Allow per-column foreign data wrapper options.

Shigeru Hanada, with fairly minor editing by me.

Author: robertmhaas

doc/src/sgml/catalogs.sgml

@@ -1157,6 +1157,15 @@
       </entry>
      </row>
 
+     <row>
+      <entry><structfield>attfdwoptions</structfield></entry>
+      <entry><type>text[]</type></entry>
+      <entry></entry>
+      <entry>
+       Attribute-level foreign data wrapper options, as <quote>keyword=value</> strings
+      </entry>
+     </row>
+
     </tbody>
    </tgroup>
   </table>

doc/src/sgml/information_schema.sgml

@@ -1018,6 +1018,69 @@
   </table>
  </sect1>
 
+ <sect1 id="infoschema-column-options">
+  <title><literal>column_options</literal></title>
+
+  <para>
+   The view <literal>column_options</literal> contains all the
+   options defined for foreign table columns in the current database.  Only
+   those foreign table columns are shown that the current user has access to
+   (by way of being the owner or having some privilege).
+  </para>
+
+  <table>
+   <title><literal>column_options</literal> Columns</title>
+
+   <tgroup cols="3">
+    <thead>
+     <row>
+      <entry>Name</entry>
+      <entry>Data Type</entry>
+      <entry>Description</entry>
+     </row>
+    </thead>
+
+    <tbody>
+     <row>
+      <entry><literal>table_catalog</literal></entry>
+      <entry><type>sql_identifier</type></entry>
+      <entry>Name of the database that contains the foreign table (always the current database)</entry>
+     </row>
+
+     <row>
+      <entry><literal>table_schema</literal></entry>
+      <entry><type>sql_identifier</type></entry>
+      <entry>Name of the schema that contains the foreign table</entry>
+     </row>
+
+     <row>
+      <entry><literal>table_name</literal></entry>
+      <entry><type>sql_identifier</type></entry>
+      <entry>Name of the foreign table</entry>
+     </row>
+
+     <row>
+      <entry><literal>column_name</literal></entry>
+      <entry><type>sql_identifier</type></entry>
+      <entry>Name of the column</entry>
+     </row>
+
+     <row>
+      <entry><literal>option_name</literal></entry>
+      <entry><type>sql_identifier</type></entry>
+      <entry>Name of an option</entry>
+     </row>
+
+     <row>
+      <entry><literal>option_value</literal></entry>
+      <entry><type>character_data</type></entry>
+      <entry>Value of the option</entry>
+     </row>
+    </tbody>
+   </tgroup>
+  </table>
+ </sect1>
+
  <sect1 id="infoschema-column-privileges">
   <title><literal>column_privileges</literal></title>
 

doc/src/sgml/ref/alter_foreign_table.sgml

@@ -36,6 +36,7 @@ ALTER FOREIGN TABLE <replaceable class="PARAMETER">name</replaceable>
     DROP [ COLUMN ] [ IF EXISTS ] <replaceable class="PARAMETER">column</replaceable> [ RESTRICT | CASCADE ]
     ALTER [ COLUMN ] <replaceable class="PARAMETER">column</replaceable> [ SET DATA ] TYPE <replaceable class="PARAMETER">type</replaceable>
     ALTER [ COLUMN ] <replaceable class="PARAMETER">column</replaceable> { SET | DROP } NOT NULL
+    ALTER [ COLUMN ] <replaceable class="PARAMETER">column</replaceable> OPTIONS ( [ ADD | SET | DROP ] <replaceable class="PARAMETER">option</replaceable> ['<replaceable class="PARAMETER">value</replaceable>'] [, ... ])
     OWNER TO <replaceable class="PARAMETER">new_owner</replaceable>
     OPTIONS ( [ ADD | SET | DROP ] <replaceable class="PARAMETER">option</replaceable> ['<replaceable class="PARAMETER">value</replaceable>'] [, ... ])
 </synopsis>
@@ -125,12 +126,13 @@ ALTER FOREIGN TABLE <replaceable class="PARAMETER">name</replaceable>
     <term><literal>OPTIONS ( [ ADD | SET | DROP ] <replaceable class="PARAMETER">option</replaceable> ['<replaceable class="PARAMETER">value</replaceable>'] [, ... ] )</literal></term>
     <listitem>
      <para>
-      Change options for the foreign table.
+      Change options for the foreign table or one of its columns.
       <literal>ADD</>, <literal>SET</>, and <literal>DROP</>
       specify the action to be performed.  <literal>ADD</> is assumed
-      if no operation is explicitly specified.  Option names must be
-      unique; names and values are also validated using the foreign
-      data wrapper library.
+      if no operation is explicitly specified.  Duplicate option names are not
+      allowed (although it's OK for a table option and a column option to have
+      the same name).  Option names and values are also validated using the
+      foreign data wrapper library.
      </para>
     </listitem>
    </varlistentry>

