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Topics covered

Topics covered. Overview of DEMO Capturing database schema in QL Differential query optimization Dialect DLA Capturing database schema in DLA. Capturing database schema in QL. Another view on views Another view on physical design. Tables: current practice.

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Topics covered

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  1. Topics covered Overview of DEMO • Capturing database schema in QL • Differential query optimization • Dialect DLA • Capturing database schema in DLA

  2. Capturing database schema in QL • Another view on views • Another view on physical design

  3. Tables: current practice • Tables that are base • Tables that are views (defined by queries on base tables) create table EMP ( attribute name on STR; attribute age on INT; attribute loc on STR; primary key (name); ) create view WATEMP ( select name, age from EMP where loc = ‘Waterloo’; ) create view TOREMP ( select name from EMP where loc = ‘Toronto’; )

  4. Tables: an alternative • Tables • Constraints (query containment dependencies) create table EMP ( attribute name on STR; attribute age on INT; attribute loc on STR; primary key (name); updatable; ) create table WATEMP ( attribute name on STR; attribute age on INT; ) create table TOREMP ( attribute name on STR; ) ( select name, age from EMP where loc = ‘Waterloo’ ) ´ ( select name, age from WATEMP ) ( select name from EMP where loc = ‘Toronto’ ) ´ ( select name from TOREMP )

  5. create table EMP ( attribute name on STR; attribute age on INT; attribute loc on STR; primary key (name); updatable; ) create table WATEMP ( attribute name on STR; attribute age on INT; ) create table TOREMP ( attribute name on STR; ) ( select name, age from EMP where loc = ‘Waterloo’ ) ´ ( select name, age from WATEMP ) ( select name from EMP where loc = ‘Toronto’ ) ´ ( select name from TOREMP ) ( select name from EMP ) ´ ( select name from WATEMP ) union all ( select name from TOREMP ) Table: an alternative (cont’d) • Easy to do much more!

  6. Physical design: current practice • Records and fields (implicit) • Clustered indices on base tables (a default file created) • Secondary indices on base tables • Materialized views (a default file created) • Secondary indices on materialized views • Etc. • External engines (collections of tables, views and the above) create index on EMP (loc asc, age desc) alter view WATEMP ( materialized; ) create index on WATEMP (name asc)

  7. Physical design: an alternative • Explicit named record identifiers and stored attributes • Iterator signatures • Secondary indices are also base relations alter table EMP ( record identifier emp; stored (name, age, loc); iterator; ) create table EMPX ( attribute loc on STR; attribute age on INT; attribute eref on RID; stored (loc, age, eref); iterator (loc asc, age desc); ) ( select loc, age, emp from EMP ) ´ ( select loc, age, eref from EMPX )

  8. Physical design: an alternative (cont’d) alter table WATEMP ( record identifier emp; stored (name, age); iterator; ) create table WATEMPX ( attribute name on STR; attribute eref on RID; stored (name, eref); iterator (name asc); ( select name, emp from WATEMP ) ´ ( select name, eref from WATEMPX )

  9. select name, age from EMP as e, PV as :p, (STRu QV) as name, (INTuQV) as age where e.loc = ‘Waterloo’ and e.name = :p and e.name = name and e.age = age Differential query optimization • (based on simple hill climbing) • Expand conjunctive subquery using constraints. • Initialize subplan. • Select next iterator or disjunction from query for subplan; fail if none available. • If disjunction selected, recursively apply steps 1 to 5 on each disjunct; • fail if any recursive application fails. • If expand of subplan contains subquery, return subplan; otherwise repeat from 3. select name, age from EMP where loc = ‘Waterloo’ and name = :p

