File: DBTuplesConcrete.mesa
Copyright © 1985 by Xerox Corporation. All rights reserved.
Contents: Concrete definitions of DBStorage and DBView types.
File created by Rick Cattell, 7-Jun-81
Last edited by:
Cattell on: August 2, 1983 1:44 pm
MBrown on: 9-Jun-81 15:33:33
Eric Bier on: 17-Aug-81 14:20:59
Willie-Sue on February 15, 1985 11:22:21 am PST
DIRECTORY
DBCache USING[CacheHandle],
DB,
DBStorage,
Rope;
DBTuplesConcrete: CEDAR DEFINITIONS =
BEGIN
ROPE: TYPE = Rope.ROPE;
TupleHandle, TupleSet, Index, IndexFactor: TYPE = REF TupleObject;
Domain, Relation, Attribute, DataType: TYPE = Entity;
Relship: TYPE = REF RelshipObject;
Entity: TYPE = REF EntityObject;
EntityObject: TYPE = TupleObject;
RelshipObject: TYPE = TupleObject;
SystemATuple: TYPE = REF attribute TupleObject;
SystemTSTuple: TYPE = REF tupleSet TupleObject;
SystemSTuple: TYPE = REF surrogate TupleObject;
TupleObject: TYPE = RECORD[
tid: LONG CARDINAL,
pred: TupleHandle ← NIL,
succ: TupleHandle ← NIL,
Links in doubly-linked list of all in-use TupleObjects
otherInfo: SELECT type: DBStorage.TupleObjectType FROM
stored => [ -- tid > DBStorage.MaxSystemTuplesetID
cacheHint: DBCache.CacheHandle ], -- hint in finding the cache page for the tid
tupleSet => [ -- tid IN [TupleSetTSID..IndexFactorTSID]
vTuple: DBStorage.SystemTuplesetHandle← NIL, -- corresponding system tupleset
vName: ROPE← NIL, -- name of this tupleset entity
vIsDomain: BOOL, -- TRUE if tuple set is domain, FALSE if is relation
vAttributes: LIST OF Attribute← NIL, -- if relation, list of its attributes; if domain, list of
"fake" surrogate attributes that are attributes of this domain and not client-visible
vR1to1: BOOLEAN← TRUE], -- whether 1-to-1 if relation; unused if domain
attribute => [ -- tid IN [FirstAttributeID .. MaxSystemTupleID]
vHandle: DBStorage.FieldHandle← NIL, -- handle for this attribute
vType: DataType, -- type of this attribute
vName: ROPE← NIL, -- name of this attribute
vRelation: Relation← NIL], -- relation this attribute belongs to
entity => [ -- used only for IntType, StringType, etc.
vName: ROPE← NIL, -- name of the entity
vParent: Domain← NIL], -- domain entity belongs to (always ValueTypeDomain)
surrogate => [
vRelation: Relation← NIL, -- relation this surrogate relship belongs to
vEntity: Entity← NIL, -- entity this relship corresponds to in target domain
vTargetAttribute: Attribute← NIL], -- the target (first) attribute of vRelation
ENDCASE
];
A SYSTEM tuple is of one of three types: tupleset tuples (there are 4 of these
currently), attribute tuples (about a dozen of these), and entity tuples (about 4
of these). These tuples are used in definition and access of dictionary tuples.
A SURROGATE tuple is a tuple in a surrogate relation. A surrogate relation is one
whose first, "target", attribute is an entity-valued with Key uniqueness; such a
relation's relships are not stored as tuples, but rather the 2nd through Nth
attributes are stored as attributes of tuples representing entities in the "target"
domain, i.e. the domain the target attribute references.
A DICTIONARY tuple is a real tuple stored in the database, and is of one of the 4 types
corresponding to the 4 tupleset system tuples (which one can be determined by
SL.ReadTupleSet). They describe the user's tuplesets, attributes, and indexes, and
can be be read but not modified by the user (except through the system routines:
AddField, etc.).
A DATA tuple is any other kind of tuple, namely the ones in which data are stored.
GetF[data tuple, attribute dictionary tuple] would get a field, for example.
