1. MySQL 建立连接 connect_a,连接的数据库中有 heap 表, MySQL 建立连接 connect_b, 选择与 connect_a 同一个库 这种场景下,当connect_a 建立时,系统会调用 open_table_from_share -> handler::ha_open -> ha_heap::open 打开内存表,同时给当前的线程创建一个属于自己的表描述类,这个表描述类,对应着...
Notice we did not mark any of the columns as primary key and we also did not create a clsustered index explicitly. So the physical order in which data rows are stored in this table is not guaranteed. In a nut shell, this Gender table is a heap. We also did not create any non-cls...
Server crashes when executing the script below PostgreSQL build: CFLAGS='-Og' ./configure --enable-tap-tests --with-openssl --enable-debug --enable-cassert --with-icu --with-lz4 --with-libxml To Reproduce script.sql: CREATE EXTENSION pg_mooncake;CREATETABLEheaptableUSING heapASSELECTa, repe...
When bitmap indexes exist on an index-organized table, all the bitmap indexes use a heap-organized mapping table.The mapping table stores the logical rowids of the index-organized table. Each mapping table row stores one logical rowid for the corresponding index-organized table row. The databas...
Created_tmp_tables应该小于20%，如果比值较高，就需要适当调高tmp_table_size或者max_heap_table_size...
默认情况下,vacuum表不能释放磁盘空间,只是在dead tuple做个标记位,但heap table末端的垃圾页可以被truncate,从磁盘中释放空间。例如表的末尾的100个数据块里面全是垃圾,那么这100个数据块可以truncate阶段,文件也会变小。而位于其他位置的垃圾页,不能回收,因为会影响寻址(ctid)的变化,而末尾全垃圾的页被截断时不影...
Created_tmp_tables应该小于20%，如果比值较高，就需要适当调高tmp_table_size或者max_heap_table_size...
mysql查看 max_heap_table_size 配置,linux一虚拟机安装与配置1.1虚拟化技术VMware安装创建虚拟机安装操作系统CentOS7设置时区,磁盘,用户密码。1.2配置常见参数网络:编辑->虚拟机网络编辑器->vmnet8修改网络配置信息vi编辑器简单使用dd删除一行i将文档变为可修改
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Whenever you increasetmp_table_sizeandmax_heap_table_size, keep in mind that setting these does not make queries behave better. It actually make inefficient queries behave worse than before. Under what circumstances? When a query performs a join or sort (viaORDER BY) without the benefit of an...