Get rid of pg_class.reltoastidxid.

Treat TOAST index just the same as normal one and get the OID
of TOAST index from pg_index but not pg_class.reltoastidxid.
This change allows us to handle multiple TOAST indexes, and
which is required infrastructure for upcoming
REINDEX CONCURRENTLY feature.

Patch by Michael Paquier, reviewed by Andres Freund and me.

Author: MasaoFujii

contrib/pg_upgrade/info.c

@@ -321,12 +321,19 @@ get_rel_infos(ClusterInfo *cluster, DbInfo *dbinfo)
 							  "INSERT INTO info_rels "
 							  "SELECT reltoastrelid "
 							  "FROM info_rels i JOIN pg_catalog.pg_class c "
-							  "		ON i.reloid = c.oid"));
+							  "		ON i.reloid = c.oid "
+							  "		AND c.reltoastrelid != %u", InvalidOid));
 	PQclear(executeQueryOrDie(conn,
 							  "INSERT INTO info_rels "
-							  "SELECT reltoastidxid "
-							  "FROM info_rels i JOIN pg_catalog.pg_class c "
-							  "		ON i.reloid = c.oid"));
+							  "SELECT indexrelid "
+							  "FROM pg_index "
+							  "WHERE indisvalid "
+							  "    AND indrelid IN (SELECT reltoastrelid "
+							  "        FROM info_rels i "
+							  "            JOIN pg_catalog.pg_class c "
+							  "            ON i.reloid = c.oid "
+							  "            AND c.reltoastrelid != %u)",
+							  InvalidOid));
 
 	snprintf(query, sizeof(query),
 			 "SELECT c.oid, n.nspname, c.relname, "

doc/src/sgml/catalogs.sgml

@@ -1744,15 +1744,6 @@
       </entry>
      </row>
 
-     <row>
-      <entry><structfield>reltoastidxid</structfield></entry>
-      <entry><type>oid</type></entry>
-      <entry><literal><link linkend="catalog-pg-class"><structname>pg_class</structname></link>.oid</literal></entry>
-      <entry>
-       For a TOAST table, the OID of its index.  0 if not a TOAST table.
-      </entry>
-     </row>
-
      <row>
       <entry><structfield>relhasindex</structfield></entry>
       <entry><type>bool</type></entry>

doc/src/sgml/diskusage.sgml

@@ -20,12 +20,12 @@
    stored. If the table has any columns with potentially-wide values,
    there also might be a <acronym>TOAST</> file associated with the table,
    which is used to store values too wide to fit comfortably in the main
-   table (see <xref linkend="storage-toast">).  There will be one index on the
-   <acronym>TOAST</> table, if present. There also might be indexes associated
-   with the base table.  Each table and index is stored in a separate disk
-   file &mdash; possibly more than one file, if the file would exceed one
-   gigabyte.  Naming conventions for these files are described in <xref
-   linkend="storage-file-layout">.
+   table (see <xref linkend="storage-toast">).  There will be one valid index
+   on the <acronym>TOAST</> table, if present. There also might be indexes
+   associated with the base table.  Each table and index is stored in a
+   separate disk file &mdash; possibly more than one file, if the file would
+   exceed one gigabyte.  Naming conventions for these files are described
+   in <xref linkend="storage-file-layout">.
   </para>
 
   <para>
@@ -44,7 +44,7 @@
 <programlisting>
 SELECT pg_relation_filepath(oid), relpages FROM pg_class WHERE relname = 'customer';
 
- pg_relation_filepath | relpages 
+ pg_relation_filepath | relpages
 ----------------------+----------
  base/16384/16806     |       60
 (1 row)
@@ -65,12 +65,12 @@ FROM pg_class,
       FROM pg_class
       WHERE relname = 'customer') AS ss
 WHERE oid = ss.reltoastrelid OR
-      oid = (SELECT reltoastidxid
-             FROM pg_class
-             WHERE oid = ss.reltoastrelid)
+      oid = (SELECT indexrelid
+             FROM pg_index
+             WHERE indrelid = ss.reltoastrelid)
 ORDER BY relname;
 
-       relname        | relpages 
+       relname        | relpages
 ----------------------+----------
  pg_toast_16806       |        0
  pg_toast_16806_index |        1
@@ -87,7 +87,7 @@ WHERE c.relname = 'customer' AND
       c2.oid = i.indexrelid
 ORDER BY c2.relname;
 
-       relname        | relpages 
+       relname        | relpages
 ----------------------+----------
  customer_id_indexdex |       26
 </programlisting>
@@ -101,7 +101,7 @@ SELECT relname, relpages
 FROM pg_class
 ORDER BY relpages DESC;
 
-       relname        | relpages 
+       relname        | relpages
 ----------------------+----------
  bigtable             |     3290
  customer             |     3144

doc/src/sgml/monitoring.sgml

@@ -1163,12 +1163,12 @@ postgres: <replaceable>user</> <replaceable>database</> <replaceable>host</> <re
     <row>
      <entry><structfield>tidx_blks_read</></entry>
      <entry><type>bigint</></entry>
-     <entry>Number of disk blocks read from this table's TOAST table index (if any)</entry>
+     <entry>Number of disk blocks read from this table's TOAST table indexes (if any)</entry>
     </row>
     <row>
      <entry><structfield>tidx_blks_hit</></entry>
      <entry><type>bigint</></entry>
-     <entry>Number of buffer hits in this table's TOAST table index (if any)</entry>
+     <entry>Number of buffer hits in this table's TOAST table indexes (if any)</entry>
     </row>
    </tbody>
    </tgroup>