Abstract: A request for a metadata object is received where the request includes an identifier. It is determined whether the metadata object is stored in a metadata cache, including by: selecting a sub-cache in the metadata cache based at least in part on the identifier and determining whether the metadata object is stored in that sub-cache. If it is determined the metadata object is not in the metadata cache, a request (in a format associated with the source) to obtain the metadata object is sent to a source with which the metadata object is associated. If the metadata object provided by the source is in a native format which is not the same as the common format, the metadata object is transformed from the native format into the common format. Access to the metadata object in the common format is provided.

Abstract: A method is disclosed. A finite state machine model for a single system workflow is replicated across a plurality of distributed nodes associated with a leader election protocol. A leader is determined amongst the plurality of distributed nodes to perform a next action of the finite state machine model based at least in part on the leader election protocol. One or more nodes amongst the plurality of distributed nodes are configured to submit a timeout ticket if the next action of the finite state machine model does not appear to have been performed by the leader within a prescribed time.

Abstract: Each of a plurality of subtasks is configured to explore and assess alternative solutions for a combinatorial optimization problem by a reentrant finite state machine is represented. Each of a plurality of threads is configured to perform operations comprising a subtask until either completion or a blocked state is reached and, in the event a blocked state is reached, to move on to performing another subtask that is not currently in a blocked state.

Abstract: Data movement driven placement of data in a distributed database is disclosed. A set of one or more queries anticipated to be performed with respect to a data set is received. A set of statistics associated with the data set is received. The set of queries and the statistics are used to explore algorithmically a search space of distribution policy alternatives, to determine an optimal distribution policy to distribute data comprising the data set across a plurality of database servers.

Abstract: A method is disclosed. A finite state machine model for a single system workflow is replicated across a plurality of distributed nodes associated with a leader election protocol. A leader is determined amongst the plurality of distributed nodes to perform a next action of the finite state machine model based at least in part on the leader election protocol. One or more nodes amongst the plurality of distributed nodes are configured to submit a timeout ticket if the next action of the finite state machine model does not appear to have been performed by the leader within a prescribed time.

Abstract: A method of analyzing the performance of a query optimizer includes identifying an event trigger. A reproduction object characterizing operational parameters of the customer computer at the time of the event trigger is populated. The reproduction object is transported from the customer computer to a test computer. The reproduction object is analyzed at the test computer to characterize the performance of a query optimizer.

Abstract: A request for a metadata object is received where the request includes an identifier. It is determined whether the metadata object is stored in a metadata cache, including by: selecting a sub-cache in the metadata cache based at least in part on the identifier and determining whether the metadata object is stored in that sub-cache. If it is determined the metadata object is not in the metadata cache, a request (in a format associated with the source) to obtain the metadata object is sent to a source with which the metadata object is associated. If the metadata object provided by the source is in a native format which is not the same as the common format, the metadata object is transformed from the native format into the common format. Access to the metadata object in the common format is provided.

Abstract: A method is disclosed. A finite state machine model for a single system workflow is replicated across a plurality of distributed nodes associated with a leader election protocol. A leader is determined amongst the plurality of distributed nodes to perform a next action of the finite state machine model based at least in part on the leader election protocol. One or more nodes amongst the plurality of distributed nodes are configured to submit a timeout ticket if the next action of the finite state machine model does not appear to have been performed by the leader within a prescribed time.

Abstract: A request for a metadata object is received. It is determined whether the metadata object is stored in a metadata cache. In the event the metadata object is not stored in the metadata cache, a request to obtain the metadata object is sent to a source with which the metadata object is associated in a format associated with the source. The metadata object is transformed from a native format of the source into a common format if the metadata object as provided by the source is in a native format that is not the same as the common format. Access to the metadata object in the common format is provided.

Abstract: Each of a plurality of subtasks is configured to explore and assess alternative solutions for a combinatorial optimization problem by a reentrant finite state machine is represented. Each of a plurality of threads is configured to perform operations comprising a subtask until either completion or a blocked state is reached and, in the event a blocked state is reached, to move on to performing another subtask that is not currently in a blocked state.

