Abstract: Techniques that support trail-based exploration by a user of a repository of documents are described herein. In one embodiment, trail definition data that specifies a trail is received. The trail includes an ordered series of waypoints including a trailhead, intermediate waypoints, and one or more trailends. In some embodiments, deadends may also be defined in the trial. A particular waypoint in the ordered series of waypoints is established as a current waypoint. Search terms can be received from a user to cause a search to be performed. It is then determined whether the search satisfies matching criteria associated with a waypoint that immediately follows the current waypoint in the ordered series of waypoints. If so, the user advances to the next waypoint. Otherwise, the user remains at the current waypoint. Finally, if a trailend is reached, then an action such as rewarding the user in some way may be performed.

Abstract: In a large-scale transaction such as the bulk loading of new records into an ordered, distributed database, a transaction limit such as an insert limit may be chosen, partitions on overfull storage servers may be designated to be moved to underfull storage servers, and the move assignments may be based, at least in part on the degree to which a storage server is underfull and the move and insertion costs of the partitions to be moved.

Abstract: An improved system and method for writing data dependent upon multiple reads in a distributed database is provided. A client may read several data records and may then send a request to a database server to perform a transaction to write a data record dependent upon multiple data records read. A database server may receive the request specifying a transaction to write a data record dependent upon multiple data records read and may perform the transaction by latching a master data record to be written and validating the data records the write depends upon. The multiple data records upon which the write depends may be validated by verifying the multiple data records are current versions of the data records stored in the distributed database. Data intensive applications may use this transaction type in large scale distributed database systems to provide stronger consistency without significantly degrading performance and scalability.

Abstract: An improved system and method for asynchronous update of indexes in a distributed database is provided. A database server may receive the request to update the data and may update the data in a primary data table of the distributed database. An asynchronous index update of the indexes may be initiated at the time a record is updated in a data table and then control may be returned to a client to perform another data update. An activity cache may be provided for caching the records updated by a client so that when the client requests a subsequent read, the updated records may be available in the activity cache to support the various guarantees for reading the data. Advantageously, the asynchronous index update scheme may provide increased performance and more scalability while efficiently maintaining indexes over database tables in a large scale, replicated, distributed database.

Abstract: An improved system and method for parallel retrieval of data from a distributed database is provided. A parallel interface may be provided for use by a cluster of client machine for parallel retrieval of partial results from parallel execution of a database query by a cluster of database servers storing a distributed database. A query interface may be augmented for inputting a database query and specifying the number of instances of parallel retrieval of results from query execution. To do so, a commercial query language may be augmented for sending a query request that may include a parameter specifying the database query and an additional parameter specifying the desired retrieval parallelism. The augmented query interface may return a list of retrieval point addresses for retrieving the partial results assigned to each of the retrieval point addresses from parallel execution of the database query.

Abstract: Computer-implemented methods, modules and clients relate to expanded, pruned sample table for testing database queries against a base table. The expanded, pruned sample table is formed from the base table by a process of initial sampling, synthesis, and pruning.

Abstract: Methods and apparatuses are provided for dynamically reorganizing the data within a replicated database system. One method, for example, includes performing a split operation across a plurality of replicated databases with regard to an existing partition therein, wherein the existing partition comprises a plurality of data records and the two new partitions each include at least a portion of the plurality of data records, and allowing at least one type of access to the plurality of data records during the split operation.

Abstract: A technique is described that reduces the complexity and resource consumption associated with performing record expiry in a distributed database system. In accordance with the technique, a record is checked to see if it has expired only when it has been accessed for a read or a write. If at the time of a read a record is determined to have expired, then it is not served. If at the time of a write a record is determined to have expired, then the write is treated as an insertion of a new record, and steps are taken to treat the insertion consistently with regard to the previous expired version. A background process is used to delete records that have not been written to or actively deleted by a client after expiration.

Abstract: A novel method is employed for collecting optimizer statistics for optimizing database queries by gathering feedback from the query execution engine about the observed cardinality of predicates and constructing and maintaining multidimensional histograms. This makes use of the correlation between data columns without employing an inefficient data scan. The maximum entropy principle is used to approximate the true data distribution by a histogram distribution that is as “simple” as possible while being consistent with the observed predicate cardinalities. Changes in the underlying data are readily adapted to, automatically detecting and eliminating inconsistent feedback information in an efficient manner. The size of the histogram is controlled by retaining only the most “important” feedback.

Abstract: The system includes a query engine and an advertisement engine. The query engine is configured to receive a query from the user. The advertisement engine generates advertisement results corresponding to the query. The advertisement results are selected from entries in an advertisement database, where the entries include predicate values corresponding to a domain. The advertisement engine generates a diverse advertisement result that is a subset of the database entries that match the query. The diversity result varies at least one predicate by selecting entries for the list that include a proportional representation of each available predicate value in the database that matches the query.

Abstract: A system for generating an ordered list. The system may include a query engine and an advertisement engine. The query engine receives a query from the user and determines parameters to match with the advertisement. The advertisement engine receives the parameters and generates a list of items based on the parameters. The system may function in a precompute mode to calculate intervals for each available item to minimize the variable processing costs for each item. Further, the number of intervals a crossed item may be selected in a manner to satisfy a given space constraint. By characterizing each item by a minimum price within each interval, the system can quickly query the interval matching the desired quantity for each item and determined if the minimum price for that interval is less than the top-k prices already included in the list.

Abstract: A system and method for deriving user intent from a query. The system includes a query engine, and an advertisement engine. The query engine receives a query from the user. The query engine analyzes the query to determine a query intent that is matched to a domain. The query may be further analyzed to derive predicate values based on the query and the domain hierarchy. The domain and associated information may then be matched to a list of advertisements. The advertisement may be assigned an ad match score based on a correlation between the query information and various listing information provided in the advertisement.

Abstract: A system and method for generating advertisements based on search intent. The system includes a query engine, and an advertisement engine. The query engine receives a query from the user. The query engine analyzes the query to determine a query intent that is matched to a predetermined domain. A translated query is generated including the domain type. Once a domain is selected, the query may be further analyzed to determine generic domain information. The domain and associated information may then be matched to a list of advertisements. The advertisement may be assigned an ad match score based on a correlation between the query information and various listing information provided in the advertisement.

Abstract: A novel method is employed for collecting optimizer statistics for optimizing database queries by gathering feedback from the query execution engine about the observed cardinality of predicates and constructing and maintaining multidimensional histograms. This makes use of the correlation between data columns without employing an inefficient data scan. The maximum entropy principle is used to approximate the true data distribution by a histogram distribution that is as “simple” as possible while being consistent with the observed predicate cardinalities. Changes in the underlying data are readily adapted to, automatically detecting and eliminating inconsistent feedback information in an efficient manner. The size of the histogram is controlled by retaining only the most “important” feedback.

Abstract: System and apparatus for using block-level sampling for histograms construction as well as distinct-value estimations. For histogram construction, the system implements a two-phase adaptive method in which the sample size required to reach a desired accuracy is decided based on a first phase sample. This method is significantly faster than previous iterative block-level sampling methods proposed for the same problem. For distinct-value estimation, it is shown that existing estimators designed for uniform-random samples may perform very poorly with block-level samples. An exemplary system computes an appropriate subset of a block-level sample that is suitable for use with most existing estimators.