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Commita0c6dfe

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Allow default expressions to be attached to columns of foreign tables.
There's still some discussion about exactly how postgres_fdw ought tohandle this case, but there seems no debate that we want to allow defaultsto be used for inserts into foreign tables. So remove the core-coderestrictions that prevented it.While at it, get rid of the special grammar productions for CREATE FOREIGNTABLE, and instead add explicit FEATURE_NOT_SUPPORTED error checks for thedisallowed cases. This makes the grammar a shade smaller, and moreimportantly results in much more intelligible error messages forunsupported cases. It's also one less thing to fix if we ever startsupporting constraints on foreign tables.
1 parent1ba0119 commita0c6dfe

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7 files changed

+123
-64
lines changed

7 files changed

+123
-64
lines changed

‎doc/src/sgml/ref/alter_foreign_table.sgml

Lines changed: 18 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -32,9 +32,11 @@ ALTER FOREIGN TABLE [ IF EXISTS ] <replaceable class="PARAMETER">name</replaceab
3232

3333
<phrase>where <replaceable class="PARAMETER">action</replaceable> is one of:</phrase>
3434

35-
ADD [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> <replaceable class="PARAMETER">data_type</replaceable> [NULL | NOT NULL ]
35+
ADD [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> <replaceable class="PARAMETER">data_type</replaceable> [COLLATE <replaceable class="PARAMETER">collation</replaceable> ] [ <replaceable class="PARAMETER">column_constraint</replaceable> [ ... ] ]
3636
DROP [ COLUMN ] [ IF EXISTS ] <replaceable class="PARAMETER">column_name</replaceable> [ RESTRICT | CASCADE ]
3737
ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> [ SET DATA ] TYPE <replaceable class="PARAMETER">data_type</replaceable>
38+
ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> SET DEFAULT <replaceable class="PARAMETER">expression</replaceable>
39+
ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> DROP DEFAULT
3840
ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> { SET | DROP } NOT NULL
3941
ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> SET STATISTICS <replaceable class="PARAMETER">integer</replaceable>
4042
ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> SET ( <replaceable class="PARAMETER">attribute_option</replaceable> = <replaceable class="PARAMETER">value</replaceable> [, ... ] )
@@ -59,6 +61,9 @@ ALTER FOREIGN TABLE [ IF EXISTS ] <replaceable class="PARAMETER">name</replaceab
5961
<para>
6062
This form adds a new column to the foreign table, using the same syntax as
6163
<xref linkend="SQL-CREATEFOREIGNTABLE">.
64+
Unlike the case when adding a column to a regular table, nothing happens
65+
to the underlying storage: this action simply declares that
66+
some new column is now accessible through the foreign table.
6267
</para>
6368
</listitem>
6469
</varlistentry>
@@ -97,6 +102,18 @@ ALTER FOREIGN TABLE [ IF EXISTS ] <replaceable class="PARAMETER">name</replaceab
97102
</listitem>
98103
</varlistentry>
99104

105+
<varlistentry>
106+
<term><literal>SET</literal>/<literal>DROP DEFAULT</literal></term>
107+
<listitem>
108+
<para>
109+
These forms set or remove the default value for a column.
110+
Default values only apply in subsequent <command>INSERT</command>
111+
or <command>UPDATE</> commands; they do not cause rows already in the
112+
table to change.
113+
</para>
114+
</listitem>
115+
</varlistentry>
116+
100117
<varlistentry>
101118
<term><literal>SET</literal>/<literal>DROP NOT NULL</literal></term>
102119
<listitem>

‎doc/src/sgml/ref/create_foreign_table.sgml

Lines changed: 30 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -19,12 +19,18 @@
1919
<refsynopsisdiv>
2020
<synopsis>
2121
CREATE FOREIGN TABLE [ IF NOT EXISTS ] <replaceable class="PARAMETER">table_name</replaceable> ( [
22-
{<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 ] }
22+
<replaceable class="PARAMETER">column_name</replaceable> <replaceable class="PARAMETER">data_type</replaceable> [ OPTIONS ( <replaceable class="PARAMETER">option</replaceable> '<replaceable class="PARAMETER">value</replaceable>' [, ... ] ) ] [COLLATE <replaceable>collation</replaceable> ] [ <replaceable class="PARAMETER">column_constraint</replaceable> [ ... ] ]
2323
[, ... ]
2424
] )
2525
SERVER <replaceable class="parameter">server_name</replaceable>
2626
[ OPTIONS ( <replaceable class="PARAMETER">option</replaceable> '<replaceable class="PARAMETER">value</replaceable>' [, ... ] ) ]
2727

