![Precompiler
The OPEN, FETCH and CLOSE statements are converted into
function calls. The precompiler generates the code for these calls
and puts it at the end of the source module.
EXEC SQL FETCH csr1 INTO :host_a, :host_b, :host_c;
// EXEC SQL FETCH csr1
static int16 fetch_csr1()
{
if ( ! csr1.rslt )
return SQL_ERROR;
if ( csr1.row >= mysql_num_rows(csr1.rslt) )
return SQL_NO_DATA;
MYSQL_ROW row = mysql_fetch_row(csr1.rslt);
SQLBindColPoly(row[0], host_a, sizeof(host_a));
SQLBindColPoly(row[1], host_b, sizeof(host_b));
SQLBindColPoly(row[2], host_c, sizeof(host_c));
++csr1.row;
return SQL_SUCCESS;
}
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Sabre presentation for MySQL user conference 2004
- 1. MySQL at Sabre Alan Walker Sabre Labs February 2004 Confidential
- 2. Agenda • Sabre Holdings Overview • Business drivers for MySQL & Open Source • Shopping for fares • Air Travel Shopping Engine (ATSE) • Data replication strategy • ESQL precompiler for MySQL • Other MySQL users at Sabre 2 22
- 3. Who is Sabre Holdings? A world leader in travel commerce, retailing travel products, and providing distribution and technology solutions for the travel industry 3 33
- 5. Sabre Holdings Fast Facts • Industry leader in multiple travel channels • Revenues of $2.06 billion in 2002 • S&P 500 company • NYSE:TSG • Headquarters in Dallas/Fort Worth, Texas • 6,500 employees in 45 countries 5 55
- 6. Business drivers Over 3 billion fare combinations for a single customer request Multiple airlines, flights, fare types, dates prices, taxes, surcharges 6 66
- 7. Business drivers • No direct revenue for shopping queries • Revenue for booking, but not looking (searching) • Look-to-book ratio increasing • Competition requires staying on the “leading edge” • Highly reliable and scalable database • Fast processors • Large real memory • Smart algorithms • Shopping is a good fit for horizontal scale • Pricing requires higher precision 7 77
- 8. Business drivers Application DB / Middleware Computing Stack Commodity Point Operating System Hardware Hardware, operating system, database and middleware are becoming commodities. This drives the cost down rapidly. Open source software is a major driver of this effect. 8 88
- 9. Business Solution • Linux servers alongside HP NonStop servers to create “hybrid” Air Travel Shopping Engine (ATSE) platform • HP NonStop delivers high availability and reliability – Better than or equal to legacy, but at significantly lower cost – Best fit for critical workloads and master database management • Linux / MySQL delivers 64-bit memory and faster CPUs – Lower availability and reliability than HP NonStop but at significantly lower cost – Best fit for CPU-intensive shopping workloads Most cost-effective platform for the shopping workload 9 99
- 10. Business drivers • Sabre’s legacy • World’s first commercial OLTP system in 1960 • Mainframe clusters running TPF • Operating system customized to our needs • True 7*24 application, with zero scheduled downtime • Most application code in assembler • Sabre’s future • Higher-level languages • Relational databases • Internet • Open systems • Reduce specialized training • Use off the shelf software • HP NonStop with OSS is a key component (LINUX?) 10 10 10
- 11. Shopping • Finding cheap air fares is hard! • With 50+ connect points to consider, and >100 fares per leg, we need to evaluate >3 billion combinations • Up to a million fares can change every day • Availability changes continuously • Solve it >100 times per second • Other functions • Price 250 tickets per second • Process 1000 flight routing requests per second 11 11 11
- 12. Pricing • Shopping vs. Pricing • Shopping is the problem of finding low fares • Pricing is used to print the ticket • Pricing has to be accurate, or we pay the difference to the airline • Many internet search engines still rely on mainframes to actually print the ticket • Pricing also requires additional functions, such as refunds, exchanges and auditing 12 12 12
- 13. Algorithms • Fare-led search • Graph-based algorithm that searches all fare combinations across 50+ connect points • Can generate up to a 4-segment connection • Search space of >3 billion fare combinations • Match or exceed any competitor in finding lowest fare • Only loses to competitors to have access to exclusive private fares and/or other discounts • Search actually checks Direct Connect Availability, so that low fare options are actually bookable 13 13 13
