Hi Amit I understand, I've read the source code of analyze.c and implemented a java version. Stakind1(most common values) indicates "=" operator and stakind2(histogram) indicates "<" operator by default, I'm wondering where I can find the corresponding operatorID of eq/lt for a specific data type. For example, "=" operator for the type "varchar" is "texteq" and "<" operator for varchar is "text_lt" "=" operator for the type "int4" is "int4eq" and "<" operator for int4 is "int4lt" etc.
And another question is that how to update or insert a column with type of "anyarray", since I want to mock the statistic data of tables, the type of stavalues in pg_statistic is anyarray, is there any way to manually modify that column, by some kind of function or hook? If I ran the query like: UPDATE pg_statistic SET stavalues2=array[1,2,8] WHERE ... Then I will get error 42804 indicates that the expected type is anyarry but text[] is found in the query. Thanks very much! 2014/1/15 Amit Langote <amitlangot...@gmail.com> > On Wed, Jan 15, 2014 at 11:08 PM, Felix.徐 <ygnhz...@gmail.com> wrote: > > Hi all, > > I'm studying pg_statistic table and I find that column staop is related > to > > pg_operator, and different data types relate to different staop, but I > don't > > know where pgsql stores the mapping between pg_type and pg_operator, does > > anyone have any idea about it? thanks! > > Rather, different "kinds" of statistics are related to different > operators. So, "staop2" would refer to an operator suitable/applicable > for the statistics of kind "stakind2". > > For example stakind2 for some attribute could be value "3" which > refers to statistic kind "histogram". In this case, staop2 for the > same attribute could refer to operator, say, "<" because this > particular operator could benefit from histogram distribution of > values. (off course, "<" may be overloaded for different types; but > point to take from this is that any "<" uses the statistic called > histogram.) > > -- > Amit Langote >
