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Appendix: how the ENVS and QRES stacks work ( M0 example)

Appendix: how the ENVS and QRES stacks work ( M0 example). Presentation prepared for OMG Object Database Technology Working Group OMG TECHNICAL MEETING, Anaheim, CA USA September 25-29,  2006 by Prof . Kazimierz Subieta Polish-Japanese Institute of Information Technology, Warsaw, Poland

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Appendix: how the ENVS and QRES stacks work ( M0 example)

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  1. Appendix: how the ENVS and QRES stacks work (M0 example) Presentation prepared for OMG Object Database Technology Working Group OMG TECHNICAL MEETING, Anaheim, CA USASeptember 25-29,  2006 by Prof. Kazimierz Subieta Polish-Japanese Institute of Information Technology, Warsaw, Poland subieta@pjwstk.edu.pl http://www.ipipan.waw.pl/~subieta SBA/SBQL pages:http://www.sbql.pl

  2. Query addressing a tiny database • Query: For each department get its reference and the average sal of its employees. • SBQL: Deptjoinavg((employs.Emp).sal) • Tiny database: • Expected result: bag{ struct{i17, 2500}, struct{i22, 1450} }

  3. Query syntax tree and execution scenario Deptjoin avg( ( employs . Emp ) . sal ) join Dept avg 2nd dot . 1st dot . sal employs Emp 1stemploys 1stEmp 1stDept 2ndemploys 2ndEmp 2ndDept 3rdemploys 3rdEmp avg join 1st dot 2nd dot

  4. 0 Deptjoinavg((employs.Emp). sal) Start Emp(i1) Emp(i5) Emp(i9) Dept(i17) Dept(i22) empty ENVS QRES

  5. 1 Deptjoin avg( ( employs . Emp ) . sal ) After binding Dept Emp(i1) Emp(i5) Emp(i9) Dept(i17) Dept(i22) bag{ i17 , i22 } ENVS QRES

  6. 2 Deptjoin avg( ( employs . Emp ) . sal ) join starts 1st loop of the iteration over top of QRES dname(i18) loc(i19) loc(i20) employs(i21) nested Emp(i1) Emp(i5) Emp(i9) Dept(i17) Dept(i22) bag{ i17 , i22 } ENVS QRES

  7. 3 Deptjoin avg( ( employs . Emp ) . sal ) After binding employs dname(i18) loc(i19) loc(i20) employs(i21) i21 Emp(i1) Emp(i5) Emp(i9) Dept(i17) Dept(i22) bag{ i17 , i22 } ENVS QRES

  8. 4 Deptjoin avg( ( employs . Emp ) . sal ) dot starts iteration on top of QRES nested Emp(i1) dname(i18) loc(i19) loc(i20) employs(i21) i21 Emp(i1) Emp(i5) Emp(i9) Dept(i17) Dept(i22) bag{ i17 , i22 } ENVS QRES

  9. 5 Deptjoin avg( ( employs . Emp ) . sal ) After binding Emp Emp(i1) dname(i18) loc(i19) loc(i20) employs(i21) i1 i21 Emp(i1) Emp(i5) Emp(i9) Dept(i17) Dept(i22) bag{ i17 , i22 } ENVS QRES

  10. 6 Deptjoin avg( ( employs . Emp ) . sal ) Closing the iteration by the first dot dname(i18) loc(i19) loc(i20) employs(i21) i1 Emp(i1) Emp(i5) Emp(i9) Dept(i17) Dept(i22) bag{ i17 , i22 } ENVS QRES

  11. 7 Deptjoin avg( ( employs . Emp ) . sal ) Second dot starts iteration over top of QRES name(i2) sal(i3) worksIn(i4) nested dname(i18) loc(i19) loc(i20) employs(i21) i1 Emp(i1) Emp(i5) Emp(i9) Dept(i17) Dept(i22) bag{ i17 , i22 } ENVS QRES

  12. 8 Deptjoin avg( ( employs . Emp ) . sal ) After binding sal name(i2) sal(i3) worksIn(i4) dname(i18) loc(i19) loc(i20) employs(i21) i3 i1 Emp(i1) Emp(i5) Emp(i9) Dept(i17) Dept(i22) bag{ i17 , i22 } ENVS QRES

  13. 9 Deptjoin avg( ( employs . Emp ) . sal ) Closing the iteration by the second dot dname(i18) loc(i19) loc(i20) employs(i21) i3 Emp(i1) Emp(i5) Emp(i9) Dept(i17) Dept(i22) bag{ i17 , i22 } ENVS QRES