  10. select name, age from EMP as e, PV as :p, (STRu QV) as name, (INTuQV) as age, WATEMP as w where e.loc = ‘Waterloo’ and e.name = :p and e.name = name and e.age = age and e.name = w.name and e.age = w.age Differential query optimization (cont’d) • Expand conjunctive subquery using constraints. select name, age from EMP as e, PV as :p, (STRu QV) as name, (INTuQV) as age where e.loc = ‘Waterloo’ and e.name = :p and e.name = name and e.age = age ( select name, age from EMP where loc = ‘Waterloo’ ) ´ ( select name, age from WATEMP )

  11. select name, age from EMP as e, PV as :p, (STRu QV) as name, (INTuQV) as age, WATEMP as w, WATEMPX as x where e.loc = ‘Waterloo’ and e.name = :p and e.name = name and e.age = age and e.name = w.name and e.age = w.age and w.name = x.name and w.emp = x.eref Differential query optimization (cont’d) • Expand conjunctive subquery using constraints. select name, age from EMP as e, PV as :p, (STRu QV) as name, (INTuQV) as age, WATEMP as w where e.loc = ‘Waterloo’ and e.name = :p and e.name = name and e.age = age and e.name = w.name and e.age = w.age ( select name, emp from WATEMP ) ´ ( select name, eref from WATEMPX )

  12. select from PV as :p (plan) (query parameter) Differential query optimization (cont’d) select name, age from EMP as e, PV as :p, (STRu QV) as name, (INTuQV) as age, WATEMP as w, WATEMPX as x where e.loc = ‘Waterloo’ and e.name = :p and e.name = name and e.age = age and e.name = w.name and e.age = w.age and w.name = x.name and w.emp = x.eref (expanded query) • Initialize subplan.

  13. Differential query optimization (cont’d) select name, age from EMP as e, PV as :p, (STRu QV) as name, (INTuQV) as age, WATEMP as w, WATEMPX as x where e.loc = ‘Waterloo’ and e.name = :p and e.name = name and e.age = age and e.name = w.name and e.age = w.age and w.name = x.name and w.emp = x.eref (expanded query) • Select next iterator or disjunction from query for subplan; fail if none available. select from PV as :p (plan)

  14. Differential query optimization (cont’d) select name, age from EMP as e, PV as :p, (STRu QV) as name, (INTuQV) as age, WATEMP as w, WATEMPX as x where e.loc = ‘Waterloo’ and e.name = :p and e.name = name and e.age = age and e.name = w.name and e.age = w.age and w.name = x.name and w.emp = x.eref (expanded query) • Select next iterator or disjunction from query for subplan; fail if none available. select name from PV as :p, (STRu QV) as name where name = :p (plan) (nested loops;string copy)

  15. select name, age from EMP as e, PV as :p, (STRu QV) as name, (INTuQV) as age where e.loc = ‘Waterloo’ and e.name = :p and e.name = name and e.age = age (expanded query) Differential query optimization (cont’d) • If expand of subplan contains subquery, return subplan; otherwise repeat from 3. select name from PV as :p, (STRu QV) as name where name = :p (plan)

  16. select name, age from EMP as e, PV as :p, (STRu QV) as name, (INTuQV) as age where e.loc = ‘Waterloo’ and e.name = :p and e.name = name and e.age = age (expanded query) Differential query optimization (cont’d) • If expand of subplan contains subquery, return subplan; otherwise repeat from 3. select name from PV as :p, (STRu QV) as name where name = :p (expanded plan)

  17. Differential query optimization (cont’d) select name, age from EMP as e, PV as :p, (STRu QV) as name, (INTuQV) as age, WATEMP as w, WATEMPX as x where e.loc = ‘Waterloo’ and e.name = :p and e.name = name and e.age = age and e.name = w.name and e.age = w.age and w.name = x.name and w.emp = x.eref (expanded query) • Select next iterator or disjunction from query for subplan; fail if none available. select name from PV as :p, (STRu QV) as name where name = :p (plan)

