International Business Machines Corporation

Guang Zhou Zhang

Sheng Zhao

Chen Wang

Zan Zhou

Fu Fei Xu

Jing Jing Liu

Lei Qiu

Qi Chen

Yun Feng Sun

Hai Feng Li

Shang Shun Lei

Embodiments relate to an eigenvalue-based data query. An aspect includes receiving a query request that includes a query statement. Another aspect includes calculating eigenvalues of key component elements in the query statement. Another aspect includes matching eigenvalues of nodes in an execution plan of a historical query statement to the eigenvalues of the key component elements. Yet another aspect includes based on determining success of matching the eigenvalues of the key component elements to the eigenvalues of the nodes in an execution plan of the historical query statement, generating an execution plan of the query statement.

Eigenvalue-based data query

An index is created for a database by selecting at least one column of a database table as a basis to create the index, generating at least one index of a tree structure according to the at least one column, where a pointer stored in a leaf node of the at least one index is null. In an example embodiment, a value to a pointer is stored in a leaf node according to an intermediate result in response to the intermediate result being generated, where the pointer stored in the leaf node points to a data page storing the intermediate result. The created index can be reused and the intermediate result can be effectively used, such that the efficiency of database operation is improved.

Creating indexes for databases

Mechanisms for performing database queries are provided. With these mechanisms, in response to a query request, a query plan intended for minimum query response time and a query plan intended for minimum query total time for the query request are obtained execution of the minimum query response time query plan and the minimum query total time query plan is started. Before the execution of the minimum query total time query plan reaches a specified point, an initial query result obtained from the execution of the minimum query response time query plan is output. In response to the execution of the minimum query total time query plan reaching the specified point, continuing the execution of the minimum query total time query plan to output remaining query results.

Database query

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Guang Zhou Zhang