On 2021/04/16 15:13, Bharath Rupireddy wrote:
On Fri, Apr 16, 2021 at 8:24 AM Fujii Masao <masao.fu...@oss.nttdata.com> wrote:
We are still discussing whether RESTRICT option should be pushed down to
a foreign data wrapper. But ISTM at least we could reach the consensus about
the drop of extra information for each foreign table. So what about applying
the attached patch and remove the extra information at first?
Thanks for the patch, here are some comments:
Thanks for the review!
1) Maybe new empty lines would be better so that the code doesn't look
cluttered:
relids = lappend_oid(relids, myrelid); --> a new line after this.
/* Log this relation only if needed for logical decoding */
if (RelationIsLogicallyLogged(rel))
relids = lappend_oid(relids, childrelid); --> a new line after this.
/* Log this relation only if needed for logical decoding */
relids = lappend_oid(relids, relid); --> a new line after this.
/* Log this relation only if needed for logical decoding */
if (RelationIsLogicallyLogged(rel))
Applied. Attached is the updated version of the patch
(truncate_foreign_table_dont_pass_only_clause_v2.patch).
This patch includes the patch that Horiguchi-san posted upthead.
I'm thinking to commit this patch at first.
2) Instead of
on foreign tables. <literal>rels</literal> is the list of
<structname>Relation</structname> data structure that indicates
a foreign table to truncate.
I think it is better with:
on foreign tables. <literal>rels</literal> is the list of
<structname>Relation</structname> data structures, where each
entry indicates a foreign table to truncate.
Justin posted the patch that improves the documents including
this description. I think that we should revisit that patch.
Attached is the updated version of that patch.
(truncate_foreign_table_docs_v1.patch)
3) How about adding an extra para(after below para in
postgres_fdw.sgml) on WHY we don't push "ONLY" to foreign tables while
truncating? We could add to the same para for other options if at all
we don't choose to push them.
<command>DELETE</command>, or <command>TRUNCATE</command>.
(Of course, the remote user you have specified in your user mapping must
have privileges to do these things.)
I agree to document the behavior that ONLY option is always ignored
for foreign tables. But I'm not sure if we can document WHY.
Because I could not find the past discussion about why ONLY option is
ignored on SELECT, etc... Maybe it's enough to document the behavior?
4) Isn't it better to mention the "ONLY" option is not pushed to remote
-- truncate with ONLY clause
TRUNCATE ONLY tru_ftable_parent;
TRUNCATE ONLY tru_ftable; -- truncate both parent and child
SELECT count(*) FROM tru_ftable; -- 0
5) I may be missing something here, why is even after ONLY is ignored
in the below truncate command, the sum is 126? Shouldn't it truncate
both tru_ftable_parent and
-- truncate with ONLY clause
TRUNCATE ONLY tru_ftable_parent;
SELECT sum(id) FROM tru_ftable_parent; -- 126
Because TRUNCATE ONLY command doesn't truncate tru_ftable_child talbe
that inehrits tru_ftable_parent. No?
Regards,
--
Fujii Masao
Advanced Computing Technology Center
Research and Development Headquarters
NTT DATA CORPORATION
diff --git a/contrib/postgres_fdw/deparse.c b/contrib/postgres_fdw/deparse.c
index bdc4c3620d..7a798530e3 100644
--- a/contrib/postgres_fdw/deparse.c
+++ b/contrib/postgres_fdw/deparse.c
@@ -2179,24 +2179,19 @@ deparseAnalyzeSql(StringInfo buf, Relation rel, List
**retrieved_attrs)
void
deparseTruncateSql(StringInfo buf,
List *rels,
- List *rels_extra,
DropBehavior behavior,
