeric, four digits
You can use the following extra format codes too:
.. code-block:: perl
%D Database name
%t Table name
Example:
.. code-block:: perl
--file '/var/log/archive/%Y-%m-%d-%D.%t'
The file's contents are in the same format used by SELECT INTO OUTFILE, as
documented in the MySQL manual: rows terminated by newlines, columns
terminated by tabs, NULL characters are represented by \N, and special
characters are escaped by \. This lets you reload a file with LOAD DATA
INFILE's default settings.
If you want a column header at the top of the file, see "--header". The file
is auto-flushed by default; see "--buffer".
.. option:: --for-update
Adds the FOR UPDATE modifier to SELECT statements.
For details, see `http://dev.mysql.com/doc/en/innodb-locking-reads.html <http://dev.mysql.com/doc/en/innodb-locking-reads.html>`_.
.. option:: --header
Print column header at top of "--file".
Writes column names as the first line in the file given by "--file". If the
file exists, does not write headers; this keeps the file loadable with LOAD
DATA INFILE in case you append more output to it.
.. option:: --help
Show help and exit.
.. option:: --high-priority-select
Adds the HIGH_PRIORITY modifier to SELECT statements.
See `http://dev.mysql.com/doc/en/select.html <http://dev.mysql.com/doc/en/select.html>`_ for details.
.. option:: --host
short form: -h; type: string
Connect to host.
.. option:: --ignore
Use IGNORE for INSERT statements.
Causes INSERTs into "--dest" to be INSERT IGNORE.
.. option:: --limit
type: int; default: 1
Number of rows to fetch and archive per statement.
Limits the number of rows returned by the SELECT statements that retrieve rows
to archive. Default is one row. It may be more efficient to increase the
limit, but be careful if you are archiving sparsely, skipping over many rows;
this can potentially cause more contention with other queries, depending on the
storage engine, transaction isolation level, and options such as
"--for-update".
.. option:: --local
Do not write OPTIMIZE or ANALYZE queries to binlog.
Adds the NO_WRITE_TO_BINLOG modifier to ANALYZE and OPTIMIZE queries. See
"--analyze" for details.
.. option:: --low-priority-delete
Adds the LOW_PRIORITY modifier to DELETE statements.
See `http://dev.mysql.com/doc/en/delete.html <http://dev.mysql.com/doc/en/delete.html>`_ for details.
.. option:: --low-priority-insert
Adds the LOW_PRIORITY modifier to INSERT or REPLACE statements.
See `http://dev.mysql.com/doc/en/insert.html <http://dev.mysql.com/doc/en/insert.html>`_ for details.
.. option:: --max-lag
type: time; default: 1s
Pause archiving if the slave given by "--check-slave-lag" lags.
This option causes pt-archiver to look at the slave every time it's about
to fetch another row. If the slave's lag is greater than the option's value,
or if the slave isn't running (so its lag is NULL), pt-table-checksum sleeps
for "--check-interval" seconds and then looks at the lag again. It repeats
until the slave is caught up, then proceeds to fetch and archive the row.
This option may eliminate the need for "--sleep" or "--sleep-coef".
.. option:: --no-ascend
Do not use ascending index optimization.
The default ascending-index optimization causes \ ``pt-archiver``\ to optimize
repeated \ ``SELECT``\ queries so they seek into the index where the previous query
ended, then scan along it, rather than scanning from the beginning of the table
every time. This is enabled by default because it is generally a good strategy
for repeated accesses.
Large, multiple-column indexes may cause the WHERE clause to be complex enough
that this could actually be less efficient. Consider for example a four-column
PRIMARY KEY on (a, b, c, d). The WHERE clause to start where the last query
ended is as follows:
.. code-block:: perl
WHERE (a > ?)
OR (a = ? AND b > ?)
OR (a = ? AND b = ? AND c > ?)
OR (a = ? AND b = ? AND c = ? AND d >= ?)
