Abstract: Techniques are disclosed relating to determining whether to utilize an alternative query plan for a subsequent execution of a database query. A computer system accesses a trace record detailing an execution of the database query in accordance with a first query plan selected by a query optimizer. The computer system may determine, based on the trace record, whether the execution of the database query satisfies a set of performance criteria. In response to determining that the execution of the database query does not satisfy the set of performance criteria, the computer system may determine whether one or more alternative query plans for the query include a second query plan that is predicted to be more performant than the first query plan. The computer system may provide an instruction to utilize the second query plan in place of the first query plan for the subsequent execution of the database query.

Abstract: Techniques are disclosed relating to implementing multiple index scans. A computer system may store a database table comprising fields and indexes corresponding to those fields. The computer system may receive a request to access records based on a Boolean expression that affects a selection of records from the database table and that comprises clauses, at least two of which are joined by an AND operation. The computer system may access the requested records. The accessing may include, for a given one of the at least two clauses, performing an index scan on an index that corresponds to the given clause to identify records that satisfy that clause. The computer system may update a hash table based on the identified records and then identify the requested records based on the hash table. The Boolean expression may include clauses joined by an OR operation that are processed using multiple index scans.

Abstract: Techniques are disclosed that relate to capturing and replaying database queries to assess the impacts of updates to a database system. A system may receive a plurality of queries from a set of users to execute against a database that stores data. The system identifies one or more of the queries that are deemed relevant to updates being made to the database system. The system executes the received queries and captures query execution information for the one or more identified queries. The system replays, based on the execution information, the one or more queries using the database system with the one or more updates enabled to determine a first performance of the database system. The system may generate a report indicating whether the first performance represents a reduction in performance relative to a second performance of the database system with the one or more updates disabled.

Abstract: Techniques are disclosed that relate to capturing and replaying database queries to assess the impacts of updates to a database system. A system may receive a plurality of queries from a set of users to execute against a database that stores data. The system identifies one or more of the queries that are deemed relevant to updates being made to the database system. The system executes the received queries and captures query execution information for the one or more identified queries. The system replays, based on the execution information, the one or more queries using the database system with the one or more updates enabled to determine a first performance of the database system. The system may generate a report indicating whether the first performance represents a reduction in performance relative to a second performance of the database system with the one or more updates disabled.

Abstract: In an embodiment, a computer system performs a hash join. During a build phase, the computer system constructs a hash table in memory based on rows of a first table. The constructing may result in build batches of rows, including one build batch stored in memory and multiple build batches stored in a storage. The computer system determines whether any of the multiple build batches is skewed according to a data skew condition. In response to determining that there is at least one build batch that is skewed, the computer system loads one or more of the multiple build batches into memory such that there are at least two build batches stored in memory. During a probe phase, the computer system identifies, based on the at least two build batches stored in memory, rows of a second table to join with the rows of the first table.

Abstract: Methods and apparatus for an autonomous stage-switching multi-stage cooling device are disclosed are disclosed. A disclosed example coolant distribution unit (CDU) includes an enclosure, an inlet and an outlet of the CDU to be fluidly coupled to a cooling block associated with a heat generating source, at least one sensor to measure a first temperature corresponding to the inlet and a second temperature corresponding to the outlet, and a plurality of valves to be controlled by a controller to control a flow of fluid from the inlet to at least one of an ambient cooler or a sub-ambient cooler based on: (i) a comparison of the first temperature to an ambient temperature and (ii) a comparison of the second temperature to a target temperature.

Abstract: 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.

Abstract: An apparatus is described. The apparatus includes a metallic chamber having a first outer surface with first Peltier devices and a second outer surface with second Peltier devices. The first and second outer surfaces face in opposite directions such that the first Peltier devices are to cool first semiconductor chips that face the first outer surface and the second Peltier devices are to cool second semiconductor chips that face the second outer surface.

Abstract: A preparation method for a molybdenite/ZnO nanorod-based pillared structure and an application thereof are provided, belonging to the field of gas sensing technology. The specific steps include: (1) dispersing commercially available molybdenite in a zinc acetate methanol solution to obtain a solution A; (2) adding a sodium hydroxide methanol solution to the solution A to obtain molybdenite/ZnO nanoparticles; (3) dispersing the molybdenite/ZnO nanoparticles in deionized water to obtain a molybdenite/ZnO nanoparticle suspension; (4) adding the molybdenite/ZnO nanoparticle suspension to a sodium hydroxide solution of ?-Zn(OH)2, heating and aging, stirring, washing, and drying overnight to obtain molybdenite/ZnO nanorods with pillared heterostructure.

Abstract: 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.

Abstract: 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.

Abstract: An apparatus is described. The apparatus includes a cover to enclose a junction between respective ends of first and second fluidic conduits. The first and second fluidic conduits transport a coolant fluid within an electronic system. The apparatus also includes a leak detection device to be located within a region that is enclosed by the cover when the junction is enclosed by the cover. The leak detection device is to detect a leak of the coolant fluid at the junction when the junction is enclosed by the cover. The first and second fluidic conduits extend outside the cover when the junction is enclosed by the cover. Another apparatus is also described. The other apparatus includes a leak detection device to detect a leak of coolant fluid from a specific component or junction in a liquid cooling system of an electronic system.

Abstract: Techniques for heat sinks and cold plates for compute systems are disclosed. In one embodiment, a heat sink includes two sub-heat sinks that are mechanically connected but thermally isolated. The two sub-heat sinks can independently cool different dies on the same integrated circuit component. In another embodiment, a system includes an integrated circuit component that is cooled by a first water block and a second water block. The first water block forms a loop with a gap in it, and the second water block has a pedestal that extends through the gap in the first water block to contact the integrated circuit component. The first water block and the second water block can independently cool different dies on the same integrated circuit component.

Abstract: 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.

Abstract: A data integrity protection method is applied to an electronic device, and the electronic device stores vendor data and first verification information. The first verification information is stored in a first storage area of the electronic device and is used to perform integrity verification on the vendor data. The method includes: First data is obtained. Digital signature is performed on the first data to generate second data and second verification information. The second data and the second verification information are stored, where the second verification information is stored in a second storage area of the electronic device. According to the data integrity protection method provided in this embodiment of this application, firmware or software customized by a third-party integrator is supported in being reloaded to a system for running, thereby simplifying a process and improving integrated development efficiency of an electronic device.

Abstract: 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.

Abstract: Techniques are disclosed relating to database configuration settings overrides. In some embodiments, a database system stores a set of default configuration settings that control operation of the database system. The database system receives a query requesting data from the database system, and metadata about the query. The database system determines, based on the query and the metadata, that a configuration settings override has been specified for the query, where the configuration settings override indicates that one or more of the default configuration settings are to be replaced with one or more configuration settings specific to the query. In response to the determining that a configuration settings override has been specified, the database system executes the query using the one or more specific configuration settings.

Abstract: 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.

Abstract: 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.

Abstract: 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.