Change publication's publish_generated_columns option type to enum.

The current boolean publish_generated_columns option only supports a
binary choice, which is insufficient for future enhancements where
generated columns can be of different types (e.g., stored or virtual). The
supported values for the publish_generated_columns option are 'none' and
'stored'.

Author: Vignesh C <vignesh21@gmail.com>
Reviewed-by: Peter Smith <smithpb2250@gmail.com>
Reviewed-by: Peter Eisentraut <peter@eisentraut.org>
Reviewed-by: Amit Kapila <amit.kapila16@gmail.com>
Discussion: https://postgr.es/m/d718d219-dd47-4a33-bb97-56e8fc4da994@eisentraut.org
Discussion: https://postgr.es/m/B80D17B2-2C8E-4C7D-87F2-E5B4BE3C069E@gmail.com

Author: Amit Kapila

doc/src/sgml/catalogs.sgml

@@ -6394,6 +6394,20 @@ SCRAM-SHA-256$<replaceable>&lt;iteration count&gt;</replaceable>:<replaceable>&l
       </para></entry>
      </row>
 
+     <row>
+      <entry role="catalog_table_entry"><para role="column_definition">
+       <structfield>pubgencols</structfield> <type>char</type>
+      </para>
+      <para>
+       Controls how to handle generated column replication when there is no
+       publication column list:
+       <literal>n</literal> = generated columns in the tables associated with
+       the publication should not be replicated,
+       <literal>s</literal> = stored generated columns in the tables associated
+       with the publication should be replicated.
+      </para></entry>
+     </row>
+
      <row>
       <entry role="catalog_table_entry"><para role="column_definition">
        <structfield>pubviaroot</structfield> <type>bool</type>

doc/src/sgml/ref/create_publication.sgml

@@ -89,10 +89,10 @@ CREATE PUBLICATION <replaceable class="parameter">name</replaceable>
 
      <para>
       When a column list is specified, only the named columns are replicated.
-      The column list can contain generated columns as well. If no column list
-      is specified, all table columns (except generated columns) are replicated
-      through this publication, including any columns added later. It has no
-      effect on <literal>TRUNCATE</literal> commands. See
+      The column list can contain stored generated columns as well. If no
+      column list is specified, all table columns (except generated columns)
+      are replicated through this publication, including any columns added
+      later. It has no effect on <literal>TRUNCATE</literal> commands. See
       <xref linkend="logical-replication-col-lists"/> for details about column
       lists.
      </para>
@@ -190,20 +190,31 @@ CREATE PUBLICATION <replaceable class="parameter">name</replaceable>
        </varlistentry>
 
        <varlistentry id="sql-createpublication-params-with-publish-generated-columns">
-        <term><literal>publish_generated_columns</literal> (<type>boolean</type>)</term>
+        <term><literal>publish_generated_columns</literal> (<type>enum</type>)</term>
         <listitem>
          <para>
           Specifies whether the generated columns present in the tables
-          associated with the publication should be replicated.
-          The default is <literal>false</literal>.
+          associated with the publication should be replicated. Possible values
+          are <literal>none</literal> and <literal>stored</literal>.
+         </para>
+
+         <para>
+          The default is <literal>none</literal> meaning the generated
+          columns present in the tables associated with publication will not be
+          replicated.
+         </para>
+
+         <para>
+          If set to <literal>stored</literal>, the stored generated columns
+          present in the tables associated with publication will be replicated.
          </para>
 
          <note>
           <para>
            If the subscriber is from a release prior to 18, then initial table
            synchronization won't copy generated columns even if parameter
-           <literal>publish_generated_columns</literal> is true in the
-           publisher.
+           <literal>publish_generated_columns</literal> is <literal>stored</literal>
+           in the publisher.
           </para>
          </note>
         </listitem>

src/backend/catalog/pg_publication.c

@@ -622,10 +622,11 @@ pub_collist_to_bitmapset(Bitmapset *columns, Datum pubcols, MemoryContext mcxt)
 /*
  * Returns a bitmap representing the columns of the specified table.
  *
- * Generated columns are included if include_gencols is true.
+ * Generated columns are included if include_gencols_type is
+ * PUBLISH_GENCOLS_STORED.
  */
 Bitmapset *
-pub_form_cols_map(Relation relation, bool include_gencols)
+pub_form_cols_map(Relation relation, PublishGencolsType include_gencols_type)
 {
 	Bitmapset  *result = NULL;
 	TupleDesc	desc = RelationGetDescr(relation);
@@ -634,9 +635,20 @@ pub_form_cols_map(Relation relation, bool include_gencols)
 	{
 		Form_pg_attribute att = TupleDescAttr(desc, i);
 
