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 <[email protected]>
postgres · Dec 20, 2016 · 1753b1b · 1753b1b
1 parent db80acf
commit 1753b1b
Show file tree

Hide file tree

Showing 19 changed files with 490 additions and 269 deletions.
diff --git a/doc/src/sgml/catalogs.sgml b/doc/src/sgml/catalogs.sgml
@@ -260,6 +260,11 @@
       <entry>security labels on database objects</entry>
      </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>
@@ -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>
 

diff --git a/src/backend/catalog/Makefile b/src/backend/catalog/Makefile
@@ -42,6 +42,7 @@ POSTGRES_BKI_SRCS = $(addprefix $(top_srcdir)/src/include/catalog/,\
 	pg_foreign_table.h pg_policy.h pg_replication_origin.h \
 	pg_default_acl.h pg_init_privs.h pg_seclabel.h pg_shseclabel.h \
 	pg_collation.h pg_partitioned_table.h pg_range.h pg_transform.h \
+	pg_sequence.h \
 	toasting.h indexing.h \
     )
 

diff --git a/src/backend/catalog/dependency.c b/src/backend/catalog/dependency.c
@@ -66,6 +66,7 @@
 #include "commands/proclang.h"
 #include "commands/schemacmds.h"
 #include "commands/seclabel.h"
+#include "commands/sequence.h"
 #include "commands/trigger.h"
 #include "commands/typecmds.h"
 #include "nodes/nodeFuncs.h"
@@ -1114,6 +1115,11 @@ doDeletion(const ObjectAddress *object, int flags)
 					else
 						heap_drop_with_catalog(object->objectId);
 				}
+
+				/* for a sequence, in addition to dropping the heap, also
+				 * delete pg_sequence tuple */
+				if (relKind == RELKIND_SEQUENCE)
+					DeleteSequenceTuple(object->objectId);
 				break;
 			}
 

diff --git a/src/backend/catalog/information_schema.sql b/src/backend/catalog/information_schema.sql
@@ -1535,15 +1535,16 @@ CREATE VIEW sequences AS
            CAST(64 AS cardinal_number) AS numeric_precision,
            CAST(2 AS cardinal_number) AS numeric_precision_radix,
            CAST(0 AS cardinal_number) AS numeric_scale,
-           CAST(p.start_value AS character_data) AS start_value,
-           CAST(p.minimum_value AS character_data) AS minimum_value,
-           CAST(p.maximum_value AS character_data) AS maximum_value,
-           CAST(p.increment AS character_data) AS increment,
-           CAST(CASE WHEN p.cycle_option THEN 'YES' ELSE 'NO' END AS yes_or_no) AS cycle_option
-    FROM pg_namespace nc, pg_class c, LATERAL pg_sequence_parameters(c.oid) p
+           CAST(s.seqstart AS character_data) AS start_value,
+           CAST(s.seqmin AS character_data) AS minimum_value,
+           CAST(s.seqmax AS character_data) AS maximum_value,
+           CAST(s.seqincrement AS character_data) AS increment,
+           CAST(CASE WHEN s.seqcycle THEN 'YES' ELSE 'NO' END AS yes_or_no) AS cycle_option
+    FROM pg_namespace nc, pg_class c, pg_sequence s
     WHERE c.relnamespace = nc.oid
           AND c.relkind = 'S'
           AND (NOT pg_is_other_temp_schema(nc.oid))
+          AND c.oid = s.seqrelid
           AND (pg_has_role(c.relowner, 'USAGE')
                OR has_sequence_privilege(c.oid, 'SELECT, UPDATE, USAGE') );
 

diff --git a/src/backend/catalog/system_views.sql b/src/backend/catalog/system_views.sql
@@ -169,15 +169,15 @@ CREATE OR REPLACE VIEW pg_sequences AS
         N.nspname AS schemaname,
         C.relname AS sequencename,
         pg_get_userbyid(C.relowner) AS sequenceowner,
-        p.start_value AS start_value,
-        p.minimum_value AS min_value,
-        p.maximum_value AS max_value,
-        p.increment AS increment_by,
-        p.cycle_option AS cycle,
-        p.cache_size AS cache_size,
+        S.seqstart AS start_value,
+        S.seqmin AS min_value,
+        S.seqmax AS max_value,
+        S.seqincrement AS increment_by,
+        S.seqcycle AS cycle,
+        S.seqcache AS cache_size,
         pg_sequence_last_value(C.oid) AS last_value
-    FROM pg_class C LEFT JOIN pg_namespace N ON (N.oid = C.relnamespace),
-         LATERAL pg_sequence_parameters(C.oid) p
+    FROM pg_sequence S JOIN pg_class C ON (C.oid = S.seqrelid)
+         LEFT JOIN pg_namespace N ON (N.oid = C.relnamespace)
     WHERE NOT pg_is_other_temp_schema(N.oid)
           AND relkind = 'S';