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  2. Worst-case optimal join algorithm - Wikipedia

    en.wikipedia.org/wiki/Worst-case_optimal_join...

    An illustration of properties of join algorithms. When performing a join between more than two relations on more than two attributes, binary join algorithms such as hash join operate over two relations at a time, and join them on all attributes in the join condition; worst-case optimal algorithms such as generic join operate on a single attribute at a time but join all the relations on this ...

  3. Constraint logic programming - Wikipedia

    en.wikipedia.org/wiki/Constraint_logic_programming

    Domain-specific constraints may come to the constraint store both from the body of a clauses and from equating a literal with a clause head: for example, if the interpreter rewrites the literal A(X+2) with a clause whose fresh variant head is A(Y/2), the constraint X+2=Y/2 is added to the constraint store. If a variable appears in a real or ...

  4. Guard (computer science) - Wikipedia

    en.wikipedia.org/wiki/Guard_(computer_science)

    # This function has no guard clause def f_noguard (x): if isinstance (x, int): #code #code #code return x + 1 else: return None # Equivalent function with a guard clause. Note that most of the code is less indented, which makes it easier to read and reason about def f_guard (x): if not isinstance (x, int): return None #code #code #code return x + 1

  5. Nested loop join - Wikipedia

    en.wikipedia.org/wiki/Nested_loop_join

    algorithm nested_loop_join is for each tuple r in R do for each tuple s in S do if r and s satisfy the join condition then yield tuple <r,s> This algorithm will involve n r *b s + b r block transfers and n r +b r seeks, where b r and b s are number of blocks in relations R and S respectively, and n r is the number of tuples in relation R.

  6. Conditional (computer programming) - Wikipedia

    en.wikipedia.org/wiki/Conditional_(computer...

    If-then-else flow diagram A nested if–then–else flow diagram. In computer science, conditionals (that is, conditional statements, conditional expressions and conditional constructs) are programming language constructs that perform different computations or actions or return different values depending on the value of a Boolean expression, called a condition.

  7. Boolean satisfiability problem - Wikipedia

    en.wikipedia.org/wiki/Boolean_satisfiability_problem

    A variant of the 3-satisfiability problem is the one-in-three 3-SAT (also known variously as 1-in-3-SAT and exactly-1 3-SAT). Given a conjunctive normal form with three literals per clause, the problem is to determine whether there exists a truth assignment to the variables so that each clause has exactly one TRUE literal (and thus exactly two ...

  8. Block nested loop - Wikipedia

    en.wikipedia.org/wiki/Block_nested_loop

    A block-nested loop (BNL) is an algorithm used to join two relations in a relational database. [1]This algorithm [2] is a variation of the simple nested loop join and joins two relations and (the "outer" and "inner" join operands, respectively).

  9. Conjunctive normal form - Wikipedia

    en.wikipedia.org/wiki/Conjunctive_normal_form

    In Boolean algebra, a formula is in conjunctive normal form (CNF) or clausal normal form if it is a conjunction of one or more clauses, where a clause is a disjunction of literals; otherwise put, it is a product of sums or an AND of ORs.