- 14. Algorithms • Dynamic schedules • Connections are not generated overnight and stored • Not limited to routes explicitly setup by airlines or other marketing staff • Availability Manager • Flexible rules to access airline availability • Current methods – Direct Connect – Host Availability – Teletype (AVS) • Can also use – Cached DCA – Inventory proxy 14 14 14
- 15. ATSE Hybrid • Air shopping for desirable itineraries • Must search through multiple airlines, flights, fare types, dates, adjacent airports, etc. • Must calculate prices, taxes, surcharges • Complexity • Single round-trip request can have over 3 billion fare combinations • Search is CPU and memory intensive • Business driver • No direct revenue for shopping transactions • Increasing look to book ratio 15 15 15
- 16. ATSE Hybrid • Combine Linux servers and HP NonStop servers • HP NonStop delivers high availability and reliability • Better than or equal to TPF at significantly lower cost • Master database management • Data replicated in real-time to Linux servers • PNR pricing, schedules and availability • Linux delivers 64-bit memory model and faster CPUs • Lower availability and reliability than HP NonStop but at significantly lower cost • Horizontally scaled server farm with spare capacity • Best fit for CPU-intensive shopping workloads 16 16 16
- 17. ATSE Hybrid IBM Fare and Rule Updates Schedule and Availability Updates IBM PSS MVS d i g i t a l d i g i t a l d i g i t a l d i g i t a l d i g i t a l d i g i t a l HP Non-Stop Air Shopping Transactions Shopping Availability Transactions Requests Naming Service And Load Balancing DB Image Load and Updates E/R Logging and Billing Linux Server Farm Load Information Linux Linux Linux Linux Linux Linux Linux Linux Linux Linux Linux Linux Linux Linux Linux Linux Linux Linux Linux Linux Linux Linux Linux Linux 17 17 17
- 18. ATSE Linux servers • In production since July 2003 • Started with HP rp5405 servers (Unix PA-RISC) – Migrated to Itanium in December 2003 • Using 45 HP rx5670 servers – 4-way, 1.5 GHz, 6MB L2 cache, 32GB RAM, 4x72GB SCSI • Software • MySQL 4.0.15 • GNU compilers – g++ 3.2.3 and glibc 2.3.2 • TAO object request broker • Redhat RHAS 2.1 • GoldenGate Extractor/Replicator • Monitoring – Prognosis, CA Unicenter, scripts 18 18 18
- 19. ATSE Software • Extensive use of open source software • MySQL 4.0.15 • GNU compilers – g++ 3.2.3 and glibc 2.3.2 • TAO object request broker • Redhat Linux AS 3.0 • Third party software • GoldenGate Extractor/Replicator • Monitoring – Prognosis, CA Unicenter, scripts • Internally developed applications and scripts 19 19 19
- 20. Data replication • HP NonStop (Tandem) is master database • Golden Gate Software used to replicate to MySQL – Extracts data form undo/redo logs on the NonStop server – Performs INSERT / UPDATE / DELETE on MySQL – Software performs catch-up / resync in case of crashes or other failures • Each Linux server has an identical copy of the database – 50GB database on each server, all InnoDB • Replication volume • 150 tables replicated (over 300 on NonStop server) • Can replicate 1M fare changes / hour • Data updates on 7x24 basis 20 20 20
- 21. Data replication HP NonStop SQL/MP DB TMF Log Linux IA-64 Data Pump Queue Extract Receive Updater Queue MySQL DB = Golden Gate Software 21 21 21
- 23. Results Reduced development costs Decreased fare loading cycle times Competitive Advantage Increased functionality Reduced runtime costs (over 80% compared to legacy) 23 23 23
- 24. Hybrid • Horizontal scalability • Ability to throw inexpensive CPUs at the problem • Tolerate failure of a single server • How do we get there from here? • Database and network functions remain on Himalaya • C++ code readily ports to Linux • Publish/subscribe metaphor for data in memory • 64-bit addressing to avoid memory constraints 24 24 24
- 25. Connectivity • CORBA • Major functions use CORBA internally • CORBA requests to TPF for availability • CORBA to CTS for DCA this Summer (bypass TPF) • Asynchronous messaging via MQ Series • XML • Currently uses XML requests from TPF (over RPPC) for pricing functions • Working on direct access from Travelocity to ATSE – Will be used for BIP – Already working over HTTP (development systems) – Working on security & billing for production 25 25 25
