Abstract: Techniques for automatic error mitigation in database systems using alternate plans are provided. After receiving a database statement, an error is detected as a result of compiling the database statement. In response to detecting the error, one or more alternate plans that were used to process the database statement or another database statement that is similar to the database statement are identified. A particular alternate plan of the one or more alternate plans is selected. A result of the database statement is generated based on processing the particular alternate plan.

Abstract: A histogram-augmented dynamic sampling approach is provided for determining cardinality of a two-table join. The approach has a pre-processing phase in which data structures are created that will be used during a compilation phase for cardinality estimation. These data structures include a row histogram and a key histogram, which are created for selected columns of a first table. A cardinality estimation phase uses the data structures to estimate the cardinality of various joins at the time of query compilation. In this phase, the system executes queries that join the histograms with a second table, to perform the cardinality estimation.

Abstract: Techniques are provided for gathering statistics in a database system. The techniques involve gathering some statistics using an “on-the-fly” technique, some statistics through a “high-frequency” technique, and yet other statistics using a “prediction” technique. The technique used to gather each statistic is based, at least in part, on the overhead required to gather the statistic. For example, low-overhead statistics may be gathered “on-the-fly” using the same process that is performing the operation that affects the statistic, while statistics whose gathering incurs greater overhead may be gathered in the background, while the database is live, using the high-frequency technique. The prediction technique may be used for relatively-high overhead statistics that can be predicted based on historical data and the current value of predictor statistics.

Abstract: Disclosed is an approach for applying fine-grained hints to obtain optimal control over error handling during query compilation. Using fine-grained hints causes less disruption to the query plans generated by the optimizer as they constrain specific features while retaining scope for the rest of the optimizer functionality. This approach provides a query plan of better quality that avoid errors, particularly in comparison to coarse-grained approaches that restrict processing to earlier database versions or which disables cost-based processing.

Abstract: Techniques for automatic error mitigation in database systems using alternate plans are provided. After receiving a database statement, an error is detected as a result of compiling the database statement. In response to detecting the error, one or more alternate plans that were used to process the database statement or another database statement that is similar to the database statement are identified. A particular alternate plan of the one or more alternate plans is selected. A result of the database statement is generated based on processing the particular alternate plan.

Abstract: Disclosed is an approach for applying fine-grained hints to obtain optimal control over error handling during query compilation. Using fine-grained hints causes less disruption to the query plans generated by the optimizer as they constrain specific features while retaining scope for the rest of the optimizer functionality. This approach provides a query plan of better quality that avoid errors, particularly in comparison to coarse-grained approaches that restrict processing to earlier database versions or which disables cost-based processing.

Abstract: Techniques are described for responding to aggregate queries using optimizer statistics already available in the data dictionary of the database in which the database object targeting by the aggregate query resides, without the user creating any additional objects (e.g. materialized views) and without requiring the objects to be loaded into volatile memory in a columnar fashion. The user query is rewritten to produce a transformed query that targets the dictionary tables to form the aggregate result without scanning the user tables. “Accuracy indicators” may be maintained to indicate whether those statistics are accurate. Only accurate statistics are used to answer queries that require accurate answers. The accuracy check can be made during runtime, allowing the query plan of the transformed query to be used regardless of the accuracy of the statistics. For queries that request approximations, inaccurate statistics may be used so long as the statistics are “accurate enough”.

Abstract: Techniques are provided for gathering statistics in a database system. The techniques involve gathering some statistics using an “on-the-fly” technique, some statistics through a “high-frequency” technique, and yet other statistics using a “prediction” technique. The technique used to gather each statistic is based, at least in part, on the overhead required to gather the statistic. For example, low-overhead statistics may be gathered “on-the-fly” using the same process that is performing the operation that affects the statistic, while statistics whose gathering incurs greater overhead may be gathered in the background, while the database is live, using the high-frequency technique. The prediction technique may be used for relatively-high overhead statistics that can be predicted based on historical data and the current value of predictor statistics.

Abstract: Techniques for processing queries are provided. In one approach, an execution plan for a query includes multiple sub-plans, one or more of which are selected at runtime while one or more other sub-plans are not executed during execution of the execution plan. In another approach, data about misestimate is generated and stored persistently for subsequent queries. In another approach, statistics for a database object are generated automatically and efficiently while the database object is created or data items are added thereto. In another approach, a hybrid histogram is created that includes a feature of frequency histograms and a feature of height-balanced histograms. In another approach, computer jobs are executed in such a way to avoid deadlock. In another approach, changes to a database object trigger a hard parse of a query even though an execution plan already exists for the query.

Abstract: Techniques for processing queries are provided. In one approach, an execution plan for a query includes multiple sub-plans, one or more of which are selected at runtime while one or more other sub-plans are not executed during execution of the execution plan. In another approach, data about misestimate is generated and stored persistently for subsequent queries. In another approach, statistics for a database object are generated automatically and efficiently while the database object is created or data items are added thereto. In another approach, a hybrid histogram is created that includes a feature of frequency histograms and a feature of height-balanced histograms. In another approach, computer jobs are executed in such a way to avoid deadlock. In another approach, changes to a database object trigger a hard parse of a query even though an execution plan already exists for the query.

