10 things every developer should know about their database to run word press optimally
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The document presents essential tips for optimizing WordPress databases, shared by Otto Kekäläinen at WordCamp Barcelona 2018. Key recommendations include creating database backups, utilizing WP-CLI for managing database tasks, and understanding the significance of autoload options in the wp_options table. Additionally, it emphasizes learning SQL, proper database configurations, and regular performance monitoring to maintain an efficient WordPress environment.
![TIP #12: EXPLAIN, PLEASE
● You can append ‘EXPLAIN’ to any query and the
optimizer will tell how it is running the query
● EXPLAIN SELECT * FROM wp_options WHERE
autoload = 'yes';
MariaDB [wp_palvelu_06a4ad]> explain SELECT * FROM wp_options WHERE autoload = 'yes';
+------+-------------+------------+------+---------------+------+---------+------+------+-------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+------+-------------+------------+------+---------------+------+---------+------+------+-------------+
| 1 | SIMPLE | wp_options | ALL | NULL | NULL | NULL | NULL | 415 | Using where |
+------+-------------+------------+------+---------------+------+---------+------+------+-------------+](https://image.slidesharecdn.com/nllvbuxgrjutkxaw9ajg-signature-08ae1abc04f69c254ced42123a74d94e196dde1573a72794cf4a4407960c918f-poli-181005094214/85/10-things-every-developer-should-know-about-their-database-to-run-word-press-optimally-21-320.jpg)
10 things every developer should know about their database to run word press optimally
- 1. EXTENDED EDITION 1013 THINGS EVERY DEVELOPER SHOULD KNOW ABOUT THEIR DATABASE TO RUN WORDPRESS OPTIMALLY WordCamp Barcelona 2018 Otto Kekäläinen Seravo.com @ottokekalainen #wcbcn
- 2. ● Linux and open source advocate ● Written WP themes and plugins, contributed to WordPress Core, MySQL, MariaDB… ● CEO, sysadmin and developer at Seravo.com – WordPress hosting and upkeep Otto Kekäläinen
- 3. Enterprise grade hosting and upkeep for WordPress
- 4. The database is involved in both! ○ contains all your valuable data ○ often the bottleneck of performance Common Issues in WordPress: Security & Speed
- 5. DATABASE THE SINGLE MOST IMPORTANT PART OF YOUR WORDPRESS INFRASTRUCTURE
- 6. TIP #1: MAKE (USE OF) DB DUMPS Benefits ● Copying your WordPress files is not enough for a backup ● The database dump file format is ○ plain-text: view and modify it as much as you like ○ interoperable: import it into a MySQL or MariaDB database server anywhere Command line: mysqldump or wp db export
- 7. TIP #1: MAKE (USE OF) DB DUMPS $ wp db export --skip-extended-insert --allow-root --single-transaction example-after.sql $ diff -u example-before.sql example-after.sql --- example-before.sql 2018-08-30 10:58:23.243836204 +0300 +++ example-after.sql 2018-08-30 10:57:57.771762687 +0300 @@ -2,3 +2,4 @@ INSERT INTO `wp_terms` VALUES (70,'transients','transients',0,0); INSERT INTO `wp_terms` VALUES (71,'code','code',0,0); INSERT INTO `wp_terms` VALUES (72,'performance','performance',0,0); +INSERT INTO `wp_terms` VALUES (73,'WordPress','wordpress',0,0); What are these tables and columns? See codex.wordpress.org/Database_Description
- 8. TIP #2: LEARN WP-CLI DB COMMANDS List them all with wp db --help My most used ones: ● wp db export/import ● wp db size --tables --all-tables --size_format=mb ● wp db cli ● wp db search --one_line ● wp search-replace --all-tables http://example.com https://example.com ^ My favourite!
- 9. TIP #3: USE ADMINER TO BROWSE ● Adminer is one file, easy to install and update ● Less security vulnerabilities than in PHPMyAdmin
- 10. TIP #4: WP_OPTIONS AND AUTOLOAD ● Every single WordPress page load runs this query SELECT * FROM wp_options WHERE autoload = 'yes'
- 11. TIP #4: WP_OPTIONS AND AUTOLOAD ● If wp_options table is larger than 1 MB, try to clean it up ● Find rows with the largest amount of data in the option_value field: ○ SELECT option_name, length(option_value) FROM wp_options WHERE autoload='yes' ORDER BY length(option_value) DESC LIMIT 30 ● File bugs against stupid plugins polluting your options table ● If cannot be cleaned, add an index on autoload ○ CREATE INDEX autoloadindex ON wp_options(autoload, option_name)
- 12. TIP #5: WP_POSTMETA BLOAT ● Any site using custom post types or WooCommerce is likely to have a big wp_postmeta table. While every post adds just one new row (and many fields) to the database and keeping the number of column names constant, the use of add_post_meta() calls will bloat the database with tens or hundreds of rows per post where each row only contains two fields: name and value. ● Find the meta_key naming patterns with most amount of rows: ○ SELECT substring(meta_key, 1, 20) AS key_start, count(*) AS count FROM wp_postmeta GROUP BY key_start ORDER BY count DESC LIMIT 30
- 13. Unfortunately database bloat and stupid use of database is common in plugins. We need to do more to raise awareness about database best practices!