  14. 10 Deptjoin avg( ( employs . Emp ) . sal ) After performing avg on top of QRES dname(i18) loc(i19) loc(i20) employs(i21) 2500 Emp(i1) Emp(i5) Emp(i9) Dept(i17) Dept(i22) bag{ i17 , i22 } ENVS QRES

  15. 11 Deptjoin avg( ( employs . Emp ) . sal ) join forms the first partial result Partial result of join: struct{ i17, 2500 } dname(i18) loc(i19) loc(i20) employs(i21) 2500 Emp(i1) Emp(i5) Emp(i9) Dept(i17) Dept(i22) bag{ i17 , i22 } ENVS QRES

  16. 12 Deptjoin avg( ( employs . Emp ) . sal ) After ending the 1st loop by join Partial result of join: struct{ i17, 2500 } Emp(i1) Emp(i5) Emp(i9) Dept(i17) Dept(i22) bag{ i17 , i22 } ENVS QRES

  17. 13 Deptjoin avg( ( employs . Emp ) . sal ) join starts 2nd loop of the iteration over top of QRES Partial result of join: struct{ i17, 2500 } dname(i23) loc(i24) employs(i25) employs(i26) nested Emp(i1) Emp(i5) Emp(i9) Dept(i17) Dept(i22) bag{ i17 , i22 } ENVS QRES

  18. 14 Deptjoin avg( ( employs . Emp ) . sal ) After binding employs Partial result of join: struct{ i17, 2500 } dname(i23) loc(i24) employs(i25) employs(i26) bag{ i25 , i26 } Emp(i1) Emp(i5) Emp(i9) Dept(i17) Dept(i22) bag{ i17 , i22 } ENVS QRES

  19. 15 Deptjoin avg( ( employs . Emp ) . sal ) First dot starts 1st loop of iteration on top of QRES Partial result of join: struct{ i17, 2500 } Emp(i5) nested dname(i23) loc(i24) employs(i25) employs(i26) bag{ i25 , i26 } Emp(i1) Emp(i5) Emp(i9) Dept(i17) Dept(i22) bag{ i17 , i22 } ENVS QRES

  20. 16 Deptjoin avg( ( employs . Emp ) . sal ) After binding Emp Partial result of join: struct{ i17, 2500 } Emp(i5) dname(i23) loc(i24) employs(i25) employs(i26) i5 bag{ i25 , i26 } Emp(i1) Emp(i5) Emp(i9) Dept(i17) Dept(i22) bag{ i17 , i22 } ENVS QRES

  21. 17 Deptjoin avg( ( employs . Emp ) . sal ) Forming 1st partial result of the first dot Partial result of join: struct{ i17, 2500 } Partial result of dot: i5 dname(i23) loc(i24) employs(i25) employs(i26) bag{ i25 , i26 } Emp(i1) Emp(i5) Emp(i9) Dept(i17) Dept(i22) bag{ i17 , i22 } ENVS QRES

  22. 18 Deptjoin avg( ( employs . Emp ) . sal ) Firstdot starts 2nd loop of iteration on top of QRES Partial result of join: struct{ i17, 2500 } Partial result of dot: i5 Emp(i9) nested dname(i23) loc(i24) employs(i25) employs(i26) bag{ i25 , i26 } Emp(i1) Emp(i5) Emp(i9) Dept(i17) Dept(i22) bag{ i17 , i22 } ENVS QRES

  23. 19 Deptjoin avg( ( employs . Emp ) . sal ) After binding Emp Partial result of join: struct{ i17, 2500 } Partial result of dot: i5 Emp(i9) dname(i23) loc(i24) employs(i25) employs(i26) i9 bag{ i25 , i26 } Emp(i1) Emp(i5) Emp(i9) Dept(i17) Dept(i22) bag{ i17 , i22 } ENVS QRES

  24. 20 Deptjoin avg( ( employs . Emp ) . sal ) Forming 2nd partial result of the first dot Partial result of join: struct{ i17, 2500 } i9 Partial results of dot: i5 dname(i23) loc(i24) employs(i25) employs(i26) bag{ i25 , i26 } Emp(i1) Emp(i5) Emp(i9) Dept(i17) Dept(i22) bag{ i17 , i22 } ENVS QRES

  25. 21 Deptjoin avg( ( employs . Emp ) . sal ) Closing iteration by the first dot, forming its result Partial result of join: struct{ i17, 2500 } dname(i23) loc(i24) employs(i25) employs(i26) bag{ i5 , i9 } Emp(i1) Emp(i5) Emp(i9) Dept(i17) Dept(i22) bag{ i17 , i22 } ENVS QRES

