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* POC: PLpgSQL FOREACH IN JSON ARRAY
@ 2026-02-28 07:10 Pavel Stehule <[email protected]>
2026-03-11 20:57 ` Re: POC: PLpgSQL FOREACH IN JSON ARRAY Peter Eisentraut <[email protected]>
0 siblings, 1 reply; 6+ messages in thread
From: Pavel Stehule @ 2026-02-28 07:10 UTC (permalink / raw)
To: PostgreSQL Hackers <[email protected]>
Hi
I wrote PoC for previously proposed plpgsql statement FOREACH IN JSON ARRAY
It looks like:
do $$
declare x int;
begin
foreach x in json array '[1,2,3,4]'
loop
raise notice 'x: %', x;
end loop;
end;
$$
do $$
declare x int; y int;
begin
foreach x, y in json array '[{"x": 100, "y": 1000}, {"y": 1000, "x":
100}]'
loop
raise notice 'x: %, y: %', x, y;
end loop;
end
$$
My first motivation for this patch is performance. This is faster (3 - 4 x)
than using FOR IN SELECT FROM json_array_elements, because there is no
overhead of SQL executor. Second motivation is a little bit better
readability, because inside plpgsql' statements we have info about used
variables and we can use it.
The behavior is very similar to FOREACH IN ARRAY with one significant
difference - the values of JSON objects are assigned to the composite
variable or lists of variables by names (not by position). It made this
decision because jsonb doesn't preserve the position of the field in
object, and then assignment based on position cannot work.
The code is relatively short now - about 400 lines +/- and the code is
simple without risks.
There are some open questions - mainly if default mode for mapping json
fields to plpgsql variables should be in lax or strict mode. Now, it is
something between (cast errors are raised) - it is consistent
with jsonb_populate_record - but it should not be the final design. I
cannot say what is better - currently implemented behavior is consistent
with common plpgsql behaviour, but SQL/JSON is different. I can imagine
that default behaviour will be lax, and with some optional clauses we can
push behave to strict mode. I have no strong opinion about it. Maybe I
prefer the current "strict" behaviour a little bit, because it is more
"safe", but it is only my personal opinion. But again, I have no strong
opinion about this question and I very much invite any discussion about it.
This is proof of concept patch - casting between plpgsql arrays and json
arrays is not supported, documentation and regress tests are minimalistic,
but it is good enough for testing and good enough for decision, if this
feature is wanted or not (or if it needs some modifications).
This is a new feature (and proprietary feature). There should not be any
compatibility issues.
What do you think about this feature?
Regards
Pavel
Attachments:
[text/x-patch] v20260228-1-0001-FOREACH-scalar-IN-JSON-ARRAY.patch (28.0K, 3-v20260228-1-0001-FOREACH-scalar-IN-JSON-ARRAY.patch)
download | inline diff:
From c9f041e5408351961425eabeef161c4b72b93d1c Mon Sep 17 00:00:00 2001
From: "[email protected]" <[email protected]>
Date: Mon, 23 Feb 2026 12:53:44 +0100
Subject: [PATCH] FOREACH scalar IN JSON ARRAY
this patch introduce FOREACH scalar_var IN JSON ARRAY. The design is based
on behave of jsonb_array_elements functions. In this case, FOREACH enforce
casting to target type (because we know target type) and try to reduce
IO casting. Attention: IO casting can be more strict, then casting based
on cast functions.
DECLARE t int;
BEGIN
-- this can work because we use cast numeric -> int
FOREACH t IN JSON ARRAY '[1,2,3.14]'
LOOP
-- this fails, because IO cast is used, and integer input function
-- allows only digits
FOREAC t IN JSON ARRAY '[1,2,3,"3.14"]'
LOOP
Conceptual question is if casting should be strict like "old" PostgreSQL
json function or lax as "new" SQL/JSON functions? I can imagine lax mode
as default with possibility to switch to strict mode (this is not implemented
now):
FOREACH t IN JSON ARRAY '[1,2,3]' ERROR ON EMPTY ERROR ON ERROR
LOOP
...
The performance (best case for iteration over 1000 fields array) is about
4x better than when FOR IN SELECT jsonb_array_elements is used.
---
doc/src/sgml/plpgsql.sgml | 63 ++++
src/backend/utils/adt/jsonb_util.c | 1 +
src/pl/plpgsql/src/Makefile | 2 +-
.../plpgsql/src/expected/plpgsql_foreach.out | 119 +++++++
src/pl/plpgsql/src/meson.build | 1 +
src/pl/plpgsql/src/pl_comp.c | 4 +-
src/pl/plpgsql/src/pl_exec.c | 296 +++++++++++++++++-
src/pl/plpgsql/src/pl_funcs.c | 29 ++
src/pl/plpgsql/src/pl_gram.y | 39 ++-
src/pl/plpgsql/src/pl_unreserved_kwlist.h | 1 +
src/pl/plpgsql/src/plpgsql.h | 35 ++-
src/pl/plpgsql/src/sql/plpgsql_foreach.sql | 89 ++++++
12 files changed, 669 insertions(+), 10 deletions(-)
create mode 100644 src/pl/plpgsql/src/expected/plpgsql_foreach.out
create mode 100644 src/pl/plpgsql/src/sql/plpgsql_foreach.sql
diff --git a/doc/src/sgml/plpgsql.sgml b/doc/src/sgml/plpgsql.sgml
index 561f6e50d63..c11f44676bf 100644
--- a/doc/src/sgml/plpgsql.sgml
+++ b/doc/src/sgml/plpgsql.sgml
@@ -2780,6 +2780,69 @@ NOTICE: row = {10,11,12}
</para>
</sect2>
+ <sect2 id="plpgsql-foreach-json-array">
+ <title>Looping through JSON arrays</title>
+
+ <para>
+ The <literal>FOREACH</literal> loop is much like a <literal>FOREACH</literal> loop,
+ but instead of iterating through elements of the array,
+ it iterates through the elements of an JSON array value
+ (expression is internaly casted to jsonb type).
