Abstract: Techniques are disclosed for selecting between query execution plans in part based on VM mirroring costs. In one embodiment, a query optimizer determines runtimes for multiple query execution plans, and modifies these runtimes based on flashing cost, which is itself determined based on the amount of memory which needs to be flashed to the secondary memory if each execution plan is executed. In so doing, the query optimizer may select a execution plan which takes a longer to run, but incurs less flashing cost. By considering both the query runtime itself and the flashing cost, the query optimizer may be better able to determine the fastest query execution plan to execute.

Abstract: An apparatus and method utilize partitioned database tables divided into data allocation containers (DACs) where data is placed into the DACs based on usage of the data in past queries. Records that are used most often are placed together and records that are used less often are placed together to improve database performance. In preferred embodiments, a database manager determines where to place data into the DACs based on how often the data is selected by a database query using a DAC selection ratio (DSR). The database manager may determine when to perform table maintenance to move rows of data to the appropriate DACs based on a timestamp or last check date (LCD) stored in the database.

Abstract: An apparatus and method utilize partitioned database tables divided into data allocation containers (DACs) where data is placed into the DACs based on usage of the data in past queries. Records that are used most often are placed together and records that are used less often are placed together to improve database performance. In preferred embodiments, a database manager determines where to place data into the DACs based on how often the data is selected by a database query using a DAC selection ratio (DSR). The database manager may determine when to perform table maintenance to move rows of data to the appropriate DACs based on a timestamp or last check date (LCD) stored in the database.

Abstract: A disappearing index allows faster processing of a database query without the startup time of a prior art sparse index. The disappearing index starts as a full index but is trimmed of index values that point to a row in the table that is not selected by the query. Thus the traditional index disappears as it becomes a sparse index tailored to the query. The query is able to execute faster using the now sparse index since the target database table is not accessed for duplicate values in the base table of the query. The query optimizer may determine to use a disappearing index based on estimates of the number of duplicate values in the base table. When the query is complete, the created disappearing table may be discarded or used for other queries that match the selection of the query that created the disappearing index.

Abstract: In an embodiment, a query plan is compressed to data in a cache at a high compression level if a runtime of a query that the query plan implements is greater than a high time threshold. The query plan is compressed to the data in the cache at a medium compression level if the runtime of the query that the query plan implements is less than the high time threshold and greater than a low time threshold. The query plan is stored to the data in the cache at an uncompressed level if the runtime of the query that the query plan implements is less than the low time threshold.

Abstract: System, method, and computer program product to intelligently utilize non-matching weighted objects, by determining that a sort sequence of a query does not match a sort sequence of a shared weight object of a database, modifying the query based on the sort sequence of the query, and executing the modified query to obtain a result set, wherein the result set does not include a set of rows that would have been returned using the shared weight object to process the unmodified query.

Abstract: In an embodiment, a first query is received that specifies a first object identifier. If a first query plan exists that implements the first query, except that the first query plan does not comprise the first object identifier and instead comprises a parameter marker in place of the first object identifier, a first query execution plan is created from the first query plan, substituting the first object identifier in the first query execution plan for the parameter marker, and the first query execution plan is executed to read a first object identified by the first object identifier.

Abstract: A method, system, and computer program product to manage a database is disclosed. The method, system, and computer program product may include structuring the database to have a first table having an index and a second table. A first key of the first table may be related to a second key of the second table. The method, system, and computer program product may include creating an entry locator in the index. The method, system, and computer program product may include maintaining an association between the second key of the second table and the entry locator of the index.

Abstract: A method, system, and computer program product to manage a database is disclosed. The method, system, and computer program product may include structuring the database to have a first table having an index and a second table. A first key of the first table may be related to a second key of the second table. The method, system, and computer program product may include creating an entry locator in the index. The method, system, and computer program product may include maintaining an association between the second key of the second table and the entry locator of the index.

Abstract: In an embodiment, a hit percentage of an expected affinity for a first query is calculated, wherein the expected affinity comprises a first address range in a query plan cache, a hit percentage of a candidate affinity for the first query is calculated, wherein the candidate affinity comprises a second address range in a query plan cache, and if the hit percentage of the candidate affinity is greater than the hit percentage of the expected affinity by more than a threshold amount, query plans in the candidate affinity are swapped with query plans in the expected affinity.