bool restart_seqs)
{
- ListCell *lc1,
- *lc2;
+ ListCell *cell;
appendStringInfoString(buf, "TRUNCATE ");
- forboth(lc1, rels, lc2, rels_extra)
+ foreach(cell, rels)
{
- Relation rel = lfirst(lc1);
- int extra = lfirst_int(lc2);
+ Relation rel = lfirst(cell);
- if (lc1 != list_head(rels))
+ if (cell != list_head(rels))
appendStringInfoString(buf, ", ");
- if (extra & TRUNCATE_REL_CONTEXT_ONLY)
- appendStringInfoString(buf, "ONLY ");
deparseRelation(buf, rel);
}
diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out
b/contrib/postgres_fdw/expected/postgres_fdw.out
index 5070d93239..d32f291089 100644
--- a/contrib/postgres_fdw/expected/postgres_fdw.out
+++ b/contrib/postgres_fdw/expected/postgres_fdw.out
@@ -8218,13 +8218,13 @@ drop table loc3;
-- test for TRUNCATE
-- ===================================================================
CREATE TABLE tru_rtable0 (id int primary key);
-CREATE TABLE tru_rtable1 (id int primary key);
CREATE FOREIGN TABLE tru_ftable (id int)
SERVER loopback OPTIONS (table_name 'tru_rtable0');
INSERT INTO tru_rtable0 (SELECT x FROM generate_series(1,10) x);
CREATE TABLE tru_ptable (id int) PARTITION BY HASH(id);
CREATE TABLE tru_ptable__p0 PARTITION OF tru_ptable
FOR VALUES WITH (MODULUS 2, REMAINDER 0);
+CREATE TABLE tru_rtable1 (id int primary key);
CREATE FOREIGN TABLE tru_ftable__p1 PARTITION OF tru_ptable
FOR VALUES WITH (MODULUS 2, REMAINDER 1)
SERVER loopback OPTIONS (table_name 'tru_rtable1');
@@ -8388,22 +8388,23 @@ SELECT sum(id) FROM tru_ftable; -- 95
95
(1 row)
-TRUNCATE ONLY tru_ftable; -- truncate only parent portion
-SELECT sum(id) FROM tru_ftable; -- 60
- sum
------
- 60
+TRUNCATE ONLY tru_ftable; -- truncate both of parent and child
+SELECT count(*) FROM tru_ftable; -- 0
+ count
+-------
+ 0
(1 row)
INSERT INTO tru_rtable0 (SELECT x FROM generate_series(21,25) x);
-SELECT sum(id) FROM tru_ftable; -- 175
+INSERT INTO tru_rtable0_child (SELECT x FROM generate_series(26,30) x);
+SELECT sum(id) FROM tru_ftable; -- 255
sum
-----
- 175
+ 255
(1 row)
TRUNCATE tru_ftable; -- truncate both of parent and child
-SELECT count(*) FROM tru_ftable; -- empty
+SELECT count(*) FROM tru_ftable; -- 0
count
-------
0
diff --git a/contrib/postgres_fdw/postgres_fdw.c
b/contrib/postgres_fdw/postgres_fdw.c
index c590f374c6..c521cba3fc 100644
--- a/contrib/postgres_fdw/postgres_fdw.c
+++ b/contrib/postgres_fdw/postgres_fdw.c
@@ -401,7 +401,6 @@ static void postgresExplainForeignModify(ModifyTableState
*mtstate,
static void postgresExplainDirectModify(ForeignScanState *node,
ExplainState *es);
static void postgresExecForeignTruncate(List *rels,
-
List *rels_extra,
DropBehavior behavior,
bool restart_seqs);
static bool postgresAnalyzeForeignTable(Relation relation,
@@ -2881,7 +2880,6 @@ postgresExplainDirectModify(ForeignScanState *node,
ExplainState *es)
*/
static void
postgresExecForeignTruncate(List *rels,
- List *rels_extra,
DropBehavior behavior,
bool restart_seqs)
{
@@ -2964,7 +2962,7 @@ postgresExecForeignTruncate(List *rels,
/* Construct the TRUNCATE command string */
initStringInfo(&sql);
- deparseTruncateSql(&sql, rels, rels_extra, behavior, restart_seqs);
+ deparseTruncateSql(&sql, rels, behavior, restart_seqs);
/* Issue the TRUNCATE command to remote server */
do_sql_command(conn, sql.data);
diff --git a/contrib/postgres_fdw/postgres_fdw.h
b/contrib/postgres_fdw/postgres_fdw.h
index 5d44b75314..9591c0f6c2 100644
--- a/contrib/postgres_fdw/postgres_fdw.h
+++ b/contrib/postgres_fdw/postgres_fdw.h
@@ -209,7 +209,6 @@ extern void deparseAnalyzeSql(StringInfo buf, Relation rel,
