Pg::Explain - Object approach at reading explain analyze output
Version 2.7
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)' ); ...
What is the detected format of source plan. One of: TEXT, JSON, YAML, OR XML.
How much time PostgreSQL spent planning the query. In milliseconds.
All buffers used by query - for planning and execution. Mathematically: sum of planning_buffers and top_level->buffers.
How much buffers PostgreSQL used for planning. Either undef or object of Pg::Explain::Buffers class.
How much time PostgreSQL spent executing the query. In milliseconds.
How much time PostgreSQL spent working on this query. This was part of EXPLAIN OUTPUT only for PostgreSQL 9.3 or older.
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
Contains information about JIT timings, as object of Pg::Explain::JIT class.
If there was no JIT info, it will return undef.
What query this explain is for. This is available only for auto-explain plans. If not available, it will be undef.
If explain contains information about specific settings that were changed in Pg, this hashref will contain it.
If there are none - if will be undef.
Adds new information about trigger time.
It will be available at $node->trigger_times (returns arrayref)
How long did the query run. Tries to get the value from various sources (total_runtime, execution_time, or top_node->actual_time_last).
Returns node with given id from current explain.
If there is second argument present, and it's Pg::Explain::Node object, it sets internal cache for this id and this node.
Returns original source (text version) of explain.
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.
Object constructor.
Takes one of (only one!) (source, source_file) parameters, and either parses it from given source, or first reads given file.
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.
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.
Certain types of nodes (CTE Scans, and InitPlans) can cause issues with "naive" calculations of node exclusive time.
To fix that whole tree will be scanned, and, if neccessary, node->exclusive_fix will be modified.
Modifies node->exclusive_fix according to times that were used by CTEs.
Modifies node->exclusive_fix according to times that were used by InitScans.
Handles parallelism by setting "force_loops" if plan is analyzed and there are gather nodes.
Generally, for each
Helper function to read source from file.
Returns parsed plan back as plain text format (regenerated from in-memory structure).
This is mostly useful for (future at the moment) anonymizations.
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' => '12.44', 'planning_buffers' => {...}, 'execution_time' => '12.44', 'total_runtime' => '12.44', 'trigger_times' => [ { 'name' => ..., 'time' => ..., 'calls' => ... }, ... ], }
Used to remove all individual values from the explain, while still retaining all values that are needed to see what's wrong.
If there are any arguments, these are treated as strings, anonymized using anonymizer used for plan, and are returned in the same order.
This is mainly useful to anonymize queries.
hubert depesz lubaczewski, <depesz at depesz.com>
<depesz at depesz.com>
Please report any bugs or feature requests to depesz at depesz.com.
depesz at depesz.com
You can find documentation for this module with the perldoc command.
perldoc Pg::Explain
Copyright 2008-2023 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.
To install Pg::Explain, copy and paste the appropriate command in to your terminal.
cpanm
cpanm Pg::Explain
CPAN shell
perl -MCPAN -e shell install Pg::Explain
For more information on module installation, please visit the detailed CPAN module installation guide.