/ 
Pg-Explain-0.96
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/ Pg::Explain

NAME

Pg::Explain - Object approach at reading explain analyze output

VERSION

Version 0.96

SYNOPSIS

Quick summary of what the module does.

Perhaps a little code snippet.

use Pg::Explain;

my $explain = Pg::Explain->new('source_file' => 'some_file.out');
...

my $explain = Pg::Explain->new(
    'source' => 'Seq Scan on tenk1  (cost=0.00..333.00 rows=10000 width=148)'
);
...

FUNCTIONS

source_format

What is the detected format of source plan. One of: TEXT, JSON, YAML, OR XML.

planning_time

How much time PostgreSQL spent planning the query. In milliseconds.

execution_time

How much time PostgreSQL spent executing the query. In milliseconds.

total_runtime

How much time PostgreSQL spent working on this query. This was part of EXPLAIN OUTPUT only for PostgreSQL 9.3 or older.

trigger_times

Information about triggers that were called during execution of this query. Array of hashes, where each hash can contains:

  • name - name of the trigger

  • calls - how many times it was called

  • time - total time spent in all executions of this trigger

add_trigger_time

Adds new information about trigger time.

It will be available at $node->trigger_times (returns arrayref)

runtime

How long did the query run. Tries to get the value from various sources (total_runtime, execution_time, or top_node->actual_time_last).

source

Returns original source (text version) of explain.

source_filtered

Returns filtered source explain.

Currently there are only two filters:

  • remove quotes added by pgAdmin3

  • remove + character at the end of line, added by default psql config.

new

Object constructor.

Takes one of (only one!) (source, source_file) parameters, and either parses it from given source, or first reads given file.

top_node

This method returns the top node of parsed plan.

For example - in this plan:

                          QUERY PLAN
--------------------------------------------------------------
 Limit  (cost=0.00..0.01 rows=1 width=4)
   ->  Seq Scan on test  (cost=0.00..14.00 rows=1000 width=4)

top_node is Pg::Explain::Node element with type set to 'Limit'.

Generally every output of plans should start with ->top_node(), and descend recursively in it, using subplans(), initplans() and sub_nodes() methods.

parse_source

Internally (from ->BUILD()) called function which checks which parser to use (text, json, xml, yaml), runs appropriate function, and stores top level node in $self->top_node.

check_for_parallelism

Handles parallelism by setting "force_loops" if plan is analyzed and there are gather nodes.

Generally, for each

_read_source_from_file

Helper function to read source from file.

as_text

Returns parsed plan back as plain text format (regenerated from in-memory structure).

This is mostly useful for (future at the moment) anonymizations.

get_struct

Function which returns simple, not blessed, hashref with all information about the explain.

This can be used for debug purposes, or as a base to print information to user.

Output looks like this:

{
    'top_node'               => {....},
    'planning_time'          => '12.34',
    'execution_time'         => '12.34',
    'total_runtime'          => '12.34',
    'trigger_times'          => [
       { 'name' => ..., 'time' => ..., 'calls' => ... },
       ...
    ],
}

anonymize

Used to remove all individual values from the explain, while still retaining all values that are needed to see what's wrong.

AUTHOR

hubert depesz lubaczewski, <depesz at depesz.com>

BUGS

Please report any bugs or feature requests to depesz at depesz.com.

SUPPORT

You can find documentation for this module with the perldoc command.

perldoc Pg::Explain

COPYRIGHT & LICENSE

Copyright 2008-2015 hubert depesz lubaczewski, all rights reserved.

This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.