RelshipSet: TYPE = REF RelshipSetObject;
RelshipSetObject: TYPE = RECORD[
scan: SELECT type: * FROM
tupleSet => [ -- scan all relships in the tupleset, serially testing each
serialCheck: AttributeValueList, -- if non-NIL, serially check that tuples satisfy this
scanHandle: DBStorage.TuplesetScanHandle, -- this scan gives the tuples to consider
surrogate: Relation← NIL], -- if non-NIL, above gives entities, must convert to surrogate
index => [ -- scan all relships in an index, serially testing each
serialCheck: AttributeValueList, -- if non-NIL, serially check that tuples satisfy this
scanHandle: DBStorage.IndexScanHandle, -- this scan gives the tuples to consider
surrogate: Relation← NIL], -- if non-NIL, above gives entities, must convert to surrogate
group => [ -- scan all relships referencing a particular entity
serialCheck: AttributeValueList, -- if non-NIL, serially check that tuples satisfy this
scanHandle: DBStorage.GroupScanHandle, -- this scan gives the tuples to consider
surrogate: Relation← NIL], -- if non-NIL, above gives entities, must convert to surrogate
justOne => [ -- just return hereItIs for first NextRelship call [hereItIs set to NIL after that]
hereItIs: Relship],
empty => -- NextRelship always returns NIL on one of these
NULL,
segment => [ -- scan multiple segments, concatenating the RelationSubset results
remainingSegments: LIST OF ATOM, -- remaining segments to search
previousSegments: LIST OF ATOM, -- segments already searched
relation: Relation, -- relation we are scanning (passed by client)
constraint: AttributeValueList, -- the constraint passed by client
start: FirstLast, -- passed by client
currentRelshipSet: RelshipSet], -- the RelshipSet in the current segment
ENDCASE
];
EntitySet: TYPE = REF EntitySetObject;
EntitySetObject: TYPE = RECORD[
SELECT scan: * FROM
index => [ -- scan of a domain index by name
scanHandle: DBStorage.IndexScanHandle],
tupleSet => [ -- scan of entire domain, no constraint
scanHandle: DBStorage.TuplesetScanHandle],
empty => -- NextEntity always returns NIL on one of these
NULL,    
nested => [ -- scan multiple domains, concatenating the DomainSubset results
remainingDomains: LIST OF Domain, -- (sub-)domains still to scan
previousDomains: LIST OF Domain, -- domains already scanned
lowName, highName: ROPE, -- passed by client
start: FirstLast, -- passed by client
currentEntitySet: EntitySet], -- current set; go on to next domain when done
segment => [ -- scan multiple segments, concatenating the DomainSubset results
remainingSegments: LIST OF ATOM, -- remaining segments to search
previousSegments: LIST OF ATOM, -- segments already scanned
domain: Domain, -- domain we are scanning (passed by client)
lowName, highName: ROPE, -- passed by client
start: FirstLast, -- passed by client
searchSubDomains: BOOL← FALSE, -- passed by client (not currently used)
currentEntitySet: EntitySet], -- the EntitySet in the current segment
ENDCASE
];
FirstLast: TYPE = DB.FirstLast;
AttributeValueList: TYPE = DB.AttributeValueList;
AttributeList: TYPE = DB.AttributeList;
END.
Edited by:
Cattell on 23-Nov-81 13:12:33: added nameElement EntitySet variant.
Cattell on 29-Dec-81 14:16:20: removed it again, don't need it; added empty variant, made all variants lower case names.
Cattell on 29-Dec-81 16:32:50: what Eric was calling a system EntitySetObject was really a group EntitySetObject, i changed it to use an entity position. Took out DBTuples dependency.
Cattell on July 16, 1982 3:11 pm: Removed RefSet, MatchSet, RefSetObject, MatchSetObject. Added empty variant of RelshipSet.
Cattell on October 22, 1982 12:28 pm: Changes for new properties, indexes, and system entities. Reduced size of largest variant of TupleHandle.
Cattell on November 4, 1982 9:29 am: More revisions. Didn't need to reduce size of largest variant of TupleHandle, since allocation machinery only allocates for size needed. Put vAttributes into tupleSet variant. Added surrogate field to tupleset, index, and group variants of RelshipSets. Added augment variant to RelshipSets and EntitySets for future use; may have to change later.
Willie-Sue on February 15, 1985: made Cedar, added tioga formatting