28+
<phrase>where <replaceable class="PARAMETER">column_constraint</replaceable> is:</phrase>
29+
30+
[ CONSTRAINT <replaceable class="PARAMETER">constraint_name</replaceable> ]
31+
{ NOT NULL |
32+
NULL |
33+
DEFAULT <replaceable>default_expr</replaceable> }
2834
</synopsis>
2935
</refsynopsisdiv>
3036

@@ -131,6 +137,27 @@ CREATE FOREIGN TABLE [ IF NOT EXISTS ] <replaceable class="PARAMETER">table_name
131137
</listitem>
132138
</varlistentry>
133139

140+
<varlistentry>
141+
<term><literal>DEFAULT
142+
<replaceable>default_expr</replaceable></literal></term>
143+
<listitem>
144+
<para>
145+
The <literal>DEFAULT</> clause assigns a default data value for
146+
the column whose column definition it appears within. The value
147+
is any variable-free expression (subqueries and cross-references
148+
to other columns in the current table are not allowed). The
149+
data type of the default expression must match the data type of the
150+
column.
151+
</para>
152+
153+
<para>
154+
The default expression will be used in any insert operation that
155+
does not specify a value for the column. If there is no default
156+
for a column, then the default is null.
157+
</para>
158+
</listitem>
159+
</varlistentry>
160+
134161
<varlistentry>
135162
<term><replaceable class="PARAMETER">server_name</replaceable></term>
136163
<listitem>
@@ -190,6 +217,8 @@ SERVER film_server;
190217
<acronym>SQL</acronym> standard; however, much as with
191218
<link linkend="sql-createtable"><command>CREATE TABLE</></link>,
192219
<literal>NULL</> constraints and zero-column foreign tables are permitted.
220+
The ability to specify a default value is also a <productname>PostgreSQL</>
221+
extension.
193222
</para>
194223

195224
</refsect1>

‎src/backend/commands/tablecmds.c

Lines changed: 2 additions & 12 deletions
Original file line numberDiff line numberDiff line change
@@ -465,7 +465,7 @@ DefineRelation(CreateStmt *stmt, char relkind, Oid ownerId)
465465
if (stmt->constraints!=NIL&&relkind==RELKIND_FOREIGN_TABLE)
466466
ereport(ERROR,
467467
(errcode(ERRCODE_WRONG_OBJECT_TYPE),
468-
errmsg("constraintson foreign tablesare not supported")));
468+
errmsg("constraints are not supported on foreign tables")));
469469

470470
/*
471471
* Look up the namespace in which we are supposed to create the relation,
@@ -588,11 +588,6 @@ DefineRelation(CreateStmt *stmt, char relkind, Oid ownerId)
588588
{
589589
RawColumnDefault*rawEnt;
590590

591-
if (relkind==RELKIND_FOREIGN_TABLE)
592-
ereport(ERROR,
593-
(errcode(ERRCODE_WRONG_OBJECT_TYPE),
594-
errmsg("default values on foreign tables are not supported")));
595-
596591
Assert(colDef->cooked_default==NULL);
597592

598593
rawEnt= (RawColumnDefault*)palloc(sizeof(RawColumnDefault));
@@ -2978,7 +2973,7 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
29782973
* substitutes default values into INSERTs before it expands
29792974
* rules.
29802975
*/
2981-
ATSimplePermissions(rel,ATT_TABLE |ATT_VIEW);
2976+
ATSimplePermissions(rel,ATT_TABLE |ATT_VIEW |ATT_FOREIGN_TABLE);
29822977
ATSimpleRecursion(wqueue,rel,cmd,recurse,lockmode);
29832978
/* No command-specific prep needed */
29842979
pass=cmd->def ?AT_PASS_ADD_CONSTR :AT_PASS_DROP;
@@ -4528,11 +4523,6 @@ ATExecAddColumn(List **wqueue, AlteredTableInfo *tab, Relation rel,
45284523
{
45294524
RawColumnDefault*rawEnt;
45304525

4531-
if (relkind==RELKIND_FOREIGN_TABLE)
4532-
ereport(ERROR,
4533-
(errcode(ERRCODE_WRONG_OBJECT_TYPE),
4534-
errmsg("default values on foreign tables are not supported")));
4535-
45364526
rawEnt= (RawColumnDefault*)palloc(sizeof(RawColumnDefault));
45374527
rawEnt->attnum=attribute.attnum;
45384528
rawEnt->raw_default=copyObject(colDef->raw_default);

