摘要:
A cluster manager is configured to manage a plurality of copies of a mid-tier database as a mid-tier database cluster. The cluster manager may concurrently manage a backend database system. The cluster manager is configured to monitor for and react to failures of mid-tier database nodes. The cluster manager may react to a mid-tier database failure by, for example, assigning a new active node, creating a new standby node, creating new copies of the mid-tier databases, implementing new replication or backup schemes, reassigning the node's virtual address to another node, or relocating applications that were directly linked to the mid-tier database to another host. Each node or an associated agent may configure the cluster manager to behave in this fashion during initialization, based on common cluster configuration information. Each copy of the mid-tier database may be, for example, a memory resident database. Thus, a node must reload the entire database into memory to recover a copy of the database.
摘要:
A cluster manager is configured to manage a plurality of copies of a mid-tier database as a mid-tier database cluster. The cluster manager may concurrently manage a backend database system. The cluster manager is configured to monitor for and react to failures of mid-tier database nodes. The cluster manager may react to a mid-tier database failure by, for example, assigning a new active node, creating a new standby node, creating new copies of the mid-tier databases, implementing new replication or backup schemes, reassigning the node's virtual address to another node, or relocating applications that were directly linked to the mid-tier database to another host. Each node or an associated agent may configure the cluster manager to behave in this fashion during initialization, based on common cluster configuration information. Each copy of the mid-tier database may be, for example, a memory resident database. Thus, a node must reload the entire database into memory to recover a copy of the database.
摘要:
A replication track is a designated group of transactions that are to be replicated at a destination database in a way that, with respect to any other transaction in the replication track, preserves transactional dependency. Further, transactions in a replication track can be replicated at the destination database without regard to transactional dependency of other transactions in another track. This facilitates concurrent parallel replication of transactions of different tracks. Replicating data in this manner is referred to herein as track replication. An application may request execution of transactions and designate different tracks for transactions.
摘要:
A replication track is a designated group of transactions that are to be replicated at a destination database in a way that, with respect to any other transaction in the replication track, preserves transactional dependency. Further, transactions in a replication track can be replicated at the destination database without regard to transactional dependency of other transactions in another track. This facilitates concurrent parallel replication of transactions of different tracks. Replicating data in this manner is referred to herein as track replication. An application may request execution of transactions and designate different tracks for transactions.
摘要:
In column domain dictionary compression, column values in one or more columns are tokenized by a single dictionary. The domain of the dictionary is the entire set of columns. A dictionary may not only map a token to a tokenized value, but also to a count (“token count”) of the number of occurrences of the token and corresponding tokenized value in the dictionary's domain. Such information may be used to compute queries on the base table.
摘要:
A method, system, and computer program product is disclosed for caching results in a client-side cache. Embodiments of a method, a system, and a computer program product are disclosed that associate a first snapshot of a database with a client that indicates a state of the database after a last database request by the client, and indicate any number of invalid cached results in the client cache for the client based upon the first snapshot. In some embodiments, the method further includes receiving a second snapshot that indicates a state of the database upon receipt of a database server request by the client, and updating the first snapshot with the second snapshot.
摘要:
A plurality of mid-tier databases form a single, consistent cache grid for data in a one or more backend data sources, such as a database system. The mid-tier databases may be standard relational databases. Cache agents at each mid-tier database swap in data from the backend database as needed. Consistency in the cache grid is maintained by ownership locks. Cache agents prevent database operations that will modify cached data in a mid-tier database unless and until ownership of the cached data can be acquired for the mid-tier database. Cache groups define what backend data may be cached, as well as a general structure in which the backend data is to be cached. Metadata for cache groups is shared to ensure that data is cached in the same form throughout the entire grid. Ownership of cached data can then be tracked through a mapping of cached instances of data to particular mid-tier databases.
摘要:
A standby database system or another replica data system replicates changes, made to data blocks at a source database system or another primary data copy, to replicas of the data blocks at the standby database system or other replica. While replicating the changes to the data blocks thereof, the standby database system (or other replica) receives queries (or reads) issued thereto and computes the queries based on data read from the data blocks thereof.
摘要:
A standby database system or another replica data system replicates changes, made to data blocks at a source database system or another primary data copy, to replicas of the data blocks at the standby database system or other replica. While replicating the changes to the data blocks thereof, the standby database system (or other replica) receives queries (or reads) issued thereto and computes the queries based on data read from the data blocks thereof.
摘要:
A method, system, and computer program product forcost based analysis for data access in a database management system. In one approach, the method, system, and computer program productperforms identifying data to access, determining a first cost for direct I/O storage access and a second cost for cache access, performing a comparison between the first cost and the second cost, and accessing a first portion of identified data based upon the comparison.
摘要翻译:一种用于数据库管理系统中数据访问的方法,系统和计算机程序产品forcost based analysis。 在一种方法中,方法,系统和计算机程序产品实现识别要访问的数据,确定用于直接I / O存储访问的第一成本和用于高速缓存访问的第二成本,执行第一成本和第二成本之间的比较,以及 基于比较来访问所识别的数据的第一部分。