+
+<synopsis>
+<optional> <<<replaceable>label</replaceable>>> </optional>
+FOREACH <replaceable>target</replaceable> IN JSON ARRAY <replaceable>expression</replaceable> LOOP
+ <replaceable>statements</replaceable>
+END LOOP <optional> <replaceable>label</replaceable> </optional>;
+</synopsis>
+ </para>
+
+ <para>
+ Target can be scalar variable, composite variable or list of
+ scalar variables. When variable is not scalar, then assigned value
+ should be a JSON object and the JSON attributes are assigned by names.
+
+<programlisting>
+CREATE FUNCTION scan_rows(jsonb) RETURNS void AS $$
+DECLARE
+ x int;
+BEGIN
+ FOREACH x IN JSON ARRAY $1
+ LOOP
+ RAISE NOTICE 'row = %', x;
+ END LOOP;
+END;
+$$ LANGUAGE plpgsql;
+
+SELECT scan_rows('[1,2,3]');
+NOTICE: row = 1
+NOTICE: row = 2
+NOTICE: row = 3
+
+CREATE FUNCTION scan_rows(jsonb) RETURNS void AS $$
+DECLARE
+ x int; y varchar;
+BEGIN
+ FOREACH x, y IN JSON ARRAY $1
+ LOOP
+ RAISE NOTICE 'x: %, y: %', x, y;
+ END LOOP;
+END;
+$$ LANGUAGE plpgsql;
+
+SELECT scan_rows('[{},{"x":10},{"y":"Hi"},{"y":"Hi", "x":1000}]');
+NOTICE: x: <NULL>, y: <NULL>
+NOTICE: x: 10, y: <NULL>
+NOTICE: x: <NULL>, y: Hi
+NOTICE: x: 1000, y: Hi
+</programlisting>
+ </para>
+
+ <para>
+ Assigning to PLpgSQL array variables is not supported.
+ </para>
+ </sect2>
+
<sect2 id="plpgsql-error-trapping">
<title>Trapping Errors</title>
diff --git a/src/backend/utils/adt/jsonb_util.c b/src/backend/utils/adt/jsonb_util.c
index 91fb9ea09bf..7513b1198dd 100644
--- a/src/backend/utils/adt/jsonb_util.c
+++ b/src/backend/utils/adt/jsonb_util.c
@@ -18,6 +18,7 @@
#include "common/hashfn.h"
#include "miscadmin.h"
#include "port/pg_bitutils.h"
+#include "utils/builtins.h"
#include "utils/date.h"
#include "utils/datetime.h"
#include "utils/datum.h"
diff --git a/src/pl/plpgsql/src/Makefile b/src/pl/plpgsql/src/Makefile
index 63cb96fae3e..5bd0cf31dfc 100644
--- a/src/pl/plpgsql/src/Makefile
+++ b/src/pl/plpgsql/src/Makefile
@@ -35,7 +35,7 @@ REGRESS_OPTS = --dbname=$(PL_TESTDB)
REGRESS = plpgsql_array plpgsql_cache plpgsql_call plpgsql_control \
plpgsql_copy plpgsql_domain plpgsql_misc \
plpgsql_record plpgsql_simple plpgsql_transaction \
- plpgsql_trap plpgsql_trigger plpgsql_varprops
+ plpgsql_trap plpgsql_trigger plpgsql_varprops plpgsql_foreach
# where to find gen_keywordlist.pl and subsidiary files
TOOLSDIR = $(top_srcdir)/src/tools
diff --git a/src/pl/plpgsql/src/expected/plpgsql_foreach.out b/src/pl/plpgsql/src/expected/plpgsql_foreach.out
new file mode 100644
index 00000000000..43ae84412f1
--- /dev/null
+++ b/src/pl/plpgsql/src/expected/plpgsql_foreach.out
@@ -0,0 +1,119 @@
+-- numeric to numeric
+do $$
+declare x numeric;
+begin
+ foreach x in json array '[10,20,30,3.14, null]'
+ loop
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+NOTICE: 10
+NOTICE: 20
+NOTICE: 30
+NOTICE: 3.14
+NOTICE: <NULL>
+-- numeric to int by cast
+do $$
+declare x int;
+begin
+ foreach x in json array '[10,20,30,3.14, null]'
+ loop
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+NOTICE: 10
+NOTICE: 20
+NOTICE: 30
+NOTICE: 3
+NOTICE: <NULL>
+-- conversion "3.14" to int should to fail due IO cast
+do $$
+declare x int;
+begin
+ foreach x in json array '["10",20,30,"3.14"]'
+ loop
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+NOTICE: 10
+NOTICE: 20
+NOTICE: 30
+ERROR: invalid input syntax for type integer: "3.14"
+CONTEXT: PL/pgSQL function inline_code_block line 4 at FOREACH over json array
+-- jsonb to jsonb
+do $$
+declare x jsonb;
+begin
+ foreach x in json array '[10,20,30,3.14, null, "Hi"]'
+ loop
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+NOTICE: 10
+NOTICE: 20
+NOTICE: 30
+NOTICE: 3.14
+NOTICE: null
+NOTICE: "Hi"
+-- jsonb to json
+do $$
+declare x json;
+begin
+ foreach x in json array '[10,20,30,3.14, null, "Hi"]'
+ loop
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+NOTICE: 10
+NOTICE: 20
+NOTICE: 30
+NOTICE: 3.14
+NOTICE: null
+NOTICE: "Hi"
+-- iteration over composites
+do $$
+declare x int; y numeric; z varchar;
+begin
+ foreach x, y, z in json array '[{}, {"z":"Hi"}, {"y": 3.14}, {"z":"Hi", "x":10, "y":3.14}]'
+ loop
+ raise notice 'x: %, y: %, z: %', x, y, z;
+ end loop;
+end;
+$$;
+NOTICE: x: <NULL>, y: <NULL>, z: <NULL>
+NOTICE: x: <NULL>, y: <NULL>, z: Hi
+NOTICE: x: <NULL>, y: 3.14, z: <NULL>
+NOTICE: x: 10, y: 3.14, z: Hi
+create type t3 as (x int, y numeric, z varchar);
+do $$
+declare c t3;
+begin
+ foreach c in json array '[{}, {"z":"Hi"}, {"y": 3.14}, {"z":"Hi", "x":10, "y":3.14}]'
+ loop
+ raise notice 'x: %, y: %, z: %', c.x, c.y, c.z;
