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Remove undocumented IS [NOT] OF syntax.
This feature was added a long time ago, in 7c1e67b and eb121ba, but never documented in any user-facing way. (Documentation added in 6126d3e was commented out almost immediately, in 8272fc3.) That's because, while this syntax is defined by SQL:99, our implementation is only vaguely related to the standard's semantics. The standard appears to intend a run-time not parse-time test, and it definitely intends that the test should understand subtype relationships. No one has stepped up to fix that in the intervening years, but people keep coming across the code and asking why it's not documented. Let's just get rid of it: if anyone ever wants to make it work per spec, they can easily recover whatever parts of this code are still of value from our git history. If there's anyone out there who's actually using this despite its undocumented status, they can switch to using pg_typeof() instead, eg. "pg_typeof(something) = 'mytype'::regtype". That gives essentially the same semantics as what our IS OF code did. (We didn't have that function last time this was discussed, or we would have ripped out IS OF then.) Discussion: https://postgr.es/m/CAKFQuwZ2pTc-DSkOiTfjauqLYkNREeNZvWmeg12Q-_69D+sYZA@mail.gmail.com Discussion: https://postgr.es/m/BAY20-F23E9F2B4DAB3E4E88D3623F99B0@phx.gbl Discussion: https://postgr.es/m/3E7CF81D.1000203@joeconway.com
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12 files changed

+38
-139
lines changed

12 files changed

+38
-139
lines changed

‎doc/src/sgml/func.sgml

Lines changed: 0 additions & 19 deletions
Original file line numberDiff line numberDiff line change
@@ -762,25 +762,6 @@ repeat('Pg', 4) <returnvalue>PgPgPgPg</returnvalue>
762762
expression must be of Boolean type.
763763
</para>
764764

765-
<!-- IS OF does not conform to the ISO SQL behavior, so it is undocumented here
766-
<para>
767-
<indexterm>
768-
<primary>IS OF</primary>
769-
</indexterm>
770-
<indexterm>
771-
<primary>IS NOT OF</primary>
772-
</indexterm>
773-
It is possible to check the data type of an expression using the
774-
predicates
775-
<synopsis>
776-
<replaceable>expression</replaceable> IS OF (typename, ...)
777-
<replaceable>expression</replaceable> IS NOT OF (typename, ...)
778-
</synopsis>
779-
They return a boolean value based on whether the expression's data
780-
type is one of the listed data types.
781-
</para>
782-
-->
783-
784765
<para>
785766
Some comparison-related functions are also available, as shown in <xref
786767
linkend="functions-comparison-func-table"/>.

‎src/backend/catalog/sql_features.txt

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -373,7 +373,7 @@ S096 Optional array bounds YES
373373
S097 Array element assignment NO
374374
S098 ARRAY_AGG YES
375375
S111 ONLY in query expressions YES
376-
S151 Type predicate NO
376+
S151 Type predicate NO see pg_typeof()
377377
S161 Subtype treatment NO
378378
S162 Subtype treatment for references NO
379379
S201 SQL-invoked routines on arrays YES

‎src/backend/nodes/outfuncs.c

Lines changed: 0 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -3213,10 +3213,6 @@ _outAExpr(StringInfo str, const A_Expr *node)
32133213
appendStringInfoString(str, " NULLIF ");
32143214
WRITE_NODE_FIELD(name);
32153215
break;
3216-
case AEXPR_OF:
3217-
appendStringInfoString(str, " OF ");
3218-
WRITE_NODE_FIELD(name);
3219-
break;
32203216
case AEXPR_IN:
32213217
appendStringInfoString(str, " IN ");
32223218
WRITE_NODE_FIELD(name);

