Salesforce, Inc.

Prateek Swamy

Yi Xia

Colm McHugh

Bradley Glasbergen

Rui Zhang

Rama Krishna Korlapati

Punit B Shah

Yen-Li Laih

Techniques are disclosed relating to database query optimizers. In some embodiments, a system receives, from a query optimizer, a plurality of query plans for a database maintained by the database system. The system retrieves a set of database statistics for the database and generates, via a data synthesizer, a plurality of synthetic datasets, where generating a given synthetic dataset is performed based on a given query plan of the plurality of query plans and the set of database statistics, and includes generating a plurality of synthetic data tuples. The system executes the plurality of query plans on the plurality of synthetic datasets and updates the query optimizer based on results of executing the plurality of query plans on the plurality of synthetic datasets. The disclosed data synthesis may advantageously improve query performance due to more efficient query plans being selected for execution of requested queries.

Synthetic data generation for query plans

Techniques are disclosed relating to query planning and execution. A computer system can receive a database statement that comprises a LIKE predicate that defines a set of pattern parameters. The computer system may generate first and second query paths for a query plan associated with the database statement. The first query path utilizes an index associated with a database table specified by the database statement while the second query path does not utilize the index. The computer system executes the database statement in accordance with the query plan and values that are provided for the set of pattern parameters. As a part of executing the database statement, the computer system may evaluate those values to determine whether they are prefix constants and execute the first query path instead of the second query path if all the values are prefix constants.

Database like peeking

Techniques are disclosed that relate to manipulating a chain of database objects without locking the chain. A computer system may maintain a chain that orders a set of database objects stored in a cache of the computer system. The computer system may receive a set of requests to perform database transactions. Based on those received set of requests, the computer system may determine to perform a plurality of chain operations that involve modifying the chain. The computer system may perform two or more of the plurality of chain operations at least partially in parallel using a set of atomic operations without acquiring a lock on the chain.

Mechanisms for maintaining chains without locks

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Livermore, CA, United States of America

Prateek Swamy