Abstract: Embodiments of the present disclosure disclose a terminal holder and a far-field voice interaction system. A specific implementation of the terminal holder includes: a far-field voice pickup device and a voice analysis device. The far-field voice pickup device receives voice sent by a user, and sends the voice to the voice analysis device. The voice analysis device analyzes the voice, determines whether the voice contains a preset wake-up word, and sends the voice to a terminal in communication connection with the terminal holder when the preset wake-up word is contained. This embodiment receives voice sent by a user through the terminal holder supporting a far-field voice pickup function, thereby facilitating the far-field voice control over the terminal.

Abstract: Disclosed a method for preparing a matrix protective coating, including a preprocessing step and a like transfer membrane coating preparation step. The like transfer membrane coating preparation step includes the following steps: mixing, drying and cooling YSZ powder and polytetrafluoroethylene powder to obtain a mixture, and then spraying the mixture onto the surface of a preprocessed matrix by an atmospheric plasma spraying method, wherein spraying parameters are set as follows: a moving speed of a spray gun is 440-460 mm/s; the current is 550-600 A, the voltage is 40-50 V, and the power is 24.8-30 kW; the compressed air is 0.6-0.7 MPa; the powder feeding carrier gas Ar is 3-6 L/min; a powder feeding rate is 25-28 g/min; and a spraying distance is 108-112 mm. The wear resistance of the coating of the present invention is significantly improved; the corrosion resistance is excellent; and the superhydrophobic property is excellent.

Abstract: Techniques are provided for gathering statistics in a database system. The techniques involve gathering some statistics using an “on-the-fly” technique, some statistics through a “high-frequency” technique, and yet other statistics using a “prediction” technique. The technique used to gather each statistic is based, at least in part, on the overhead required to gather the statistic. For example, low-overhead statistics may be gathered “on-the-fly” using the same process that is performing the operation that affects the statistic, while statistics whose gathering incurs greater overhead may be gathered in the background, while the database is live, using the high-frequency technique. The prediction technique may be used for relatively-high overhead statistics that can be predicted based on historical data and the current value of predictor statistics.

Abstract: The present invent belongs to the technical field of plating by sputtering coating forming materials, and particularly relates to a contact coating of an electrical connector. In the coating, chromium nitride is doped with precious metal elements.

Abstract: A wear-resistant super-hydrophobic protective coating for a substrate includes a pretreated surface and a composite coating. The composite coating is formed of a mixture of a ZrO2 powder, a PTFE powder and a silicone powder by spraying. A method for preparing the protective coating on a substrate is also provided.

Abstract: A method for processing data from an online on-demand service platform is provided. The method may include obtaining a plurality of first groups of orders from a first time period for an on-demand service provided by the online on-demand service platform. Each group of the plurality of first groups of orders may be associated with a service requester and a plurality of service providers. The method may also include determining a first behavior feature of the plurality of service providers and a second behavior feature of the service requester for each group of the plurality of first groups of orders. The method may also include determining a plurality of training samples based on a plurality of pairs of first behavior features and second behavior features. The method may further include determining feature weights for service evaluation using the plurality of training samples.

Abstract: Techniques are provided for merging (a) statistics associated with data added to a table in a bulk load operation with (b) statistics associated with data that existed in the table before the bulk load operation. The statistics associated with the bulk load data are generated on-the-fly during the bulk load, and are merged with the pre-existing statistics as part of the same transaction that is used to perform the bulk load operation. Consequently, execution plans for queries that are assigned snapshot times after the commit time of the bulk load transaction will be selected based on the new statistics, while execution plans for queries that are assigned snapshot times before the commit time of the bulk load transaction will be selected based on the pre-existing statistics.

Abstract: The disclosure is directed to methods, kits, and compositions, for amplifying and detecting a human hepatitis C virus (HCV) in a sample, which comprises a variety of combinations of forward oligonucleotide primers, reverse oligonucleotide primers, and oligonucleotide probes.

Abstract: A method for processing data from an online on-demand service platform is provided. The method may include obtaining a plurality of first groups of orders from a first time period for an on-demand service provided by the online on-demand service platform. Each group of the plurality of first groups of orders may be associated with a service requester and a plurality of service providers. The method may also include determining a first behavior feature of the plurality of service providers and a second behavior feature of the service requester for each group of the plurality of first groups of orders. The method may also include determining a plurality of training samples based on a plurality of pairs of first behavior features and second behavior features. The method may further include determining feature weights for service evaluation using the plurality of training samples.

Abstract: The present disclosure provides a page displaying method, device, apparatus based on an H5 webpage, and a computer readable storage medium. The page displaying method based on an H5 webpage includes: loading a main page in a webpage view; obtaining content of an H5 webpage; establishing a page tag, in which the page tag includes the content of the H5 webpage; and loading the page tag in the main page.