╨╧рб▒с>■  ■                                                                                                                                                                                                                                                                                                                                                                                                                                                    ▄еhcр eщщ ююююююю  E]X╡Nю юююю└╝лI;┐╛ююююParallel Server - a review Abstract This tutorial paper outlines the significant features of the Oracle Parallel Server option. Starting from a basic description of what the Parallel Server is, and why you might want to use to, the paper moves on to cover in some detail the key technical features of the Parallel Server. The paper describes problems of implementing the Parallel Server, reviews features of Oracle that exist to reduce the risk, or overhead, of using the Parallel Server, highlights some traps which are not otherwise documented, and summarizes key differences between Oracle 7.3 with Oracle 8.0 The paper is aimed at a technical audience who will already have some familiarity with the performance monitoring (v$) views and the internal working of the database system. Synopsis Part 1: What is the Oracle Parallel Server (OPS) An overview of the Parallel Server Option - introducing the idea of multiple instances addressing one set of data files, independent log files and the problems of synchronization. Part 2: Why Use OPS Given that there are features to OPS which promise trouble ahead, why would anyone want to use it, and what types of database activity would be suitable candidates for OPS. OPS for resilience - one failed instance does not stop the system Scaling - getting very large jobs completed more rapidly Scaling - allowing more concurrent users to run small jobs Part 3: MPP and DLM A high-level view of massively parallel (or share-nothing) architecture, and why this imposes special requirements for cache management. An outline of how distributed lock management works, and how this allows Oracle to handle Parallel Cache Management, and dictionary cache coherency. Part 4: Setting up the database The init.ora parameters that are most relevant to OPS, and how to use them. This will cover both Oracle 7 and Oracle 8 parameters. In particular the significance of gc_files_to_locks, and fine-grain locking; private rollback segments and redo logging. Part 5: Documented Issues and features Some of the more common problems of OPS - pinging; recovery, startup and shutdown; and some of the enhancements in Oracle which aim to address problems of OPS - free list groups, reverse key indexes. Part 6: Monitoring OPS The special v$ (or GV$) views that are especially relevant to OPS; what they can be used for , what they tell you, and how much they can be trusted. Particular emphasis will be placed on the Oracle 8.0 views, which have been enhanced quite considerably over the Oracle 7.3 views. Part 7: Side-effects There are a number of СunexpectedТ effects that appear in large systems when the Oracle Parallel Server is combined with other advanced options. Partition Views introduce problems of parse locks, Parallel Query introduces overheads in inter-node communications and global checkpoints, Partitioned tables introduce overheads into dictionary cache coherency. Non-PCM locks can become more of a bottleneck than pinging. Part 8: Strategies A few design strategies and hints at the physical build level that may help to reduce the overhead and hassle of managing a Parallel Server system Part 9: Conclusion A brief review of the good and bad points of OPS, features to take advantage of, and features to treat with caution. бд╨/ер=жзиайак$W  ЕЪ║  ╠ ф ■  ╕╠_sщ¤¤¤¤¤¤¤¤¤√u]$FGkl%W  ╧JЕЪ╣ ║ █ ┌  ╠ ф ■  ╕╠_sшщ■№······№°·°·ЇЇЇ°··°·°·°·°·°·°··╨ K@ё Normal]a .@. 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