Boosting MySQL (for starters)
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The document emphasizes the importance of proper database design and optimization, advising against default denormalization and promoting careful selection of data types to enhance performance and scalability. It covers topics such as the significance of efficient schema design, the impact of various data types on storage, and the value of indexing in query performance. Key takeaways include the recommendation to avoid overly large data types and to utilize surrogate keys effectively while maintaining optimal indexing strategies.
Boosting MySQL (for starters)
- 2. This is not a DB optimization talk It’s a talk about how doing things in a specific way leads to getting way better results by default
- 3. “Preoptimization” Don’t denormalize by default Maintenance is King (by default) 1 Thread Performance != Parallel Performance MyISAM vs InnoDB Fast != Scalable
- 5. I’ll just tune MySQL Parameters… Will get you out of SOME trouble But not a good “default” solution, specially if the base is flawed Please do tune MySQLs defaults Not the theme for today
- 7. Start with your Schema Your schema is probably the root cause of your “My DB doesn’t scale” problems The solution is not “have a loose/no schema” How to fake a DB Design (Curtis Ovid Poe) https://www.youtube.com/watch?v=y1tcbhWLiUM
- 8. Data types: how (not) to bloat your DB Selecting data types with a bit of care is very productive It makes more data fit in less space Optimizes use of InnoDB Buffer Pool, MyISAM Key Buffer, Join Buffer, Sort Buffer, Smaller indexes
- 9. Your new best friend http://dev.mysql.com/doc/refman/5.6/en/storage-requirements.html http://dev.mysql.com/doc/refman/5.5/en/storage-requirements.html …
- 10. DataTypes: NULL vs NOT NULL I don’t care about the NULL debate Saves Space Gives the DB hints Use NULLs wisely
- 12. DataTypes: Integers INT(1) == INT(10) == 4 bytes That’s it!
- 13. DataTypes: Integer family TINYINT: 1 byte SMALLINT: 2 bytes MEDIUMINT: 3 bytes INT BIGINT:8 bytes UNSIGNED: “double” the range
- 14. INTS and surrogate keys It’s good to have a surrogate key Just unique index the unique column Why? InnoDB stores the PK on the leafs of all indexes Indexes bloat if they’re “big keys”
- 15. Id columns for your tables INT by default for “things that can get big” Smaller INTs for smaller sets Do you really need a BIGINT? The magnitude comparison trick: Epochs in Unix have 4 bytes The epoch has been counting since 1970. Will run out in 2038 An INT can identify ONE THING HAPPENING EVERY SECOND for 68 YEARS! Do you STILL need a BIGINT?
- 16. DataTypes: Integer family TINYINT: 1 byte SMALLINT: 2 bytes MEDIUMINT: 3 bytes INT BIGINT:8 bytes UNSIGNED: “double” the range
- 17. DataTypes: Integer family TINYINT: 1 byte SMALLINT: 2 bytes MEDIUMINT: 3 bytes INT BIGINT:8 bytes UNSIGNED: “double” the range
- 19. DataTypes: Texts Texts are strings of bytes with a charset and a collation BINARY and VARBINARY CHAR and VARCHAR
- 20. DataTypes: Texts BINARY(10) == 10 bytes CHAR(10) ==? 10 bytes
- 21. DataTypes: Texts BINARY(10) == 10 bytes CHAR(10) ==? 10 bytes CHAR(10) latin1: 10 bytes CHAR(19) utf-8: 30 bytes
- 22. DataTypes: Texts BINARY(10) == 10 bytes CHAR(10) ==? 10 bytes CHAR(10) latin1: 10 bytes CHAR(19) utf-8: 30 bytes VARBINARY(10) == 1 to 11 bytes VARCHAR(10) ==? 1 to 11 bytes
- 23. DataTypes: Texts BINARY(10) == 10 bytes CHAR(10) ==? 10 bytes CHAR(10) latin1: 10 bytes CHAR(10) utf-8: 30 bytes VARBINARY(10) == 1 to 11 bytes VARCHAR(10) ==? 1 to 11 bytes VARCHAR(10) latin 1: 1 to 11 bytes VARCHAR(10) utf-8: 1 to 31 bytes
- 24. So I’ll just go for VARCHAR(255) on all text columns “After all… I’ll just consume the number of bytes + 1”