Populating the placeholders with values uses memory and CPU, adds network
traffic and parsing overhead, and may make the query harder for MySQL to
optimize. A four-column key isn't a big deal, but a ten-column key in which
every column allows \ ``NULL``\ might be.
Ascending the index might not be necessary if you know you are simply removing
rows from the beginning of the table in chunks, but not leaving any holes, so
starting at the beginning of the table is actually the most efficient thing to
do.
See also "--ascend-first". See "EXTENDING" for a discussion of how this
interacts with plugins.
.. option:: --no-delete
Do not delete archived rows.
Causes \ ``pt-archiver``\ not to delete rows after processing them. This disallows
"--no-ascend", because enabling them both would cause an infinite loop.
If there is a plugin on the source DSN, its \ ``before_delete``\ method is called
anyway, even though \ ``pt-archiver``\ will not execute the delete. See
"EXTENDING" for more on plugins.
.. option:: --optimize
type: string
Run OPTIMIZE TABLE afterwards on "--source" and/or "--dest".
Runs OPTIMIZE TABLE after finishing. See "--analyze" for the option syntax
and `http://dev.mysql.com/doc/en/optimize-table.html <http://dev.mysql.com/doc/en/optimize-table.html>`_ for details on OPTIMIZE
TABLE.
.. option:: --password
short form: -p; type: string
Password to use when connecting.
.. option:: --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.
.. option:: --plugin
type: string
Perl module name to use as a generic plugin.
Specify the Perl module name of a general-purpose plugin. It is currently used
only for statistics (see "--statistics") and must have \ ``new()``\ and a
\ ``statistics()``\ method.
The \ ``new( src =``\ $src, dst => $dst, opts => $o )> method gets the source
and destination DSNs, and their database connections, just like the
connection-specific plugins do. It also gets an OptionParser object (\ ``$o``\ ) for
accessing command-line options (example: \ ``$o-``\ get('purge');>).
The \ ``statistics(\%stats, $time)``\ method gets a hashref of the statistics
collected by the archiving job, and the time the whole job started.
.. option:: --port
short form: -P; type: int
Port number to use for connection.
.. option:: --primary-key-only
Primary key columns only.
A shortcut for specifying "--columns" with the primary key columns. This is
an efficiency if you just want to purge rows; it avoids fetching the entire row,
when only the primary key columns are needed for \ ``DELETE``\ statements. See also
"--purge".
.. option:: --progress
type: int
Print progress information every X rows.
Prints current time, elapsed time, and rows archived every X rows.
.. option:: --purge
Purge instead of archiving; allows omitting "--file" and "--dest".
Allows archiving without a "--file" or "--dest" argument, which is
effectively a purge since the rows are just deleted.
If you just want to purge rows, consider specifying the table's primary key
columns with "--primary-key-only". This will prevent fetching all columns
from the server for no reason.
.. option:: --quick-delete
Adds the QUICK modifier to DELETE statements.
See `http://dev.mysql.com/doc/en/delete.html <http://dev.mysql.com/doc/en/delete.html>`_ for details. As stated in the
documentation, in some cases it may be faster to use DELETE QUICK followed by
OPTIMIZE TABLE. You can use "--optimize" for this.
.. option:: --quiet
short form: -q
Do not print any output, such as for "--statistics".
Suppresses normal output, including the output of "--statistics", but doesn't
suppress the output from "--why-quit".
.. option:: --replace
Causes INSERTs into "--dest" to be written as REPLACE.
.. option:: --retries
type: int; default: 1
Number of retries per timeout or deadlock.
Specifies the number of times pt-archiver should retry when there is an
InnoDB lock wait timeout or deadlock. When retries are exhausted,
pt-archiver will exit with an error.
Consider carefully what you want to happen when you are archiving between a
mixture of transactional and non-transactional storage engines. The INSERT to
"--dest" and DELETE from "--source" are on separate connections, so they
do not actually participate in the same transaction even if they're on the same
server. However, pt-archiver implements simple distributed transactions in
code, so commits and rollbacks should happen as desired across the two
connections.
