| Symbol | Definition | |
|
|---|
| \lceil\; \rceil | CEIL, next higher integer. | |
|
| \lfloor\;\rfloor | FLOOR, next lower integer. | |
|
| \approx | approximately equal. | |
|
| >> | much greater than. | |
|
| ! | factorial. | |
|
| # | number of. | |
|
| \log\sb{y}x | logarithm base y of x. | |
|
| \log{x} | natural logarithm of x, base e = 2.71828182846. | |
|
| \sum\sb{k}f(k) | sum of all f(k) for the integer k's specified}. | |
|
| xMODy | modulo function, x reduced by y until x< y. | |
|
| \jop | one of the comparison operators >\ge;=;\ne\;\le\;<. | |
|
| \and | and, true if both sides are true. | |
|
| \or | or, true if either side is true. | |
|
| | | where, precedes a conditional clause. | |
|
| \dbinter | set intersection. | |
|
| \dbunion | set union. | |
|
| \dbsetdif | set difference. | |
|
| \dbcross | cartesian product. | |
|
| \dbselect | select tuples from a relation. | |
|
| \dbproject | project attributes from a relation. | |
|
| \dbthetajoin{a = b} | join two relations based on equality of the attributes a, b. | |
|
| \refto | reference connection. | |
|
| \ownto | ownership connection. | |
|
| \subto | subset connection. | |
|
| \subset | subset of. | |
|
| \in | member of. | |
|
| \All | for all. | |
|
| \becomes | becomes. | |
|
| { . . . } | enclose a set. | |
|
| [ . . . ] | enclose a reference. | |
|
| \propersubset | proper subset. | |
|
| Operation | Function | |
|
|---|
| a + b | addition. | |
|
| a - b | subtraction. | |
|
| a * b | multiplication. | |
|
| a / b | division. | |
|
| MOD(a,b) | modulo, integer remainder of division. | |
|
| a ** b | exponentiation, a to the power b. | |
|
| a = b | depending on context in PL/1, assignment or equality comparison. | |
|
| a < b | greater than comparison, true if a greater than b. | |
|
| a> L{b} | greater or equal comparison, true if a greater or equal to b. | |
|
| a \AND b | and, true if both a, b true, (& in PL/1). | |
|
| a \OR b | or, true if either a, b true, (| in PL/1). | |
|
| \NT c | not, true if c false and vice versa. | |
|
| s \CAT w | catenation, string s connected to string w
to form a single new string. | |
|
| s | c | where, do s if the predicate (conditional) clause c is true. | |
|
| R \DBUNION S | union of relations R and S. | |
|
| R \DBINTER S | intersection of relations R and S. | |
|
| R \DBCROSS S | cross product of relations R and S. | |
|
| R \DBSETDIF S | difference, remove tuples matching S from R. | |
|
| \DBSELECT R.ex | select tuples of R according to expression ex. | |
|
| \DBPROJECT R.a | projection of attributes a of R. | |
|
| R.a\DBJOIN S.b | Join R and S, on equality of attribute values in a and b. | |
|
| R.a\DBOUTERJOIN S.b | Outerjoin including all tuples . | |
|
| , | field separator. | |
|
| \kg | key and goal fields separator. | |
|
| ; | statement separator. | |
|
| . | termination of computational section. | |
|
| ss, ... | section ss may be repeated. | |
|
| [ ss ] | section ss is optional. | |
|
| { ss|tt} | sections ss, tt are alternatives. | |
|
| ::= | is defined by. | |
|
| /* Note */ | explanatory comments. | |
|
| a.b | qualification of variable b by a higher-level
variable a,\ie, employee.name. | |
|
| 'Word' | character string constant. | |
|
| _ | (underline) pseudo-alphabetic character without
syntactic meaning used for legibility within variable names, | |
|
