Parsing strange v1.1

Parsing Strange:URL to SQL to HTML

Hal Sternhttp://snowmanonfire.com headshot by Richard Stevens

http://dieselsweeties.com

Why Do You Care?

• Database performance = user experience• A little database expertise goes a long way• Use taxonomies for more than sidebar lists• WordPress is a powerful CMS

>Change default behaviors>Defy the common wisdom>Integrate other content sources/filters

Disclaimers

• I’m somewhat social, for Jersey• I’m (old) old school

>If using PHP echo gives you hives……take a Benadryl now

• If “INNER JOIN” makes you giggle, you’re in the wrong session/conference/fantasy

• I suck at art and design

Flow of Control

• Web server URL manipulation>Real file or permalink URL?

• URL to query variables>What to display? Tag? Post? Category?

• Query variables to SQL generation>How exactly to get that content?

• Template file selection>How will content be displayed?

• Content manipulation

Whose File Is This?

• User URL request passed to web server• Web server checks.htaccess file>WP install root >Other .htaccess

files may interfere• Basic rewriting rules:

If file or directory URL doesn’t exist, start WordPress via index.php

<IfModule mod_rewrite.c>RewriteEngine OnRewriteBase /whereyouputWordPress/RewriteCond %{REQUEST_FILENAME} !-fRewriteCond %{REQUEST_FILENAME} !-dRewriteRule . /index.php [L]</IfModule>

What Happens Before The Loop

• Parse URL into a query• Set conditionals & select templates• Execute the query & cache results• Run the Loop:

<?phpif (have_posts()) : while (have_posts()) :

the_post(); //loop content endwhile;endif;?>

Examining the Query String

• SQL passed to MySQL in WP_Query object’s request element

• Brute force: edit theme footer.php to see main loop’s query for displayed page

<?php global $wp_query; echo ”SQL for this page "; echo $wp_query->request; echo "<br>";?>

“Home Page” Query Deconstruction

SELECT SQL_CALC_FOUND_ROWS wp_posts.* FROM wp_posts WHERE 1=1 AND wp_posts.post_type = 'post’ AND(wp_posts.post_status = 'publish' OR wp_posts.post_status = 'private’)ORDER BY wp_posts.post_date DESC LIMIT 0, 10

Get all fields from posts table, but limit number of returned rows

Only get posts, and those that are published or private to the user

Sort the results by date in descending order

Start results starting with record 0 and up to 10 more results

Query Parsing

• parse_request() method of WP_Query extracts query variables from URL

• Execute rewrite rules>Pick off ?p=67 style http GET variables>Match permalink structure>Match keywords like “author” and “tag”

Query Variables to SQL

• Query type: post by title, posts by category or tag, posts by date

• Variables for the query>Slug values for category/tags>Month/day numbers>Explicit variable values?p=67 for post_id

Simple Title Slug Parsing

• Rewrite matches root of permalink, extracts tail of URL as a title slug

SELECT wp_posts.* FROM wp_posts WHERE 1=1 AND YEAR(wp_posts.post_date)='2010' AND wp_posts.post_name = 'premio-sausage' AND wp_posts.post_type = 'post' ORDER BY wp_posts.post_date DESC

/2010/premio-sausage

Graphs and JOIN Operations

• WordPress treats tags and categories as “terms”, mapped 1:N to posts

• Relational databases aren’t ideal for this>INNER JOIN builds intermediate tables on

common key values• Following link in a social graph is

equivalent to an INNER JOIN on tables of linked items

WordPress Taxonomy Tables

• Term relationships table maps N:1 terms to each post

• Term taxonomy maps slugs 1:N to taxonomies

• Term table has slugs for URL mapping

wp_term_relationshipsobject_idterm_taxonomy_id

wp_postspost_id….post_date… post_content

wp_term_taxonomyterm_taxonomy_idterm_idtaxonomydescription

wp_termsterm_idnameslug

SELECT SQL_CALC_FOUND_ROWS wp_posts.* FROM wp_postsINNER JOIN wp_term_relationships ON(wp_posts.ID = wp_term_relationships.object_id)INNER JOIN wp_term_taxonomy ON (wp_term_relationships.term_taxonomy_id = wp_term_taxonomy.term_taxonomy_id)INNER JOIN wp_terms ON (wp_term_taxonomy.term_id = wp_terms.term_id)WHERE 1=1 AND wp_term_taxonomy.taxonomy = 'post_tag' AND wp_terms.slug IN ('premio') AND wp_posts.post_type = 'post' AND (wp_posts.post_status = 'publish' OR wp_posts.post_status = 'private') GROUP BY wp_posts.ID ORDER BY wp_posts.post_date DESC LIMIT 0, 10

Taxonomy Lookup/tag/premio

Parsing strange v1.1

Technology

October 2008csa3180: Setence Parsing Algorithms 1 1 CSA350: NLP Algorithms Sentence Parsing I The Parsing Problem Parsing as Search Top Down/Bottom Up

– 1 – CSCE 531 Spring 2006 Lecture 8 Bottom Up Parsing Topics Overview Bottom-Up Parsing Handles Shift-reduce parsing Operator precedence parsing Readings:

Scene Graph Parsing as Dependency Parsing · 2018-05-15 · Scene Graph Parsing as Dependency Parsing Yu-Siang Wang National Taiwan University b03202047@ntu.edu.tw Chenxi Liu( ) Johns

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Dependency Parsing (3) - University Of Maryland · Dependency Parsing: what you should know •Transition-based dependency parsing •Shift-reduce parsing •Transition systems: arc

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Bare-Bones Dependency Parsing - Uppsala Universitynivre/docs/BareBones.pdf · I Parsing methods for bare-bones dependency parsing I Chart parsing techniques ... [Kuhlmann and Satta

Pika parsing: reformulating packrat parsing as a dynamic ... · Pika parsing maintains the linear-time performance characteristics of packrat parsing as a function of input length

Syntax and Parsing of Semitic Languages - Tsarfatytsarfaty.com/pdfs/semitic.pdfSyntax and Parsing of Semitic Languages 3 1.1 Parsing Systems Syntactic Analysis A parsing system is

Chem Trails Strange Days Strange Skies

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Statistical Dependency Parsing - Uppsala Universitynivre/docs/StatState.pdf · I Methods for statistical dependency parsing I Chart parsing techniques I Parsing as constraint satisfaction

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Bare-Bones Dependency Parsing - Uppsala Universitystp.lingfil.uu.se/~nivre/docs/BareBones.pdf · I Parsing methods for bare-bones dependency parsing I Chart parsing ... Eisner 2000]:

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