At this time I have not written any code to handle errors with transactional
storage engines other than InnoDB. Request that feature if you need it.
.. option:: --run-time
type: time
Time to run before exiting.
Optional suffix s=seconds, m=minutes, h=hours, d=days; if no suffix, s is used.
.. option:: --[no]safe-auto-increment
default: yes
Do not archive row with max AUTO_INCREMENT.
Adds an extra WHERE clause to prevent pt-archiver from removing the newest
row when ascending a single-column AUTO_INCREMENT key. This guards against
re-using AUTO_INCREMENT values if the server restarts, and is enabled by
default.
The extra WHERE clause contains the maximum value of the auto-increment column
as of the beginning of the archive or purge job. If new rows are inserted while
pt-archiver is running, it will not see them.
.. option:: --sentinel
type: string; default: /tmp/pt-archiver-sentinel
Exit if this file exists.
The presence of the file specified by "--sentinel" will cause pt-archiver to
stop archiving and exit. The default is /tmp/pt-archiver-sentinel. You
might find this handy to stop cron jobs gracefully if necessary. See also
"--stop".
.. option:: --set-vars
type: string; default: wait_timeout=10000
Set these MySQL variables.
Specify any variables you want to be set immediately after connecting to MySQL.
These will be included in a \ ``SET``\ command.
.. option:: --share-lock
Adds the LOCK IN SHARE MODE modifier to SELECT statements.
See `http://dev.mysql.com/doc/en/innodb-locking-reads.html <http://dev.mysql.com/doc/en/innodb-locking-reads.html>`_.
.. option:: --skip-foreign-key-checks
Disables foreign key checks with SET FOREIGN_KEY_CHECKS=0.
.. option:: --sleep
type: int
Sleep time between fetches.
Specifies how long to sleep between SELECT statements. Default is not to
sleep at all. Transactions are NOT committed, and the "--file" file is NOT
flushed, before sleeping. See "--txn-size" to control that.
If "--commit-each" is specified, committing and flushing happens before
sleeping.
.. option:: --sleep-coef
type: float
Calculate "--sleep" as a multiple of the last SELECT time.
If this option is specified, pt-archiver will sleep for the query time of the
last SELECT multiplied by the specified coefficient.
This is a slightly more sophisticated way to throttle the SELECTs: sleep a
varying amount of time between each SELECT, depending on how long the SELECTs
are taking.
.. option:: --socket
short form: -S; type: string
Socket file to use for connection.
.. option:: --source
type: DSN
DSN specifying the table to archive from (required). This argument is a DSN.
See DSN OPTIONS for the syntax. Most options control how pt-archiver
connects to MySQL, but there are some extended DSN options in this tool's
syntax. The D, t, and i options select a table to archive:
.. code-block:: perl
--source h=my_server,D=my_database,t=my_tbl
The a option specifies the database to set as the connection's default with USE.
If the b option is true, it disables binary logging with SQL_LOG_BIN. The m
option specifies pluggable actions, which an external Perl module can provide.
The only required part is the table; other parts may be read from various
places in the environment (such as options files).
The 'i' part deserves special mention. This tells pt-archiver which index
it should scan to archive. This appears in a FORCE INDEX or USE INDEX hint in
the SELECT statements used to fetch archivable rows. If you don't specify
anything, pt-archiver will auto-discover a good index, preferring a \ ``PRIMARY
KEY``\ if one exists. In my experience this usually works well, so most of the
time you can probably just omit the 'i' part.
The index is used to optimize repeated accesses to the table; pt-archiver
remembers the last row it retrieves from each SELECT statement, and uses it to
construct a WHERE clause, using the columns in the specified index, that should
allow MySQL to start the next SELECT where the last one ended, rather than
potentially scanning from the beginning of the table with each successive
SELECT. If you are using external plugins, please see "EXTENDING" for a
discussion of how they interact with ascending indexes.