‎src/backend/parser/gram.y

Lines changed: 8 additions & 30 deletions
Original file line numberDiff line numberDiff line change
@@ -330,7 +330,6 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
330330
%type<list>stmtblockstmtmulti
331331
OptTableElementListTableElementListOptInheritdefinition
332332
OptTypedTableElementListTypedTableElementList
333-
OptForeignTableElementListForeignTableElementList
334333
reloptionsopt_reloptions
335334
OptWithopt_distinctopt_definitionfunc_argsfunc_args_list
336335
func_args_with_defaultsfunc_args_with_defaults_list
@@ -408,7 +407,6 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
408407
%type<vsetstmt>set_restset_rest_moreSetResetClauseFunctionSetResetClause
409408

410409
%type<node>TableElementTypedTableElementConstraintElemTableFuncElement
411-
ForeignTableElement
412410
%type<node>columnDefcolumnOptions
413411
%type<defelt>def_elemreloption_elemold_aggr_elem
414412
%type<node>def_argcolumnElemwhere_clausewhere_or_current_clause
@@ -4137,57 +4135,37 @@ AlterForeignServerStmt: ALTER SERVER name foreign_server_version alter_generic_o
41374135

41384136
CreateForeignTableStmt:
41394137
CREATEFOREIGNTABLEqualified_name
4140-
OptForeignTableElementList
4138+
'('OptTableElementList')'
41414139
SERVERnamecreate_generic_options
41424140
{
41434141
CreateForeignTableStmt *n = makeNode(CreateForeignTableStmt);
41444142
$4->relpersistence = RELPERSISTENCE_PERMANENT;
41454143
n->base.relation =$4;
4146-
n->base.tableElts =$5;
4144+
n->base.tableElts =$6;
41474145
n->base.inhRelations = NIL;
41484146
n->base.if_not_exists =false;
41494147
/* FDW-specific data*/
4150-
n->servername =$7;
4151-
n->options =$8;
4148+
n->servername =$9;
4149+
n->options =$10;
41524150
$$ = (Node *) n;
41534151
}
41544152
|CREATEFOREIGNTABLEIF_PNOTEXISTSqualified_name
4155-
OptForeignTableElementList
4153+
'('OptTableElementList')'
41564154
SERVERnamecreate_generic_options
41574155
{
41584156
CreateForeignTableStmt *n = makeNode(CreateForeignTableStmt);
41594157
$7->relpersistence = RELPERSISTENCE_PERMANENT;
41604158
n->base.relation =$7;
4161-
n->base.tableElts =$8;
4159+
n->base.tableElts =$9;
41624160
n->base.inhRelations = NIL;
41634161
n->base.if_not_exists =true;
41644162
/* FDW-specific data*/
4165-
n->servername =$10;
4166-
n->options =$11;
4163+
n->servername =$12;
4164+
n->options =$13;
41674165
$$ = (Node *) n;
41684166
}
41694167
;
41704168

4171-
OptForeignTableElementList:
4172-
'('ForeignTableElementList')'{$$ =$2; }
4173-
|'('')'{$$ = NIL; }
4174-
;
4175-
4176-
ForeignTableElementList:
4177-
ForeignTableElement
4178-
{
4179-
$$ = list_make1($1);
4180-
}
4181-
|ForeignTableElementList','ForeignTableElement
4182-
{
4183-
$$ = lappend($1,$3);
4184-
}
4185-
;
4186-
4187-
ForeignTableElement:
4188-
columnDef{$$ =$1; }
4189-
;
4190-
41914169
/*****************************************************************************
41924170
*
41934171
*QUERY:

‎src/backend/parser/parse_utilcmd.c

Lines changed: 52 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -70,6 +70,7 @@ typedef struct
7070
RangeVar*relation;/* relation to create */
7171
Relationrel;/* opened/locked rel, if ALTER */
7272
List*inhRelations;/* relations to inherit from */
73+
boolisforeign;/* true if CREATE/ALTER FOREIGN TABLE */
7374
boolisalter;/* true if altering existing table */
7475
boolhasoids;/* does relation have an OID column? */
7576
List*columns;/* ColumnDef items */
@@ -195,9 +196,15 @@ transformCreateStmt(CreateStmt *stmt, const char *queryString)
195196

