Rethink recent fix for pg_dump's handling of extension config tables.

Commit 3eb3d3e78 was a few bricks shy of a load: while it correctly
set the table's "interesting" flag when deciding to dump the data of
an extension config table, it was not correct to clear that flag
if we concluded we shouldn't dump the data.  This led to the crash
reported in bug #16655, because in fact we'll traverse dumpTableSchema
anyway for all extension tables (to see if they have user-added
seclabels or RLS policies).

The right thing to do is to force "interesting" true in makeTableDataInfo,
and otherwise leave the flag alone.  (Doing it there is more future-proof
in case additional calls are added, and it also avoids setting the flag
unnecessarily if that function decides the table is non-dumpable.)

This investigation also showed that while only the --inserts code path
had an obvious failure in the case considered by 3eb3d3e78, the COPY
code path also has a problem with not having loaded table subsidiary
data.  That causes fmtCopyColumnList to silently return an empty string
instead of the correct column list.  That accidentally mostly works,
which perhaps is why we didn't notice this before.  It would only fail
if the restore column order is different from the dump column order,
which only happens in weird inheritance cases, so it's not surprising
nobody had hit the case with an extension config table.  Nonetheless,
it's a bug, and it goes a long way back, not just to v12 where the
--inserts code path started to have a problem with this.

In hopes of catching such cases a bit sooner in future, add some
Asserts that "interesting" has been set in both dumpTableData and
dumpTableSchema.  Adjust the test case added by 3eb3d3e78 so that it
checks the COPY rather than INSERT form of that bug, allowing it to
detect the longer-standing symptom.

Per bug #16655 from Cameron Daniel.  Back-patch to all supported
branches.

Discussion: https://postgr.es/m/16655-5c92d6b3a9438137@postgresql.org
Discussion: https://postgr.es/m/18048b44-3414-b983-8c7c-9165b177900d@2ndQuadrant.com

src/bin/pg_dump/pg_dump.c

@@ -2110,6 +2110,9 @@ dumpTableData(Archive *fout, TableDataInfo *tdinfo)
 	char	   *copyStmt;
 	const char *copyFrom;
 
+	/* We had better have loaded per-column details about this table */
+	Assert(tbinfo->interesting);
+
 	if (!dopt->dump_inserts)
 	{
 		/* Dump/restore using COPY */
@@ -2287,6 +2290,9 @@ makeTableDataInfo(DumpOptions *dopt, TableInfo *tbinfo, bool oids)
 	addObjectDependency(&tdinfo->dobj, tbinfo->dobj.dumpId);
 
 	tbinfo->dataObj = tdinfo;
+
+	/* Make sure that we'll collect per-column info for this table. */
+	tbinfo->interesting = true;
 }
 
 /*
@@ -15553,6 +15559,9 @@ dumpTableSchema(Archive *fout, TableInfo *tbinfo)
 	int			j,
 				k;
 
+	/* We had better have loaded per-column details about this table */
+	Assert(tbinfo->interesting);
+
 	qrelname = pg_strdup(fmtId(tbinfo->dobj.name));
 	qualrelname = pg_strdup(fmtQualifiedDumpable(tbinfo));
 

src/test/modules/test_pg_dump/t/001_base.pl

@@ -135,6 +135,20 @@ my %pgdump_runs = (
 			"$tempdir/defaults_tar_format.tar",
 		],
 	},
+	exclude_table => {
+		dump_cmd => [
+			'pg_dump',
+			'--exclude-table=regress_table_dumpable',
+			"--file=$tempdir/exclude_table.sql",
+			'postgres',
+		],
+	},
+	extension_schema => {
+		dump_cmd => [
+			'pg_dump',                              '--schema=public',
+			"--file=$tempdir/extension_schema.sql", 'postgres',
+		],
+	},
 	pg_dumpall_globals => {
 		dump_cmd => [
 			'pg_dumpall',                             '--no-sync',
@@ -219,6 +233,7 @@ my %full_runs = (
 	clean_if_exists => 1,
 	createdb        => 1,
 	defaults        => 1,
+	exclude_table   => 1,
 	no_privs        => 1,
 	no_owner        => 1,);
 