+ end loop;
+end;
+$$;
+NOTICE: x: <NULL>, y: <NULL>, z: <NULL>
+NOTICE: x: <NULL>, y: <NULL>, z: Hi
+NOTICE: x: <NULL>, y: 3.14, z: <NULL>
+NOTICE: x: 10, y: 3.14, z: Hi
+do $$
+declare c t3;
+begin
+ foreach c.x, c.y, c.z in json array '[{}, {"z":"Hi"}, {"y": 3.14}, {"z":"Hi", "x":10, "y":3.14}]'
+ loop
+ raise notice 'x: %, y: %, z: %', c.x, c.y, c.z;
+ end loop;
+end;
+$$;
+NOTICE: x: <NULL>, y: <NULL>, z: <NULL>
+NOTICE: x: <NULL>, y: <NULL>, z: Hi
+NOTICE: x: <NULL>, y: 3.14, z: <NULL>
+NOTICE: x: 10, y: 3.14, z: Hi
+drop type t3;
diff --git a/src/pl/plpgsql/src/meson.build b/src/pl/plpgsql/src/meson.build
index 6ff27006cfc..609eed7a28d 100644
--- a/src/pl/plpgsql/src/meson.build
+++ b/src/pl/plpgsql/src/meson.build
@@ -88,6 +88,7 @@ tests += {
'plpgsql_trap',
'plpgsql_trigger',
'plpgsql_varprops',
+ 'plpgsql_foreach',
],
},
}
diff --git a/src/pl/plpgsql/src/pl_comp.c b/src/pl/plpgsql/src/pl_comp.c
index 5ecc7766757..8fa60976cfd 100644
--- a/src/pl/plpgsql/src/pl_comp.c
+++ b/src/pl/plpgsql/src/pl_comp.c
@@ -1253,6 +1253,7 @@ make_datum_param(PLpgSQL_expr *expr, int dno, int location)
PLpgSQL_datum *datum;
Param *param;
MemoryContext oldcontext;
+ char *refname;
/* see comment in resolve_column_ref */
estate = expr->func->cur_estate;
@@ -1273,7 +1274,8 @@ make_datum_param(PLpgSQL_expr *expr, int dno, int location)
datum,
¶m->paramtype,
¶m->paramtypmod,
- ¶m->paramcollid);
+ ¶m->paramcollid,
+ &refname);
param->location = location;
return (Node *) param;
diff --git a/src/pl/plpgsql/src/pl_exec.c b/src/pl/plpgsql/src/pl_exec.c
index 84552e32c87..3383b42c39a 100644
--- a/src/pl/plpgsql/src/pl_exec.c
+++ b/src/pl/plpgsql/src/pl_exec.c
@@ -41,6 +41,8 @@
#include "utils/builtins.h"
#include "utils/datum.h"
#include "utils/fmgroids.h"
+#include "utils/jsonb.h"
+#include "utils/jsonfuncs.h"
#include "utils/lsyscache.h"
#include "utils/memutils.h"
#include "utils/rel.h"
@@ -305,6 +307,8 @@ static int exec_stmt_forc(PLpgSQL_execstate *estate,
PLpgSQL_stmt_forc *stmt);
static int exec_stmt_foreach_a(PLpgSQL_execstate *estate,
PLpgSQL_stmt_foreach_a *stmt);
+static int exec_stmt_foreach_json_a(PLpgSQL_execstate *estate,
+ PLpgSQL_stmt_foreach_json_a *stmt);
static int exec_stmt_open(PLpgSQL_execstate *estate,
PLpgSQL_stmt_open *stmt);
static int exec_stmt_fetch(PLpgSQL_execstate *estate,
@@ -2075,6 +2079,10 @@ exec_stmts(PLpgSQL_execstate *estate, List *stmts)
rc = exec_stmt_foreach_a(estate, (PLpgSQL_stmt_foreach_a *) stmt);
break;
+ case PLPGSQL_STMT_FOREACH_JSON_A:
+ rc = exec_stmt_foreach_json_a(estate, (PLpgSQL_stmt_foreach_json_a *) stmt);
+ break;
+
case PLPGSQL_STMT_EXIT:
rc = exec_stmt_exit(estate, (PLpgSQL_stmt_exit *) stmt);
break;
@@ -2995,6 +3003,240 @@ exec_stmt_forc(PLpgSQL_execstate *estate, PLpgSQL_stmt_forc *stmt)
}
+/*
+ * Convert JsonbValue to Datum that can be assigned to PLpgSQL_var.
+ */
+static Datum
+JsonbValueToDatum(JsonbValue *jbv,
+ Oid *typid, int32 *typmod, bool *isnull,
+ Oid expected_typid, int32 expected_typmod,
+ void **cache, MemoryContext mcxt)
+{
+ if (expected_typid == JSONBOID)
+ {
+ *typid = JSONBOID;
+ *typmod = -1;
+ *isnull = false;
+
+ return PointerGetDatum(JsonbValueToJsonb(jbv));
+ }
+ else if (expected_typid == JSONOID)
+ {
+ Jsonb *jsonb;
+ char *str;
+
+ /* serialize JsonValue to JSON text */
+ jsonb = JsonbValueToJsonb(jbv);
+ str = JsonbToCString(NULL, &jsonb->root, VARSIZE(jsonb));
+
+ *typid = TEXTOID;
+ *typmod = -1;
+ *isnull = false;
+
+ return PointerGetDatum(cstring_to_text(str));
+ }
+ else if (jbv->type == jbvNull)
+ {
+ *typid = expected_typid;
+ *typmod = -1;
+ *isnull = true;
+
+ return (Datum) 0;
+ }
+ else if (jbv->type == jbvString)
+ {
+ *typid = TEXTOID;
+ *typmod = -1;
+ *isnull = false;
+
+ return PointerGetDatum(cstring_to_text_with_len(jbv->val.string.val, jbv->val.string.len));
+ }
+ else if (jbv->type == jbvNumeric)
+ {
+ *typid = NUMERICOID;
+ *typmod = -1;
+ *isnull = false;
+
+ return PointerGetDatum(jbv->val.numeric);
+ }
+ else if (jbv->type == jbvBool)
+ {
+ *typid = BOOLOID;
+ *typmod = -1;
+ *isnull = false;
+
+ return BoolGetDatum(jbv->val.boolean);
+ }
+ else
+ {
+ Jsonb *jsonb;
+ Datum result;
+
+ jsonb = JsonbValueToJsonb(jbv);
+ result = json_populate_type(PointerGetDatum(jsonb), JSONBOID,
+ expected_typid, expected_typmod,
+ cache, mcxt,
+ isnull, false, NULL);
+
+ *typid = expected_typid;
+ *typmod = expected_typmod;
+
+ return result;
+ }
+}
+
+/* ----------
+ * exec_stmt_foreach_json_a Loop over elements in json array
+ *
+ * When target is a composite, then target is populated like json_to_populate_record.