- 26. Timeline • 2000 • Proof Of Concept, April – August • 5 core developers, partnership with Compaq • 2001 • Development & training began in February • Initial hardware delivered • 2002 • Phase 1 in production since July • Zero downtime since implementation • Rapidly developing additional functionality • Wow – this is from an ancient slide, huh? 26 26 26
- 27. Precompiler • Challenge • 500K lines of C/C++, 150+ files with embedded SQL • We did not want to rewrite ESQL / C code by hand • Solution • Wrote a precompiler that converts ESQL to inline MySQL calls • About 1000 lines of awk • We are willing to share this code with others EXEC SQL int double char EXEC SQL BEGIN DECLARE SECTION; host_a; host_b; host_c; END DECLARE SECTION; EXEC SQL DECLARE csr1 CURSOR FOR SELECT a, b, c FROM table1 WHERE x = :hostvar1; EXEC SQL OPEN csr1; while (rc >= 0 && rc != 100){ EXEC SQL FETCH csr1 INTO :host_a, :host_b, :host_c; printf("Fetch %d, %lf, %sn", host_a, host_b, host_c); } EXEC SQL CLOSE csr1; 27 27 27
- 28. Precompiler • How it works • Convert C / ESQL to C++ code • Polymorphism matches data types in the declare section • Can ignore the declare section EXEC SQL int double char EXEC SQL BEGIN DECLARE SECTION; host_a; host_b; host_c; END DECLARE SECTION; // EXEC int double char // EXEC SQL BEGIN DECLARE SECTION; host_a; host_b; host_c; SQL END DECLARE SECTION; 28 28 28
- 29. Precompiler Cursor declarations (SELECT statements) are converted to a static struct. The struct has the text of the SQL, as well as statement handles for doing prepare / execute (where applicable) EXEC SQL DECLARE csr1 CURSOR FOR SELECT a, b, c FROM table1 WHERE x = :hostvar1; // EXEC SQL DECLARE csr1 static e2mysql csr1 = { " SELECT a,b,c FROM table1 WHERE x = :hostvar1" , NULL , 0}; 29 29 29
- 30. Precompiler The OPEN, FETCH and CLOSE statements are converted into function calls. The precompiler generates the code for these calls and puts it at the end of the source module. EXEC SQL FETCH csr1 INTO :host_a, :host_b, :host_c; // EXEC SQL FETCH csr1 static int16 fetch_csr1() { if ( ! csr1.rslt ) return SQL_ERROR; if ( csr1.row >= mysql_num_rows(csr1.rslt) ) return SQL_NO_DATA; MYSQL_ROW row = mysql_fetch_row(csr1.rslt); SQLBindColPoly(row[0], host_a, sizeof(host_a)); SQLBindColPoly(row[1], host_b, sizeof(host_b)); SQLBindColPoly(row[2], host_c, sizeof(host_c)); ++csr1.row; return SQL_SUCCESS; } 30 30 30
- 31. Precompiler A lightweight wrapper around the database API lets us use polymorphism to convert to the types specified in the declare section. There is a wrapper function for each simple C++ type that we handle. inline int32 SQLBindColPoly(const char* value, int32& parm, uint16 size) { parm = atoi(value); return SQL_SUCCESS; } 31 31 31
- 32. Precompiler • Notes • Light-weight C++ wrapper to MySQL API • The precompiler understands some SQL syntax and does some modifications of NonStop SQL/MP statements • We have also used our precompiler to target other DBMS – ODBC API – Oracle – PostgreSQL • Since we convert C to C++, this may be problematic for ESQL programs that used deprecated K&R syntax – C++ compilers are stricter than C compilers – However, we did not have this problem with our application 32 32 32
- 33. Other MySQL applications at Sabre • ATSE is our largest and most mission critical • We have other production systems that rely on MySQL • Site59.com is the most visible • MySQL also used for some internal databases • More under development • MySQL / Linux / SATA drives make cheap data marts • Sometimes cheaper to replicate to a data mart than to upgrade a central data warehouse • Currently testing with a 1.5B row database 33 33 33
- 34. Site59 • Last minute travel packages • Acquired by Travelocity in March 2002 • Sales volume? • Transaction rates? • All dynamic content generated using PHP & MySQL 34 34 34
- 35. Site59 Site59 implements a fairly “classic” dynamic website using MySQL. Dynamic content is generated at about 30Mbits / second. Extensive use is made of single and dual processor Linux machines (IA-32) Presentation (Apache/PHP) Internet HTTP Application Server Reservations System Gateway XML/HTTP Frontend DB (MySQL, Linux) Replication Backend DB (Oracle, Sun) 35 35 35
- 36. Travel Commerce Processing Chain Session Shop Price Sell Fulfill 36 36 36