-		if (att->attisdropped || (att->attgenerated && !include_gencols))
+		if (att->attisdropped)
 			continue;
 
+		if (att->attgenerated)
+		{
+			/* We only support replication of STORED generated cols. */
+			if (att->attgenerated != ATTRIBUTE_GENERATED_STORED)
+				continue;
+
+			/* User hasn't requested to replicate STORED generated cols. */
+			if (include_gencols_type != PUBLISH_GENCOLS_STORED)
+				continue;
+		}
+
 		result = bms_add_member(result, att->attnum);
 	}
 
@@ -1068,7 +1080,7 @@ GetPublication(Oid pubid)
 	pub->pubactions.pubdelete = pubform->pubdelete;
 	pub->pubactions.pubtruncate = pubform->pubtruncate;
 	pub->pubviaroot = pubform->pubviaroot;
-	pub->pubgencols = pubform->pubgencols;
+	pub->pubgencols_type = pubform->pubgencols_type;
 
 	ReleaseSysCache(tup);
 
@@ -1276,9 +1288,23 @@ pg_get_publication_tables(PG_FUNCTION_ARGS)
 			{
 				Form_pg_attribute att = TupleDescAttr(desc, i);
 
-				if (att->attisdropped || (att->attgenerated && !pub->pubgencols))
+				if (att->attisdropped)
 					continue;
 
+				if (att->attgenerated)
+				{
+					/* We only support replication of STORED generated cols. */
+					if (att->attgenerated != ATTRIBUTE_GENERATED_STORED)
+						continue;
+
+					/*
+					 * User hasn't requested to replicate STORED generated
+					 * cols.
+					 */
+					if (pub->pubgencols_type != PUBLISH_GENCOLS_STORED)
+						continue;
+				}
+
 				attnums[nattnums++] = att->attnum;
 			}
 

src/backend/commands/publicationcmds.c

@@ -70,6 +70,7 @@ static void PublicationDropTables(Oid pubid, List *rels, bool missing_ok);
 static void PublicationAddSchemas(Oid pubid, List *schemas, bool if_not_exists,
 								  AlterPublicationStmt *stmt);
 static void PublicationDropSchemas(Oid pubid, List *schemas, bool missing_ok);
+static char defGetGeneratedColsOption(DefElem *def);
 
 
 static void
@@ -80,7 +81,7 @@ parse_publication_options(ParseState *pstate,
 						  bool *publish_via_partition_root_given,
 						  bool *publish_via_partition_root,
 						  bool *publish_generated_columns_given,
-						  bool *publish_generated_columns)
+						  char *publish_generated_columns)
 {
 	ListCell   *lc;
 
@@ -94,7 +95,7 @@ parse_publication_options(ParseState *pstate,
 	pubactions->pubdelete = true;
 	pubactions->pubtruncate = true;
 	*publish_via_partition_root = false;
-	*publish_generated_columns = false;
+	*publish_generated_columns = PUBLISH_GENCOLS_NONE;
 
 	/* Parse options */
 	foreach(lc, options)
@@ -160,7 +161,7 @@ parse_publication_options(ParseState *pstate,
 			if (*publish_generated_columns_given)
 				errorConflictingDefElem(defel, pstate);
 			*publish_generated_columns_given = true;
-			*publish_generated_columns = defGetBoolean(defel);
+			*publish_generated_columns = defGetGeneratedColsOption(defel);
 		}
 		else
 			ereport(ERROR,
@@ -344,15 +345,16 @@ pub_rf_contains_invalid_column(Oid pubid, Relation relation, List *ancestors,
  *    by the column list. If any column is missing, *invalid_column_list is set
  *    to true.
  * 2. Ensures that all the generated columns referenced in the REPLICA IDENTITY
- *    are published either by listing them in the column list or by enabling
- *    publish_generated_columns option. If any unpublished generated column is
- *    found, *invalid_gen_col is set to true.
+ *    are published, either by being explicitly named in the column list or, if
+ *    no column list is specified, by setting the option
+ *    publish_generated_columns to stored. If any unpublished
+ *    generated column is found, *invalid_gen_col is set to true.
  *
  * Returns true if any of the above conditions are not met.
  */
 bool
 pub_contains_invalid_column(Oid pubid, Relation relation, List *ancestors,
-							bool pubviaroot, bool pubgencols,
+							bool pubviaroot, char pubgencols_type,
 							bool *invalid_column_list,
 							bool *invalid_gen_col)
 {
@@ -394,10 +396,10 @@ pub_contains_invalid_column(Oid pubid, Relation relation, List *ancestors,
 