doc/src/sgml/ref/create_foreign_table.sgml

@@ -19,7 +19,7 @@
  <refsynopsisdiv>
 <synopsis>
 CREATE FOREIGN TABLE [ IF NOT EXISTS ] <replaceable class="PARAMETER">table_name</replaceable> ( [
-  { <replaceable class="PARAMETER">column_name</replaceable> <replaceable class="PARAMETER">data_type</replaceable> [ NULL | NOT NULL ] }
+  { <replaceable class="PARAMETER">column_name</replaceable> <replaceable class="PARAMETER">data_type</replaceable> [ OPTIONS ( <replaceable class="PARAMETER">option</replaceable> '<replaceable class="PARAMETER">value</replaceable>' [, ... ] ) ] [ NULL | NOT NULL ] }
     [, ... ]
 ] )
   SERVER <replaceable class="parameter">server_name</replaceable>
@@ -138,10 +138,12 @@ CREATE FOREIGN TABLE [ IF NOT EXISTS ] <replaceable class="PARAMETER">table_name
     <term><literal>OPTIONS ( <replaceable class="PARAMETER">option</replaceable> '<replaceable class="PARAMETER">value</replaceable>' [, ...] )</literal></term>
     <listitem>
      <para>
-      Options to be associated with the new foreign table.
+      Options to be associated with the new foreign table or one of its
+      columns.
       The allowed option names and values are specific to each foreign
       data wrapper and are validated using the foreign-data wrapper's
-      validator function. Option names must be unique.
+      validator function.  Duplicate option names are not allowed (although
+      it's OK for a table option and a column option to have the same name).
      </para>
     </listitem>
    </varlistentry>

doc/src/sgml/ref/psql-ref.sgml

@@ -891,6 +891,12 @@ testdb=>
         below.)
         </para>
 
+        <para>
+        For some types of relation, <literal>\d</> shows additional information
+        for each column: column values for sequences, indexed expression for
+        indexes and per-column foreign data wrapper options for foreign tables.
+        </para>
+
         <para>
         The command form <literal>\d+</literal> is identical, except that
         more information is displayed: any comments associated with the

src/backend/access/common/tupdesc.c

@@ -363,7 +363,7 @@ equalTupleDescs(TupleDesc tupdesc1, TupleDesc tupdesc2)
 			return false;
 		if (attr1->attcollation != attr2->attcollation)
 			return false;
-		/* attacl and attoptions are not even present... */
+		/* attacl, attoptions and attfdwoptions are not even present... */
 	}
 
 	if (tupdesc1->constr != NULL)
@@ -483,7 +483,7 @@ TupleDescInitEntry(TupleDesc desc,
 	att->attisdropped = false;
 	att->attislocal = true;
 	att->attinhcount = 0;
-	/* attacl and attoptions are not present in tupledescs */
+	/* attacl, attoptions and attfdwoptions are not present in tupledescs */
 
 	tuple = SearchSysCache1(TYPEOID, ObjectIdGetDatum(oidtypeid));
 	if (!HeapTupleIsValid(tuple))

src/backend/catalog/genbki.pl

@@ -369,7 +369,8 @@ sub emit_pgattr_row
         attislocal    => 't',
         attinhcount   => '0',
         attacl        => '_null_',
-        attoptions    => '_null_'
+        attoptions    => '_null_',
+        attfdwoptions => '_null_'
     );
     return {%PGATTR_DEFAULTS, %row};
 }
@@ -400,6 +401,7 @@ sub emit_schemapg_row
     # Only the fixed-size portions of the descriptors are ever used.
     delete $row->{attacl};
     delete $row->{attoptions};
+    delete $row->{attfdwoptions};
 