Abstract: Each of a plurality of subtasks is configured to explore and assess alternative solutions for a combinatorial optimization problem by a reentrant finite state machine is represented. Each of a plurality of threads is configured to perform operations comprising a subtask until either completion or a blocked state is reached and, in the event a blocked state is reached, to move on to performing another subtask that is not currently in a blocked state.

Abstract: A method of analyzing the performance of a query optimizer includes identifying an event trigger. A reproduction object characterizing operational parameters of the customer computer at the time of the event trigger is populated. The reproduction object is transported from the customer computer to a test computer. The reproduction object is analyzed at the test computer to characterize the performance of a query optimizer.

Abstract: A method of accumulating and aggregating statistics concerning the use of database table indexes includes using a plurality of counters to register index use. The plurality of counters allow multiple instances of index usage to be recorded simultaneously. A missing index may be detected using an optimal index in a query plan. The optimal index is compared against the available indexes to determine if an index is missing. Statistics may be gathered against the used and missing indexes.

Abstract: Validation of large numbers of alternative execution plans for a database query, either an exhaustive enumeration of the complete space of alternatives, or else an unbiased random sample, is performed by efficiently constructing execution trees from a data structure having groups alternative operators that are ranked in a directory. Each global rank of a plan identifies that plan uniquely among all the alternative plans. The operators are unranked from the directory according to a specification that characterizes the desired plans.

Abstract: A method of accumulating and aggregating statistics concerning the use of database table indexes includes using a plurality of counters to register index use. The plurality of counters allow multiple instances of index usage to be recorded simultaneously. A missing index may be detected using an optimal index in a query plan. The optimal index is compared against the available indexes to determine if an index is missing. Statistics may be gathered against the used and missing indexes.

Abstract: Validation of large numbers of alternative execution plans for a database query, either an exhaustive enumeration of the complete space of alternatives, or else an unbiased random sample, is performed by efficiently constructing execution trees from a data structure having groups alternative operators that are ranked in a directory. Each global rank of a plan identifies that plan uniquely among all the alternative plans. The operators are unranked from the directory according to a specification that characterizes the desired plans.

Abstract: Validation of large numbers of alternative execution plans for a database query, either an exhaustive enumeration of the complete space of alternatives, or else an unbiased random sample, is performed by efficiently constructing execution trees from a data structure having groups alternative operators that are ranked in a directory. Each global rank of a plan identifies that plan uniquely among all the alternative plans. The operators are unranked from the directory according to a specification that characterizes the desired plans.

Abstract: Validation of large numbers of alternative execution plans for a database query, either an exhaustive enumeration of the complete space of alternatives, or else an unbiased random sample, is performed by efficiently constructing execution trees from a data structure having groups alternative operators that are ranked in a directory. Each global rank of a plan identifies that plan uniquely among all the alternative plans. The operators are unranked from the directory according to a specification that characterizes the desired plans.

Abstract: Validation of large numbers of alternative execution plans for a database query, either an exhaustive enumeration of the complete space of alternatives, or else an unbiased random sample, is performed by efficiently constructing execution trees from a data structure having groups alternative operators that are ranked in a directory. Each global rank of a plan identifies that plan uniquely among all the alternative plans. The operators are unranked from the directory according to a specification that characterizes the desired plans.

Abstract: In the course of an optimization, a query can be broken down into its sub-expressions. Materialized views may be substituted for the sub-expressions during query optimization. Encoded sub-expressions are generated and used in the comparison with stored materialized views. Instead of discarding the encoding of a query's sub-expression if no matching materialization is found, the encoding is stored. If subsequently submitted queries contain the same sub-expression, a view matching mechanism will find the previously stored encoding. Because no materialization is associated with this expression, the view is not substituted. However, usage statistics counters are updated; e.g., a counter is incremented indicating that the sub-expression was found in another query. Because view matching is applied to the sub-expression that are candidates for being materialized, the statistics accurately reflect which are the most frequently occurring candidate sub-expressions in a workload.