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Pavel Petrenko

on 26 February 2013

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Transcript of NFNF

Non-First Normal Form Computer Science Department
Professorship of Data Management Systems
Submitted by: Pavlo Petrenko
Advisors: Prof. Dr. W. Benn, Dipl.-Inf. J.Fliege Implementation on PostgreSQL GUI for Managing Books Technologies Architecture Demo Implementation of nest and unnest Extension of
arithmetic operators (=, !=) for sets Operators for set inclusion Justification for choosing
the programming language Problem Definition NFNF Definition Example NFNF Introduction Typical tasks of a DBMS
Shortcomings of the first normal form
Expensive JOIN-operation
Repetition Not normalized relation Allow sets and sets of sets to be attribute domains
Support of nest and unnest operations
Extension of relational algebra with
arithmetic comparison symbols (=, <, >, etc.)
set inclusion symbols (is subset, is proper subset, etc)
logic symbols (conjunction, disjunctions, etc.) PL/pgSQL advantages:
fully featured programming language, allows much more procedural control than SQL, including the ability to use loops and other control structures.
Extra round trips between client and server are eliminated.
Multiple rounds of query parsing can be avoided
Possible to use all the data types, operators and functions of SQL SELECT ARRAY[‘Knuth’, ‘Codd’] = ARRAY[‘Codd’, Knuth’]
=> false
SELECT set_equals_to(ARRAY ['Knuth’, ‘Codd’], ARRAY[‘Codd’, Knuth’] => true Before nest Back-end: PostgreSQL/PL pgSQL
Web services: SOAP (WCF.NET)/C#
Front-end: ASP.NET/C# Set-based search
Strict search
Search with relative complement Usage of set-valued attributes
in relations Set-valued select operations First normal form Books Authors Array of text (text[]) is taken as a container of nested attributes.
Any type can be converted to it
Out-of-box functions for working with text[] (e.g. <@ - "is contained by"-operator)
Caller of unnest-operation must be aware of the nested data type
Nesting of nesting types may be challenging:
Possible solution: encoding Use of sort operation Subset Trivial case
SELECT ARRAY[‘Charles Leiserson’] <@ ARRAY[ ‘Charles Leiserson’, ‘Clifford Stein’, ‘Thomas Cormen’ , ‘Ronald Rivest’] returns true
Nesting of middle names, e.g. Steven L. Coates
Solution 1
SELECT ARRAY[‘Charles Leiserson’] <@ (‘Charles$#Leiserson’, ‘Clifford$#Stein’, ‘Thomas$#Cormen’ , ‘Ronald$#Rivest’) returns false
Solution 2
RETURN $1 <@ parse_nested ($2); Is subset
Is proper subset
Relative Complement Proper Subset RETURN arg0 <@ parse_nested(arg1) AND arg0 <> parse_nested(arg1);
Operator <#@= Union Possible implementations
RETURN parse_nested($1) || parse_nested($2);
Using SQL UNION operator
Operator + Intersection RETURN array(SELECT unnest($1) INTERSECT (SELECT unnest($2)));
Operator * Relative Complement (\) RETURN array(SELECT unnest($1) EXCEPT (SELECT unnest($2)));
The allowed symbols, specified in the documentation are the following: + - * / < > = ~ ! @ # % ^ & | ` ?.
Operator - Operator <#@ After nest SELECT "ISBN", "Title", "Price", "Category", "NestedName" FROM "N1NF" WHERE ARRAY['Wall', ‘Christiansen’] <#@= "NestedName"
Full transcript