  18. Differential query optimization (cont’d) select name, age from EMP as e, PV as :p, (STRu QV) as name, (INTuQV) as age, WATEMP as w, WATEMPX as x where e.loc = ‘Waterloo’ and e.name = :p and e.name = name and e.age = age and e.name = w.name and e.age = w.age and w.name = x.name and w.emp = x.eref (expanded query) • Select next iterator or disjunction from query for subplan; fail if none available. select name from PV as :p, (STRu QV) as name, WATEMPX as x where name = :p and x.name = name (plan) (nested loops;index scan)

  19. select name, age from EMP as e, PV as :p, (STRu QV) as name, (INTuQV) as age where e.loc = ‘Waterloo’ and e.name = :p and e.name = name and e.age = age (expanded query) Differential query optimization (cont’d) • If expand of subplan contains subquery, return subplan; otherwise repeat from 3. select name from PV as :p, (STRu QV) as name, WATEMPX as x where name = :p and x.name = name (plan)

  20. select name, age from EMP as e, PV as :p, (STRu QV) as name, (INTuQV) as age where e.loc = ‘Waterloo’ and e.name = :p and e.name = name and e.age = age (expanded query) Differential query optimization (cont’d) • If expand of subplan contains subquery, return subplan; otherwise repeat from 3. select name, age from PV as :p, (STRu QV) as name, WATEMPX as x, WATEMP as w, INT as age, EMP as e where name = :p and x.name = name and w.name = x.name and w.emp = x.eref and e.name = w.name and e.age = w.age and e.age = age and e.loc = ‘Waterloo’ (expandedplan)

  21. Differential query optimization (cont’d) select name, age from EMP as e, PV as :p, (STRu QV) as name, (INTuQV) as age, WATEMP as w, WATEMPX as x where e.loc = ‘Waterloo’ and e.name = :p and e.name = name and e.age = age and e.name = w.name and e.age = w.age and w.name = x.name and w.emp = x.eref (expanded query) • Select next iterator or disjunction from query for subplan; fail if none available. select name from PV as :p, (STRu QV) as name, WATEMPX as x where name = :p and x.name = name (plan)

  22. Differential query optimization (cont’d) select name, age from EMP as e, PV as :p, (STRu QV) as name, (INTuQV) as age, WATEMP as w, WATEMPX as x where e.loc = ‘Waterloo’ and e.name = :p and e.name = name and e.age = age and e.name = w.name and e.age = w.age and w.name = x.name and w.emp = x.eref (expanded query) • Select next iterator or disjunction from query for subplan; fail if none available. select name from PV as :p, (STRu QV) as name, WATEMPX as x, WATEMP as w where name = :p and x.name = name and w.emp = x.eref (plan) (nested loops;pointer navigation)

  23. select name, age from EMP as e, PV as :p, (STRu QV) as name, (INTuQV) as age where e.loc = ‘Waterloo’ and e.name = :p and e.name = name and e.age = age (expanded query) Differential query optimization (cont’d) • If expand of subplan contains subquery, return subplan; otherwise repeat from 3. select name from PV as :p, (STRu QV) as name, WATEMPX as x, WATEMP as w where name = :p and x.name = name and w.emp = x.eref (plan)

  24. select name, age from EMP as e, PV as :p, (STRu QV) as name, (INTuQV) as age where e.loc = ‘Waterloo’ and e.name = :p and e.name = name and e.age = age (expanded query) Differential query optimization (cont’d) • If expand of subplan contains subquery, return subplan; otherwise repeat from 3. select name, age from PV as :p, (STRu QV) as name, WATEMPX as x, WATEMP as w, INT as age, EMP as e where name = :p and x.name = name and w.emp = x.eref and w.name = x.name and e.name = w.name and e.age = w.age and e.age = age and e.loc = ‘Waterloo’ (expandedplan)