The 'a' and 'b' options allow you to control how statements flow through the
binary log. If you specify the 'b' option, binary logging will be disabled on
the specified connection. If you specify the 'a' option, the connection will
\ ``USE``\ the specified database, which you can use to prevent slaves from
executing the binary log events with \ ``--replicate-ignore-db``\ options. These
two options can be used as different methods to achieve the same goal: archive
data off the master, but leave it on the slave. For example, you can run a
purge job on the master and prevent it from happening on the slave using your
method of choice.
\ **WARNING**\ : Using a default options file (F) DSN option that defines a
socket for "--source" causes pt-archiver to connect to "--dest" using
that socket unless another socket for "--dest" is specified. This
means that pt-archiver may incorrectly connect to "--source" when it
is meant to connect to "--dest". For example:
.. code-block:: perl
--source F=host1.cnf,D=db,t=tbl --dest h=host2
When pt-archiver connects to "--dest", host2, it will connect via the
"--source", host1, socket defined in host1.cnf.
.. option:: --statistics
Collect and print timing statistics.
Causes pt-archiver to collect timing statistics about what it does. These
statistics are available to the plugin specified by "--plugin"
Unless you specify "--quiet", \ ``pt-archiver``\ prints the statistics when it
exits. The statistics look like this:
.. code-block:: perl
Started at 2008-07-18T07:18:53, ended at 2008-07-18T07:18:53
Source: D=db,t=table
SELECT 4
INSERT 4
DELETE 4
Action Count Time Pct
commit 10 0.1079 88.27
select 5 0.0047 3.87
deleting 4 0.0028 2.29
inserting 4 0.0028 2.28
other 0 0.0040 3.29
The first two (or three) lines show times and the source and destination tables.
The next three lines show how many rows were fetched, inserted, and deleted.
The remaining lines show counts and timing. The columns are the action, the
total number of times that action was timed, the total time it took, and the
percent of the program's total runtime. The rows are sorted in order of
descending total time. The last row is the rest of the time not explicitly
attributed to anything. Actions will vary depending on command-line options.
If "--why-quit" is given, its behavior is changed slightly. This option
causes it to print the reason for exiting even when it's just because there are
no more rows.
This option requires the standard Time::HiRes module, which is part of core Perl
on reasonably new Perl releases.
.. option:: --stop
Stop running instances by creating the sentinel file.
Causes pt-archiver to create the sentinel file specified by "--sentinel" and
exit. This should have the effect of stopping all running instances which are
watching the same sentinel file.
.. option:: --txn-size
type: int; default: 1
Number of rows per transaction.
Specifies the size, in number of rows, of each transaction. Zero disables
transactions altogether. After pt-archiver processes this many rows, it
commits both the "--source" and the "--dest" if given, and flushes the
file given by "--file".
This parameter is critical to performance. If you are archiving from a live
server, which for example is doing heavy OLTP work, you need to choose a good
balance between transaction size and commit overhead. Larger transactions
create the possibility of more lock contention and deadlocks, but smaller
transactions cause more frequent commit overhead, which can be significant. To
give an idea, on a small test set I worked with while writing pt-archiver, a
value of 500 caused archiving to take about 2 seconds per 1000 rows on an
otherwise quiet MySQL instance on my desktop machine, archiving to disk and to
another table. Disabling transactions with a value of zero, which turns on
autocommit, dropped performance to 38 seconds per thousand rows.
If you are not archiving from or to a transactional storage engine, you may
want to disable transactions so pt-archiver doesn't try to commit.
.. option:: --user
short form: -u; type: string
User for login if not current user.
.. option:: --version
Show version and exit.
.. option:: --where
type: string
WHERE clause to limit which rows to archive (required).
Specifies a WHERE clause to limit which rows are archived. Do not include the
word WHERE. You may need to quote the argument to prevent your shell from
interpreting it. For example:
.. code-block:: perl
--where 'ts < current_date - interval 90 day'
For safety, "--where" is required. If you do not require a WHERE clause, use
"--where" 1=1.
.. option:: --why-quit
Print reason for exiting unless rows exhausted.