196197
cxt.pstate=pstate;
197198
if (IsA(stmt,CreateForeignTableStmt))
199+
{
198200
cxt.stmtType="CREATE FOREIGN TABLE";
201+
cxt.isforeign= true;
202+
}
199203
else
204+
{
200205
cxt.stmtType="CREATE TABLE";
206+
cxt.isforeign= false;
207+
}
201208
cxt.relation=stmt->relation;
202209
cxt.rel=NULL;
203210
cxt.inhRelations=stmt->inhRelations;
@@ -515,11 +522,23 @@ transformColumnDefinition(CreateStmtContext *cxt, ColumnDef *column)
515522
break;
516523

517524
caseCONSTR_CHECK:
525+
if (cxt->isforeign)
526+
ereport(ERROR,
527+
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
528+
errmsg("constraints are not supported on foreign tables"),
529+
parser_errposition(cxt->pstate,
530+
constraint->location)));
518531
cxt->ckconstraints=lappend(cxt->ckconstraints,constraint);
519532
break;
520533

521534
caseCONSTR_PRIMARY:
522535
caseCONSTR_UNIQUE:
536+
if (cxt->isforeign)
537+
ereport(ERROR,
538+
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
539+
errmsg("constraints are not supported on foreign tables"),
540+
parser_errposition(cxt->pstate,
541+
constraint->location)));
523542
if (constraint->keys==NIL)
524543
constraint->keys=list_make1(makeString(column->colname));
525544
cxt->ixconstraints=lappend(cxt->ixconstraints,constraint);
@@ -531,7 +550,12 @@ transformColumnDefinition(CreateStmtContext *cxt, ColumnDef *column)
531550
break;
532551

533552
caseCONSTR_FOREIGN:
534-
553+
if (cxt->isforeign)
554+
ereport(ERROR,
555+
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
556+
errmsg("constraints are not supported on foreign tables"),
557+
parser_errposition(cxt->pstate,
558+
constraint->location)));
535559
/*
536560
* Fill in the current attribute's name and throw it into the
537561
* list of FK constraints to be processed later.
@@ -555,8 +579,8 @@ transformColumnDefinition(CreateStmtContext *cxt, ColumnDef *column)
555579
}
556580

557581
/*
558-
*GenerateALTER FOREIGN TABLE ALTER COLUMN statementwhich adds
559-
* per-column foreign data wrapper optionsfor this column.
582+
*If needed, generateALTER FOREIGN TABLE ALTER COLUMN statementto add
583+
* per-column foreign data wrapper optionsto this column after creation.
560584
*/
561585
if (column->fdwoptions!=NIL)
562586
{
@@ -587,6 +611,13 @@ transformColumnDefinition(CreateStmtContext *cxt, ColumnDef *column)
587611
staticvoid
588612
transformTableConstraint(CreateStmtContext*cxt,Constraint*constraint)
589613
{
614+
if (cxt->isforeign)
615+
ereport(ERROR,
616+
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
617+
errmsg("constraints are not supported on foreign tables"),
618+
parser_errposition(cxt->pstate,
619+
constraint->location)));
620+
590621
switch (constraint->contype)
591622
{
592623
caseCONSTR_PRIMARY:
@@ -640,7 +671,14 @@ transformTableLikeClause(CreateStmtContext *cxt, TableLikeClause *table_like_cla
640671
char*comment;
641672
ParseCallbackStatepcbstate;
642673

643-
setup_parser_errposition_callback(&pcbstate,cxt->pstate,table_like_clause->relation->location);
674+
setup_parser_errposition_callback(&pcbstate,cxt->pstate,
675+
table_like_clause->relation->location);
676+
677+
/* we could support LIKE in many cases, but worry about it another day */
678+
if (cxt->isforeign)
679+
ereport(ERROR,
680+
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
681+
errmsg("LIKE is not supported for foreign tables")));
644682

645683
relation=relation_openrv(table_like_clause->relation,AccessShareLock);
646684

@@ -2334,7 +2372,16 @@ transformAlterTableStmt(AlterTableStmt *stmt, const char *queryString)
23342372
pstate->p_sourcetext=queryString;
23352373

23362374
cxt.pstate=pstate;
2337-
cxt.stmtType="ALTER TABLE";
2375+
if (stmt->relkind==OBJECT_FOREIGN_TABLE)
2376+
{
2377+
cxt.stmtType="ALTER FOREIGN TABLE";
2378+
cxt.isforeign= true;
2379+
}
2380+
else
2381+
{
2382+
cxt.stmtType="ALTER TABLE";
2383+
cxt.isforeign= false;
2384+
}
23382385
cxt.relation=stmt->relation;
23392386
cxt.rel=rel;
23402387
cxt.inhRelations=NIL;

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