- 25. So I’ll just go for VARCHAR(255) on all text columns “After all… I’ll just consume the number of bytes + 1” When we need a temporary table https://dev.mysql.com/doc/refman/5.6/en/memory-storage-engine.html “MEMORY tables use a fixed-length row-storage format. Variable-length types such as VARCHAR are stored using a fixed length”
- 27. So I’ll just go for VARCHAR(255) on all text columns Congrats! All your VARCHAR(255) are now CHAR(255) in memory That’s 255 bytes latin-1. Or 765 bytes utf-8 O_o Note: do the maths on VARCHAR(65535)
- 28. DataTypes: BLOBS TEXT == BLOB == problems TEXT = BLOB + charset + collation TEXT fields are not unlimited! TINYTEXT and TINYBLOB (up to 256 bytes == x chars) TEXT / BLOB (up to 65KB == x chars) MEDIUMBLOB / MEDIUMTEXT (up to 16MB == x chars) LONGTEXT / LONGBLOB (up to 2GB == x chars)
- 29. SELECT * IS YOUR FRIEND? IF a SELECT contains a BLOB/TEXT column Temporary tables go DIRECTLY to DISK
- 31. SELECT * IS YOUR FRIEND? IF a SELECT contains a BLOB/TEXT column Temporary tables go DIRECTLY to DISK Note: “Big” columns belong on a filesystem or an object store
- 32. DataTypes: Small Sets ENUM One value out of the possibilities (‘big’, ‘small’) SET A set of possible values (‘pool’,’terrace’,’fence’) SETS are NOT good for finding stuff FIND_IN_SET is a function. No indexes Default to a separate table + relation
- 33. DataTypes: Dates YEAR = 1 byte (range from 1901 to 2155) DATE = 3 bytes TIME = 3 bytes DATETIME = 8 bytes TIMESTAMP = 4 bytes Timestamp is an epoch. Ideal for “things that happen now” (sold time, renewal date, etc)
- 34. Masked Data
- 35. Masked Types An IP Address 234.34.123.92 CHAR(15)? VARCHAR(15)?
- 36. Masked Types
- 37. INT
- 38. INSERT INTO table (col) VALUES (INET_ATON(’10.10.10.10’)); SELECT INET_NTOA(col) FROM table;
- 39. Masked Types MD5("The quick brown fox jumps over the lazy cat") 71bd588d5ad9b6abe87b831b45f8fa95 CHAR(32)
- 40. BINARY(16)
- 41. Masked Types UUIDs HASH functions Network masks
- 44. Index the two sides of relations PK
- 45. Index the two sides of relations Index this guy too!
- 46. Index the two sides of relations Index this guy too! And this guy!
- 49. PK is (contract_id, customer_id) (Implied uniqueness) Index “both ways”: (customer_id, contract_id) InnoDB optimization: Don’t index the full (customer_id, contract_id). The index ALREADY HAS customer_id in it’s leafs. So just index (customer_id) N-M relation: Junction tables
- 51. Don’t operate on fields Because they can’t use indexes WHERE column = ‘x’ WHERE column > 2000 WHERE column LIKE ‘prefix%’ WHERE column + 2000 > 2013 WHERE FIND_IN_SET(column) WHERE CONCAT(f1,f2) = “xxxx.com” WHERE YEAR(date) = 2015 WHERE column LIKE ‘%.com’
- 52. Polish your maths: Algebra Doesn’t use index WHERE column + 2000 > 2013 WHERE FIND_IN_SET(‘pool’,column) WHERE CONCAT(f1,’.’,f2) = “xxxx.com” WHERE YEAR(date) = 2015 WHERE column LIKE ‘%.com’ Uses index WHERE column > 13 ? WHERE f1 = ‘xxxx’ AND f2 = ‘com’ WHERE date BETWEEN ’01-01-2015’ and ’31-12-2015’ ?
- 53. The old switcheroo… Doesn’t use index WHERE column + 2000 > 2013 WHERE FIND_IN_SET(‘pool’,column) WHERE CONCAT(f1,’.’,f2) = “xxxx.com” WHERE YEAR(date) = 2015 WHERE column LIKE ‘%.com’ Uses index WHERE has_pool = 1 WHERE column_rev LIKE ‘moc.%’
- 54. The old switcheroo… Doesn’t use index WHERE column + 2000 > 2013 WHERE FIND_IN_SET(‘pool’,column) WHERE CONCAT(f1,’.’,f2) = “xxxx.com” WHERE YEAR(date) = 2015 WHERE column LIKE ‘%.com’ Uses index WHERE has_pool = 1 UPDATE t SET has_pool = FIND_IN_SET(‘pool’,column); WHERE column_rev LIKE ‘moc.%’ UPDATE t SET column_rev=REVERSE(column)
- 56. CAT IS HERE
- 57. Wrap up Schema Data Types How to select them Masked Types Indexes Relations Using them
- 58. Wrap up Smaller is better VS