The search algorithm makes use of rewritting rules to get a set of equivalent b _ schemas , utilize the cost model to estimate the cost of each b _ schema and iterative search the min - cost b _ schema 引入一種搜索算法進(jìn)行優(yōu)化處理。該算法利用改寫規(guī)則得到一組等價(jià)的b _ schema集合,對(duì)b _ schema進(jìn)行代價(jià)估計(jì)、比較,迭代得到代價(jià)最小的b _ schema 。