+ * jsonb doesn't preserve attribute order, so position based mapping between
+ * target and source can be possibly dangerous (with unexpected behave).
+ * ----------
+ */
+static int
+exec_stmt_foreach_json_a(PLpgSQL_execstate *estate,
+ PLpgSQL_stmt_foreach_json_a *stmt)
+{
+ Oid exprtypeid;
+ int32 exprtypmod;
+ Datum exprdatum;
+ PLpgSQL_datum *loop_var;
+ Oid loop_var_typid;
+ int32 loop_var_typmod;
+ Oid loop_var_collation;
+ char *loop_var_name;
+ Jsonb *jb;
+ JsonbIterator *it;
+ JsonbValue jbv;
+ JsonbIteratorToken r;
+ MemoryContext stmt_mcontext;
+ MemoryContext oldcontext;
+ MemoryContext tmp_cxt;
+ bool found = false;
+ bool isnull;
+ bool skipNested = false;
+ int rc = PLPGSQL_RC_OK;
+ void *cache = NULL;
+
+ /* get the value of the expression */
+ exprdatum = exec_eval_expr(estate, stmt->expr, &isnull,
+ &exprtypeid, &exprtypmod);
+ if (isnull)
+ ereport(ERROR,
+ (errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
+ errmsg("FOREACH expression must not be null")));
+
+ /*
+ * Do as much as possible of the code below in stmt_mcontext, to avoid any
+ * leaks from called subroutines. We need a private stmt_mcontext since
+ * we'll be calling arbitrary statement code.
+ */
+ stmt_mcontext = get_stmt_mcontext(estate);
+ push_stmt_mcontext(estate);
+ oldcontext = MemoryContextSwitchTo(stmt_mcontext);
+
+ tmp_cxt = AllocSetContextCreate(CurrentMemoryContext,
+ "FOREACH IN JSON ARRAY temporary cxt",
+ ALLOCSET_DEFAULT_SIZES);
+
+ /* cast to jsonb */
+ exprdatum = exec_cast_value(estate, exprdatum, &isnull,
+ exprtypeid, exprtypmod,
+ JSONBOID, -1);
+
+ Assert(!isnull);
+
+ /*
+ * We must copy the array into stmt_mcontext, else it will disappear in
+ * exec_eval_cleanup. This is annoying, but cleanup will certainly happen
+ * while running the loop body, so we have little choice.
+ */
+ jb = DatumGetJsonbPCopy(exprdatum);
+
+ /* Clean up any leftover temporary memory */
+ exec_eval_cleanup(estate);
+
+ /*
+ * This is compatible with jsonb_array_element. SQL/JSON functions are not
+ * too strict like PostgreSQL proprietary (old json) functions. In SQL/JSON
+ * a scalar is equal to one element array. The basic question is if FOREACH
+ * should be more restrictive like old JSON function, or less restrictive
+ * like SQL/JSON functions.
+ */
+ if (JB_ROOT_IS_SCALAR(jb))
+ ereport(ERROR,
+ (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+ errmsg("cannot extract elements from a scalar")));
+ else if (!JB_ROOT_IS_ARRAY(jb))
+ ereport(ERROR,
+ (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+ errmsg("cannot extract elements from an object")));
+
+ /* Set up the loop variable and see if it is of an array type */
+ loop_var = estate->datums[stmt->varno];
+
+ plpgsql_exec_get_datum_type_info(estate, loop_var,
+ &loop_var_typid, &loop_var_typmod,
+ &loop_var_collation, &loop_var_name);
+
+ it = JsonbIteratorInit(&jb->root);
+
+ while ((r = JsonbIteratorNext(&it, &jbv, skipNested)) != WJB_DONE)
+ {
+ skipNested = true;
+
+ if (r == WJB_ELEM)
+ {
+ Datum val;
+ Oid valtypid;
+ int32 valtypmod;
+ bool valisnull;
+
+ MemoryContextSwitchTo(tmp_cxt);
+
+ val = JsonbValueToDatum(&jbv,
+ &valtypid, &valtypmod, &valisnull,
+ loop_var_typid, loop_var_typmod,
+ &cache, stmt_mcontext);
+
+ /* exec_assign_value and exec_stmts must run in the main context */
+ MemoryContextSwitchTo(oldcontext);
+
+ /* Assign current element/slice to the loop variable */
+ exec_assign_value(estate, loop_var, val,
+ valisnull, valtypid, valtypmod);
+
+ MemoryContextReset(tmp_cxt);
+
+ /*
+ * Execute the statements
+ */
+ rc = exec_stmts(estate, stmt->body);
+
+ LOOP_RC_PROCESSING(stmt->label, break);
+
+ MemoryContextSwitchTo(stmt_mcontext);
+ }
+ }
+
+ /* Restore memory context state */
+ MemoryContextSwitchTo(oldcontext);
+ pop_stmt_mcontext(estate);
+
+ /* Release temporary memory, including the array value */
+ MemoryContextReset(stmt_mcontext);
+
+ /*
+ * Set the FOUND variable to indicate the result of executing the loop
+ * (namely, whether we looped one or more times). This must be set here so
+ * that it does not interfere with the value of the FOUND variable inside
+ * the loop processing itself.