‎src/backend/parser/gram.y

Lines changed: 0 additions & 16 deletions
Original file line numberDiff line numberDiff line change
@@ -13238,14 +13238,6 @@ a_expr: c_expr { $$ = $1; }
1323813238
{
1323913239
$$ = (Node *) makeSimpleA_Expr(AEXPR_NOT_DISTINCT, "=", $1, $6, @2);
1324013240
}
13241-
| a_expr IS OF '(' type_list ')' %prec IS
13242-
{
13243-
$$ = (Node *) makeSimpleA_Expr(AEXPR_OF, "=", $1, (Node *) $5, @2);
13244-
}
13245-
| a_expr IS NOT OF '(' type_list ')' %prec IS
13246-
{
13247-
$$ = (Node *) makeSimpleA_Expr(AEXPR_OF, "<>", $1, (Node *) $6, @2);
13248-
}
1324913241
| a_expr BETWEEN opt_asymmetric b_expr AND a_expr %prec BETWEEN
1325013242
{
1325113243
$$ = (Node *) makeSimpleA_Expr(AEXPR_BETWEEN,
@@ -13464,14 +13456,6 @@ b_expr: c_expr
1346413456
{
1346513457
$$ = (Node *) makeSimpleA_Expr(AEXPR_NOT_DISTINCT, "=", $1, $6, @2);
1346613458
}
13467-
| b_expr IS OF '(' type_list ')' %prec IS
13468-
{
13469-
$$ = (Node *) makeSimpleA_Expr(AEXPR_OF, "=", $1, (Node *) $5, @2);
13470-
}
13471-
| b_expr IS NOT OF '(' type_list ')' %prec IS
13472-
{
13473-
$$ = (Node *) makeSimpleA_Expr(AEXPR_OF, "<>", $1, (Node *) $6, @2);
13474-
}
1347513459
| b_expr IS DOCUMENT_P %prec IS
1347613460
{
1347713461
$$ = makeXmlExpr(IS_DOCUMENT, NULL, NIL,

‎src/backend/parser/parse_expr.c

Lines changed: 0 additions & 54 deletions
Original file line numberDiff line numberDiff line change
@@ -94,7 +94,6 @@ static Node *transformAExprOpAny(ParseState *pstate, A_Expr *a);
9494
static Node *transformAExprOpAll(ParseState *pstate, A_Expr *a);
9595
static Node *transformAExprDistinct(ParseState *pstate, A_Expr *a);
9696
static Node *transformAExprNullIf(ParseState *pstate, A_Expr *a);
97-
static Node *transformAExprOf(ParseState *pstate, A_Expr *a);
9897
static Node *transformAExprIn(ParseState *pstate, A_Expr *a);
9998
static Node *transformAExprBetween(ParseState *pstate, A_Expr *a);
10099
static Node *transformBoolExpr(ParseState *pstate, BoolExpr *a);
@@ -228,9 +227,6 @@ transformExprRecurse(ParseState *pstate, Node *expr)
228227
case AEXPR_NULLIF:
229228
result = transformAExprNullIf(pstate, a);
230229
break;
231-
case AEXPR_OF:
232-
result = transformAExprOf(pstate, a);
233-
break;
234230
case AEXPR_IN:
235231
result = transformAExprIn(pstate, a);
236232
break;
@@ -1168,51 +1164,6 @@ transformAExprNullIf(ParseState *pstate, A_Expr *a)
11681164
return (Node *) result;
11691165
}
11701166

1171-
/*
1172-
* Checking an expression for match to a list of type names. Will result
1173-
* in a boolean constant node.
1174-
*/
1175-
static Node *
1176-
transformAExprOf(ParseState *pstate, A_Expr *a)
1177-
{
1178-
Node *lexpr = a->lexpr;
1179-
Const *result;
1180-
ListCell *telem;
1181-
Oid ltype,
1182-
rtype;
1183-
bool matched = false;
1184-
1185-
if (operator_precedence_warning)
1186-
emit_precedence_warnings(pstate, PREC_GROUP_POSTFIX_IS, "IS",
1187-
lexpr, NULL,
1188-
a->location);
1189-
1190-
lexpr = transformExprRecurse(pstate, lexpr);
1191-
1192-
ltype = exprType(lexpr);
1193-
foreach(telem, (List *) a->rexpr)
1194-
{
1195-
rtype = typenameTypeId(pstate, lfirst(telem));
1196-
matched = (rtype == ltype);
1197-
if (matched)
1198-
break;
1199-
}
1200-
1201-
/*
1202-
* We have two forms: equals or not equals. Flip the sense of the result
1203-
* for not equals.
1204-
*/
1205-
if (strcmp(strVal(linitial(a->name)), "<>") == 0)
1206-
matched = (!matched);
1207-
1208-
result = (Const *) makeBoolConst(matched, false);
1209-
1210-
/* Make the result have the original input's parse location */
1211-
result->location = exprLocation((Node *) a);
1212-
1213-
return (Node *) result;
1214-
}
1215-
12161167
static Node *
12171168
transformAExprIn(ParseState *pstate, A_Expr *a)
12181169
{
@@ -3257,11 +3208,6 @@ operator_precedence_group(Node *node, const char **nodename)
32573208
*nodename = "IS";
32583209
group = PREC_GROUP_INFIX_IS;
32593210
}
3260-
else if (aexpr->kind == AEXPR_OF)
3261-
{
3262-
*nodename = "IS";
3263-
group = PREC_GROUP_POSTFIX_IS;
3264-
}
32653211
else if (aexpr->kind == AEXPR_IN)
32663212
{
32673213
*nodename = "IN";

