DB2
1、 对后续用到的表建立索引(注意在插入数据之前建立或者在插入后建立但是要runstats)
说明：插入之前建立的话，在表插入数据的过程中，索引也随着更新，这样的话需要较大的日志空间，因此速度会比较慢，可以采用不计日志的方式插入;数据差完之后再建立索引的话，该表的日志统计信息没有更新，因此执行计划会很差，用不到索引，runstats on tabble asiainfo.aaaa and indexes all之后，索引统计信息就会更新，这样执行计划会考虑到使用索引，因此速度快。
2、将比较大的表建在多节点的表空间上，同时建好索引
说明：现有的db2数据仓库每个节点使用2个CPU，4G内存，DIM表空间计划是存放维表的表空间，因此是单节点的。在使用这个表空间的中的表的时候，最多只会用到2个CPU，4G内存，加上其他的表空间也都要用到这两个CPU和这4G内存，因此资源比较有限。建议较大的表不要放在这个表空间中，而是建立好分区键，放在多节点的表空间中，这样检索这个表的时候32个节点同时检索，最后汇总到0节点上进行展现，速度当然会非常的快。另外，虽然32节点并行性好，但是如果建立好索引的话，速度会更快!!
3、将插入的表使用不计日志的方式插入
说明：数据库为了保证数据的一致性和可回退性，插入、更新或者删除数据的时候要计日志，这样在失败的时候可以回退，但是如果并发较多或者操作非常大的话，会导致争抢日志的情况，导致操作非常缓慢。如果使用不计日志的方式进行插入、更新或者删除操作的话，日志使用极少，但是如果操作失败的话是无法回退的，这样一致性得不到保证，这个表只能删除重建!!!!
4、将表建立表级锁，减少锁数量的使用
说明：数据库的锁的最大数量是有限制的，并且每个锁都要占一定的内存，因此如果锁的数量非常多，使用的内存也就多，导致资源紧张。
5、建立临时表的时候尽量只插入用的到的数据，不插用不到的数据。
说明：程序中好多地方为了提高速度，将用到的数据先插入到一个临时表中，但是插入了非常多的没有使用的数据，这样导致临时表也非常大，所以尽可能的只向临时表中插入用的到的数据，并且尽可能的使用索引，可以大大的提高速度。
6、关于左关联的一点使用心得
在on的条件里面尽量的只写关联条件和对左关联的表作限制，而对主表的限制不要写在这里。如果写在里面的话，不但速度非常慢，而且可能会出现莫名其妙的结果
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