List
**retrieved_attrs);
extern void deparseTruncateSql(StringInfo buf,
List *rels,
- List *rels_extra,
DropBehavior
behavior,
bool restart_seqs);
extern void deparseStringLiteral(StringInfo buf, const char *val);
diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql
b/contrib/postgres_fdw/sql/postgres_fdw.sql
index 74590089bd..65643e120d 100644
--- a/contrib/postgres_fdw/sql/postgres_fdw.sql
+++ b/contrib/postgres_fdw/sql/postgres_fdw.sql
@@ -2355,7 +2355,6 @@ drop table loc3;
-- test for TRUNCATE
-- ===================================================================
CREATE TABLE tru_rtable0 (id int primary key);
-CREATE TABLE tru_rtable1 (id int primary key);
CREATE FOREIGN TABLE tru_ftable (id int)
SERVER loopback OPTIONS (table_name 'tru_rtable0');
INSERT INTO tru_rtable0 (SELECT x FROM generate_series(1,10) x);
@@ -2363,6 +2362,7 @@ INSERT INTO tru_rtable0 (SELECT x FROM
generate_series(1,10) x);
CREATE TABLE tru_ptable (id int) PARTITION BY HASH(id);
CREATE TABLE tru_ptable__p0 PARTITION OF tru_ptable
FOR VALUES WITH (MODULUS 2, REMAINDER 0);
+CREATE TABLE tru_rtable1 (id int primary key);
CREATE FOREIGN TABLE tru_ftable__p1 PARTITION OF tru_ptable
FOR VALUES WITH (MODULUS 2, REMAINDER 1)
SERVER loopback OPTIONS (table_name 'tru_rtable1');
@@ -2439,13 +2439,14 @@ INSERT INTO tru_rtable0 (SELECT x FROM
generate_series(5,9) x);
INSERT INTO tru_rtable0_child (SELECT x FROM generate_series(10,14) x);
SELECT sum(id) FROM tru_ftable; -- 95
-TRUNCATE ONLY tru_ftable; -- truncate only parent portion
-SELECT sum(id) FROM tru_ftable; -- 60
+TRUNCATE ONLY tru_ftable; -- truncate both of parent and child
+SELECT count(*) FROM tru_ftable; -- 0
INSERT INTO tru_rtable0 (SELECT x FROM generate_series(21,25) x);
-SELECT sum(id) FROM tru_ftable; -- 175
+INSERT INTO tru_rtable0_child (SELECT x FROM generate_series(26,30) x);
+SELECT sum(id) FROM tru_ftable; -- 255
TRUNCATE tru_ftable; -- truncate both of parent and child
-SELECT count(*) FROM tru_ftable; -- empty
+SELECT count(*) FROM tru_ftable; -- 0
-- cleanup
DROP FOREIGN TABLE tru_ftable_parent, tru_ftable_child,
tru_pk_ftable,tru_ftable__p1,tru_ftable;
diff --git a/doc/src/sgml/fdwhandler.sgml b/doc/src/sgml/fdwhandler.sgml
index 98882ddab8..3fe373ef00 100644
--- a/doc/src/sgml/fdwhandler.sgml
+++ b/doc/src/sgml/fdwhandler.sgml
@@ -1071,28 +1071,16 @@ EndDirectModify(ForeignScanState *node);
<para>
<programlisting>
void
-ExecForeignTruncate(List *rels, List *rels_extra,
- DropBehavior behavior, bool restart_seqs);
+ExecForeignTruncate(List *rels,
+ DropBehavior behavior,
+ bool restart_seqs);
</programlisting>
Truncate a set of foreign tables specified in <literal>rels</literal>.
This function is called when <xref linkend="sql-truncate"/> is executed
on foreign tables. <literal>rels</literal> is the list of
<structname>Relation</structname> data structure that indicates
- a foreign table to truncate. <literal>rels_extra</literal> the list of
- <literal>int</literal> value, which delivers extra information about
- a foreign table to truncate. Possible values are
- <literal>TRUNCATE_REL_CONTEXT_NORMAL</literal>, which means that
- the foreign table is specified WITHOUT <literal>ONLY</literal> clause
- in <command>TRUNCATE</command>,
- <literal>TRUNCATE_REL_CONTEXT_ONLY</literal>, which means that
- the foreign table is specified WITH <literal>ONLY</literal> clause,
- and <literal>TRUNCATE_REL_CONTEXT_CASCADING</literal>,
- which means that the foreign table is not specified explicitly,
- but will be truncated due to dependency (for example, partition table).