  25. Differential query optimization (cont’d) select name, age from EMP as e, PV as :p, (STRu QV) as name, (INTuQV) as age, WATEMP as w, WATEMPX as x where e.loc = ‘Waterloo’ and e.name = :p and e.name = name and e.age = age and e.name = w.name and e.age = w.age and w.name = x.name and w.emp = x.eref (expanded query) • Select next iterator or disjunction from query for subplan; fail if none available. select name from PV as :p, (STRu QV) as name, WATEMPX as x, WATEMP as w where name = :p and x.name = name and w.emp = x.eref (plan)

  26. Differential query optimization (cont’d) select name, age from EMP as e, PV as :p, (STRu QV) as name, (INTuQV) as age, WATEMP as w, WATEMPX as x where e.loc = ‘Waterloo’ and e.name = :p and e.name = name and e.age = age and e.name = w.name and e.age = w.age and w.name = x.name and w.emp = x.eref (expanded query) • Select next iterator or disjunction from query for subplan; fail if none available. select name, age from PV as :p, (STRu QV) as name, WATEMPX as x, WATEMP as w, (INTuQV) as age where name = :p and x.name = name and w.emp = x.eref and age = w.age (plan) (nested loops;field extraction)

  27. select name, age from EMP as e, PV as :p, (STRu QV) as name, (INTuQV) as age where e.loc = ‘Waterloo’ and e.name = :p and e.name = name and e.age = age (expanded query) Differential query optimization (cont’d) • If expand of subplan contains subquery, return subplan; otherwise repeat from 3. select name, age from PV as :p, (STRu QV) as name, WATEMPX as x, WATEMP as w, (INTuQV) as age where name = :p and x.name = name and w.emp = x.eref and age = w.age (plan)

  28. select name, age from EMP as e, PV as :p, (STRu QV) as name, (INTuQV) as age where e.loc = ‘Waterloo’ and e.name = :p and e.name = name and e.age = age (expanded query) Differential query optimization (cont’d) • If expand of subplan contains subquery, return subplan; otherwise repeat from 3. select name, age from PV as :p, (STRu QV) as name, WATEMPX as x, WATEMP as w, (INTuQV) as age, EMP as e where name = :p and x.name = name and w.emp = x.eref and age = w.age and w.name = x.name and e.name = w.name and e.age = w.age and e.age = age and e.loc = ‘Waterloo’ (expandedplan)

  29. Differential query optimization (cont’d) select name, age from PV as :p, // input parameter (STRuQV) as name, // string copy WATEMPX as x, // index scan WATEMP as w, // pointer navigation (INTuQV) as age // field extraction where name = :p and x.name = name and w.emp = x.eref and age = x.age (final plan)

  30. Dialect DLA D ::= (universal concept) | >D (primitive concept) | C (C)I (bottom concept) | ? ; (negation) | :D D – (D)I (intersection) | D1uD2 (D1)IÅ (D2)I (union) | D1tD2 (D1)I[ (D2)I (attribute value restriction) | 8A.D {e : (A)I(e) 2 (D)I} (quantified attribute inverse) | (>n A) {e1 : |{e2 : (A)I(e2) =e1}| ¸n} (quantified attribute inverse) | (6n A) {e1 : n¸ |{e2 : (A)I(e2) =e1}|} (path agreement) | Pf1 = Pf2 {e : (Pf1)I(e) = (Pf2)I(e)} (path disagreement) | Pf1¹Pf2 {e : (Pf1)I(e) ¹ (Pf2)I(e)} (path functional dependency) | C : L1!L2 (next slide) (an individual) | ¤2D Pf ::= id | A . Pf L ::= id | A | L . L | L , L | { L }

  31. Semantics of PFDs (C : L1!L2 )I ´fe1 : 8e22 (C)I : Æ (Pf )I (e1) = (Pf )I (e2) !Æ (Pf )I (e1) = (Pf )I (e2)g Pf2L(L1) Pf 2L(L2) where L(id) ´ {id} L(A) ´ {A . id} L(L1 . L2) ´ {Pf1±Pf2 : Pf12L(L1) ÆPf22L(L2)} L(L1 , L2) ´L(L1) [ L(L2) L({L}) ´L(L) where id ±Pf´Pf (A . Pf1) ±Pf2´A . (Pf1±Pf2)

