Re: How are pg_operator and pg_type related with each other?

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 <amitlangote09(at)gmail(dot)com>

> On Wed, Jan 15, 2014 at 11:08 PM, Felix.徐 <ygnhzeus(at)gmail(dot)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
>