摘要:
An adaptive query execution plan enhancement is provided by: selecting a sample of literal sets from an execution history of a query statement; determining a plurality of access paths by applying each literal set in the sample to the query statement; for each given access path of the plurality of access paths, determining a total execution cost by applying each literal set in the sample to the given access path; and selecting a preferred access path from the plurality of access paths based on the total execution costs for each given access path. A plurality of preferred access paths for a plurality of query statements in an application workload is collected and may be presented as a query execution plan enhancement recommendation to users.
摘要:
A method for identifying matching transactions between two log files where each transaction includes one or more statements. Each log file record records the execution of a statement and includes a transaction identifier. Each record in turn in one log file is compared to an advancing window of records in the other log file. A first table contains associations of statements to transactions and transactions to statements for records in the window. If a match is found between a record in the one file and a record in the window, information associating partial transactions in the one file to potential transactions of the records in the window is added to a second table. If an end-of-transaction record is read from the one file, a best match is found between the ended transaction and the potential transactions based on information in the first and second tables.
摘要:
A system for establishing a connection between a data server and a middleware server is disclosed. The system includes defining a plurality of trust attributes corresponding to a trusted context between the middleware server and the data server and validating the plurality of trust attributes against a plurality of attributes corresponding to the middleware server. The plurality of attributes provided in a connection request. The system also includes establishing the trusted context based on the validating the plurality of trust attributes.
摘要:
A method for providing a timestamp for data in a database system, in which the database system operates in accordance with a database schema. The method includes providing a hidden timestamp column in a table in the database system, in which the hidden timestamp column includes a timestamp value for each row of data in the table. The timestamp value indicates a last time a corresponding row of data in the table was previously modified. The hidden timestamp column does not appear in the database schema by default and exposes the timestamp value for a given row of data in the table only to a query that calls the timestamp column by name.
摘要:
In a system for avoiding section collision for application server requests over a single database connection, the database server assigns query identifiers to each instance of the same cursor opened for the same processing level within an application, allowing multiple instances of the same cursor to be processed in parallel without section collision. The application server assigns a command source identifier to each statement sent over a single database connection to uniquely identify the application source of the statement. This applies for multiples of the same statement sent by different application sources within the same application, for a single statement containing multiple application sources, and for multiple statements from different applications multiplexed over a single database connection. These statements can be processed separately from and in parallel with the each other without section collision.
摘要:
A system for processing diverse and non-diverse result sets is described. The system includes a client process in a client computer system that constructs a client process execution request identifying a stored procedure and specifying constraints on the quantity of response data that the client process is capable of handling. The client process execution request is transferred from the client process in the client computer system to a server process in a server computer system. The server process invokes the stored procedure identified by the client process execution request. Execution of the stored procedure results in the generation of answer set data for a plurality of diverse query result sets. Result set generators obtain answer set data for X of the query result sets, where X is defined by the constraints. The server process then generates an initial response containing, for each of the X query result sets, an amount of the obtained answer set data consistent with the constraints. The initial response is transferred from the server computer system to the client process in the client computer system. The client application is then able to access and process answer set data for the diverse result sets in any order.
摘要:
In a particular embodiment, a method includes storing, at a staging table of a database, a data update generated based on a transaction performed with respect to a data table that is associated with one or more indexes. Each index of the one or more indexes is maintained externally to the database. The method further includes maintaining the data update at the staging table at least until index update data is received at the database. The index update data represents a modification, based on the data update, to a particular index of the one or more the indexes.
摘要:
According to one embodiment of the present invention, a system processes a database query, and comprises a computer system including at least one processor. The system identifies one or more expressions within the database query utilizing a database object with value masking. Masking requirements are determined for each identified expression and the database object utilized by that identified expression is replicated to provide masked and actual versions of that database object in response to the masking requirements for that expression including masked values and actual values of that database object. The value masking of the database object is applied to the identified expressions within the database query based on the determined masking requirements to produce search results with masked values for the database query. Embodiments of the present invention further include a method and computer program product for processing a database query in substantially the same manner described above.
摘要:
A row property provides a mechanism for implementing advanced functional behavior in a relational database management system (RDBMS) without introducing new data types. A row property is part of a table definition, such that, when a table is defined in the RDBMS, at least one row property is specified for one or more associated columns of rows of the table, wherein the row property has an associated functional behavior that is predefined within the RDBMS. The columns associated with the row property are generally of existing data types supported by an RDBMS. A row property may be invoked when the RDBMS processes a language statement that references the row property. When the row property is invoked, the RDBMS executes programming logic associated with the row property, in order to perform the advanced functional behavior using data stored in the associated columns.
摘要:
In a method for avoiding section collision for application server requests over a single database connection, the database server assigns query identifiers to each instance of the same cursor opened for the same processing level within an application, allowing multiple instances of the same cursor to be processed in parallel without section collision. The application server assigns a command source identifier to each statement sent over a single database connection to uniquely identify the application source of the statement. This applies for multiples of the same statement sent by different application sources within the same application, for a single statement containing multiple application sources, and for multiple statements from different applications multiplexed over a single database connection. These statements can be processed separately from and in parallel with the each other without section collision.