  32. EMP 28 INT age emp RID @2 emp (RID) name (STR) age (INT) loc (STR) EMP @1 @2 @3 Mary Ann Fred 37 28 33 Waterloo Toronto Waterloo Toronto STR loc name STR Ann 37 INT age emp RID @1 EMP name STR Mary Waterloo STR loc emp RID @3 EMP 33 INT age name STR Fred Sample partial database

  33. DLA: primitive concepts • STR 28 INT age emp RID @2 EMP Toronto STR loc name STR Ann 37 INT age emp RID @1 EMP name STR Mary Waterloo STR loc emp RID @3 EMP 33 INT age name STR Fred

  34. DLA: primitive concepts (cont’d) • STR • EMP 28 INT age emp RID @2 EMP Toronto STR loc name STR Ann 37 INT age emp RID @1 EMP name STR Mary Waterloo STR loc emp RID @3 EMP 33 INT age name STR Fred

  35. DLA: attribute value restriction • STR • EMP • 8loc.STR 28 INT age emp RID @2 EMP Toronto STR loc name STR Ann 37 INT age emp RID @1 EMP name STR Mary Waterloo STR loc emp RID @3 EMP 33 INT age name STR Fred

  36. DLA: path functional dependencies • STR • EMP • 8loc.STR • EMP:{loc}!{name} 28 INT age emp RID @2 EMP Toronto STR loc name STR Ann 37 INT age emp RID @1 EMP name STR Mary Waterloo STR loc emp RID @3 EMP 33 INT age name STR Fred

  37. DLA: quantified attribute inverse • STR • EMP • 8loc.STR • EMP:{loc}!{name} • (> 1loc) 28 INT age emp RID @2 EMP Toronto STR loc name STR Ann 37 INT age emp RID @1 EMP name STR Mary Waterloo STR loc emp RID @3 EMP 33 INT age name STR Fred

  38. DLA: path agreement • STR • EMP • 8loc.STR • EMP:{loc}!{name} • (> 1loc) • name = loc 28 INT age emp RID @2 EMP Toronto STR loc name STR Ann 37 INT age emp RID @1 EMP name STR Mary Waterloo STR loc emp RID @3 EMP 33 INT age name STR Fred

  39. DLA: intersection • STR • EMP • 8loc.STR • EMP:{loc}!{name} • (> 1loc) • name = loc • RIDu(> 1emp) 28 INT age emp RID @2 EMP Toronto STR loc name STR Ann 37 INT age emp RID @1 EMP name STR Mary Waterloo STR loc emp RID @3 EMP 33 INT age name STR Fred

  40. DLA: negation • STR • EMP • 8loc.STR • EMP:{loc}!{name} • (> 1loc) • name = loc • RIDu(> 1emp) • :(> 1emp) 28 INT age emp RID @2 EMP Toronto STR loc name STR Ann 37 INT age emp RID @1 EMP name STR Mary Waterloo STR loc emp RID @3 EMP 33 INT age name STR Fred

  41. 28 INT age emp RID @2 EMP Toronto STR loc name STR Ann 37 INT age emp RID @1 EMP name STR Mary Waterloo STR loc emp RID @3 EMP 33 INT age name STR Fred DLA: dependencies Models • EMPv8loc.STR

  42. 28 INT age emp RID @2 EMP Toronto STR loc name STR Ann 37 INT age emp RID @1 EMP name STR Mary Waterloo STR loc emp RID @3 EMP 33 INT age name STR Fred DLA: dependencies (cont’d) Models • EMPv8loc.STR • (> 1loc)v:INT