+ */
+ exec_set_found(estate, found);
+
+ return rc;
+}
+
/* ----------
* exec_stmt_foreach_a Loop over elements or slices of an array
*
@@ -5522,7 +5764,8 @@ plpgsql_exec_get_datum_type(PLpgSQL_execstate *estate,
void
plpgsql_exec_get_datum_type_info(PLpgSQL_execstate *estate,
PLpgSQL_datum *datum,
- Oid *typeId, int32 *typMod, Oid *collation)
+ Oid *typeId, int32 *typMod, Oid *collation,
+ char **refname)
{
switch (datum->dtype)
{
@@ -5534,6 +5777,54 @@ plpgsql_exec_get_datum_type_info(PLpgSQL_execstate *estate,
*typeId = var->datatype->typoid;
*typMod = var->datatype->atttypmod;
*collation = var->datatype->collation;
+ *refname = var->refname;
+ break;
+ }
+
+ case PLPGSQL_DTYPE_ROW:
+ {
+ PLpgSQL_row *row = (PLpgSQL_row *) datum;
+
+ if (!row->rowtupdesc)
+ {
+ int i;
+
+ row->rowtupdesc = CreateTemplateTupleDesc(row->nfields);
+
+ for (i = 0; i < row->nfields; i++)
+ {
+ PLpgSQL_datum *var = estate->datums[row->varnos[i]];
+ Oid vartypid;
+ int32 vartypmod;
+ Oid varcollation;
+ char *varname;
+
+ /*
+ * We cannot to use fieldnames for tupdescentry, because
+ * these names can be suffixed by name of row variable.
+ * Unfortunately, the PLpgSQL_recfield is not casted to
+ * PLpgSQL_variable.
+ */
+ plpgsql_exec_get_datum_type_info(estate, var,
+ &vartypid, &vartypmod,
+ &varcollation, &varname);
+
+ TupleDescInitEntry(row->rowtupdesc, i + 1,
+ varname, vartypid, vartypmod,
+ 0);
+ TupleDescInitEntryCollation(row->rowtupdesc, i + 1,
+ varcollation);
+ }
+
+ /* Make sure we have a valid type/typmod setting */
+ BlessTupleDesc(row->rowtupdesc);
+ }
+
+ *typeId = row->rowtupdesc->tdtypeid;
+ *typMod = row->rowtupdesc->tdtypmod;
+ /* composite types are never collatable */
+ *collation = InvalidOid;
+ *refname = row->refname;
break;
}
@@ -5556,6 +5847,7 @@ plpgsql_exec_get_datum_type_info(PLpgSQL_execstate *estate,
}
/* composite types are never collatable */
*collation = InvalidOid;
+ *refname = rec->refname;
break;
}
@@ -5593,6 +5885,7 @@ plpgsql_exec_get_datum_type_info(PLpgSQL_execstate *estate,
*typeId = recfield->finfo.ftypeid;
*typMod = recfield->finfo.ftypmod;
*collation = recfield->finfo.fcollation;
+ *refname = recfield->fieldname;
break;
}
@@ -5601,6 +5894,7 @@ plpgsql_exec_get_datum_type_info(PLpgSQL_execstate *estate,
*typeId = InvalidOid; /* keep compiler quiet */
*typMod = -1;
*collation = InvalidOid;
+ *refname = NULL;
break;
}
}
diff --git a/src/pl/plpgsql/src/pl_funcs.c b/src/pl/plpgsql/src/pl_funcs.c
index 92cd9116c0e..7511fab7e68 100644
--- a/src/pl/plpgsql/src/pl_funcs.c
+++ b/src/pl/plpgsql/src/pl_funcs.c
@@ -253,6 +253,8 @@ plpgsql_stmt_typename(PLpgSQL_stmt *stmt)
return _("FOR over cursor");
case PLPGSQL_STMT_FOREACH_A:
return _("FOREACH over array");
+ case PLPGSQL_STMT_FOREACH_JSON_A:
+ return _("FOREACH over json array");
case PLPGSQL_STMT_EXIT:
return ((PLpgSQL_stmt_exit *) stmt)->is_exit ? "EXIT" : "CONTINUE";
case PLPGSQL_STMT_RETURN:
@@ -467,6 +469,14 @@ plpgsql_statement_tree_walker_impl(PLpgSQL_stmt *stmt,
{
PLpgSQL_stmt_foreach_a *fstmt = (PLpgSQL_stmt_foreach_a *) stmt;
+ E_WALK(fstmt->expr);
+ S_LIST_WALK(fstmt->body);
+ break;
+ }
+ case PLPGSQL_STMT_FOREACH_JSON_A:
+ {
+ PLpgSQL_stmt_foreach_json_a *fstmt = (PLpgSQL_stmt_foreach_json_a *) stmt;
+
E_WALK(fstmt->expr);
S_LIST_WALK(fstmt->body);
break;
@@ -795,6 +805,7 @@ static void dump_fori(PLpgSQL_stmt_fori *stmt);
static void dump_fors(PLpgSQL_stmt_fors *stmt);
static void dump_forc(PLpgSQL_stmt_forc *stmt);
static void dump_foreach_a(PLpgSQL_stmt_foreach_a *stmt);
+static void dump_foreach_json_a(PLpgSQL_stmt_foreach_json_a *stmt);
static void dump_exit(PLpgSQL_stmt_exit *stmt);
static void dump_return(PLpgSQL_stmt_return *stmt);
static void dump_return_next(PLpgSQL_stmt_return_next *stmt);
@@ -861,6 +872,9 @@ dump_stmt(PLpgSQL_stmt *stmt)
case PLPGSQL_STMT_FOREACH_A:
dump_foreach_a((PLpgSQL_stmt_foreach_a *) stmt);
break;
+ case PLPGSQL_STMT_FOREACH_JSON_A:
+ dump_foreach_json_a((PLpgSQL_stmt_foreach_json_a *) stmt);
+ break;
case PLPGSQL_STMT_EXIT:
dump_exit((PLpgSQL_stmt_exit *) stmt);
break;
@@ -1157,6 +1171,21 @@ dump_foreach_a(PLpgSQL_stmt_foreach_a *stmt)
printf(" ENDFOREACHA");
}
+static void
+dump_foreach_json_a(PLpgSQL_stmt_foreach_json_a *stmt)
+{
+ dump_ind();
+ printf("FOREACHA var %d ", stmt->varno);
+ printf("IN JSON ARRAY ");
+ dump_expr(stmt->expr);
+ printf("\n");
+
+ dump_stmts(stmt->body);