     # Expand booleans from 'f'/'t' to 'false'/'true'.
     # Some values might be other macros (eg FLOAT4PASSBYVAL), don't change.

src/backend/catalog/heap.c

@@ -126,7 +126,7 @@ static List *insert_ordered_unique_oid(List *list, Oid datum);
  */
 
 /*
- * The initializers below do not include the attoptions or attacl fields,
+ * The initializers below do not include trailing variable length fields,
  * but that's OK - we're never going to reference anything beyond the
  * fixed-size portion of the structure anyway.
  */
@@ -620,6 +620,7 @@ InsertPgAttributeTuple(Relation pg_attribute_rel,
 	/* start out with empty permissions and empty options */
 	nulls[Anum_pg_attribute_attacl - 1] = true;
 	nulls[Anum_pg_attribute_attoptions - 1] = true;
+	nulls[Anum_pg_attribute_attfdwoptions - 1] = true;
 
 	tup = heap_form_tuple(RelationGetDescr(pg_attribute_rel), values, nulls);
 

src/backend/catalog/information_schema.sql

@@ -2534,6 +2534,39 @@ GRANT SELECT ON element_types TO PUBLIC;
 
 -- SQL/MED views; these use section numbers from part 9 of the standard.
 
+/* Base view for foreign table columns */
+CREATE VIEW _pg_foreign_table_columns AS
+    SELECT n.nspname,
+           c.relname,
+           a.attname,
+           a.attfdwoptions
+    FROM pg_foreign_table t, pg_authid u, pg_namespace n, pg_class c,
+         pg_attribute a
+    WHERE u.oid = c.relowner
+          AND (pg_has_role(c.relowner, 'USAGE')
+               OR has_column_privilege(c.oid, a.attnum, 'SELECT, INSERT, UPDATE, REFERENCES'))
+          AND n.oid = c.relnamespace
+          AND c.oid = t.ftrelid
+          AND c.relkind = 'f'
+          AND a.attrelid = c.oid
+          AND a.attnum > 0;
+
+/*
+ * 24.2
+ * COLUMN_OPTIONS view
+ */
+CREATE VIEW column_options AS
+    SELECT CAST(current_database() AS sql_identifier) AS table_catalog,
+           c.nspname AS table_schema,
+           c.relname AS table_name,
+           c.attname AS column_name,
+           CAST((pg_options_to_table(c.attfdwoptions)).option_name AS sql_identifier) AS option_name,
+           CAST((pg_options_to_table(c.attfdwoptions)).option_value AS character_data) AS option_value
+    FROM _pg_foreign_table_columns c;
+
+GRANT SELECT ON column_options TO PUBLIC;
+
+
 /* Base view for foreign-data wrappers */
 CREATE VIEW _pg_foreign_data_wrappers AS
     SELECT w.oid,

src/backend/commands/tablecmds.c

@@ -346,6 +346,8 @@ static void ATPrepAlterColumnType(List **wqueue,
 static bool ATColumnChangeRequiresRewrite(Node *expr, AttrNumber varattno);
 static void ATExecAlterColumnType(AlteredTableInfo *tab, Relation rel,
 					  AlterTableCmd *cmd, LOCKMODE lockmode);
+static void ATExecAlterColumnGenericOptions(Relation rel, const char *colName,
+								List *options, LOCKMODE lockmode);
 static void ATPostAlterTypeCleanup(List **wqueue, AlteredTableInfo *tab, LOCKMODE lockmode);
 static void ATPostAlterTypeParse(Oid oldId, char *cmd,
 					 List **wqueue, LOCKMODE lockmode, bool rewrite);
@@ -2648,6 +2650,7 @@ AlterTableGetLockLevel(List *cmds)
 			case AT_DropNotNull:		/* may change some SQL plans */
 			case AT_SetNotNull:
 			case AT_GenericOptions:
+			case AT_AlterColumnGenericOptions:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -2925,6 +2928,12 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			ATPrepAlterColumnType(wqueue, tab, rel, recurse, recursing, cmd, lockmode);
 			pass = AT_PASS_ALTER_TYPE;
 			break;
+		case AT_AlterColumnGenericOptions:
+			ATSimplePermissions(rel, ATT_FOREIGN_TABLE);
+			/* This command never recurses */
+			/* No command-specific prep needed */
+			pass = AT_PASS_MISC;
+			break;
 		case AT_ChangeOwner:	/* ALTER OWNER */
 			/* This command never recurses */
 			/* No command-specific prep needed */
@@ -3169,6 +3178,9 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 		case AT_AlterColumnType:		/* ALTER COLUMN TYPE */
 			ATExecAlterColumnType(tab, rel, cmd, lockmode);
 			break;
+		case AT_AlterColumnGenericOptions:	/* ALTER COLUMN OPTIONS */
+			ATExecAlterColumnGenericOptions(rel, cmd->name, (List *) cmd->def, lockmode);
+			break;
 		case AT_ChangeOwner:	/* ALTER OWNER */
 			ATExecChangeOwner(RelationGetRelid(rel),
 							  get_role_oid(cmd->name, false),
@@ -7397,6 +7409,100 @@ ATExecAlterColumnType(AlteredTableInfo *tab, Relation rel,
 	heap_freetuple(heapTup);
 }
 