Causes pt-archiver to print a message if it exits for any reason other than
running out of rows to archive. This can be useful if you have a cron job with
"--run-time" specified, for example, and you want to be sure pt-archiver is
finishing before running out of time.
If "--statistics" is given, the behavior is changed slightly. It will print
the reason for exiting even when it's just because there are no more rows.
This output prints even if "--quiet" is given. That's so you can put
\ ``pt-archiver``\ in a \ ``cron``\ job and get an email if there's an abnormal exit.
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``
copy: no
Database to USE when executing queries.
* ``A``
dsn: charset; copy: yes
Default character set.
* ``b``
copy: no
If true, disable binlog with SQL_LOG_BIN.
* ``D``
dsn: database; copy: yes
Database that contains the table.
* ``F``
dsn: mysql_read_default_file; copy: yes
Only read default options from the given file
* ``h``
dsn: host; copy: yes
Connect to host.
* ``i``
copy: yes
Index to use.
* ``m``
copy: no
Plugin module name.
* ``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.
* ``t``
copy: yes
Table to archive from/to.
* ``u``
dsn: user; copy: yes
User for login if not current user.
EXTENDING
=========
:program:`pt-archiver` is extensible by plugging in external Perl modules to handle some logic and/or actions. You can specify a module for both the "--source" and the "--dest", with the 'm' part of the specification. For example:
.. code-block:: perl
--source D=test,t=test1,m=My::Module1 --dest m=My::Module2,t=test2
This will cause pt-archiver to load the ``My::Module1`` and ``My::Module2`` packages, create instances of them, and then make calls to them during the archiving process.
You can also specify a plugin with "--plugin".
The module must provide this interface:
::
new(dbh => $dbh, db => $db_name, tbl => $tbl_name)
The plugin's constructor is passed a reference to the database handle, the
database name, and table name. The plugin is created just after pt-archiver
opens the connection, and before it examines the table given in the arguments.
This gives the plugin a chance to create and populate temporary tables, or do
other setup work.
::
before_begin(cols => \@cols, allcols => \@allcols)
This method is called just before pt-archiver begins iterating through rows
and archiving them, but after it does all other setup work (examining table
structures, designing SQL queries, and so on). This is the only time
pt-archiver tells the plugin column names for the rows it will pass the
plugin while archiving.
The \ ``cols``\ argument is the column names the user requested to be archived,
either by default or by the "--columns" option. The \ ``allcols``\ argument is
the list of column names for every row pt-archiver will fetch from the source
table. It may fetch more columns than the user requested, because it needs some
columns for its own use. When subsequent plugin functions receive a row, it is
the full row containing all the extra columns, if any, added to the end.
::
is_archivable(row => \@row)
This method is called for each row to determine whether it is archivable. This applies only to "--source". The argument is the row itself, as an arrayref. If the method returns true, the row will be archived; otherwise it will be skipped.
Skipping a row adds complications for non-unique indexes. Normally
pt-archiver uses a WHERE clause designed to target the last processed row as
the place to start the scan for the next SELECT statement. If you have skipped
the row by returning false from is_archivable(), pt-archiver could get into
an infinite loop because the row still exists. Therefore, when you specify a
plugin for the "--source" argument, pt-archiver will change its WHERE clause
slightly. Instead of starting at "greater than or equal to" the last processed
row, it will start "strictly greater than." This will work fine on unique
indexes such as primary keys, but it may skip rows (leave holes) on non-unique
indexes or when ascending only the first column of an index.
\ ``pt-archiver``\ will change the clause in the same way if you specify
"--no-delete", because again an infinite loop is possible.
If you specify the "--bulk-delete" option and return false from this method,
\ ``pt-archiver``\ may not do what you want. The row won't be archived, but it will be deleted, since bulk deletes operate on ranges of rows and don't know which rows the plugin selected to keep.
If you specify the "--bulk-insert" option, this method's return value will
influence whether the row is written to the temporary file for the bulk insert,
so bulk inserts will work as expected. However, bulk inserts require bulk
deletes.