+
+ dump_ind();
+ printf(" ENDFOREACHA");
+}
+
static void
dump_open(PLpgSQL_stmt_open *stmt)
{
diff --git a/src/pl/plpgsql/src/pl_gram.y b/src/pl/plpgsql/src/pl_gram.y
index 5009e59a78f..23b465b10d5 100644
--- a/src/pl/plpgsql/src/pl_gram.y
+++ b/src/pl/plpgsql/src/pl_gram.y
@@ -178,6 +178,7 @@ static void check_raise_parameters(PLpgSQL_stmt_raise *stmt);
PLpgSQL_diag_item *diagitem;
PLpgSQL_stmt_fetch *fetch;
PLpgSQL_case_when *casewhen;
+ PLpgSQL_stmt_foreach *foreach;
}
%type <declhdr> decl_sect
@@ -220,6 +221,7 @@ static void check_raise_parameters(PLpgSQL_stmt_raise *stmt);
%type <casewhen> case_when
%type <list> case_when_list opt_case_else
+%type <foreach> foreach_type
%type <boolean> getdiag_area_opt
%type <list> getdiag_list
@@ -341,6 +343,7 @@ static void check_raise_parameters(PLpgSQL_stmt_raise *stmt);
%token <keyword> K_PRINT_STRICT_PARAMS
%token <keyword> K_PRIOR
%token <keyword> K_QUERY
+%token <keyword> K_JSON
%token <keyword> K_RAISE
%token <keyword> K_RELATIVE
%token <keyword> K_RETURN
@@ -1671,16 +1674,29 @@ for_variable : T_DATUM
}
;
-stmt_foreach_a : opt_loop_label K_FOREACH for_variable foreach_slice K_IN K_ARRAY expr_until_loop loop_body
+stmt_foreach_a : opt_loop_label K_FOREACH for_variable foreach_slice K_IN foreach_type expr_until_loop loop_body
{
- PLpgSQL_stmt_foreach_a *new;
+ PLpgSQL_stmt_foreach *new;
- new = palloc0_object(PLpgSQL_stmt_foreach_a);
- new->cmd_type = PLPGSQL_STMT_FOREACH_A;
+ new = $6;
new->lineno = plpgsql_location_to_lineno(@2, yyscanner);
new->stmtid = ++plpgsql_curr_compile->nstatements;
new->label = $1;
- new->slice = $4;
+
+ if ($4 > 0)
+ {
+ /* slicing is supported only by FOREACH IN ARRAY */
+ if (new->cmd_type == PLPGSQL_STMT_FOREACH_A)
+ {
+ ((PLpgSQL_stmt_foreach_a *) new)->slice = $4;
+ }
+ else
+ ereport(ERROR,
+ (errcode(ERRCODE_SYNTAX_ERROR),
+ errmsg("not zero slice is allowed only for arrays"),
+ parser_errposition(@4)));
+ }
+
new->expr = $7;
new->body = $8.stmts;
@@ -1719,6 +1735,19 @@ foreach_slice :
}
;
+foreach_type :
+ K_ARRAY
+ {
+ $$ = (PLpgSQL_stmt_foreach *) palloc0_object(PLpgSQL_stmt_foreach_a);
+ $$->cmd_type = PLPGSQL_STMT_FOREACH_A;
+ }
+ | K_JSON K_ARRAY
+ {
+ $$ = (PLpgSQL_stmt_foreach *) palloc0_object(PLpgSQL_stmt_foreach_json_a);
+ $$->cmd_type = PLPGSQL_STMT_FOREACH_JSON_A;
+ }
+ ;
+
stmt_exit : exit_type opt_label opt_exitcond
{
PLpgSQL_stmt_exit *new;
diff --git a/src/pl/plpgsql/src/pl_unreserved_kwlist.h b/src/pl/plpgsql/src/pl_unreserved_kwlist.h
index 6379e86c8cb..d7588d3b4ad 100644
--- a/src/pl/plpgsql/src/pl_unreserved_kwlist.h
+++ b/src/pl/plpgsql/src/pl_unreserved_kwlist.h
@@ -69,6 +69,7 @@ PG_KEYWORD("import", K_IMPORT)
PG_KEYWORD("info", K_INFO)
PG_KEYWORD("insert", K_INSERT)
PG_KEYWORD("is", K_IS)
+PG_KEYWORD("json", K_JSON)
PG_KEYWORD("last", K_LAST)
PG_KEYWORD("log", K_LOG)
PG_KEYWORD("merge", K_MERGE)
diff --git a/src/pl/plpgsql/src/plpgsql.h b/src/pl/plpgsql/src/plpgsql.h
index addb14a9959..4a1e9ba65bc 100644
--- a/src/pl/plpgsql/src/plpgsql.h
+++ b/src/pl/plpgsql/src/plpgsql.h
@@ -112,6 +112,7 @@ typedef enum PLpgSQL_stmt_type
PLPGSQL_STMT_FORS,
PLPGSQL_STMT_FORC,
PLPGSQL_STMT_FOREACH_A,
+ PLPGSQL_STMT_FOREACH_JSON_A,
PLPGSQL_STMT_EXIT,
PLPGSQL_STMT_RETURN,
PLPGSQL_STMT_RETURN_NEXT,
@@ -766,6 +767,20 @@ typedef struct PLpgSQL_stmt_dynfors
List *params; /* USING expressions */
} PLpgSQL_stmt_dynfors;
+/*
+ * FOREACH loop (ancestor IN ARRAY and IN JSON ARRAY loop)
+ */
+typedef struct PLpgSQL_stmt_foreach
+{
+ PLpgSQL_stmt_type cmd_type;
+ int lineno;
+ unsigned int stmtid;
+ char *label;
+ int varno; /* loop target variable */
+ PLpgSQL_expr *expr; /* set expression */
+ List *body; /* List of statements */
+} PLpgSQL_stmt_foreach;
+
/*
* FOREACH item in array loop
*/
@@ -776,11 +791,27 @@ typedef struct PLpgSQL_stmt_foreach_a
unsigned int stmtid;
char *label;
int varno; /* loop target variable */
- int slice; /* slice dimension, or 0 */
PLpgSQL_expr *expr; /* array expression */
List *body; /* List of statements */
+ /* end of fields that must match PLpgSQL_stmt_foreach */
+ int slice; /* slice dimension, or 0 */
} PLpgSQL_stmt_foreach_a;
+/*
+ * FOREACH item in array loop
+ */
+typedef struct PLpgSQL_stmt_foreach_json_a
+{
+ PLpgSQL_stmt_type cmd_type;
+ int lineno;
+ unsigned int stmtid;
+ char *label;
+ int varno; /* loop target variable */
+ PLpgSQL_expr *expr; /* array expression */