‎src/include/nodes/parsenodes.h

Lines changed: 0 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -258,7 +258,6 @@ typedef enum A_Expr_Kind
258258
AEXPR_DISTINCT, /* IS DISTINCT FROM - name must be "=" */
259259
AEXPR_NOT_DISTINCT, /* IS NOT DISTINCT FROM - name must be "=" */
260260
AEXPR_NULLIF, /* NULLIF - name must be "=" */
261-
AEXPR_OF, /* IS [NOT] OF - name must be "=" or "<>" */
262261
AEXPR_IN, /* [NOT] IN - name must be "=" or "<>" */
263262
AEXPR_LIKE, /* [NOT] LIKE - name must be "~~" or "!~~" */
264263
AEXPR_ILIKE, /* [NOT] ILIKE - name must be "~~*" or "!~~*" */

‎src/test/regress/expected/arrays.out

Lines changed: 8 additions & 8 deletions
Original file line numberDiff line numberDiff line change
@@ -1149,10 +1149,10 @@ SELECT ARRAY[1,2,3]::text[]::int[]::float8[] AS "{1,2,3}";
11491149
{1,2,3}
11501150
(1 row)
11511151

1152-
SELECT ARRAY[1,2,3]::text[]::int[]::float8[] is of (float8[]) as "TRUE";
1153-
TRUE
1154-
------
1155-
t
1152+
SELECT pg_typeof(ARRAY[1,2,3]::text[]::int[]::float8[]) AS "double precision[]";
1153+
double precision[]
1154+
--------------------
1155+
double precision[]
11561156
(1 row)
11571157

11581158
SELECT ARRAY[['a','bc'],['def','hijk']]::text[]::varchar[] AS "{{a,bc},{def,hijk}}";
@@ -1161,10 +1161,10 @@ SELECT ARRAY[['a','bc'],['def','hijk']]::text[]::varchar[] AS "{{a,bc},{def,hijk
11611161
{{a,bc},{def,hijk}}
11621162
(1 row)
11631163

1164-
SELECT ARRAY[['a','bc'],['def','hijk']]::text[]::varchar[] is of (varchar[]) as "TRUE";
1165-
TRUE
1166-
------
1167-
t
1164+
SELECT pg_typeof(ARRAY[['a','bc'],['def','hijk']]::text[]::varchar[]) AS "character varying[]";
1165+
character varying[]
1166+
---------------------
1167+
character varying[]
11681168
(1 row)
11691169

11701170
SELECT CAST(ARRAY[[[[[['a','bb','ccc']]]]]] as text[]) as "{{{{{{a,bb,ccc}}}}}}";

‎src/test/regress/expected/domain.out

Lines changed: 8 additions & 14 deletions
Original file line numberDiff line numberDiff line change
@@ -70,22 +70,16 @@ from basictest;
7070
(3 rows)
7171

7272
-- check that union/case/coalesce type resolution handles domains properly
73-
select coalesce(4::domainint4, 7) is of (int4) as t;
74-
t
75-
---
76-
t
77-
(1 row)
78-
79-
select coalesce(4::domainint4, 7) is of (domainint4) as f;
80-
f
81-
---
82-
f
73+
select pg_typeof(coalesce(4::domainint4, 7));
74+
pg_typeof
75+
-----------
76+
integer
8377
(1 row)
8478

85-
select coalesce(4::domainint4, 7::domainint4) is of (domainint4) as t;
86-
t
87-
---
88-
t
79+
select pg_typeof(coalesce(4::domainint4, 7::domainint4));
80+
pg_typeof
81+
------------
82+
domainint4
8983
(1 row)
9084

9185
drop table basictest;

‎src/test/regress/expected/with.out

Lines changed: 14 additions & 14 deletions
Original file line numberDiff line numberDiff line change
@@ -142,26 +142,26 @@ SELECT * FROM t LIMIT 10;
142142

143143
-- Test behavior with an unknown-type literal in the WITH
144144
WITH q AS (SELECT 'foo' AS x)
145-
SELECT x, x IS OF (text) AS is_text FROM q;
146-
x | is_text
147-
-----+---------
148-
foo | t
145+
SELECT x, pg_typeof(x) FROM q;
146+
x | pg_typeof
147+
-----+-----------
148+
foo | text
149149
(1 row)
150150

