The document summarizes the scaling challenges faced by Fotolog, a large photo blogging community. It discusses how Fotolog grew to hosting hundreds of millions of photos and billions of comments. It describes Fotolog's technology stack including their use of MySQL, Memcached, 3Par storage and CDNs. It also outlines some of the MySQL scaling techniques used, such as sharding, replication, table partitioning and optimization.

4. Fotolog (Screenshot of home page)

5. Fotolog (Screenshot of a fotolog member page)

11. Partitioning SHARD 1 SHARD 2 SHARD 3 Table_v1 Table_v2 Table_v3 Table_v4

12. Partitioning thoughts

13. Ideal distribution

14. GB current db4 db18 db22 db23 db24 db25 db26 db27 db28 db30 db32 Application Servers 4 18 22 23 24 25 26 27 28 30 32 read write Single Point of Failure

15. GB Scalability db4 db18 db22 db23 db24 db25 db26 db27 db28 db30 db32 Application Servers 4 18 22 23 24 25 26 27 28 30 32 read write 00-08 09-17 18-26 27-35 36-44 45-53 54-62 63-71 72-80 81-89 90-99 Slave Master/DRBD

16. Current Scheme for fl_db1 repl. PH Application Servers read write Slave DB2 DB1 DB3 DB8 DB12 Application Servers Issuing PH Queries RTX Repl. Repl. Repl. DB7 DB9 DB15 FSW 05DHN AEK 16JOQUZ 28IP _ 39B 4C 7GLVY M DB10 DB11 DB13 DB14 DB16 29 FF. Repl.

17. Proposed Scheme for PH (Write & Read) Application Servers 7 8 9 10 11 12 13 14 15 16 29 read write 00-08 09-17 18-26 27-35 36-44 45-53 54-62 63-71 72-80 81-89 90-99 TO USER CLUSTER

18. AUTO-INC table lock contention SEL SEL SEL SEL SEL SEL SEL SEL SEL SEL M Y S Q L Thread concurrency SELECTs do very well with Increased concurrency. QPS: 500+ GOOD TIMES SELECT INSERT

19. AUTO-INC table lock contention SEL SEL SEL SEL SEL INS INS M Y S Q L Thread concurrency As more SELECTs come, AUTO-INC lock contention Starts causing problem. WARNING SEL SEL SEL SELECT INSERT

20. AUTO-INC table lock contention INS SEL INS SEL INS INS INS INS INS INS M Y S Q L Thread concurrency PROBLEM SEL SEL SEL SEL INS INS INS INS INS SELECT INSERT

21. InnoDB Tablespace Structure (Simplified) PK / CLUSTERED INDEX SECONDARY INDEX PK (clustered index key) 6 byte header Links together consecutive records & used in row-level locking Clustered index contains Fields for all user-defined columns 6 byte trx id 7 byte roll pointer 6 byte row id If no PK or UNIQUE NOT NULL defined Record Directory Array of Pointers to each field of the record 1 byte: If the total length of fields in record is 128 bytes 2 bytes: otherwise Data part of record

22. InnoDB Index Structure (Simplified) DATA PAGE PK INDEX / CLUSTERED INDEX SECONDARY INDEX PK ROW DATA PK

27. Pending reads / writes / Proposed Throughput not as important as number of requests

28. Pending reads / writes / Proposed

29. Pending reads

33. Questions?