- There is one-to-one mapping between <literal>rels</literal> and
- <literal>rels_extra</literal>. The number of entries is the same
- between the two lists.
+ a foreign table to truncate.
</para>
<para>
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 096a6f2891..6e320f96ad 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -323,7 +323,6 @@ typedef struct ForeignTruncateInfo
{
Oid serverid;
List *rels;
- List *rels_extra;
} ForeignTruncateInfo;
/*
@@ -1620,7 +1619,6 @@ ExecuteTruncate(TruncateStmt *stmt)
{
List *rels = NIL;
List *relids = NIL;
- List *relids_extra = NIL;
List *relids_logged = NIL;
ListCell *cell;
@@ -1654,9 +1652,7 @@ ExecuteTruncate(TruncateStmt *stmt)
rels = lappend(rels, rel);
relids = lappend_oid(relids, myrelid);
- relids_extra = lappend_int(relids_extra, (recurse ?
-
TRUNCATE_REL_CONTEXT_NORMAL :
-
TRUNCATE_REL_CONTEXT_ONLY));
+
/* Log this relation only if needed for logical decoding */
if (RelationIsLogicallyLogged(rel))
relids_logged = lappend_oid(relids_logged, myrelid);
@@ -1704,8 +1700,7 @@ ExecuteTruncate(TruncateStmt *stmt)
rels = lappend(rels, rel);
relids = lappend_oid(relids, childrelid);
- relids_extra = lappend_int(relids_extra,
-
TRUNCATE_REL_CONTEXT_CASCADING);
+
/* Log this relation only if needed for logical
decoding */
if (RelationIsLogicallyLogged(rel))
relids_logged =
lappend_oid(relids_logged, childrelid);
@@ -1718,7 +1713,7 @@ ExecuteTruncate(TruncateStmt *stmt)
errhint("Do not specify the ONLY
keyword, or use TRUNCATE ONLY on the partitions directly.")));
}
- ExecuteTruncateGuts(rels, relids, relids_extra, relids_logged,
+ ExecuteTruncateGuts(rels, relids, relids_logged,
stmt->behavior,
stmt->restart_seqs);
/* And close the rels */
@@ -1739,15 +1734,13 @@ ExecuteTruncate(TruncateStmt *stmt)
*
* explicit_rels is the list of Relations to truncate that the command
* specified. relids is the list of Oids corresponding to explicit_rels.
- * relids_extra is the list of integer values that deliver extra information
- * about relations in explicit_rels. relids_logged is the list of Oids
- * (a subset of relids) that require WAL-logging. This is all a bit redundant,
- * but the existing callers have this information handy in this form.
+ * relids_logged is the list of Oids (a subset of relids) that require
+ * WAL-logging. This is all a bit redundant, but the existing callers have
+ * this information handy in this form.
*/
void
ExecuteTruncateGuts(List *explicit_rels,
List *relids,
- List *relids_extra,
List *relids_logged,
DropBehavior behavior, bool
restart_seqs)
{
@@ -1760,8 +1753,6 @@ ExecuteTruncateGuts(List *explicit_rels,
ResultRelInfo *resultRelInfo;
SubTransactionId mySubid;
ListCell *cell;
- ListCell *lc1,
- *lc2;
Oid *logrelids;
/*
@@ -1799,8 +1790,7 @@ ExecuteTruncateGuts(List *explicit_rels,
truncate_check_activity(rel);
rels = lappend(rels, rel);
relids = lappend_oid(relids, relid);
- relids_extra = lappend_int(relids_extra,
-
TRUNCATE_REL_CONTEXT_CASCADING);
+
/* Log this relation only if needed for logical
decoding */
if (RelationIsLogicallyLogged(rel))
relids_logged =
lappend_oid(relids_logged, relid);
@@ -1901,11 +1891,9 @@ ExecuteTruncateGuts(List *explicit_rels,
*/
mySubid = GetCurrentSubTransactionId();
- Assert(list_length(rels) == list_length(relids_extra));
- forboth(lc1, rels, lc2, relids_extra)
+ foreach(cell, rels)
{
- Relation rel = (Relation) lfirst(lc1);
- int extra = lfirst_int(lc2);
+ Relation rel = (Relation) lfirst(cell);
/*
* Save OID of partitioned tables for later; nothing else to do
for
@@ -1952,7 +1940,6 @@ ExecuteTruncateGuts(List *explicit_rels,
{
ft_info->serverid = serverid;
ft_info->rels = NIL;
- ft_info->rels_extra = NIL;
}
/*
@@ -1960,7 +1947,6 @@ ExecuteTruncateGuts(List *explicit_rels,
* foreign table belongs to.