| | In COBOL - is used for this function. | |
|
| Symbol | Brief definition | Text definition | |
|
|---|
| A | average space required for attribute name | Sec. 3-1-3. | |
|
| a | number of different attributes in a file | Sec. 3-1-1. | |
|
| a\toprime | average number of attributes in a record | Sec. 3-1-1, 3-6-3. | |
|
| B | blocksize | Sec. 2-2. | |
|
| b | blockcount | Sec. 2-2-2. | |
|
| btt | block transfer time = B/t | Eq. 2-13. | |
|
| \Bfr | blocking factor \approx B/R | Eqs. 2-5, 2-6, 2-7, 2-20. | |
|
| C | Cost factors | Sec. 5-4-6, 5-5-2. | |
|
| c | computational overhead per record, when not negligible | Sec. 2-3-4. | |
|
| D | space required for data | Eq. 5-1, Sec 5-3-3. | |
|
| d | number of records that have been invalidated | Sec. 3-1-3. | |
% |
| e | = 2.718281828459. | |
|
| \sbscr{F} | subscript denoting a fetch for a specific record | Sec. 3-0-2. | |
|
| G | space required for an interblock gap | Sec. 2-2-3. | |
|
| h | classification variable | Sec. 5-4-3. | |
|
| \sbscr{I} | subscript denoting insertion of a record | Sec. 3-0-2. | |
|
| j | number of cylinders | Sec. 2-2-1. | |
|
| K | projection list | Sec. 7-3-2. | |
|
| {\tbf K } | Kilo or thousand (1024) times. | |
|
| k | number of tracks per cylinder | Sec. 2-2-5, Table 2-1. | |
|
| L | load frequency factors; selection list | Sec. 5-1; 7-3-3. | |
|
| M | multiprogramming factor | Eq. 5-19. | |
|
| {\tbf M } | Mega or million (1\,048\,576) times. | |
|
| m | number of available slots for records | Sec. 3-5-1. | |
|
| \sbscr{N} | subscript denoting getting the next serial record | Sec. 3-0-2. | |
|
| n | number of records in a file | Sec. 3-1-3. | |
|
| o | number of records that overflow | Secs. 3-1-3, 3-2-3, 3-3-3, 3-5-3. | |
|
| P | space required for a pointer | Sec. 2-3-3. | |
|
| p | collision cost, also probability | Eqs. 3-73, 3-74, 3-79, Fig. 3-23. | |
|
| q | production demand by a file application | Eq. 5-2, 5-4 to 5-6. | |
|
| R | space required for a complete record; relation | Sec. 3-0-2; 7-1-1. | |
|
| \sbscr{RW} | subscript indicating rewriting | Sec. 2-3-6. | |
|
| r | rotational latency time | Eq. 2-3. | |
|
| SI | storage space for index | Eq. 3-52. | |
|
| s | average seek time | Eq. 2-2. | |
|
| s\toprime | effective seek time | Eqs. 2-15, 2-16. | |
|
| T | the time required for various operations; set of tuples | Sec. 3-0-2; 7-3. | |
|
| T\sb{sort} | the time required to sort a file | Eq. 3-11} . | |
|
| t | transfer rate from a storage unit to processing memory | Sec. 2-2-5. | |
|
| t\toprime | bulk transfer rate | Eqs. 2-17, 2-18, 2-19. | |
|
| \sbscr{U} | subscript denoting an update of a record | Sec. 3-0-2. | |
|
| u | utilization | Eqs. 5-3, 5-7 to 5-18, 5-20. | |
|
| uf | utilization factor | Eqs. 6-25, 6-29. | |
|
| V | average space for value part of an attribute | Sec. 3-1-3. | |
|
| v | number of records updated | Sec. 3-2-3. | |
|
| w | wait time in queues | Eq. 6-26. | |
|
| W | wasted space due to gaps per record | Eqs. 2-9, 2-10, 2-11, 2-21. | |
|
| \sbscr{X} | subscript denoting an exhaustive search | Sec. 3-0-2. | |
|
| x | number of levels in an index structure, master level | Eq. 3-27, 3-49, 3-97. | |
|
| \sbscr{Y} | subscript denoting a reorganization of a file | Sec. 3-0-2. | |
|
| y | fanout ratio | Eq. 3-26, 3-48. | |
|
| \sbscr{Z} | subscript denoting an update by replacement with a larger record | Sec. 3-0-2. | |
|