Provided by: percona-toolkit_3.0.13-1_all bug


       pt-table-usage - Analyze how queries use tables.


       Usage: pt-table-usage [OPTIONS] [FILES]

       pt-table-usage reads queries from a log and analyzes how they use tables.  If no FILE is
       specified, it reads STDIN.  It prints a report for each query.


       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,

       ·   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


       pt-table-usage reads queries from a log and analyzes how they use tables.  The log should
       be in MySQL's slow query log format.

       Table usage is more than simply an indication of which tables the query reads or writes.
       It also indicates data flow: data in and data out.  The tool determines the data flow by
       the contexts in which tables appear.  A single query can use a table in several different
       contexts simultaneously.  The tool's output lists every context for every table.  This
       CONTEXT-TABLE list indicates how data flows between tables.  The "OUTPUT" section lists
       the possible contexts and describes how to read a table usage report.

       The tool analyzes data flow down to the level of individual columns, so it is helpful if
       columns are identified unambiguously in the query.  If a query uses only one table, then
       all columns must be from that table, and there's no difficulty.  But if a query uses
       multiple tables and the column names are not table-qualified, then it is necessary to use
       "EXPLAIN EXTENDED", followed by "SHOW WARNINGS", to determine to which tables the columns

       If the tool does not know the query's default database, which can occur when the database
       is not printed in the log, then "EXPLAIN EXTENDED" can fail. In this case, you can specify
       a default database with "--database". You can also use the "--create-table-definitions"
       option to help resolve ambiguities.


       The tool prints a usage report for each table in every query, similar to the following:

         Query_id: 0x1CD27577D202A339.1
         UPDATE t1
         SELECT DUAL
         JOIN t1
         JOIN t2
         WHERE t1

         Query_id: 0x1CD27577D202A339.2
         UPDATE t2
         SELECT DUAL
         JOIN t1
         JOIN t2
         WHERE t1

       The first line contains the query ID, which by default is the same as those shown in pt-
       query-digest reports. It is an MD5 checksum of the query's "fingerprint," which is what
       remains after removing literals, collapsing white space, and a variety of other
       transformations. The query ID has two parts separated by a period: the query ID and the
       table number. If you wish to use a different value to identify the query, you can specify
       the "--id-attribute" option.

       The previous example shows two paragraphs for a single query, not two queries.  Note that
       the query ID is identical for the two, but the table number differs.  The table number
       increments by 1 for each table that the query updates.  Only multi-table UPDATE queries
       can update multiple tables with a single query, so the table number is 1 for all other
       types of queries.  (The tool does not support multi-table DELETE queries.) The example
       output above is from this query:

         UPDATE t1 AS a JOIN t2 AS b USING (id)

       The "SET" clause indicates that the query updates two tables: "a" aliased as "t1", and "b"
       aliased as "t2".

       After the first line, the tool prints a variable number of CONTEXT-TABLE lines.  Possible
       contexts are as follows:

       ·   SELECT

           SELECT means that the query retrieves data from the table for one of two reasons. The
           first is to be returned to the user as part of a result set. Only SELECT queries
           return result sets, so the report always shows a SELECT context for SELECT queries.

           The second case is when data flows to another table as part of an INSERT or UPDATE.
           For example, the UPDATE query in the example above has the usage:

             SELECT DUAL

           This refers to:


           The tool uses DUAL for any values that do not originate in a table, in this case the
           literal values "bar" and "bat".  If that "SET" clause were "SET" instead,
           then the complete usage would be:

             Query_id: 0x1CD27577D202A339.1
             UPDATE t1
             SELECT t2
             JOIN t1
             JOIN t2
             WHERE t1

           The presence of a SELECT context after another context, such as UPDATE or INSERT,
           indicates where the UPDATE or INSERT retrieves its data.  The example immediately
           above reflects an UPDATE query that updates rows in table "t1" with data from table

       ·   Any other verb

           Any other verb, such as INSERT, UPDATE, DELETE, etc. may be a context.  These verbs
           indicate that the query modifies data in some way.  If a SELECT context follows one of
           these verbs, then the query reads data from the SELECT table and writes it to this
           table.  This happens, for example, with INSERT..SELECT or UPDATE queries that use
           values from tables instead of constant values.

           These query types are not supported: SET, LOAD, and multi-table DELETE.

       ·   JOIN

           The JOIN context lists tables that are joined, either with an explicit JOIN in the
           FROM clause, or implicitly in the WHERE clause, such as " =".

       ·   WHERE

           The WHERE context lists tables that are used in the WHERE clause to filter results.
           This does not include tables that are implicitly joined in the WHERE clause; those are
           listed as JOIN contexts.  For example:

             WHERE > 100 AND < 200 AND IS NOT NULL

           Results in:

             WHERE t1
             WHERE t2

           The tool lists only distinct tables; that is why table "t1" is listed only once.

