Abstract: A method and apparatus are provided for allocating buffer memory for database sort operations. A database parameter is set to determine whether and how direct write buffers are to be allocated for sort operations. If the parameter is set to a first value, then direct write buffers will be used to perform writes to disk. The size and number of direct write buffers to be used will be determined by the values set in other database parameters. If the parameter is set to a second value, then no direct write buffers will be used, and sort operations will write to disk through a buffer cache. If the parameter is set to a third value, direct write buffers will be allocated a portion of the memory available to perform the sort operation. The size and number of direct write buffers will be determined in accordance with database formulae that are designed to optimize sort and data write performance.

Abstract: A method and apparatus for compressing data is provided. The invention compresses an input bit stream into a compressed output bit stream. The input bit streams are byte aligned and classified. Bytes with all bits set to value zero are classified as gap bytes. Bytes with only one bit set to value one are classified as offset bytes. All other bytes are classified as map bytes. Groups of adjacent bytes are organized into two types of groups. The first type is a gap bit group. A gap map group contains gap bytes and one offset byte. The second type is the gap map group. It contains gap bytes and map bytes. The number of gap bytes in a group is called a gap size. The groups are compressed into four types of atoms. Each type of atom has one control byte, zero or more gap size bytes, and zero or map bytes. A control byte describes the atom. The map bytes in an atom are copies of the map bytes in the control group.

Abstract: A method and apparatus for segmenting bitmaps in a bitmap index is provided. A segmented bitmap includes a plurality of bitmap segments that are used to indicate which records in a body of records that is associated with the segmented bitmap satisfy a particular criteria. Each bitmap segment contains a string of bits that correspond to a corresponding range of records in the body of records. There may be gaps between the ranges represented by the bitmap segments when, for example, the body of records does not contain records in a particular range. For the purposes of retrieval, compression, de-compression, locking and logging, the database system treats each bitmap segment as a distinct data item.

Abstract: A method for performing logical operations on bitmap streams from segmented bitmaps. The logical operations include the AND, OR, and Set Minus operations. One embodiment of the invention performs the logical AND operation on a plurality of bitmap streams by searching for a set of overlapping bitmap segments. The ranges corresponding to the overlap among the overlapping bitmap segments are scanned to generate non-gap results. One embodiment of the invention performs the logical OR operation on a plurality of bitmap streams. To generate a result for a given range, only the bitmap segments overlapping the given range are ORed together. One embodiment of the invention performs a Set Minus between bitmap streams. A set minus is the ANDing of a first condition with the negation of another condition. To generate a set minus result, the ranges corresponding to the gaps in the bitmap associated with the negated condition are ignored.

Abstract: A method and apparatus for generating and using bitmaps in a database system that employs multi-level identifiers is provided. The generated bitmaps include bits that correspond to the identifiers that have been assigned to existing records, as well as bits that correspond to all intervening multi-level identifiers that have not yet been assigned. Therefore, when new rows are inserted into the table associated with the bitmap, new bits do not have to be inserted into the existing bitmap. When existing rows are deleted, the bits that correspond to the deleted rows are not themselves deleted, but are simply set to a value that indicates that the corresponding row does not satisfy the criteria associated with the bitmap.

Abstract: A method and apparatus for segmenting bitmaps in a bitmap index is provided. A segmented bitmap includes a plurality of bitmap segments that are used to indicate which records in a body of records that is associated with the segmented bitmap satisfy a particular criteria. Each bitmap segment contains a string of bits that correspond to a corresponding range of records in the body of records. There may be gaps between the ranges represented by the bitmap segments when, for example, the body of records does not contain records in a particular range. For the purposes of retrieval, compression, de-compression, locking and logging, the database system treats each bitmap segment as a distinct data item.

Abstract: In processing a query, a database server parses a string describing a query into a query representation. The query string is parsed again to generate a replica of the query representation. Various transformations can be applied to the replica in order to reduce the amount of processing for the query. In addition, transformations are applied to the query string before parsing again to produce a transformed query representation. A transformed query representation is selected for processing a query according to an estimated cost of using the query representation.

Abstract: A method for combining within memory a limit, a plurality of bitmap streams from bitmaps of indefinite size and number. The bitmap streams are merged into a resulting bitmap which can be used in subsequent logical operations.In order to perform a merge within a memory limit, the method relies on the data compression. When compression by itself may be ineffective, the method produces a resulting bitmap for a reduced range.The ensures the production of a resulting bitmap. When the range is reduced, the method may be repeated to produce a merge for a range beyond the reduced range.

Abstract: Isolated viral proteins, and pharmaceutical compositions made therefrom, are disclosed which are capable of binding to a .beta. chain of a Class II Major Histocompatibility Complex antigen, thereby functioning to inhibit an antigen-specific response. The viral proteins also have superantigen-like activity, and inhibit EBV infection.

Abstract: A list of indexes, from which indexes are selected for an index access path, is sorted by number of columns upon which each index is built. From the sorted list of indexes, a set of index access methods is generated in a heuristically ordered set of passes from a given WHERE clause. The index access methods that comprise the index access path are selected from the set of index access methods according to a cost/benefit analysis.

