hi.
first looking at function dumpPolicy (pg_dump.c):
appendPQExpBuffer(polprefix, "POLICY %s ON",
fmtId(polinfo->polname));
tag = psprintf("%s %s", tbinfo->dobj.name, polinfo->dobj.name);
....
if (polinfo->dobj.dump & DUMP_COMPONENT_COMMENT)
dumpComment(fout, polprefix->data, qtabname,
tbinfo->dobj.namespace->dobj.name, tbinfo->rolname,
then looking at function dumpCommentExtended:
appendPQExpBuffer(query, "COMMENT ON %s ", type);
if (namespace && *namespace)
appendPQExpBuffer(query, "%s.", fmtId(namespace));
appendPQExpBuffer(query, "%s IS ", name);
appendStringLiteralAH(query, comments->descr, fout);
appendPQExpBufferStr(query, ";\n");
appendPQExpBuffer(tag, "%s %s", type, name);
/*
* We mark comments as SECTION_NONE because they really belong in the
* same section as their parent, whether that is pre-data or
* post-data.
*/
ArchiveEntry(fout, nilCatalogId, createDumpId(),
ARCHIVE_OPTS(.tag = tag->data,
.namespace = namespace,
.owner = owner,
.description = "COMMENT",
.section = SECTION_NONE,
.createStmt = query->data,
.deps = &dumpId,
.nDeps = 1));
also looking at function ArchiveEntry in pg_backup_archiver.c
newToc->tag = pg_strdup(opts->tag);
if pg_restore --no-policies is specified then we generally don't want
to restore policies' comments too.
To do that, we need
1. we checked that COMMENTS on policies, the TocEntry->tag begins with
"POLICY". which is true, see above code walk through.
2. We also need to make sure that no other dumpComment call results in a
COMMENT command whose TocEntry->tag also starts with "POLICY".
which is also true, per https://www.postgresql.org/docs/current/sql-comment.html
after "COMMENT ON", the next word is fixed, and "POLICY" only occurs once.
If this is what we want, we can do the same for
"--no-publications", "--no-subscriptions" too.
