Re: GSoC 2017: Foreign Key Arrays

Hi, Mark!

On Tue, May 30, 2017 at 2:18 AM, Mark Rofail <markm(dot)rofail(at)gmail(dot)com> wrote:

> rhaas=# select oid, * from pg_opfamily where opfmethod = 2742;
>> oid | opfmethod | opfname | opfnamespace | opfowner
>> ------+-----------+----------------+--------------+----------
>> 2745 | 2742 | array_ops | 11 | 10
>> 3659 | 2742 | tsvector_ops | 11 | 10
>> 4036 | 2742 | jsonb_ops | 11 | 10
>> 4037 | 2742 | jsonb_path_ops | 11 | 10
>> (4 rows)
>
> I am particulary intrested in array_ops but I have failed in locating the
> code behind it. Where is it reflected in the source code
>

Let's look what particular opclass is consisting of. Besides records in
pg_opfamily, it also contains records in pg_opclass, pg_amproc and pg_amop.

=# select * from pg_opclass where opcfamily = 2745;
opcmethod | opcname | opcnamespace | opcowner | opcfamily | opcintype |
opcdefault | opckeytype
-----------+-----------+--------------+----------+-----------+-----------+------------+------------
2742 | array_ops | 11 | 10 | 2745 | 2277 |
t | 2283
(1 row)

=# select * from pg_amproc where amprocfamily = 2745;
amprocfamily | amproclefttype | amprocrighttype | amprocnum |
amproc
--------------+----------------+-----------------+-----------+----------------------------
2745 | 2277 | 2277 | 2 |
pg_catalog.ginarrayextract
2745 | 2277 | 2277 | 3 |
ginqueryarrayextract
2745 | 2277 | 2277 | 4 |
ginarrayconsistent
2745 | 2277 | 2277 | 6 |
ginarraytriconsistent
(4 rows)

=# select * from pg_amop where amopfamily = 2745;
amopfamily | amoplefttype | amoprighttype | amopstrategy | amoppurpose |
amopopr | amopmethod | amopsortfamily
------------+--------------+---------------+--------------+-------------+---------+------------+----------------
2745 | 2277 | 2277 | 1 | s |
2750 | 2742 | 0
2745 | 2277 | 2277 | 2 | s |
2751 | 2742 | 0
2745 | 2277 | 2277 | 3 | s |
2752 | 2742 | 0
2745 | 2277 | 2277 | 4 | s |
1070 | 2742 | 0
(4 rows)

These records of system catalog are defined in special headers the source
code:
src/include/catalog/pg_amop.h
src/include/catalog/pg_amproc.h
src/include/catalog/pg_opclass.h
src/include/catalog/pg_opfamily.h
These records are written to system catalog during bootstrap process (see
src/backend/catalog/README).

As you can see pg_amproc records refer some procedures. Those procedures
are actually the majority of source code behind of opclass. Those
procedures are defined in src/backend/access/gin/ginarrayproc.c.

------
Alexander Korotkov
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company