Abstract: According to one embodiment of the present invention, a method for processing a query in a column database is provided. The method for analyzing test results may include a computer, associating a first set of metadata values with a set of records in a table, wherein each record has an associated state indicated by a metadata value. The method may further include the computer receiving a query to return one or more records of the set of records. The method may further include the computer determining that one or more records in the set of records satisfies the query. The method may further include the computer determining whether at least a first record in the one or more records that satisfies the query is in a returnable state based, at least in part, on the metadata value.

Abstract: According to one embodiment of the present invention, a method for processing a query in a column database is provided. The method for analyzing test results may include a computer, associating a first set of metadata values with a set of records in a table, wherein each record has an associated state indicated by a metadata value. The method may further include the computer receiving a query to return one or more records of the set of records. The method may further include the computer determining that one or more records in the set of records satisfies the query. The method may further include the computer determining whether at least a first record in the one or more records that satisfies the query is in a returnable state based, at least in part, on the metadata value.

Abstract: Embodiments relate to hierarchical database compression. An aspect includes applying a first level of a first type of compression to a first partition of a column of a database. Another aspect includes applying a second level of the first type of compression to a subset of the first partition, wherein the first level of the first type of compression comprises a first first-level dictionary and the second level of the first type of compression comprises a first second-level dictionary, and wherein a code size of the first first-level dictionary is larger than a code size of the first second-level dictionary.

Abstract: A system joins predicate evaluated column bitmaps having varying lengths. The system includes a column unifier for querying column values with a predicate and generating an indicator bit for each of the column values that is then joined with the respective column value. The system also includes a bitmap generator for creating a column-major linear bitmap from the column values and indicator bits. The column unifier also determines an offset between adjacent indicator bits. The system also includes a converter for multiplying the column-major linear bitmap with a multiplier to shift the indicator bits into consecutive positions in the linear bitmap.

Abstract: Embodiments of the invention relate to processing queries that utilize fact and/or dimension tables. In one aspect, a pre-join filtering phase precedes a star join. The necessary conditions for the pre-join filtering are considered for a given SQL query, including an estimated size of the hash table exceeding a threshold and presence of a local predicate either on the fact table or one or more dimension tables that is not a large dimension table. Once the necessary conditions are satisfied, the execution of the query exploits the pre-join filtering to build a pre-join output filter from columns of a reduced fact table that joins with each large dimension table. Thereafter, all the dimension tables and the fact table are joined in a star join while exploiting each pre-join filter.

Abstract: Provided are techniques for using parallel inserts to insert into a column store. A list of sub-ranges for a columnar table is created. A change statement for one or more rows to be inserted into the columnar table is received. For each of the received change statements, a sub-range from the list of sub-ranges is identified and data is serially inserted into the identified sub-range of the columnar table, while allowing parallel processing of each change statement for different sub-ranges of the columnar table.

Abstract: In one embodiment, a method includes adding, by a computer processor, two or more compressed columns to one or more pages of a database. The adding is performed in parallel by a plurality of page-formatter threads. Each page-formatter thread adds data to the database from no more than a single compressed column.

Abstract: Embodiments relate to database systems. An aspect includes deferring row insert operations until occurrence of a triggering event. One method includes receiving a row insert for a tuple into a column group store table, where the tuple includes one or more tuplets and each of the tuplets corresponds to a column group in the column group store table. The method also includes copying at least one of the tuplets into an insert buffer that is specific to one of the column groups in the column group store table. The method also includes deferring the row insert into the column group store table until an occurrence of one or more triggering events. The method also includes flushing the row insert into storage associated with the column group store table, in response to the occurrence of the one or more triggering events.

Abstract: Provided are techniques for using parallel inserts to insert into a column store. A list of sub-ranges for a columnar table is created. A change statement for one or more rows to be inserted into the columnar table is received. For each of the received change statements, a sub-range from the list of sub-ranges is identified and data is serially inserted into the identified sub-range of the columnar table, while allowing parallel processing of each change statement for different sub-ranges of the columnar table.