- 14. TIP #6: LEARN SQL ● It is not enough that you know PHP, learn SQL as well. ● The database has 20 years of engineering on how to fetch a small set of data from a huge set of data as quickly as possible. Don’t try to reinvent that in PHP. ● Don’t put everything in wp_postmeta. Don’t be afraid of creating your own custom tables that have the correct columns, relations and indexes already defined. ● Learn what ‘index’ means and why you don’t want to be causing ‘full table scans’ in the database.
- 15. TIP #7: BUT DON’T USE SQL DIRECTLY ● In WordPress PHP code use get_posts() for basics ● Use the WP_Query class for more advanced cases ● When WP_Query does not fit, use the $wpdb->get_row(), $wpdb->insert() etc methods ● If you really need raw SQL, don’t access the database directly, instead use $wpdb->prepare() and $wpdb->query() to avoid SQL injection vulnerabilities
- 16. TIP #8: CONFIGURE DATABASE SERVER 1. MariaDB preferred over Oracle MySQL 2. Use a recent version (MariaDB 10.1+) 3. Storage engine: InnoDB (not MyISAM) 4. Character set: UTFMB4 (for emojis ) 5. Collation: your local sorting order A-Ö 6. ..and optimize all the other settings Or hire a database administrator, or use a WordPress hosting company that does this for you.
- 17. TIP #9: TRANSIENTS AND OBJECT CACHE ● Use Redis cache or similar to store transients and sessions so they can be removed from wp_options // Simple WP Transient API example if ( ! $result = get_transient( ‘q_result’ ) ) { $result = run_complex_and_slow_query(); set_transient( ‘q_result’, $result, 3600 ); } echo $result; ● Redis and WP Transients API will ease the load on the database and help you make super fast sites
- 18. TIP #10: MONITOR PERFORMANCE ● Take a peek with SHOW PROCESSLIST; ● Analyse unusual slowness by enabling mariadb-slow.log logging ● Enable Tideways or similar service for sampling your WordPress site PHP execution in production to find bottlenecks
- 19. AND ONE EXTRA TIP: NEVER PUSH YOUR DEV DATABASE INTO PRODUCTION
- 20. TIP #11: DB CLEANUP ● DELETE FROM `wp_posts` WHERE post_type = 'revision' AND post_date NOT LIKE '2018-%'; ● DELETE FROM wp_options WHERE option_name LIKE ('_transient_%') OR option_name LIKE ('_site_transient_%'); ● Checkout what wp-content/plugins/*/uninstall.php contains and what plugins are supposed to clean away if they are uninstalled
- 21. TIP #12: EXPLAIN, PLEASE ● You can append ‘EXPLAIN’ to any query and the optimizer will tell how it is running the query ● EXPLAIN SELECT * FROM wp_options WHERE autoload = 'yes'; MariaDB [wp_palvelu_06a4ad]> explain SELECT * FROM wp_options WHERE autoload = 'yes'; +------+-------------+------------+------+---------------+------+---------+------+------+-------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +------+-------------+------------+------+---------------+------+---------+------+------+-------------+ | 1 | SIMPLE | wp_options | ALL | NULL | NULL | NULL | NULL | 415 | Using where | +------+-------------+------------+------+---------------+------+---------+------+------+-------------+
- 22. TIP #13: TEST WITH DUMMY DATA ● While developing a site, load lots of dummy data into it so you can test how your site looks and performs with 100, 1000 or 100 000 posts. ● Basic: Import themeunittestdata.wordpress.xml ○ codex.wordpress.org/Theme_Unit_Test ● More data: wp post generate ○ curl http://loripsum.net/api/5 | wp post generate --post_content --count=10 ● More realism: wp-cli-fixtures ○ github.com/nlemoine/wp-cli-fixtures