Add pg_sequence system catalog

Move sequence metadata (start, increment, etc.) into a proper system
catalog instead of storing it in the sequence heap object.  This
separates the metadata from the sequence data.  Sequence metadata is now
operated on transactionally by DDL commands, whereas previously
rollbacks of sequence-related DDL commands would be ignored.

Reviewed-by: Andreas Karlsson <andreas@proxel.se>

1 files changed, 87 insertions, 1 deletions

diff --git a/doc/src/sgml/catalogs.sgml b/doc/src/sgml/catalogs.sgml
index 11c20191068..7a7bbde390b 100644
--- a/doc/src/sgml/catalogs.sgml
+++ b/doc/src/sgml/catalogs.sgml
@@ -261,6 +261,11 @@
      </row>
 
      <row>
+      <entry><link linkend="catalog-pg-sequence"><structname>pg_sequence</structname></link></entry>
+      <entry>information about sequences</entry>
+     </row>
+
+     <row>
       <entry><link linkend="catalog-pg-shdepend"><structname>pg_shdepend</structname></link></entry>
       <entry>dependencies on shared objects</entry>
      </row>
@@ -1546,7 +1551,8 @@
    The catalog <structname>pg_class</structname> catalogs tables and most
    everything else that has columns or is otherwise similar to a
    table.  This includes indexes (but see also
-   <structname>pg_index</structname>), sequences, views, materialized
+   <structname>pg_index</structname>), sequences (but see also
+   <structname>pg_sequence</structname>), views, materialized
    views, composite types, and TOAST tables; see <structfield>relkind</>.
    Below, when we mean all of these
    kinds of objects we speak of <quote>relations</quote>.  Not all
@@ -5587,6 +5593,86 @@
   </table>
  </sect1>
 
+ <sect1 id="catalog-pg-sequence">
+  <title><structname>pg_sequence</structname></title>
+
+  <indexterm zone="catalog-pg-sequence">
+   <primary>pg_sequence</primary>
+  </indexterm>
+
+  <para>
+   The catalog <structname>pg_sequence</structname> contains information about
+   sequences.  Some of the information about sequences, such as the name and
+   the schema, is in <structname>pg_class</structname>.
+  </para>
+
+  <table>
+   <title><structname>pg_sequence</> Columns</title>
+
+   <tgroup cols="4">
+    <thead>
+     <row>
+      <entry>Name</entry>
+      <entry>Type</entry>
+      <entry>References</entry>
+      <entry>Description</entry>
+     </row>
+    </thead>
+
+    <tbody>
+     <row>
+      <entry><structfield>seqrelid</structfield></entry>
+      <entry><type>oid</type></entry>
+      <entry><literal><link linkend="catalog-pg-class"><structname>pg_class</structname></link>.oid</literal></entry>
+      <entry>The OID of the <structname>pg_class</> entry for this sequence</entry>
+     </row>
+
+     <row>
+      <entry><structfield>seqstart</structfield></entry>
+      <entry><type>int8</type></entry>
+      <entry></entry>
+      <entry>Start value of the sequence</entry>
+     </row>
+
+     <row>
+      <entry><structfield>seqincrement</structfield></entry>
+      <entry><type>int8</type></entry>
+      <entry></entry>
+      <entry>Increment value of the sequence</entry>
+     </row>
+
+     <row>
+      <entry><structfield>seqmax</structfield></entry>
+      <entry><type>int8</type></entry>
+      <entry></entry>
+      <entry>Maximum value of the sequence</entry>
+     </row>
+
+     <row>
+      <entry><structfield>seqmin</structfield></entry>
+      <entry><type>int8</type></entry>
+      <entry></entry>
+      <entry>Minimum value of the sequence</entry>
+     </row>
+
+     <row>
+      <entry><structfield>seqcache</structfield></entry>
+      <entry><type>int8</type></entry>
+      <entry></entry>
+      <entry>Cache size of the sequence</entry>
+     </row>
+
+     <row>
+      <entry><structfield>seqcycle</structfield></entry>
+      <entry><type>bool</type></entry>
+      <entry></entry>
+      <entry>Whether the sequence cycles</entry>
+     </row>
+    </tbody>
+   </tgroup>
+  </table>
+ </sect1>
+
  <sect1 id="catalog-pg-shdepend">
   <title><structname>pg_shdepend</structname></title>