::
before_delete(row => \@row)
This method is called for each row just before it is deleted. This applies only
to "--source". This is a good place for you to handle dependencies, such as
deleting things that are foreign-keyed to the row you are about to delete. You
could also use this to recursively archive all dependent tables.
This plugin method is called even if "--no-delete" is given, but not if
"--bulk-delete" is given.
::
before_bulk_delete(first_row => \@row, last_row => \@row)
This method is called just before a bulk delete is executed. It is similar to
the \ ``before_delete``\ method, except its arguments are the first and last row of
the range to be deleted. It is called even if "--no-delete" is given.
::
before_insert(row => \@row)
This method is called for each row just before it is inserted. This applies
only to "--dest". You could use this to insert the row into multiple tables,
perhaps with an ON DUPLICATE KEY UPDATE clause to build summary tables in a data warehouse.
This method is not called if "--bulk-insert" is given.
::
before_bulk_insert(first_row => \@row, last_row => \@row, filename => bulk_insert_filename)
This method is called just before a bulk insert is executed. It is similar to
the \ ``before_insert``\ method, except its arguments are the first and last row of
the range to be deleted.
::
custom_sth(row => \@row, sql => $sql)
This method is called just before inserting the row, but after
"before_insert()". It allows the plugin to specify different \ ``INSERT``\
statement if desired. The return value (if any) should be a DBI statement
handle. The \ ``sql``\ parameter is the SQL text used to prepare the default
\ ``INSERT``\ statement. This method is not called if you specify
"--bulk-insert".
If no value is returned, the default \ ``INSERT``\ statement handle is used.
This method applies only to the plugin specified for "--dest", so if your
plugin isn't doing what you expect, check that you've specified it for the
destination and not the source.
::
custom_sth_bulk(first_row => \@row, last_row => \@row, sql => $sql, filename => $bulk_insert_filename)
If you've specified "--bulk-insert", this method is called just before the
bulk insert, but after "before_bulk_insert()", and the arguments are
different.
This method's return value etc is similar to the "custom_sth()" method.
::
after_finish()
This method is called after pt-archiver exits the archiving loop, commits all
database handles, closes "--file", and prints the final statistics, but
before pt-archiver runs ANALYZE or OPTIMIZE (see "--analyze" and
"--optimize").
If you specify a plugin for both "--source" and "--dest", pt-archiver
constructs, calls before_begin(), and calls after_finish() on the two plugins in
the order "--source", "--dest".
pt-archiver assumes it controls transactions, and that the plugin will NOT
commit or roll back the database handle. The database handle passed to the
plugin's constructor is the same handle pt-archiver uses itself. Remember
that "--source" and "--dest" are separate handles.
A sample module might look like this:
.. code-block:: perl
package My::Module;
sub new {
my ( $class, %args ) = @_;
return bless(\%args, $class);
}
sub before_begin {
my ( $self, %args ) = @_;
# Save column names for later
$self->{cols} = $args{cols};
}
sub is_archivable {
my ( $self, %args ) = @_;
# Do some advanced logic with $args{row}
return 1;
}
sub before_delete {} # Take no action
sub before_insert {} # Take no action
sub custom_sth {} # Take no action
sub after_finish {} # Take no action
1;
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:
.. code-block:: perl
PTDEBUG=1 pt-archiver ... > 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-archiver <http://www.percona.com/bugs/pt-archiver>`_.
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:
.. code-block:: perl
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:
.. code-block:: perl
wget percona.com/get/TOOL
Replace \ ``TOOL``\ with the name of any tool.
AUTHORS
=======
Baron Schwartz
ACKNOWLEDGMENTS
===============
Andrew O'Brien
ABOUT PERCONA TOOLKIT
=====================
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/ <http://www.percona.com/software/>`_ for more software developed by Percona.
COPYRIGHT, LICENSE, AND WARRANTY
================================
This program is copyright 2007-2011 Baron Schwartz, 2011 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
=======
:program:`pt-archiver` 1.0.1
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