*/
ft_info->rels = lappend(ft_info->rels, rel);
- ft_info->rels_extra = lappend_int(ft_info->rels_extra,
extra);
continue;
}
@@ -2044,7 +2030,6 @@ ExecuteTruncateGuts(List *explicit_rels,
Assert(routine->ExecForeignTruncate != NULL);
routine->ExecForeignTruncate(ft_info->rels,
-
ft_info->rels_extra,
behavior,
restart_seqs);
}
diff --git a/src/backend/replication/logical/worker.c
b/src/backend/replication/logical/worker.c
index fb3ba5c415..4dd869aaba 100644
--- a/src/backend/replication/logical/worker.c
+++ b/src/backend/replication/logical/worker.c
@@ -1795,7 +1795,6 @@ apply_handle_truncate(StringInfo s)
List *rels = NIL;
List *part_rels = NIL;
List *relids = NIL;
- List *relids_extra = NIL;
List *relids_logged = NIL;
ListCell *lc;
@@ -1825,7 +1824,6 @@ apply_handle_truncate(StringInfo s)
remote_rels = lappend(remote_rels, rel);
rels = lappend(rels, rel->localrel);
relids = lappend_oid(relids, rel->localreloid);
- relids_extra = lappend_int(relids_extra,
TRUNCATE_REL_CONTEXT_NORMAL);
if (RelationIsLogicallyLogged(rel->localrel))
relids_logged = lappend_oid(relids_logged,
rel->localreloid);
@@ -1864,7 +1862,6 @@ apply_handle_truncate(StringInfo s)
rels = lappend(rels, childrel);
part_rels = lappend(part_rels, childrel);
relids = lappend_oid(relids, childrelid);
- relids_extra = lappend_int(relids_extra,
TRUNCATE_REL_CONTEXT_CASCADING);
/* Log this relation only if needed for logical
decoding */
if (RelationIsLogicallyLogged(childrel))
relids_logged =
lappend_oid(relids_logged, childrelid);
@@ -1879,7 +1876,6 @@ apply_handle_truncate(StringInfo s)
*/
ExecuteTruncateGuts(rels,
relids,
- relids_extra,
relids_logged,
DROP_RESTRICT,
restart_seqs);
diff --git a/src/include/commands/tablecmds.h b/src/include/commands/tablecmds.h
index b808a07e46..14f4b4882f 100644
--- a/src/include/commands/tablecmds.h
+++ b/src/include/commands/tablecmds.h
@@ -21,16 +21,6 @@
#include "storage/lock.h"
#include "utils/relcache.h"
-/*
- * These values indicate how a relation was specified as the target to
- * truncate in TRUNCATE command.
- */
-#define TRUNCATE_REL_CONTEXT_NORMAL 1 /* specified without ONLY clause */
-#define TRUNCATE_REL_CONTEXT_ONLY 2 /* specified with ONLY clause */
-#define TRUNCATE_REL_CONTEXT_CASCADING 3 /* not specified but truncated
-
* due to dependency (e.g.,
-
* partition table) */
-
struct AlterTableUtilityContext; /* avoid including tcop/utility.h here
*/
@@ -68,7 +58,6 @@ extern void CheckTableNotInUse(Relation rel, const char
*stmt);
extern void ExecuteTruncate(TruncateStmt *stmt);
extern void ExecuteTruncateGuts(List *explicit_rels,
List *relids,
- List
*relids_extra,
List
*relids_logged,
DropBehavior
behavior,
bool
restart_seqs);
diff --git a/src/include/foreign/fdwapi.h b/src/include/foreign/fdwapi.h
index 4ebbca6de9..4f17becbb8 100644
--- a/src/include/foreign/fdwapi.h
+++ b/src/include/foreign/fdwapi.h
@@ -161,7 +161,6 @@ typedef List *(*ImportForeignSchema_function)
(ImportForeignSchemaStmt *stmt,
Oid serverOid);
typedef void (*ExecForeignTruncate_function) (List *rels,
-
List *rels_extra,
DropBehavior behavior,
bool restart_seqs);
diff --git a/doc/src/sgml/fdwhandler.sgml b/doc/src/sgml/fdwhandler.sgml
index 3fe373ef00..68737aee27 100644
--- a/doc/src/sgml/fdwhandler.sgml
+++ b/doc/src/sgml/fdwhandler.sgml
@@ -1076,35 +1076,32 @@ ExecForeignTruncate(List *rels,
bool restart_seqs);
</programlisting>
- Truncate a set of foreign tables specified in <literal>rels</literal>.
