Abstract: A method for obtaining data items from an unresponsive database host. The method includes receiving an indication that the database host is unresponsive, receiving, from a management server via a diagnostic connection, a first request for a first organized data item, and sending a first query, using a first interface, to a memory for the first organized data item. The method further includes receiving, from the management server via a normal connection, a second request for a second organized data item, retrieving, from memory on the database host, a first data item in response to the first query, converting the first data item into the first organized data item, and sending the first organized data item to the management server, wherein the first organized data item is analyzed to determine a source causing the database host to be unresponsive.

Abstract: A method for determining event counts for a database system includes capturing samples for the active sessions based on a pre-defined sampling frequency and identifying events from the captured samples. The method further includes determining the wait time for each of the identified events and determining an event count for the active sessions using a harmonic mean. The harmonic mean is a summation of the maximum of either one or the ratio of the sampling frequency to the determined wait time for each of the identified events.

Abstract: A method for resolving a hang in a database system includes receiving a symbolic graph having a plurality of nodes, where each node represents a database session involved in the hang during a specified time interval. The blocking time associated with each node in the symbolic graph is recursively determined. The node that has the longest blocking time is output to a display for review by the database administrator. Alternatively, the database session represented by the node having the longest blocking time may be automatically eliminated.

Abstract: A table-level histogram is maintained incrementally without requiring rescanning of the entire table when new data values are added to the table. A table has multiple partitions of data values. A histogram for data values of the partitions is generated. When a new partition of data values is added to the table, a histogram for only the new partition is generated. To generate a histogram for the entire table, the histograms for the previously generated and newly added partitions are used without needing to refer to the underlying data. A similar approach is applicable when modifying data values in a partition.

Abstract: Techniques for proactively and reactively running diagnostic functions. These diagnostic functions help to improve diagnostics of conditions detected in a monitored system and to limit/quarantine the damages caused by the detected conditions. In one embodiment, a health monitor infrastructure is provided that is configured to perform one or more health checks in a monitored system for diagnosing and/or gathering information related to the system. The one or more health checks may be invoked pro-actively on a scheduled basis, reactively in response to a condition detected in the system, or may even be invoked manually by a user such as a system administrator.

Abstract: One or more usage models are provided for a database. Each usage model includes a set of rules that are used to analyze database performance. A usage model in one or more usage models is determined. Database information is determined based on the usage model. The database information is then analyzed based on rules associated with the usage model. One or more performance problems are determined based on the analysis.

Abstract: A diagnosability system for automatically collecting, storing, communicating, and analyzing diagnostic data for one or more monitored systems. The diagnosability system comprises several components configured for the collection, storage, communication, and analysis of diagnostic data for a condition detected in monitored system. The diagnosability system enables targeted dumping of diagnostic data so that only diagnostic data that is relevant for diagnosing the condition detected in the monitored system is collected and stored. This in turn enables first failure analysis thereby reducing the time needed to resolve the condition detected in the monitored system.

Abstract: Techniques for self-diagnosing performance problems in a database are provided. The techniques include classifying one or more performance problems in a database system. One or more values for quantifying an impact of the one or more performance problems on the database system are then determined. The quantified values are determined based on the performance of operations in the database system. A performance problem based on the one or more quantified values is then determined. A solution for the performance problem is generated and may be outputted.

Abstract: A method and apparatus for approximating a database statistic, such as the number of distinct values (NDV) is provided. To approximate the NDV for a portion of a table, a synopsis of distinct values is constructed. Each value in the portion is mapped to a domain of values. The mapping function is implemented with a uniform hash function, in one embodiment. If the resultant domain value does not exist in the synopsis, the domain value is added to the synopsis. If the synopsis reaches its capacity, a portion of the domain values are discarded from the synopsis. The statistic is approximated based on the number (N) of domain values in the synopsis and the portion of the domain that is represented in the synopsis relative to the size of the domain.

Abstract: A method and apparatus for merging synopses to determine a database statistic, e.g., a number of distinct values (NDV), is disclosed. The merging can be used to determine an initial database statistic or to perform incremental statistics maintenance. For example, each synopsis can pertain to a different partition, such that merging the synopses generates a global statistic. When performing incremental maintenance, only those synopses whose partitions have changed need to be updated. Each synopsis contains domain values that summarize the statistic. However, the synopses may initially contain domain values that are not compatible with each other. Prior to merging the synopses the domain values in each synopsis is made compatible with the domain values in the other synopses. The adjustment is made such that each synopsis represents the same range of domain values, in one embodiment. After “compatible synopses” are formed, the synopses are merged by taking the union of the compatible synopses.

