11 Packaging

Qddb is available as a set of utility programs and a library of routines that are useful for building other programs. This code and documentation is available by anonymous ftp from ftp.ms.uky.edu:pub/unix/qddb/. A listing for the qs program is given in Figure 8 to demonstrate how utility programs are easily built upon the library routines.

void main(argc, argv)
    int               argc;
    char              *argv[];
{
    Schema            *schema;
    char              String[BUFSIZ];
    char              Relation[BUFSIZ], *rel;
    KeyList           *list = NULL;
    size_t            Length;
    Qddb_SearchArg    search_args;

    Qddb_Init();
    rel = Qddb_FindRelation(argv[1]);
    strcpy(Relation, rel);
    schema = Qddb_InitSchema(Relation);
    while (fgets(String, sizeof(String), stdin) != NULL) {
    char        *ptr;
    KeyList        *LastList = NULL;
    ptr = String;
    while (*ptr != '\0') {
        char    *token;
        
        token = ptr;
        while (!isspace(*ptr) && *ptr != '\0')
        ptr++;
        if (*ptr != '\0') {
            *ptr++ = '\0';
            while (isspace(*ptr))
                ptr++;
        }
        search_args.Alpha = token;
        search_args.Type  = ALPHA;
        list = Qddb_Search(schema, &search_args, &Length, -1);
        if (LastList != NULL)
            list = LastList = 
                Qddb_KeyListOp(schema, list, LastList,
                      QDDB_KEYLIST_OP_INTERSECTION, 
                      QDDB_KEYLIST_FLAG_DELDUP_SAMEENTRY);
        else
            LastList = list;
    }
    if ((argc == 3 && strcmp(argv[2],"-p") == 0) || (argc == 2))
        PrintKeyList(schema, list, True);
    else if (argc == 3 && strcmp(argv[2],"-n") == 0)
        PrintKeyList(schema, list, False);
    }
    exit(0);
}

void PrintKeyList(schema, list, Print)
    Schema          *schema;
    KeyList         *list;
    Boolean         Print;
{
    char            *Buffer = Malloc(BUFSIZ), Valid;
    int             DBFile;
    unsigned        len = BUFSIZ;

    DBFile = OpenDatabase(schema->RelationName, 0);
    while (list != NULL) {
    switch(QDDB_KEYLIST_TYPE(list)) {
    case ORIGINAL:
        if (list->Length > len) {
            len = list->Length;
            free(Buffer);
            Buffer = Malloc(len);
        }
        lseek(DBFile, list->Start, 0);
        Read(DBFile, Buffer, list->Length);
        sscanf(Buffer, "%%0 %c", &Valid);
        if (Valid == 'I')
            break;
        if (Print == True)
            Write(1, Buffer, list->Length);
        break;
    case CHANGE:
        if (Print == False)
            break;
        sprintf(Buffer, "cat %s/Changes/%d", schema->RelationName, (int)list->Number);
        system(Buffer);
        break;
    case ADDITION:
        if (Print == False)
            break;
        sprintf(Buffer, "cat %s/Additions/%d", schema->RelationName, 
            (int)list->Number);
        system(Buffer);
        break;
    default:
        PANIC("BAD TYPE IN KeyList");
    }    
    if (Print == True)
        write(1, "\n", 1);
        list = list->next;
    }
    free(Buffer);
    close(DBFile);
}

  
Figure 8: C Listing forqs

Some of the programs in the suite are:

• newdb - Create an empty relation and build a schema file.
• qadd - Add a tuple to the specified relation.
• qconv - Convert a relation in presentation format to qddb internal format.
• qedit - Search a qddb database for a Boolean combination of single-key queries and edit or list all entries found.
• qindex - Rebuild structure files, such as HashTable, Index, KeyIndex, and NumericIndex. The current implementation requires that all keys fit into memory. On small machines, such as a PC, this restriction is unacceptable. We plan to build a second version of qindex that uses temporary files instead of memory; however, the stabilization process will be considerably slower. We recommend that stabilization occur on large machines when they are available. The relation files can then be transferred to a PC for query sessions, since our format is machine-independent.
• qkeys - Rebuild Stable.keys.
• qs - Perform interactive queries; initializes by reading HashTable.
• qstab - Merge all changes and additions into Stable.
• qschemamod - Allows arbitrary update of Schema.
• qsql - Interactively process QSQL queries and updates.

The principal library routines are:

• void InitHash() - Initialize the internal hash table.
• void MakeHash(char *RelationName) - Read HashTable for the given relation.
• void ChangeEntry(char *RelationName, Entry TheEntry) - Make a change to a tuple by invalidating the old entry and adding the new one to the appropriate location.
• void AddEntry(char *RelationName, Entry TheEntry) - Add a new tuple to the relation.
• Schema *ReadRelationSchema(char *RelationName) - Read the Schema file for the relation, parse it and return an internally represented schema.
• TupleList *Search(char *RelationName, char *SearchString, unsigned long *NumberOfEntriesRead) - Search the relation for a particular string and return the TupleList and the number of entries found.
• TupleList *TupleListUnion(TupleList *TupleList1, TupleList *TupleList2) - Perform the set union on the given TupleLists and return the result. The given TupleLists are destroyed upon return from this routine.
• TupleList *TupleListIntersection(TupleList *TupleList1, TupleList *TupleList2) - Perform the set intersection on the given TupleLists and return the result. The given TupleLists are destroyed upon return from this routine.
• TupleList *TupleListNot(TupleList *In, TupleList *ButNotIn) - Perform the set exclusion on the given TupleLists; return all nodes in In but not in ButNotIn. The given TupleLists are destroyed upon return from this routine.
• unsigned long SizeOfFile(int FileDesc) - Return the size of the given file; usually used to read the contents of a file in a single read.
• void ReadEntry(int FileDesc, Entry ThisEntry, unsigned long Start, unsigned long Length) - Read an entry with the given offset and length in the file.
• void WriteEntry(int FileDesc, Entry ThisEntry) - Write the entry into the file at the current location.
• unsigned long GetEntryNumber(Entry TheEntry) - Return the unique identifier of the entry.
• Boolean EntryInvalid(Entry TheEntry) - Return True if the entry has been updated; false otherwise.