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    • 7. 发明授权
    • Bitmap index compression
    • 位图索引压缩
    • US06205442B1
    • 2001-03-20
    • US09311654
    • 1999-05-13
    • Jeffrey I. CohenMichael DepledgeHakan JakobssonMark KremerCetin OzbutunQuoc Tai Tran
    • Jeffrey I. CohenMichael DepledgeHakan JakobssonMark KremerCetin OzbutunQuoc Tai Tran
    • G06F1730
    • H03M7/30Y10S707/99932Y10S707/99933Y10S707/99934Y10S707/99937
    • 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.
    • 提供了一种用于压缩数据的方法和装置。 本发明将输入比特流压缩为压缩输出比特流。 输入位流是字节对齐和分类的。 所有位设置为零的字节被分类为间隙字节。 只有一位设置为值1的字节被分类为偏移字节。 所有其他字节被分类为映射字节。相邻字节的组被分为两种类型的组。 第一种类型是间隙位组。 间隙图组包含间隙字节和一个偏移字节。 第二种是间隙图组。 它包含间隙字节和映射字节。 一组中的间隙字节数称为间隙大小。这些组被压缩成四种类型的原子。 每种类型的原子都有一个控制字节,零个或多个间隙大小的字节,零或映射字节。 控制字节描述原子。 原子中的映射字节是控制组中映射字节的副本。
    • 8. 发明授权
    • Bitmap index compression
    • 位图索引压缩
    • US5907297A
    • 1999-05-25
    • US808560
    • 1997-02-28
    • Jeffrey I. CohenMichael DepledgeHakan JakobssonCetin Ozbutun
    • Jeffrey I. CohenMichael DepledgeHakan JakobssonCetin Ozbutun
    • H03M7/30
    • H03M7/30Y10S707/99932Y10S707/99933Y10S707/99934Y10S707/99937
    • 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.
    • 提供了一种用于压缩数据的方法和装置。 本发明将输入比特流压缩为压缩输出比特流。 输入位流是字节对齐和分类的。 所有位设置为零的字节被分类为间隙字节。 只有一位设置为值1的字节被分类为偏移字节。 所有其他字节都被分类为地图字节。 相邻字节组被分为两种类型的组。 第一种类型是间隙位组。 间隙图组包含间隙字节和一个偏移字节。 第二种是间隙图组。 它包含间隙字节和映射字节。 一组中间隙字节的数量称为间隙大小。 这些基团被压缩成四种类型的原子。 每种类型的原子都有一个控制字节,零个或多个间隙大小的字节,零或映射字节。 控制字节描述原子。 原子中的映射字节是控制组中映射字节的副本。
    • 9. 发明授权
    • Method and apparatus for processing count statements in a database system
    • 用于处理数据库系统中的计数语句的方法和装置
    • US5819256A
    • 1998-10-06
    • US752128
    • 1996-11-20
    • Cetin OzbutunMichael DepledgeHakan JakobssonJeffrey I. Cohen
    • Cetin OzbutunMichael DepledgeHakan JakobssonJeffrey I. Cohen
    • G06F17/30
    • G06F17/30324G06F17/30489Y10S707/99932
    • 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. For count queries that contain group by clauses, intermediate count values are generated for each distinct key value. The intermediate count values are summed to produce a total count value for each distinct key value.
    • 提供了一种用于处理数据库系统中的计数查询的方法和装置。 数据库服务器确定计数查询中指定的目标数据是否可能包含空值。 如果目标数据不能包含空值,则计数查询将转换为计数星形查询。 通过计数存储目标数据的记录数量而不实际读取和评估目标数据来执行计数星形查询。 如果存在目标数据的表的索引存在,则通过计数索引中的记录标识符来计数记录数,而不访问表本身。 如果索引是位图索引,则从索引中的位图中设置的位数将被计数,而不会从位图实际生成记录标识符。 许多进程用于从位图生成中间计数值。 将中间计数值相加以产生总计数值。 对于包含group by子句的计数查询,会为每个不同的键值生成中间计数值。 将中间计数值相加以产生每个不同键值的总计数值。