       ·   TLIST

           The TLIST context lists tables that the query accesses, but which do not appear in any
           other context.  These tables are usually an implicit cartesian join.  For example, the
           query "SELECT * FROM t1, t2" results in:

             Query_id: 0xBDDEB6EDA41897A8.1
             SELECT t1
             SELECT t2
             TLIST t1
             TLIST t2

           First of all, there are two SELECT contexts, because "SELECT *" selects rows from all
           tables; "t1" and "t2" in this case.  Secondly, the tables are implicitly joined, but
           without any kind of join condition, which results in a cartesian join as indicated by
           the TLIST context for each.


       pt-table-usage exits 1 on any kind of error, or 0 if no errors.


       This tool accepts additional command-line arguments.  Refer to the "SYNOPSIS" and usage
       information for details.

           Prompt for a password when connecting to MySQL.

           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.

           type: Array

           Read this comma-separated list of config files; if specified, this must be the first
           option on the command line.

           type: string; default: DUAL

           Table to print as the source for constant data (literals).  This is any data not
           retrieved from tables (or subqueries, because subqueries are not supported).  This
           includes literal values such as strings ("foo") and numbers (42), or functions such as
           "NOW()".  For example, in the query "INSERT INTO t (c) VALUES ('a')", the string 'a'
           is constant data, so the table usage report is:

             INSERT t
             SELECT DUAL

           The first line indicates that the query inserts data into table "t", and the second
           line indicates that the inserted data comes from some constant value.

           default: yes

           Continue to work even if there is an error.

           type: array

           Read "CREATE TABLE" definitions from this list of comma-separated files.  If you
           cannot use "--explain-extended" to fully qualify table and column names, you can save
           the output of "mysqldump --no-data" to one or more files and specify those files with
           this option.  The tool will parse all "CREATE TABLE" definitions from the files and
           use this information to qualify table and column names.  If a column name appears in
           multiple tables, or a table name appears in multiple databases, the ambiguities cannot
           be resolved.

           Fork to the background and detach from the shell.  POSIX operating systems only.

           short form: -D; type: string

           Default database.

           short form: -F; type: string

           Only read mysql options from the given file.  You must give an absolute pathname.

           type: DSN

           A server to execute EXPLAIN EXTENDED queries. This may be necessary to resolve
           ambiguous (unqualified) column and table names.

           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 is compiled
           into a subroutine with one argument: $event.  If the given value is a readable file,
           then pt-table-usage reads the entire file and uses its contents as the code.

           Filters are implemented in the same fashion as in the pt-query-digest tool, so please
           refer to its documentation for more information.

           Show help and exit.

           short form: -h; type: string

           Connect to host.

           type: string

           Identify each event using this attribute.  The default is to use a query ID, which is
           an MD5 checksum of the query's fingerprint.

           type: string

           Print all output to this file when daemonized.

           short form: -p; type: string

           Password to use when connecting.  If password contains commas they must be escaped
           with a backslash: "exam\,ple"

           type: string

           Create the given PID file.  The tool won't start if the PID file already exists and
           the PID it contains is different than the current PID.  However, if the PID file
           exists and the PID it contains is no longer running, the tool will overwrite the PID
           file with the current PID.  The PID file is removed automatically when the tool exits.

           short form: -P; type: int

           Port number to use for connection.

           type: array; default: time,30

           Print progress reports to STDERR.  The value is a comma-separated list with two parts.
           The first part can be percentage, time, or iterations; the second part specifies how
           often an update should be printed, in percentage, seconds, or number of iterations.

           type: string

           Analyze the specified query instead of reading a log file.

           type: time; default: 0

           Wait this long for an event from the input; 0 to wait forever.

           This option sets the maximum time to wait for an event from the input.  If an event is
           not received after the specified time, the tool stops reading the input and prints its

           This option requires the Perl POSIX module.

           type: time

           How long to run before exiting.  The default is to run forever (you can interrupt with

           type: Array

           Set the MySQL variables in this comma-separated list of "variable=value" pairs.

           By default, the tool sets:


           Variables specified on the command line override these defaults.  For example,
           specifying "--set-vars wait_timeout=500" overrides the defaultvalue of 10000.

           The tool prints a warning and continues if a variable cannot be set.

           short form: -S; type: string

           Socket file to use for connection.

           short form: -u; type: string

           User for login if not current user.

           Show version and exit.


       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

           copy: no

           Default database.

       ·   F

           dsn: mysql_read_default_file; copy: no

           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.  If password contains commas they must be escaped
           with a backslash: "exam\,ple"

       ·   P

           dsn: port; copy: yes

           Port number to use for connection.

       ·   S

           dsn: mysql_socket; copy: no

           Socket file to use for connection.

       ·   u

           dsn: user; copy: yes

           User for login if not current user.


       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-table-usage ... > FILE 2>&1

       Be careful: debugging output is voluminous and can generate several megabytes of output.


       You need Perl, DBI, DBD::mysql, and some core packages that ought to be installed in any
       reasonably new version of Perl.


       For a list of known bugs, see <>.

       Please report bugs at <>.  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


       Visit <> to download the latest release of
       Percona Toolkit.  Or, get the latest release from the command line:




       You can also get individual tools from the latest release:


       Replace "TOOL" with the name of any tool.


       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 <> to learn
       about other free, open-source software from Percona.


       This program is copyright 2012-2018 Percona LLC and/or its affiliates.


       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.


       pt-table-usage 3.0.13