  26. 22 Deptjoin avg( ( employs . Emp ) . sal ) Second dot starts 1st loop of iteration on top of QRES Partial result of join: struct{ i17, 2500 } name(i6) sal(i7) worksIn(i8) nested dname(i23) loc(i24) employs(i25) employs(i26) bag{ i5 , i9 } Emp(i1) Emp(i5) Emp(i9) Dept(i17) Dept(i22) bag{ i17 , i22 } ENVS QRES

  27. 23 Deptjoin avg( ( employs . Emp ) . sal ) After binding sal Partial result of join: struct{ i17, 2500 } name(i6) sal(i7) worksIn(i8) dname(i23) loc(i24) employs(i25) employs(i26) i7 bag{ i5 , i9 } Emp(i1) Emp(i5) Emp(i9) Dept(i17) Dept(i22) bag{ i17 , i22 } ENVS QRES

  28. 24 Deptjoin avg( ( employs . Emp ) . sal ) Forming 1st partial result of the second dot Partial result of join: struct{ i17, 2500 } Partial result of dot: i7 dname(i23) loc(i24) employs(i25) employs(i26) bag{ i5 , i9 } Emp(i1) Emp(i5) Emp(i9) Dept(i17) Dept(i22) bag{ i17 , i22 } ENVS QRES

  29. 25 Deptjoin avg( ( employs . Emp ) . sal ) Second dot starts 2nd loop of iteration on top of QRES Partial result of join: struct{ i17, 2500 } Partial result of dot: i7 name(i10) sal(i11) address(i12) worksIn(i16) nested dname(i23) loc(i24) employs(i25) employs(i26) bag{ i5 , i9 } Emp(i1) Emp(i5) Emp(i9) Dept(i17) Dept(i22) bag{ i17 , i22 } ENVS QRES

  30. 26 Deptjoin avg( ( employs . Emp ) . sal ) After binding sal Partial result of join: struct{ i17, 2500 } Partial result of dot: i7 name(i10) sal(i11) address(i12) worksIn(i16) dname(i23) loc(i24) employs(i25) employs(i26) i11 bag{ i5 , i9 } Emp(i1) Emp(i5) Emp(i9) Dept(i17) Dept(i22) bag{ i17 , i22 } ENVS QRES

  31. 27 Deptjoin avg( ( employs . Emp ) . sal ) Forming 2nd partial result of the second dot Partial result of join: struct{ i17, 2500 } i11 Partial result of dot: i7 dname(i23) loc(i24) employs(i25) employs(i26) bag{ i5 , i9 } Emp(i1) Emp(i5) Emp(i9) Dept(i17) Dept(i22) bag{ i17 , i22 } ENVS QRES

  32. 28 Deptjoin avg( ( employs . Emp ) . sal ) Closing iteration by the second dot, forming its result Partial result of join: struct{ i17, 2500 } dname(i23) loc(i24) employs(i25) employs(i26) bag{ i7 , i11 } Emp(i1) Emp(i5) Emp(i9) Dept(i17) Dept(i22) bag{ i17 , i22 } ENVS QRES

  33. 29 Deptjoin avg( ( employs . Emp ) . sal ) After performing avg on top of QRES Partial result of join: struct{ i17, 2500 } dname(i23) loc(i24) employs(i25) employs(i26) 1450 Emp(i1) Emp(i5) Emp(i9) Dept(i17) Dept(i22) bag{ i17 , i22 } ENVS QRES

  34. 30 Deptjoin avg( ( employs . Emp ) . sal ) join forms 2nd partial result Partial results of join: struct{ i17, 2500 } struct{ i22, 1450 } dname(i23) loc(i24) employs(i25) employs(i26) 1450 Emp(i1) Emp(i5) Emp(i9) Dept(i17) Dept(i22) bag{ i17 , i22 } ENVS QRES

  35. 31 Deptjoin avg( ( employs . Emp ) . sal ) Closing the iteration by join, forming the final result Emp(i1) Emp(i5) Emp(i9) Dept(i17) Dept(i22) bag{ struct{ i17, 2500}, struct{ i22 , 1450} } ENVS QRES

  36. In closing … • Please note that this evaluation scenario concerns the formal semantics executed by the abstract machine. • Our goal is clear, universal and free of ambiguities semantic specification rather than performance. • In real implementation there are many obvious optimizations. • The evaluation process is also the subject of many sophisticated optimizations (rewriting, indices, caching,…) . • The entire process is executed in the main memory, hence the computations are not critical. • Critical computations concern the access to external storage and network, and avoiding unnecessary (redundant) computations. • This is the subject of major SBA optimization methods.

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