Abstract: A method and apparatus for compressing data is provided. The invention compresses an input bit stream into a compressed output bit stream. The input bit streams are byte aligned and classified. Bytes with all bits set to value zero are classified as gap bytes. Bytes with only one bit set to value one are classified as offset bytes. All other bytes are classified as map bytes. Groups of adjacent bytes are organized into two types of groups. The first type is a gap bit group. A gap map group contains gap bytes and one offset byte. The second type is the gap map group. It contains gap bytes and map bytes. The number of gap bytes in a group is called a gap size. The groups are compressed into four types of atoms. Each type of atom has one control byte, zero or more gap size bytes, and zero or map bytes. A control byte describes the atom. The map bytes in an atom are copies of the map bytes in the control group.

Abstract: A method and system for selectively disabling the logging of database operations during the execution of database processes or the creation of database objects is disclosed. According to the method, changes made to the database through data manipulation statements or queries can include a statement that the change to be executed is not to be logged. If the operation is to be logged, a log buffer stores the information about the changes and a log writer background process writes the operation entries to disk. Similarly, the creation or manipulation of database objects through object manipulation statements can be logged or not logged. As with logged data manipulation statements, if the manipulation of a database object is to be logged, a log buffer stores the information about the changes and a log writer background process writes the operation entries to disk.

Abstract: A method and apparatus provide bitmapped indexing with high granularity locking. Whenever a change is made to a data table upon which a bitmapped index is based, two differential entries are generated and stored as index entries in the bitmapped index. Each differential entry identifies a bit to be flipped in the corresponding bitmap index entry. When applied to corresponding bitmap index entry, the changes are reflected in the appropriate bitmaps. Whenever a bitmap is read from the bitmapped index, any corresponding differential entries are applied so that the resulting bitmap reflects the change made to the data table.

Abstract: A method and apparatus for updating a segmented bitmapped index to reflect a change made to data upon which the segmented index is based. Change records specifying changes to bitmap segments contained in the segmented bitmapped index are sorted by key value (bitmap segment) and row ID (bit) before being applied to the segmented bitmapped index. When the change records are being applied to the bitmap segment contained in the segmented bitmapped index, the index entry containing the bitmap segment to be updated is locked. If a new bitmap segment must be generated, the index entry covering a row in the data having a row ID less than the row ID of the change is first locked. Then a new index entry is generated, stored in the segmented bitmapped index, and the locked index entry unlocked.

Abstract: A method and apparatus for parallelizing operations that change a database is provided. A coordinator process receives a statement that requires data to be written into the database. In response to the statement, the coordinator process assigns granules of work to multiple processes. Each of the multiple processes executes the granule of work by writing to the database a distinct portion of the set of data that is to be added to the database. The various portions of data are then merged to create the set of data to be added to the database.

Abstract: The present invention performs parallel processing of aggregate functions in a computing system. Partitioned into multiple subsets of data and each of the multiple subsets of data is allocated to one of a plurality of processes. Intermediate aggregations are performed in parallel by the plurality of processes on each of the multiple subsets of data. Each intermediate aggregation yields at least one intermediate value, wherein the at least one intermediate value is represented in an internal type format. The intermediate values from each of the intermediate aggregations are merged into a final aggregation value.

Abstract: A full-length cDNA copy of an attenuated, cell culture-adapted hepatitis-A virus genome has been constructed. The HAV cDNA when inserted, without the oligo (dG) oligo (dC) tails, into an RNA transcription vector yielded a plasmid designated pHAV/7. Transfection of monkey kidney cells with pHAV/7 DNA yielded HAV. Transfection with RNA transcripts produced in vitro from pHAV/7 yielded about 10-fold more HAV than transfection with pHAV/7 DNA. HAV thus produced are useful as a vaccine.

Abstract: A method and apparatus for processing count queries in a database system is provided. The database server determines whether it is possible for the target data specified in a count query to contain null values. If the target data cannot contain null values, the count query is converted into a count star query. Count star queries are executed by counting the number of records that store the target data without actually reading and evaluating the target data. If an index for the table that stores the target data exists, then the number of records are counted without accessing the table itself by counting record identifiers in the index. If the index is a bitmap index, the number of bits that are set in bitmaps from the index are counted without actually generating record identifiers from the bitmaps. Many processes are used to generate intermediate count values from the bitmaps. The intermediate count values are summed to produce a total count value.

Abstract: A method and apparatus are provided for allocating buffer memory for database sort operations. A database parameter is set to determine whether and how direct write buffers are to be allocated for sort operations. If the parameter is set to a first value, then no direct write buffers will be used, and sort operations will write to disk through a buffer cache. If the parameter is set to a second value, then direct write buffers will be used to perform writes to disk. Then size and number of direct write buffers to be used will be determined by the values set in other database parameters. If the parameter is set to a third value, direct write buffers will be allocated a portion of the memory available to perform the sort operation. The size and number of direct write buffers will be determined in accordance with database formulae that are designed to optimize sort and data write performance.

Abstract: Isolated viral proteins, and pharmaceutical compositions made therefrom, are disclosed which are capable of binding to a .beta. chain of a Class II Major Histocompatibility Complex antigen, thereby functioning to inhibit an antigen-specific response. The viral proteins also have superantigen-like activity, and inhibit EBV infection.