 		/*
 		 * As we don't allow a column list with REPLICA IDENTITY FULL, the
-		 * publish_generated_columns option must be set to true if the table
+		 * publish_generated_columns option must be set to stored if the table
 		 * has any stored generated columns.
 		 */
-		if (!pubgencols &&
+		if (pubgencols_type != PUBLISH_GENCOLS_STORED &&
 			relation->rd_att->constr &&
 			relation->rd_att->constr->has_generated_stored)
 			*invalid_gen_col = true;
@@ -425,10 +427,10 @@ pub_contains_invalid_column(Oid pubid, Relation relation, List *ancestors,
 		if (columns == NULL)
 		{
 			/*
-			 * The publish_generated_columns option must be set to true if the
-			 * REPLICA IDENTITY contains any stored generated column.
+			 * The publish_generated_columns option must be set to stored if
+			 * the REPLICA IDENTITY contains any stored generated column.
 			 */
-			if (!pubgencols && att->attgenerated)
+			if (pubgencols_type != PUBLISH_GENCOLS_STORED && att->attgenerated)
 			{
 				*invalid_gen_col = true;
 				break;
@@ -775,7 +777,7 @@ CreatePublication(ParseState *pstate, CreatePublicationStmt *stmt)
 	bool		publish_via_partition_root_given;
 	bool		publish_via_partition_root;
 	bool		publish_generated_columns_given;
-	bool		publish_generated_columns;
+	char		publish_generated_columns;
 	AclResult	aclresult;
 	List	   *relations = NIL;
 	List	   *schemaidlist = NIL;
@@ -834,8 +836,8 @@ CreatePublication(ParseState *pstate, CreatePublicationStmt *stmt)
 		BoolGetDatum(pubactions.pubtruncate);
 	values[Anum_pg_publication_pubviaroot - 1] =
 		BoolGetDatum(publish_via_partition_root);
-	values[Anum_pg_publication_pubgencols - 1] =
-		BoolGetDatum(publish_generated_columns);
+	values[Anum_pg_publication_pubgencols_type - 1] =
+		CharGetDatum(publish_generated_columns);
 
 	tup = heap_form_tuple(RelationGetDescr(rel), values, nulls);
 
@@ -922,7 +924,7 @@ AlterPublicationOptions(ParseState *pstate, AlterPublicationStmt *stmt,
 	bool		publish_via_partition_root_given;
 	bool		publish_via_partition_root;
 	bool		publish_generated_columns_given;
-	bool		publish_generated_columns;
+	char		publish_generated_columns;
 	ObjectAddress obj;
 	Form_pg_publication pubform;
 	List	   *root_relids = NIL;
@@ -1046,8 +1048,8 @@ AlterPublicationOptions(ParseState *pstate, AlterPublicationStmt *stmt,
 
 	if (publish_generated_columns_given)
 	{
-		values[Anum_pg_publication_pubgencols - 1] = BoolGetDatum(publish_generated_columns);
-		replaces[Anum_pg_publication_pubgencols - 1] = true;
+		values[Anum_pg_publication_pubgencols_type - 1] = CharGetDatum(publish_generated_columns);
+		replaces[Anum_pg_publication_pubgencols_type - 1] = true;
 	}
 
 	tup = heap_modify_tuple(tup, RelationGetDescr(rel), values, nulls,
@@ -2043,3 +2045,33 @@ AlterPublicationOwner_oid(Oid subid, Oid newOwnerId)
 
 	table_close(rel, RowExclusiveLock);
 }
+
+/*
+ * Extract the publish_generated_columns option value from a DefElem. "stored"
+ * and "none" values are accepted.
+ */
+static char
+defGetGeneratedColsOption(DefElem *def)
+{
+	char	   *sval;
+
+	/*
+	 * If no parameter value given, assume "stored" is meant.
+	 */
+	if (!def->arg)
+		return PUBLISH_GENCOLS_STORED;
+
+	sval = defGetString(def);
+
+	if (pg_strcasecmp(sval, "none") == 0)
+		return PUBLISH_GENCOLS_NONE;
+	if (pg_strcasecmp(sval, "stored") == 0)
+		return PUBLISH_GENCOLS_STORED;
+
+	ereport(ERROR,
+			errcode(ERRCODE_SYNTAX_ERROR),
+			errmsg("%s requires a \"none\" or \"stored\" value",
+				   def->defname));
+
+	return PUBLISH_GENCOLS_NONE;	/* keep compiler quiet */
+}