Re: Custom Scan APIs (Re: Custom Plan node)

Hi Kaigai-san,

2014-02-23 22:24 GMT+09:00 Kohei KaiGai <kaigai@kaigai.gr.jp>:
> (1) Interface to add alternative paths in addition to built-in join paths

I found that create_custom_path is not used at all in your patch.
I revised postgresql_fdw.c to use it like this.

...
    /* Create join information which is stored as private information. */
    memset(&jinfo, 0, sizeof(PgRemoteJoinInfo));
    jinfo.fdw_server_oid = o_server_oid;
    jinfo.fdw_user_oid = o_user_oid;
    jinfo.relids = joinrel->relids;
    jinfo.jointype = jointype;
    jinfo.outer_rel = o_relinfo;
    jinfo.inner_rel = i_relinfo;
    jinfo.remote_conds = j_remote_conds;
    jinfo.local_conds = j_local_conds;

    /* OK, make a CustomScan node to run remote join */
    cpath = create_customscan_path(root,
                                   joinrel,
                                   0, 0, 0,     /* estimate later */
                                   NIL,
                                   required_outer,
                                   "postgres-fdw",
                                   0,
                                   packPgRemoteJoinInfo(&jinfo));

    estimate_remote_join_cost(root, cpath, &jinfo, sjinfo);

    add_path(joinrel, &cpath->path);
...

This seems to work fine.  Is this right approach?  If so,this portion
would be a good example to replace local join with custom scan for
authors of custom scan providers.  One thing I worry is the case that
you've intentionally avoided calling create_customscan_path.

-- 
Shigeru HANADA