Abstract: Providing database support. A first group of data are received, the first group of data being expressed in a first format, and a second group of data are received, the second group of data being expressed in a second format, the second format being different from the first format. The first and second groups of data are merged, and are represented in at least one common column. Such representing includes: maintaining the first and second formats; and providing a tuple map which provides reference to the first and second formats.

Abstract: Aspects of the invention are provided for accessing a plurality of data elements. A page of column data is stored in a format that includes compressed and/or non-compressed elements, with the format including a plurality of arrays and a vector. Each of the arrays stores elements with common characteristics, with the vector functioning as a mapping to the stored data elements. The vector is leveraged to identify an array and determine an offset to support access to one or more of the data elements.

Abstract: Embodiments include a system for encoding data while it is being processed. The system includes a processor, an encoder and a decoder. The processor is configured to process a query request by determining a set of values. The encoder is configured for encoding the set of values, such that a subsequent processing operation can be performed on the encoded values. The processor performs the subsequent processing operations. The decoder is configured for decoding each value back to its value prior to being encoded upon completion of the processor completing the requested query.

Abstract: Embodiments include a method and computer program product for encoding data while it is being processed as part of a query is provided. The method includes receiving a query request and determining a set of values associated with data to be encoded for completing the query request. The method also includes encoding those values such that any subsequent processing operations can be performed on the encoded values to complete the requested query. After performing the subsequent processing operations to complete the requested query, each value is decoded back to its original value.

Abstract: Embodiments of the present invention provide query processing for column stores by accumulating table record attributes during application of query plan operators on a table. The attributes and associated attribute values are compacted when said attribute values are to be consumed for an operation in the query plan, during the execution of the query plan. Table column record values are materialized late in query plan execution.

Abstract: Embodiments of the present invention provide query processing for column stores by accumulating table record attributes during application of query plan operators on a table. The attributes and associated attribute values are compacted when said attribute values are to be consumed for an operation in the query plan, during the execution of the query plan. Table column record values are materialized late in query plan execution.

Abstract: Embodiments of the invention relate to a multi-level database compression technique to compress table data objects stored in pages. A compact dictionary structure is encoded that represents frequent values of data at any level of granularity. More than one level of compression is provided, wherein input to a finer level of granularity is an output of a coarser level of granularity. Based upon the encoded dictionary structure, a compression technique is applied to a stored page to compress each row on the page. Similarly, a de-compression technique may be applied to decompress the compressed data, utilizing the same dictionary structures at each level of granularity.

Abstract: Embodiments of the invention relate to processing queries that utilize fact and/or dimension tables. In one aspect, a pre-join filtering phase precedes a star join. The necessary conditions for the pre-join filtering are considered for a given SQL query, including an estimated size of the hash table exceeding a threshold and presence of a local predicate either on the fact table or one or more dimension tables that is not a large dimension table. Once the necessary conditions are satisfied, the execution of the query exploits the pre-join filtering to build a pre-join output filter from columns of a reduced fact table that joins with each large dimension table. Thereafter, all the dimension tables and the fact table are joined in a star join while exploiting each pre-join filter. Accordingly, the order of when joins occur is changed in order to reduce the size of the fact table and to work from the fact table to reduce the size of large dimension tables.

Abstract: Providing database support. A first group of data are received, the first group of data being expressed in a first format, and a second group of data are received, the second group of data being expressed in a second format, the second format being different from the first format. The first and second groups of data are merged, and are represented in at least one common column. Such representing includes: maintaining the first and second formats; and providing a tuple map which provides reference to the first and second formats.

Abstract: A system joins predicate evaluated column bitmaps having varying lengths. The system includes a column unifier for querying column values with a predicate and generating an indicator bit for each of the column values that is then joined with the respective column value. The system also includes a bitmap generator for creating a column-major linear bitmap from the column values and indicator bits. The column unifier also determines an offset between adjacent indicator bits. The system also includes a converter for multiplying the column-major linear bitmap with a multiplier to shift the indicator bits into consecutive positions in the linear bitmap.

Abstract: Embodiments of the present invention provide query processing for column stores by accumulating table record attributes during application of query plan operators on a table. The attributes and associated attribute values are compacted when said attribute values are to be consumed for an operation in the query plan, during the execution of the query plan. Table column record values are materialized late in query plan execution.