@@ -301,8 +316,9 @@ my %tests = (
 			\n/xm,
 		like => {
 			%full_runs,
-			data_only    => 1,
-			section_data => 1,
+			data_only        => 1,
+			section_data     => 1,
+			extension_schema => 1,
 		},
 	},
 
@@ -310,11 +326,28 @@ my %tests = (
 		regexp => qr/^
 			\QCREATE TABLE public.regress_pg_dump_table (\E
 			\n\s+\Qcol1 integer NOT NULL,\E
-			\n\s+\Qcol2 integer\E
+			\n\s+\Qcol2 integer,\E
+			\n\s+\QCONSTRAINT regress_pg_dump_table_col2_check CHECK ((col2 > 0))\E
 			\n\);\n/xm,
 		like => { binary_upgrade => 1, },
 	},
 
+	'COPY public.regress_table_dumpable (col1)' => {
+		regexp => qr/^
+			\QCOPY public.regress_table_dumpable (col1) FROM stdin;\E
+			\n/xm,
+		like => {
+			%full_runs,
+			data_only        => 1,
+			section_data     => 1,
+			extension_schema => 1,
+		},
+		unlike => {
+			binary_upgrade => 1,
+			exclude_table  => 1,
+		},
+	},
+
 	'CREATE ACCESS METHOD regress_test_am' => {
 		regexp => qr/^
 			\QCREATE ACCESS METHOD regress_test_am TYPE INDEX HANDLER bthandler;\E
@@ -436,7 +469,8 @@ my %tests = (
 		regexp => qr/^
 			\QCREATE TABLE regress_pg_dump_schema.test_table (\E
 			\n\s+\Qcol1 integer,\E
-			\n\s+\Qcol2 integer\E
+			\n\s+\Qcol2 integer,\E
+			\n\s+\QCONSTRAINT test_table_col2_check CHECK ((col2 > 0))\E
 			\n\);\n/xm,
 		like => { binary_upgrade => 1, },
 	},
@@ -536,6 +570,7 @@ my %tests = (
 		like   => {%pgdump_runs},
 		unlike => {
 			data_only          => 1,
+			extension_schema   => 1,
 			pg_dumpall_globals => 1,
 			section_data       => 1,
 			section_pre_data   => 1,
@@ -549,6 +584,7 @@ my %tests = (
 		like   => {%pgdump_runs},
 		unlike => {
 			data_only          => 1,
+			extension_schema   => 1,
 			pg_dumpall_globals => 1,
 			section_data       => 1,
 			section_pre_data   => 1,

src/test/modules/test_pg_dump/test_pg_dump--1.0.sql

@@ -5,7 +5,7 @@
 
 CREATE TABLE regress_pg_dump_table (
 	col1 serial,
-	col2 int
+	col2 int check (col2 > 0)
 );
 
 CREATE SEQUENCE regress_pg_dump_seq;
@@ -13,6 +13,11 @@ CREATE SEQUENCE regress_pg_dump_seq;
 CREATE SEQUENCE regress_seq_dumpable;
 SELECT pg_catalog.pg_extension_config_dump('regress_seq_dumpable', '');
 
+CREATE TABLE regress_table_dumpable (
+	col1 int check (col1 > 0)
+);
+SELECT pg_catalog.pg_extension_config_dump('regress_table_dumpable', '');
+
 CREATE SCHEMA regress_pg_dump_schema;
 
 GRANT USAGE ON regress_pg_dump_seq TO regress_dump_test_role;
@@ -29,7 +34,7 @@ CREATE ACCESS METHOD regress_test_am TYPE INDEX HANDLER bthandler;
 -- this extension.
 CREATE TABLE regress_pg_dump_schema.test_table (
 	col1 int,
-	col2 int
+	col2 int check (col2 > 0)
 );
 GRANT SELECT ON regress_pg_dump_schema.test_table TO regress_dump_test_role;