我正在尝试诊断为什么特定查询对SQLite的速度很慢.关于 how the query optimizer works似乎有很多信息,但关于如何实际诊断问题的信息很少.


MyTable,ix_id,25112 1 1 1 1

“25112 1 1 1 1”究竟是什么意思?




/* Store the results.  
** The result is a single row of the sqlite_stmt1 table.  The first
** two columns are the names of the table and index.  The third column
** is a string composed of a list of integer statistics about the
** index.  The first integer in the list is the total number of entires
** in the index.  There is one additional integer in the list for each
** column of the table.  This additional integer is a guess of how many
** rows of the table the index will select.  If D is the count of distinct
** values and K is the total number of rows, then the integer is computed
** as:
**        I = (K+D-1)/D
** If K==0 then no entry is made into the sqlite_stat1 table.  
** If K>0 then it is always the case the D>0 so division by zero
** is never possible.