Abstract: A method and computer-readable storage media are provided for reorganizing a database. The method may monitor the database to determine whether the database reorganization is required. The method may also include determining the database reorganization is required. The method may further include determining a first and second amount of space to add to the database for additional entries of a category of data according to a first and second predictive sizing calculation. The method may further include the selecting of either the first or second amount of space to add to the database for additional entries of the category of data during the reorganization. The method may further include performing the reorganization of the database including allocating the selected amount of space to add to the database for additional entries in the database of the category of data by using the computer system operatively coupled to the storage device.

Abstract: A method and computer-readable storage media are provided for reorganizing a database. The method may monitor the database to determine whether the database reorganization is required. The method may also include determining the database reorganization is required. The method may further include determining a first and second amount of space to add to the database for additional entries of a category of data according to a first and second predictive sizing calculation. The method may further include the selecting of either the first or second amount of space to add to the database for additional entries of the category of data during the reorganization. The method may further include performing the reorganization of the database including allocating the selected amount of space to add to the database for additional entries in the database of the category of data by using the computer system operatively coupled to the storage device.

Abstract: In an embodiment, a first key value is received. A plurality of candidate rows are found in a database table, wherein the plurality of candidate rows are deleted. For the plurality of candidate rows, a plurality of respective impacts on a plurality of respective densities of each of other key values that are stored within a first key range of the first key value are calculated. For the plurality of candidate rows, a plurality of function results of the plurality of respective impacts on the plurality of respective densities are calculated. A selected candidate row of the plurality of candidate rows with a smallest function result of the plurality of function results of the plurality of respective impacts on the plurality of respective densities is selected. The first key value is stored to the selected candidate row.

Abstract: A method, computer-readable storage medium, and computer system are provided. In an embodiment, in response to receiving a first command that specifies first data, a first cryptographic key, and a column identifier that identifies a column of rows in a database, the first data is encrypted into encrypted data using the first cryptographic key. The encrypted data is stored to a first row in the column in the database. In response to the receiving the first command, characterization data is created that specifies valid contents of the column of the rows. In response to receiving a query command that specifies a second cryptographic key and the column, the column is decrypted using the second key to create decrypted data. If the decrypted data does not satisfy the valid contents specified by the characterization data, an invalid cryptographic key action is performed.

Abstract: In an embodiment, a request is received that specifies a function and a specified key value. Rows from all tables that are accessible from the specified key value are transitively searched, wherein the transitively searching further comprises finding values in a plurality of pairs of columns, wherein found rows that are found by the transitively searching comprise values in a respective first column of the plurality of pairs of columns that satisfy a dependency relationship with values in a respective second column of the plurality of pairs of columns. The function is executed against only the found rows.

Abstract: In an embodiment, if an estimated time to perform a task by a first virtual machine is less than or equal to an expiration time of the first virtual machine minus the current time, the task is performed by the first virtual machine. If the estimated time to perform the task by the first virtual machine is greater than the expiration time of the first virtual machine minus the current time, a selected virtual machine is selected from among a plurality of virtual machines with a smallest estimated time to perform the task and a request to perform the task is sent to the selected virtual machine.

Abstract: In an embodiment, a request is received that specifies a function and a specified key value. Rows from all tables that are accessible from the specified key value are transitively searched, wherein the transitively searching further comprises finding values in a plurality of pairs of columns, wherein found rows that are found by the transitively searching comprise values in a respective first column of the plurality of pairs of columns that satisfy a dependency relationship with values in a respective second column of the plurality of pairs of columns. The function is executed against only the found rows.

Abstract: In an embodiment, if an estimated time to perform a task by a first virtual machine is less than or equal to an expiration time of the first virtual machine minus the current time, the task is performed by the first virtual machine. If the estimated time to perform the task by the first virtual machine is greater than the expiration time of the first virtual machine minus the current time, a selected virtual machine is selected from among a plurality of virtual machines with a smallest estimated time to perform the task and a request to perform the task is sent to the selected virtual machine.

Abstract: A method, apparatus and program product use a first index associated with a field in a database table to identify a range of records in the database table that includes instances of a first key value in the field and use the identified range of records to subset a second index associated with another field in a database table. The database query identifies the first key value for the field in the database table and the second key value for the other field in the database table. By doing so, information from an index may be carried over and applied to another index to subset the other index, often reducing the quantity of entries that are searched in the other index and improving performance.

Abstract: A method, system, and computer program product to create an access control bit mapping (ACBM) structure for a corresponding database table are disclosed. The ACBM structure may include a relative record number (RRN) bit map. The RRN bit map may describe the access rights for a parameter. The computer-implemented method may maintain one or more statistics describing the RRN bit map. The method may additionally provide for updating the ACBM structure. The method may also provide for using the ACBM structure to process a database query.