  43. 28 INT age emp RID @2 EMP Toronto STR loc name STR Ann 37 INT age emp RID @1 EMP name STR Mary Waterloo STR loc emp RID @3 EMP 33 INT age name STR Fred DLA: dependencies (cont’d) Models • EMPv8loc.STR • (> 1loc)v:INT • EMPvEMP:{Name}!{id}

  44. 28 INT age emp RID @2 EMP Toronto STR loc name STR Ann 37 INT age emp RID @1 EMP name STR Mary Waterloo STR loc emp RID @3 EMP 33 INT age name STR Fred DLA: dependencies (cont’d) Models • EMPv8loc.STR • (> 1loc)v:INT • EMPvEMP:{Name}!{id} • Does not model • EMPvSTR

  45. 28 INT age emp RID @2 EMP Toronto STR loc name STR Ann 37 INT age emp RID @1 EMP name STR Mary Waterloo STR loc emp RID @3 EMP 33 INT age name STR Fred DLA: dependencies (cont’d) Models • EMPv8loc.STR • (> 1loc)v:INT • EMPvEMP:{Name}!{id} • Does not model • EMPvSTR • EMPvEMP:{Loc}!{Name}

  46. Capturing database schema in DLA (recallalternative view on views) • Tables • QL dependencies create table EMP ( attribute name on STR; attribute age on INT; attribute loc on STR; primary key (name); updatable; ) create table WATEMP ( attribute name on STR; attribute age on INT; ) create table TOREMP ( attribute name on STR; ) ( select name, age from EMP where loc = ‘Waterloo’ ) ´ ( select name, age from WATEMP ) ( select name from EMP where loc = ‘Toronto’ ) ´ ( select name from TOREMP ) ( select name from EMP ) ´ ( select name from WATEMP ) union all ( select name from TOREMP )

  47. DLA schema: capturing tables EMPv (8name.STR) u (8age.INT) u (8loc.STR) WATEMPv (8name.STR) u (8age.INT) TOREMPv8name.STR (signatures; typing) create table EMP ( attribute name on STR; attribute age on INT; attribute loc on STR; primary key (name); updatable; ) create table WATEMP ( attribute name on STR; attribute age on INT; ) create table TOREMP ( attribute name on STR; )

  48. DLA schema: capturing tables EMPv (8name.STR) u (8age.INT) u (8loc.STR) WATEMPv (8name.STR) u (8age.INT) TOREMPv8name.STR EMPvEMP:{name}!{id} create table EMP ( attribute name on STR; attribute age on INT; attribute loc on STR; primary key (name); updatable; ) create table WATEMP ( attribute name on STR; attribute age on INT; ) create table TOREMP ( attribute name on STR; ) (primary keys)

  49. DLA schema: capturing tables EMPv (8name.STR) u (8age.INT) u (8loc.STR) WATEMPv (8name.STR) u (8age.INT) TOREMPv8name.STR EMPvEMP:{name}!{id} CLASS v OBJECTu:DOMAIN DOMAIN v OBJECTu:CLASS EMPvCLASSuUPDATABLEu:WATEMPu:TOREMP WATEMPvCLASSu:EMPu:TOREMP TOREMPvOBJECTu:EMPu:WATEMP INTvDOMAINu:STR STRvDOMAINu:INT create table EMP ( attribute name on STR; attribute age on INT; attribute loc on STR; primary key (name); updatable; ) create table WATEMP ( attribute name on STR; attribute age on INT; ) create table TOREMP ( attribute name on STR; ) (generalization hierarchies)

  50. QL dependencies to DLA dependencies (class assignment) ( select name, age from EMP where loc = ‘Waterloo’ ) ´ ( select name, age from WATEMP ) ( select name from EMP where loc = ‘Toronto’ ) ´ ( select name from TOREMP ) ( select name from EMP ) ´ ( select name from WATEMP ) union all ( select name from TOREMP )

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