On Mon, Mar 18, 2024 at 11:43 PM Tom Lane <t...@sss.pgh.pa.us> wrote:
>
> Alexander Korotkov <aekorot...@gmail.com> writes:
> > On Mon, Mar 18, 2024 at 2:01 AM jian he <jian.universal...@gmail.com> wrote:
> >> `
> >> Datum
> >> pg_basetype(PG_FUNCTION_ARGS)
> >> {
> >> Oid oid;
> >>
> >> oid = get_fn_expr_argtype(fcinfo->flinfo, 0);
> >> PG_RETURN_OID(getBaseType(oid));
> >> }
> >> `
>
> > Looks good to me. But should it be named pg_basetypeof()?
>
> I still don't like this approach. It forces the function to be
> used in a particular way that's highly redundant with pg_typeof.
> I think we'd be better off with
>
> pg_basetype(PG_FUNCTION_ARGS)
> {
> Oid typid = PG_GETARG_OID(0);
>
> PG_RETURN_OID(getBaseType(typid));
> }
>
> The use-case that the other definition handles would be implemented
> like
>
> pg_basetype(pg_typeof(expression))
>
trying to do it this way.
not sure the following error message is expected.
SELECT pg_basetype(-1);
ERROR: cache lookup failed for type 4294967295
From 31791e17893187d2c3c5d3644fac02ddcd4f7de6 Mon Sep 17 00:00:00 2001
From: jian he <jian.universality@gmail.com>
Date: Thu, 21 Mar 2024 10:23:04 +0800
Subject: [PATCH v5 1/1] Add pg_basetype(regtype) function to return the
basetype of a domain
Currently obtaining the base type of a domain involves a complex SQL query,
this specially in the case of recursive domain types.
To solve this, use the already available getBaseType() function,
and expose it as the pg_basetype SQL function.
if the argument is not a doamin type, return the type of the argument as is.
if the argument is a type of doamin, pg_basetype will recurse the domain dependencies chain
and return the real inner base type of the domain.
discussion: https://postgr.es/m/CAGRrpzZSX8j=MQcbCSEisFA=ic=K3bknVfnFjAv1diVJxFHJvg@mail.gmail.com
---
doc/src/sgml/func.sgml | 26 +++++++++++++++++++++++++
src/backend/utils/adt/misc.c | 10 ++++++++++
src/include/catalog/pg_proc.dat | 3 +++
src/test/regress/expected/domain.out | 29 ++++++++++++++++++++++++++++
src/test/regress/sql/domain.sql | 14 ++++++++++++++
5 files changed, 82 insertions(+)
diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index 030ea8af..983460fb 100644
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -24886,6 +24886,32 @@ SELECT pg_type_is_visible('myschema.widget'::regtype);
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_basetype</primary>
+ </indexterm>
+ <function>pg_basetype</function> ( <type>regtype</type> )
+ <returnvalue>regtype</returnvalue>
+ </para>
+ <para>
+ Returns the OID of the base type of a domain identified by its type OID.
+ If the argument is not the OID of a domain type, return the argument as is.
+ If there's a chain of domain dependencies, it will recurse until finding the base type.
+ </para>
+ <para>
+ For example:
+<programlisting>
+CREATE DOMAIN mytext as text;
+
+SELECT pg_basetype('mytext'::regtype);
+ pg_basetype
+-----------
+ text
+</programlisting>
+ </para></entry>
+ </row>
+
<row>
<entry id="pg-char-to-encoding" role="func_table_entry"><para role="func_signature">
<indexterm>
diff --git a/src/backend/utils/adt/misc.c b/src/backend/utils/adt/misc.c
index d4a92d0b..87db4ba6 100644
--- a/src/backend/utils/adt/misc.c
+++ b/src/backend/utils/adt/misc.c
@@ -565,6 +565,16 @@ pg_typeof(PG_FUNCTION_ARGS)
PG_RETURN_OID(get_fn_expr_argtype(fcinfo->flinfo, 0));
}
+/*
+ * Return the base type of the argument.
+ * iff the argument is not a type of domain, Return the type of the argument as is.
+ */
+Datum
+pg_basetype(PG_FUNCTION_ARGS)
+{
+ Oid typid = PG_GETARG_OID(0);
+ PG_RETURN_OID(getBaseType(typid));
+}
/*
* Implementation of the COLLATE FOR expression; returns the collation
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 042f66f7..5ce8ef46 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -3877,6 +3877,9 @@
{ oid => '1619', descr => 'type of the argument',
proname => 'pg_typeof', proisstrict => 'f', provolatile => 's',
prorettype => 'regtype', proargtypes => 'any', prosrc => 'pg_typeof' },
+{ oid => '6312', descr => 'get the base type of the oid of domain type',
+ proname => 'pg_basetype', proisstrict => 'f', provolatile => 's',
+ prorettype => 'regtype', proargtypes => 'regtype', prosrc => 'pg_basetype' },
{ oid => '3162',
descr => 'collation of the argument; implementation of the COLLATION FOR expression',
proname => 'pg_collation_for', proisstrict => 'f', provolatile => 's',
diff --git a/src/test/regress/expected/domain.out b/src/test/regress/expected/domain.out
index dc58793e..f79d31e4 100644
--- a/src/test/regress/expected/domain.out
+++ b/src/test/regress/expected/domain.out
@@ -1292,3 +1292,32 @@ SELECT * FROM information_schema.check_constraints
regression | public | pos_int_not_null | VALUE IS NOT NULL
(4 rows)
+--
+-- Get the base type of a domain
+--
+create domain mytext as text;
+create domain mytext_child_1 as mytext;
+create domain mytext_child_2 as mytext_child_1;
+select pg_basetype(pg_typeof('mytext'::mytext));
+ pg_basetype
+-------------
+ text
+(1 row)
+
+-- gets base types recursively
+select pg_basetype(pg_typeof('mytext_child_1'::mytext_child_1));
+ pg_basetype
+-------------
+ text
+(1 row)
+
+select pg_basetype(pg_typeof('mytext_child_2'::mytext_child_2));
+ pg_basetype
+-------------
+ text
+(1 row)
+
+drop domain mytext cascade;
+NOTICE: drop cascades to 2 other objects
+DETAIL: drop cascades to type mytext_child_1
+drop cascades to type mytext_child_2
diff --git a/src/test/regress/sql/domain.sql b/src/test/regress/sql/domain.sql
index ae1b7fbf..0f5ba98a 100644
--- a/src/test/regress/sql/domain.sql
+++ b/src/test/regress/sql/domain.sql
@@ -862,3 +862,17 @@ SELECT * FROM information_schema.check_constraints
FROM information_schema.domain_constraints
WHERE domain_name IN ('con', 'dom', 'pos_int', 'things'))
ORDER BY constraint_name;
+
+--
+-- Get the base type of a domain
+--
+create domain mytext as text;
+create domain mytext_child_1 as mytext;
+create domain mytext_child_2 as mytext_child_1;
+
+select pg_basetype(pg_typeof('mytext'::mytext));
+-- gets base types recursively
+select pg_basetype(pg_typeof('mytext_child_1'::mytext_child_1));
+select pg_basetype(pg_typeof('mytext_child_2'::mytext_child_2));
+
+drop domain mytext cascade;
\ No newline at end of file
base-commit: 30e144287a72529c9cd9fd6b07fe96eb8a1e270e
--
2.34.1
