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List: pgsql-bugs
Subject: Re: BUG #15934: pg_dump output in wrong order if custom operator class is used as subtype_opclass in
From: Tom Lane <tgl () sss ! pgh ! pa ! us>
Date: 2019-07-31 18:26:36
Message-ID: 29072.1564597596 () sss ! pgh ! pa ! us
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Content-ID: <29011.1564597505.1@sss.pgh.pa.us>
I wrote:
> Clearly, we gotta upgrade pg_dump's intelligence about handling this
> dependency structure. The most straightforward fix would involve
> promoting pg_amop (and pg_amproc) entries to be full DumpableObjects,
> but I'm apprehensive about the overhead that would add ...
After further thought, I realized we could fix it far less invasively
than that, by teaching getDependencies() to translate pg_depend entries
for the pg_amop/amproc rows to look like dependencies for their parent
opfamily. This looks messy, but in a typical database without any
custom opclasses, it's actually really cheap, because there won't be
any pg_depend entries satisfying the classid conditions.
I wasn't looking forward to back-patching the other idea, but this
patch seems like it should be pretty painless.
Again, thanks for the report!
regards, tom lane
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name="fix-dump-dependencies-for-custom-opclasses.patch";
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Content-Description: fix-dump-dependencies-for-custom-opclasses.patch
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diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c
index 8a31672..0cc9ede 100644
--- a/src/bin/pg_dump/pg_dump.c
+++ b/src/bin/pg_dump/pg_dump.c
@@ -17911,14 +17911,45 @@ getDependencies(Archive *fout)
query = createPQExpBuffer();
/*
+ * Messy query to collect the dependency data we need. Note that we
+ * ignore the sub-object column, so that dependencies of or on a column
+ * look the same as dependencies of or on a whole table.
+ *
* PIN dependencies aren't interesting, and EXTENSION dependencies were
* already processed by getExtensionMembership.
*/
appendPQExpBufferStr(query, "SELECT "
"classid, objid, refclassid, refobjid, deptype "
"FROM pg_depend "
- "WHERE deptype != 'p' AND deptype != 'e' "
- "ORDER BY 1,2");
+ "WHERE deptype != 'p' AND deptype != 'e'\n");
+
+ /*
+ * Since we don't treat pg_amop entries as separate DumpableObjects, we
+ * have to translate their dependencies into dependencies of their parent
+ * opfamily. Ignore internal dependencies though, as those will point to
+ * their parent opclass, which we needn't consider here (and if we did,
+ * it'd just result in circular dependencies). Also, "loose" opfamily
+ * entries will have dependencies on their parent opfamily, which we
+ * should drop since they'd likewise become useless self-dependencies.
+ * (But be sure to keep deps on *other* opfamilies; see amopsortfamily.)
+ */
+ appendPQExpBufferStr(query, "UNION ALL\n"
+ "SELECT 'pg_opfamily'::regclass AS classid, amopfamily AS objid, refclassid, \
refobjid, deptype " + "FROM pg_depend d, pg_amop o "
+ "WHERE deptype NOT IN ('p', 'e', 'i') AND "
+ "classid = 'pg_amop'::regclass AND objid = o.oid "
+ "AND NOT (refclassid = 'pg_opfamily'::regclass AND amopfamily = \
refobjid)\n"); +
+ /* Likewise for pg_amproc entries */
+ appendPQExpBufferStr(query, "UNION ALL\n"
+ "SELECT 'pg_opfamily'::regclass AS classid, amprocfamily AS objid, \
refclassid, refobjid, deptype " + "FROM pg_depend d, pg_amproc p "
+ "WHERE deptype NOT IN ('p', 'e', 'i') AND "
+ "classid = 'pg_amproc'::regclass AND objid = p.oid "
+ "AND NOT (refclassid = 'pg_opfamily'::regclass AND amprocfamily = \
refobjid)\n"); +
+ /* Sort the output for efficiency below */
+ appendPQExpBufferStr(query, "ORDER BY 1,2");
res = ExecuteSqlQuery(fout, query->data, PGRES_TUPLES_OK);
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