+static void
+ATExecAlterColumnGenericOptions(Relation rel,
+								const char *colName,
+								List *options,
+								LOCKMODE lockmode)
+{
+	Relation	ftrel;
+	Relation	attrel;
+	ForeignServer *server;
+	ForeignDataWrapper *fdw;
+	HeapTuple	tuple;
+	HeapTuple	newtuple;
+	bool		isnull;
+	Datum		repl_val[Natts_pg_attribute];
+	bool		repl_null[Natts_pg_attribute];
+	bool		repl_repl[Natts_pg_attribute];
+	Datum		datum;
+	Form_pg_foreign_table fttableform;
+	Form_pg_attribute atttableform;
+
+	if (options == NIL)
+		return;
+
+	/* First, determine FDW validator associated to the foreign table. */
+	ftrel = heap_open(ForeignTableRelationId, AccessShareLock);
+	tuple = SearchSysCache1(FOREIGNTABLEREL, rel->rd_id);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_OBJECT),
+				 errmsg("foreign table \"%s\" does not exist",
+						RelationGetRelationName(rel))));
+	fttableform = (Form_pg_foreign_table) GETSTRUCT(tuple);
+	server = GetForeignServer(fttableform->ftserver);
+	fdw = GetForeignDataWrapper(server->fdwid);
+
+	heap_close(ftrel, AccessShareLock);
+	ReleaseSysCache(tuple);
+
+	attrel = heap_open(AttributeRelationId, RowExclusiveLock);
+	tuple = SearchSysCacheAttName(RelationGetRelid(rel), colName);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						colName, RelationGetRelationName(rel))));
+
+	/* Prevent them from altering a system attribute */
+	atttableform = (Form_pg_attribute) GETSTRUCT(tuple);
+	if (atttableform->attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"", colName)));
+
+
+	/* Initialize buffers for new tuple values */
+	memset(repl_val, 0, sizeof(repl_val));
+	memset(repl_null, false, sizeof(repl_null));
+	memset(repl_repl, false, sizeof(repl_repl));
+
+	/* Extract the current options */
+	datum = SysCacheGetAttr(ATTNAME,
+							tuple,
+							Anum_pg_attribute_attfdwoptions,
+							&isnull);
+	if (isnull)
+		datum = PointerGetDatum(NULL);
+
+	/* Transform the options */
+	datum = transformGenericOptions(AttributeRelationId,
+									datum,
+									options,
+									fdw->fdwvalidator);
+
+	if (PointerIsValid(DatumGetPointer(datum)))
+		repl_val[Anum_pg_attribute_attfdwoptions - 1] = datum;
+	else
+		repl_null[Anum_pg_attribute_attfdwoptions - 1] = true;
+
+	repl_repl[Anum_pg_attribute_attfdwoptions - 1] = true;
+
+	/* Everything looks good - update the tuple */
+
+	newtuple = heap_modify_tuple(tuple, RelationGetDescr(attrel),
+								 repl_val, repl_null, repl_repl);
+	ReleaseSysCache(tuple);
+
+	simple_heap_update(attrel, &newtuple->t_self, newtuple);
+	CatalogUpdateIndexes(attrel, newtuple);
+
+	heap_close(attrel, RowExclusiveLock);
+
+	heap_freetuple(newtuple);
+}
+
 /*
  * Cleanup after we've finished all the ALTER TYPE operations for a
  * particular relation.  We have to drop and recreate all the indexes