摘要：
http://www.postgresql.org/docs/9.2/static/sql-prepare.htmlPREPARE creates a prepared statement. A prepared statement is a server-side object that can be used to optimize performance. When the PREPARE statement is executed, the specified statement is parsed, analyzed, and rewritten. When an EXECUTE c 阅读全文
摘要：
继续分析/* * final_cost_hashjoin * Final estimate of the cost and result size of a hashjoin path. * * Note: the numbatches estimate is also saved into 'path' for use later * * 'path' is already filled in except for the rows and cost fields and * num_batches * 'workspace' is the r 阅读全文