+ List *body; /* List of statements */
+ /* end of fields that must match PLpgSQL_stmt_foreach */
+} PLpgSQL_stmt_foreach_json_a;
+
/*
* OPEN a curvar
*/
@@ -1274,7 +1305,7 @@ extern PGDLLEXPORT Oid plpgsql_exec_get_datum_type(PLpgSQL_execstate *estate,
extern void plpgsql_exec_get_datum_type_info(PLpgSQL_execstate *estate,
PLpgSQL_datum *datum,
Oid *typeId, int32 *typMod,
- Oid *collation);
+ Oid *collation, char **refname);
/*
* Functions for namespace handling in pl_funcs.c
diff --git a/src/pl/plpgsql/src/sql/plpgsql_foreach.sql b/src/pl/plpgsql/src/sql/plpgsql_foreach.sql
new file mode 100644
index 00000000000..7e7abfe2568
--- /dev/null
+++ b/src/pl/plpgsql/src/sql/plpgsql_foreach.sql
@@ -0,0 +1,89 @@
+-- numeric to numeric
+do $$
+declare x numeric;
+begin
+ foreach x in json array '[10,20,30,3.14, null]'
+ loop
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+
+-- numeric to int by cast
+do $$
+declare x int;
+begin
+ foreach x in json array '[10,20,30,3.14, null]'
+ loop
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+
+-- conversion "3.14" to int should to fail due IO cast
+do $$
+declare x int;
+begin
+ foreach x in json array '["10",20,30,"3.14"]'
+ loop
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+
+-- jsonb to jsonb
+do $$
+declare x jsonb;
+begin
+ foreach x in json array '[10,20,30,3.14, null, "Hi"]'
+ loop
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+
+-- jsonb to json
+do $$
+declare x json;
+begin
+ foreach x in json array '[10,20,30,3.14, null, "Hi"]'
+ loop
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+
+-- iteration over composites
+do $$
+declare x int; y numeric; z varchar;
+begin
+ foreach x, y, z in json array '[{}, {"z":"Hi"}, {"y": 3.14}, {"z":"Hi", "x":10, "y":3.14}]'
+ loop
+ raise notice 'x: %, y: %, z: %', x, y, z;
+ end loop;
+end;
+$$;
+
+create type t3 as (x int, y numeric, z varchar);
+
+do $$
+declare c t3;
+begin
+ foreach c in json array '[{}, {"z":"Hi"}, {"y": 3.14}, {"z":"Hi", "x":10, "y":3.14}]'
+ loop
+ raise notice 'x: %, y: %, z: %', c.x, c.y, c.z;
+ end loop;
+end;
+$$;
+
+do $$
+declare c t3;
+begin
+ foreach c.x, c.y, c.z in json array '[{}, {"z":"Hi"}, {"y": 3.14}, {"z":"Hi", "x":10, "y":3.14}]'
+ loop
+ raise notice 'x: %, y: %, z: %', c.x, c.y, c.z;
+ end loop;
+end;
+$$;
+
+drop type t3;
--
2.53.0
^ permalink raw reply [nested|flat] 6+ messages in thread
* Re: POC: PLpgSQL FOREACH IN JSON ARRAY
2026-02-28 07:10 POC: PLpgSQL FOREACH IN JSON ARRAY Pavel Stehule <[email protected]>
@ 2026-03-11 20:57 ` Peter Eisentraut <[email protected]>
2026-03-12 07:00 ` Re: POC: PLpgSQL FOREACH IN JSON ARRAY Pavel Stehule <[email protected]>
0 siblings, 1 reply; 6+ messages in thread
From: Peter Eisentraut @ 2026-03-11 20:57 UTC (permalink / raw)
To: Pavel Stehule <[email protected]>; PostgreSQL Hackers <[email protected]>
On 28.02.26 08:10, Pavel Stehule wrote:
> I wrote PoC for previously proposed plpgsql statement FOREACH IN JSON ARRAY
Maybe this could be written in such a way that it doesn't hardcode JSON
arrays specifically, but a type could have an iteration helper function
that would feed this feature?
^ permalink raw reply [nested|flat] 6+ messages in thread
* Re: POC: PLpgSQL FOREACH IN JSON ARRAY
2026-02-28 07:10 POC: PLpgSQL FOREACH IN JSON ARRAY Pavel Stehule <[email protected]>
2026-03-11 20:57 ` Re: POC: PLpgSQL FOREACH IN JSON ARRAY Peter Eisentraut <[email protected]>
@ 2026-03-12 07:00 ` Pavel Stehule <[email protected]>
2026-03-17 06:58 ` Re: POC: PLpgSQL FOREACH IN JSON ARRAY Pavel Stehule <[email protected]>
0 siblings, 1 reply; 6+ messages in thread
From: Pavel Stehule @ 2026-03-12 07:00 UTC (permalink / raw)
To: Tom Lane <[email protected]>; +Cc: Peter Eisentraut <[email protected]>; PostgreSQL Hackers <[email protected]>
Hi
čt 12. 3. 2026 v 5:30 odesílatel Tom Lane <[email protected]> napsal:
> Peter Eisentraut <[email protected]> writes:
> > Maybe this could be written in such a way that it doesn't hardcode JSON
> > arrays specifically, but a type could have an iteration helper function
> > that would feed this feature?
>
> +1. ISTM that this feature would make sense for subscriptable types,
> so one way to shoehorn it into the system without a lot of new overhead
> could be to extend struct SubscriptRoutines to offer optional support
> function(s) for iterating through all the elements of a subscriptable
> object.