151151
WITH RECURSIVE t(n) AS (
152152
SELECT 'foo'
153153
UNION ALL
154154
SELECT n || ' bar' FROM t WHERE length(n) < 20
155155
)
156-
SELECT n, n IS OF (text) AS is_text FROM t;
157-
n | is_text
158-
-------------------------+---------
159-
foo | t
160-
foo bar | t
161-
foo bar bar | t
162-
foo bar bar bar | t
163-
foo bar bar bar bar | t
164-
foo bar bar bar bar bar | t
156+
SELECT n, pg_typeof(n) FROM t;
157+
n | pg_typeof
158+
-------------------------+-----------
159+
foo | text
160+
foo bar | text
161+
foo bar bar | text
162+
foo bar bar bar | text
163+
foo bar bar bar bar | text
164+
foo bar bar bar bar bar | text
165165
(6 rows)
166166

167167
-- In a perfect world, this would work and resolve the literal as int ...
@@ -171,7 +171,7 @@ WITH RECURSIVE t(n) AS (
171171
UNION ALL
172172
SELECT n+1 FROM t WHERE n < 10
173173
)
174-
SELECT n, n IS OF (int) AS is_int FROM t;
174+
SELECT n, pg_typeof(n) FROM t;
175175
ERROR: operator does not exist: text + integer
176176
LINE 4: SELECT n+1 FROM t WHERE n < 10
177177
^

‎src/test/regress/sql/arrays.sql

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -343,9 +343,9 @@ SELECT * FROM array_op_test WHERE t <@ '{}' ORDER BY seqno;
343343

344344
-- array casts
345345
SELECT ARRAY[1,2,3]::text[]::int[]::float8[] AS "{1,2,3}";
346-
SELECT ARRAY[1,2,3]::text[]::int[]::float8[] is of (float8[]) as "TRUE";
346+
SELECT pg_typeof(ARRAY[1,2,3]::text[]::int[]::float8[]) AS "double precision[]";
347347
SELECT ARRAY[['a','bc'],['def','hijk']]::text[]::varchar[] AS "{{a,bc},{def,hijk}}";
348-
SELECT ARRAY[['a','bc'],['def','hijk']]::text[]::varchar[] is of (varchar[]) as "TRUE";
348+
SELECT pg_typeof(ARRAY[['a','bc'],['def','hijk']]::text[]::varchar[]) AS "character varying[]";
349349
SELECT CAST(ARRAY[[[[[['a','bb','ccc']]]]]] as text[]) as "{{{{{{a,bb,ccc}}}}}}";
350350
SELECT NULL::text[]::int[] AS "NULL";
351351

‎src/test/regress/sql/domain.sql

Lines changed: 2 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -59,9 +59,8 @@ select testtext || testvarchar as concat, testnumeric + 42 as sum
5959
from basictest;
6060

6161
-- check that union/case/coalesce type resolution handles domains properly
62-
select coalesce(4::domainint4, 7) is of (int4) as t;
63-
select coalesce(4::domainint4, 7) is of (domainint4) as f;
64-
select coalesce(4::domainint4, 7::domainint4) is of (domainint4) as t;
62+
select pg_typeof(coalesce(4::domainint4, 7));
63+
select pg_typeof(coalesce(4::domainint4, 7::domainint4));
6564

6665
drop table basictest;
6766
drop domain domainvarchar restrict;

‎src/test/regress/sql/with.sql

Lines changed: 3 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -77,14 +77,14 @@ SELECT * FROM t LIMIT 10;
7777

7878
-- Test behavior with an unknown-type literal in the WITH
7979
WITH q AS (SELECT 'foo' AS x)
80-
SELECT x, x IS OF (text) AS is_text FROM q;
80+
SELECT x, pg_typeof(x) FROM q;
8181

8282
WITH RECURSIVE t(n) AS (
8383
SELECT 'foo'
8484
UNION ALL
8585
SELECT n || ' bar' FROM t WHERE length(n) < 20
8686
)
87-
SELECT n, n IS OF (text) AS is_text FROM t;
87+
SELECT n, pg_typeof(n) FROM t;
8888

8989
-- In a perfect world, this would work and resolve the literal as int ...
9090
-- but for now, we have to be content with resolving to text too soon.
@@ -93,7 +93,7 @@ WITH RECURSIVE t(n) AS (
9393
UNION ALL
9494
SELECT n+1 FROM t WHERE n < 10
9595
)
96-
SELECT n, n IS OF (int) AS is_int FROM t;
96+
SELECT n, pg_typeof(n) FROM t;
9797

9898
--
9999
-- Some examples with a tree

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