From: | Shigeru Hanada <shigeru(dot)hanada(at)gmail(dot)com> |
---|---|
To: | Kohei KaiGai <kaigai(at)kaigai(dot)gr(dot)jp> |
Cc: | Kouhei Kaigai <kaigai(at)ak(dot)jp(dot)nec(dot)com>, Stephen Frost <sfrost(at)snowman(dot)net>, Jim Mlodgenski <jimmy76(at)gmail(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, PgHacker <pgsql-hackers(at)postgresql(dot)org>, Peter Eisentraut <peter_e(at)gmx(dot)net> |
Subject: | Re: Custom Scan APIs (Re: Custom Plan node) |
Date: | 2014-02-26 03:14:13 |
Message-ID: | CAEZqfEfY=2DTudBMiW6N4bk3ziwcAnBYirPAstXEavwrOue0Dg@mail.gmail.com |
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Lists: | pgsql-hackers |
Hi Kaigai-san,
2014-02-23 22:24 GMT+09:00 Kohei KaiGai <kaigai(at)kaigai(dot)gr(dot)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
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