- This function is called when <xref linkend="sql-truncate"/> is executed
- on foreign tables. <literal>rels</literal> is the list of
- <structname>Relation</structname> data structure that indicates
- a foreign table to truncate.
+ Truncate foreign tables. This function is called when
+ <xref linkend="sql-truncate"/> is executed on a foreign table.
+ <literal>rels</literal> is a list of <structname>Relation</structname>
+ data structures for each foreign table to truncated.
</para>
<para>
- <literal>behavior</literal> defines how foreign tables should
- be truncated, using as possible values <literal>DROP_RESTRICT</literal>,
- which means that <literal>RESTRICT</literal> option is specified,
- and <literal>DROP_CASCADE</literal>, which means that
- <literal>CASCADE</literal> option is specified, in
- <command>TRUNCATE</command> command.
+ <literal>behavior</literal> is either <literal>DROP_RESTRICT</literal>
+ or <literal>DROP_CASCADE</literal>, which indicates that the
+ <literal>RESTRICT</literal> or <literal>CASCADE</literal> option was
+ requested in the original <command>TRUNCATE</command> command,
+ respectively.
</para>
<para>
- <literal>restart_seqs</literal> is set to <literal>true</literal>
- if <literal>RESTART IDENTITY</literal> option is specified in
- <command>TRUNCATE</command> command. It is <literal>false</literal>
- if <literal>CONTINUE IDENTITY</literal> option is specified.
+ If <literal>restart_seqs</literal> is <literal>true</literal>,
+ the original <command>TRUNCATE</command> command requested the
+ <literal>RESTART IDENTITY</literal> option, otherwise
+ <literal>CONTINUE IDENTITY</literal> option.
</para>
<para>
- <command>TRUNCATE</command> invokes
- <function>ExecForeignTruncate</function> once per foreign server
- that foreign tables to truncate belong to. This means that all foreign
- tables included in <literal>rels</literal> must belong to the same
- server.
+ <function>ExecForeignTruncate</function> is invoked once per
+ foreign server for which foreign tables are to be truncated.
+ This means that all foreign tables included in <literal>rels</literal>
+ must belong to the same server.
</para>
<para>
diff --git a/doc/src/sgml/postgres-fdw.sgml b/doc/src/sgml/postgres-fdw.sgml
index 5320accf6f..31b96e9d2e 100644
--- a/doc/src/sgml/postgres-fdw.sgml
+++ b/doc/src/sgml/postgres-fdw.sgml
@@ -452,11 +452,17 @@ OPTIONS (ADD password_required 'false');
<listitem>
<para>
This option controls whether <filename>postgres_fdw</filename> allows
- foreign tables to be truncated using <command>TRUNCATE</command>
+ foreign tables to be truncated using the <command>TRUNCATE</command>
command. It can be specified for a foreign table or a foreign server.
A table-level option overrides a server-level option.
The default is <literal>true</literal>.
</para>
+
+ <para>
+ Of course, if the remote table is not in fact truncatable, an error
+ would occur anyway. Use of this option primarily allows the error to
+ be thrown locally without querying the remote server.
+ </para>
</listitem>
</varlistentry>
</variablelist>
diff --git a/doc/src/sgml/ref/truncate.sgml b/doc/src/sgml/ref/truncate.sgml
index acf3633be4..9d846f88c9 100644
--- a/doc/src/sgml/ref/truncate.sgml
+++ b/doc/src/sgml/ref/truncate.sgml
@@ -173,7 +173,7 @@ TRUNCATE [ TABLE ] [ ONLY ] <replaceable
class="parameter">name</replaceable> [
<para>
<command>TRUNCATE</command> can be used for foreign tables if
- the foreign data wrapper supports, for instance,
+ supported by the foreign data wrapper, for instance,
see <xref linkend="postgres-fdw"/>.
</para>
</refsect1>
