由于某一列的数据类型都是相同的,针对于数据存储更容易进行数据压缩,每一列选择更优的数据压缩算法,大大提高了数据的压缩比重; 由于数据压缩比更好,一方面节省了磁盘空间,另一方面对于cache也有了更大的发挥空间 DBMS的功能:几乎覆盖了标准SQL的大部分语法,包括DDL和DML,以及配套的各种函数,用户管理及权限管理,数据的...
copr_cache_hit_ratio: 0.62, distsql_concurrency: 15} | data:TableFullScan_24 | 58.6 MB | N/A | | └─TableFullScan_24 | 90000.00 | 90000 | cop[tikv] | table:t2 | tikv_task:{proc max:31ms, min:0s, avg: 13ms, p80:19ms, p95:26ms, iters:181, tasks:24}, scan_detail: ...
sql="SELECT `L_ORDERKEY`, COUNT(*) AS `count(*)` FROM `lineitem` AS `lineitem` GROUP BY `L_ORDERKEY`"): rowcount =2508.0, cumulativecost=value=2.4860068E7, cpu =105038.0, memory =29796.0, io =201.0, net =4.75, id =109|
In static RAM, a form of flip flop holds each bit of memory. A flip-flop for a memory cell takes four or six transistors along with some wiring, but never has to be refreshed. This makes static RAM significantly faster than dynamic RAM. However, because it has more parts, a...
/* default behavior: look it up in the catalogs */ result = get_rel_name(indexId); if (result == NULL) elog(ERROR, "cache lookup failed for index %u", indexId); } return result;}/* * Show buffer usage details. */static voidshow_buffer_usage(ExplainState *es, const BufferUsage ...
copr_cache_hit_ratio:cop task 请求的 Coprocessor Cache 缓存命中率。Coprocessor Cache 配置。 rpc_info:按照向 TiKV 发送 RPC 请求的类型统计总数量和总时间。 backoff:包含不同类型的 backoff 以及等待总耗时。 Insert Insert 算子可能包含以下执行信息: ...
If the duration is long, the cache may not be hit. Create split reader cost: the duration that is taken to open a file. If the duration is long, the metadata of the file does not hit the cache. If this occurs, the I/O overhead is high. Get result cost: the duration from ...
evaluated only once for each set of differentvalues of the variables from its outer context. For UNCACHEABLE SUBQUERY, thesubquery is re-evaluated for each row of the outer context. Cacheability ofsubqueries is subject to the restrictions detailed in Section 7.9.3.1, “How theQuery Cache ...
configure-memory-usage.md configure-placement-rules.md configure-store-limit.md configure-time-zone.md constraints.md control-execution-plan.md coprocessor-cache.md correlated-subquery-optimization.md cost-model.md credits.md daily-check.md data-type-date-and-time.md data-type-...
In-memory package cache Package cache event monitor name The procedure searches for the section in the given location. An executable ID uniquely and consistently identifies a section. The executable ID is an opaque, binary token generated at the data server for each section that has been executed...