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Automated big table caching combines concerns with the shield storage cache to improve the in-memory question abilities of Oracle Data base, in both individual example and Oracle RAC surroundings.
In Oracle Real Program Groups (Oracle RAC) surroundings, this function is reinforced only with similar concerns. In individual example surroundings, this function is reinforced with both similar and sequential concerns.
The storage cache area arranged for the big table storage cache is used for caching information for table tests. While the big table storage cache is usually meant to improve efficiency for information factory workloads, it also enhances efficiency in Oracle Data source operating combined workloads.
Automatic big table caching uses heat range and item based methods to monitor method and big platforms. Oracle does storage cache very small platforms, but automatic big table caching does not monitor these platforms.
To allow automatic big table caching for sequential concerns, you must set a value (percentage) for the DB_BIG_TABLE_CACHE_PERCENT_TARGET initialization parameter. Furthermore, you must set the PARALLEL_DEGREE_POLICY initialization parameter to AUTO or ADAPTIVE to allow similar concerns to use automatic big table caching. In Oracle RAC surroundings, automatic big table caching is only reinforced operating in similar concerns so both configurations are needed.
If a huge table is roughly the dimensions of the combined dimension the big table storage cache of all circumstances, then the table is portioned and cached, or mostly cached, on all circumstances. An in-memory question could remove most hard drive flows for concerns on the table, or the database could wisely study from hard drive only for that part of table that does not fit in the big table storage cache. If the big table storage cache cannot storage cache all the platforms to be examined, only the most regularly utilized table are cached, and the relax are look at immediate study instantly.
The DB_BIG_TABLE_CACHE_PERCENT_TARGET parameter decides the part of shield storage cache dimension used for tests. If DB_BIG_TABLE_CACHE_PERCENT_TARGET is set to 80 (%), then 80 (%) of the shield storage cache is used for tests and the staying 20 (%) is used for OLTP workloads.
The DB_BIG_TABLE_CACHE_PERCENT_TARGET parameter is only allowed in an Oracle RAC atmosphere if PARALLEL_DEGREE_POLICY is set to AUTO or ADAPTIVE. The standard for DB_BIG_TABLE_CACHE_PERCENT_TARGET is 0 (disabled) and the maximum is 90 (%) arranging at least 10% shield storage cache for utilization besides table tests. When the value is 0, in-memory concerns run with the existing least lately used (LRU) procedure. You may modify the DB_BIG_TABLE_CACHE_PERCENT_TARGET parameter dynamically.
Use the following recommendations when establishing the DB_BIG_TABLE_CACHE_PERCENT_TARGET parameter:
If you do not allow automatic DOP in an Oracle RAC atmosphere, then you should not set this parameter because the big table storage cache area is not used in that scenario.
When establishing this parameter, you should consider the amount of work mix: how much of the amount of work is for OLTP; place, upgrade, and unique access; and how much of the amount of work includes table tests. Because information factory workloads often execute huge table tests, you may consider providing big table storage cache area a greater section of shield storage cache area for information manufacturing facilities.
This parameter can be dynamically modified if the amount of work changes. The modification could take a while based on the existing amount of work to get to the objective, because shield storage cache storage might be definitely used right at that moment.
When PARALLEL_DEGREE_POLICY is set to AUTO or ADAPTIVE, extra object-level research for a information factory fill and check out buffers are included to signify the number of similar concerns (PQ) tests on the item on the particular (helper) example.