Abstract: Techniques for proactively and reactively running diagnostic functions. These diagnostic functions help to improve diagnostics of conditions detected in a monitored system and to limit/quarantine the damages caused by the detected conditions. In one embodiment, a health monitor infrastructure is provided that is configured to perform one or more health checks in a monitored system for diagnosing and/or gathering information related to the system. The one or more health checks may be invoked pro-actively on a scheduled basis, reactively in response to a condition detected in the system, or may even be invoked manually by a user such as a system administrator.

Abstract: A diagnosability system for automatically collecting, storing, communicating, and analyzing diagnostic data for one or more monitored systems. The diagnosability system comprises several components configured for the collection, storage, communication, and analysis of diagnostic data for a condition detected in monitored system. The diagnosability system enables targeted dumping of diagnostic data so that only diagnostic data that is relevant for diagnosing the condition detected in the monitored system is collected and stored. This in turn enables first failure analysis thereby reducing the time needed to resolve the condition detected in the monitored system.

Abstract: A method and apparatus for merging synopses to determine a database statistic, e.g., a number of distinct values (NDV), is disclosed. The merging can be used to determine an initial database statistic or to perform incremental statistics maintenance. For example, each synopsis can pertain to a different partition, such that merging the synopses generates a global statistic. When performing incremental maintenance, only those synopses whose partitions have changed need to be updated. Each synopsis contains domain values that summarize the statistic. However, the synopses may initially contain domain values that are not compatible with each other. Prior to merging the synopses the domain values in each synopsis is made compatible with the domain values in the other synopses. The adjustment is made such that each synopsis represents the same range of domain values, in one embodiment. After “compatible synopses” are formed, the synopses are merged by taking the union of the compatible synopses.

Abstract: A method and apparatus for approximating a database statistic, such as the number of distinct values (NDV) is provided. To approximate the NDV for a portion of a table, a synopsis of distinct values is constructed. Each value in the portion is mapped to a domain of values. The mapping function is implemented with a uniform hash function, in one embodiment. If the resultant domain value does not exist in the synopsis, the domain value is added to the synopsis. If the synopsis reaches its capacity, a portion of the domain values are discarded from the synopsis. The statistic is approximated based on the number (N) of domain values in the synopsis and the portion of the domain that is represented in the synopsis relative to the size of the domain.

Abstract: One or more usage models are provided for a database. Each usage model includes a set of rules that are used to analyze database performance. A usage model in one or more usage models is determined. Database information is determined based on the usage model. The database information is then analyzed based on rules associated with the usage model. One or more performance problems are determined based on the analysis.

Abstract: Techniques for self-diagnosing performance problems in a database are provided. The techniques include classifying one or more performance problems in a database system. One or more values for quantifying an impact of the one or more performance problems on the database system are then determined. The quantified values are determined based on the performance of operations in the database system. A performance problem based on the one or more quantified values is then determined. A solution for the performance problem is generated and may be outputted.

Abstract: A unified database/text retrieval system converts exact database type queries into text inclusion type queries suitable for text retrieval systems through the use of pseudo keywords. Boolean combination of the text inclusion type query elements may be readily manipulated for optimization and applied to a unified index for rapid search results. Absolute relevance values and relevance multiplier values may be added to the query elements to provide a relevance-based sorting not only of text but also of exact match type search results. Relevance values may be deduced automatically from a variety of sources.

Abstract: A reverse index useful for identifying documents in information retrieval searches may be used concurrently for indexing while it is updated with new documents. Interruption to the use of the index is kept to a manageable level by partitioning the index and updating only single partitions of the index at a given time and further by bifurcating the index into a high speed supplemental portion that may be corrected concurrently on a real-time basis and which is periodically merged with the larger main portion. These two structures are merged during reading after brief locking, with pointer redirection.

Abstract: A unified database/text retrieval system converts exact database type queries into text inclusion type queries suitable for text retrieval systems through the use of pseudo keywords. Boolean combination of the text inclusion type query elements may be readily manipulated for optimization and applied to a unified index for rapid search results. Absolute relevance values and relevance multiplier values may be added to the query elements to provide a relevance-based sorting not only of text but also of exact match type search results. Relevance values may be deduced automatically from a variety of sources.

Abstract: A method for determining k nearest-neighbors to a query point in a database in which an ordering is defined for a data set P of a database, the ordering being based on l one-dimensional codes C.sub.1, . . . , C.sub.1. A single relation R is created in which R has the attributes of index-id, point-id and value. An entry (j,i,C.sub..epsilon.j (p.sub.i)) is included in relation R for each data point p.sub.i .EPSILON.P, where index-id equals j, point-id equals i, and value equals C.sub..epsilon.j (p.sub.i). A B-tree index is created based on a combination of the index-id attribute and the value attribute. A query point is received and a relation Q is created for the query point having the attributes of index-id and value. One tuple is generated in the relation Q for each j, j=1, . . . , l, where index-id equals j and value equals C.sub..epsilon.j (q). A distance d is selected. The index-id attribute for the relation R of each data point p.sub.