Horton

pg_restore --no-policies should not restore policies' comment

jian he <jian.universality@gmail.com>

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From: jian he <jian.universality@gmail.com>
To: PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2025-06-27T04:08:35Z
Lists: pgsql-hackers

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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.

Commits

  1. pg_dump: Remove unnecessary code for security labels on extensions.

  2. pg_restore: Fix security label handling with --no-publications/subscriptions.

  3. pg_dump: Fix dumping of security labels on subscriptions and event triggers.

  4. pg_restore: Fix comment handling with --no-policies.

  5. pg_restore: Fix comment handling with --no-publications / --no-subscriptions.

  6. Core support for "extensions", which are packages of SQL objects.