>
I'll try to write second patch in this way
Regards
Pavel
>
> regards, tom lane
>
^ permalink raw reply [nested|flat] 6+ messages in thread
* Re: POC: PLpgSQL FOREACH IN JSON ARRAY
2026-02-28 07:10 POC: PLpgSQL FOREACH IN JSON ARRAY Pavel Stehule <[email protected]>
2026-03-11 20:57 ` Re: POC: PLpgSQL FOREACH IN JSON ARRAY Peter Eisentraut <[email protected]>
2026-03-12 07:00 ` Re: POC: PLpgSQL FOREACH IN JSON ARRAY Pavel Stehule <[email protected]>
@ 2026-03-17 06:58 ` Pavel Stehule <[email protected]>
2026-03-21 18:40 ` Re: POC: PLpgSQL FOREACH IN JSON ARRAY Pavel Stehule <[email protected]>
0 siblings, 1 reply; 6+ messages in thread
From: Pavel Stehule @ 2026-03-17 06:58 UTC (permalink / raw)
To: Tom Lane <[email protected]>; +Cc: Peter Eisentraut <[email protected]>; PostgreSQL Hackers <[email protected]>
Hi
čt 12. 3. 2026 v 8:00 odesílatel Pavel Stehule <[email protected]>
napsal:
> Hi
>
> čt 12. 3. 2026 v 5:30 odesílatel Tom Lane <[email protected]> napsal:
>
>> Peter Eisentraut <[email protected]> writes:
>> > Maybe this could be written in such a way that it doesn't hardcode JSON
>> > arrays specifically, but a type could have an iteration helper function
>> > that would feed this feature?
>>
>> +1. ISTM that this feature would make sense for subscriptable types,
>> so one way to shoehorn it into the system without a lot of new overhead
>> could be to extend struct SubscriptRoutines to offer optional support
>> function(s) for iterating through all the elements of a subscriptable
>> object.
>>
>
>
attached patch do this - new interface has two
methods: CreateForeachAIterator and iterate
diff --git a/src/include/nodes/subscripting.h
b/src/include/nodes/subscripting.h
index 301f21dac2f..08bfe59ede4 100644
--- a/src/include/nodes/subscripting.h
+++ b/src/include/nodes/subscripting.h
@@ -154,6 +154,32 @@ typedef void (*SubscriptExecSetup) (const
SubscriptingRef *sbsref,
SubscriptingRefState *sbsrefstate,
SubscriptExecSteps *methods);
+typedef struct _ForeachAIterator ForeachAIterator;
+
+/*
+ * ForeachAIiterator is used by PLpgSQL FOREACH IN ARRAY statement.
+ * Input value should not be null, and inside CreateForeachAIterator
+ * routine must be copied to current (statement) context. "iterate"
+ * routine is called under short life memory context, that is resetted
+ * after any call.
+ */
+struct _ForeachAIterator
+{
+ bool (*iterate) (ForeachAIterator *self,
+ Datum *value,
+ bool *isnull,
+ Oid *typid,
+ int32 *typmod);
+ /* Private fields might appear beyond this point... */
+};
+
+typedef ForeachAIterator * (*CreateForeachAIterator) (Datum value,
+ Oid typid,
+ int32 typmod,
+ int slice,
+ Oid target_typid,
+ int32 target_typmod);
+
/* Struct returned by the SQL-visible subscript handler function */
typedef struct SubscriptRoutines
{
@@ -163,6 +189,9 @@ typedef struct SubscriptRoutines
bool fetch_leakproof; /* is fetch SubscriptingRef leakproof?
*/
bool store_leakproof; /* is assignment SubscriptingRef
* leakproof? */
+
+ /* returns iterator used by PL/pgSQL FOREACH statement */
+ CreateForeachAIterator create_foreach_a_iterator;
} SubscriptRoutines;
#endif /* SUBSCRIPTING_H */
Regards
Pavel
>
>
> Regards
>
> Pavel
>
>
>>
>> regards, tom lane
>>
>
Attachments:
[text/x-patch] v20260317-7-0001-FOREACH-scalar-IN-ARRAY-jsonb_expr.patch (37.0K, 3-v20260317-7-0001-FOREACH-scalar-IN-ARRAY-jsonb_expr.patch)
download | inline diff:
From b7b6509381a7d6b4629b3b25ebb4a189b1eb34be Mon Sep 17 00:00:00 2001
From: "[email protected]" <[email protected]>
Date: Mon, 23 Feb 2026 12:53:44 +0100
Subject: [PATCH] FOREACH scalar IN ARRAY jsonb_expr
this patch introduce support FOREACH scalar_var IN ARRAY expr, when the
result of the expression can be Jsonb. The design is based
on behave of jsonb_array_elements functions. In this case, FOREACH enforce
casting to target type (because we know target type) and try to reduce
IO casting. Attention: IO casting can be more strict, then casting based
on cast functions.
DECLARE t int;
BEGIN
-- this can work because we use cast numeric -> int
FOREACH t IN ARRAY '[1,2,3.14]'::jsonb
LOOP
-- this fails, because IO cast is used, and integer input function
-- allows only digits
FOREAC t IN JSON ARRAY '[1,2,3,"3.14"]'::jsonb
LOOP
Conceptual question is if casting should be strict like "old" PostgreSQL
json function or lax as "new" SQL/JSON functions? I can imagine lax mode
as default with possibility to switch to strict mode (this is not implemented
now):
FOREACH t IN ARRAY '[1,2,3]' ERROR ON EMPTY ERROR ON ERROR
LOOP
...
Because we use "old" syntax - FOREACH IN ARRAY, I prefer "old" behaviour,
that is more similar to iteration over an array.
The performance (best case for iteration over 1000 fields array) is about
4x better than when FOR IN SELECT jsonb_array_elements is used.
---
doc/src/sgml/plpgsql.sgml | 62 +++-
src/backend/utils/adt/arraysubs.c | 97 +++++-
src/backend/utils/adt/jsonbsubs.c | 181 ++++++++++-
src/include/nodes/subscripting.h | 29 ++
src/pl/plpgsql/src/Makefile | 2 +-
.../plpgsql/src/expected/plpgsql_foreach.out | 297 ++++++++++++++++++
src/pl/plpgsql/src/meson.build | 1 +
src/pl/plpgsql/src/pl_exec.c | 189 +++++------
src/pl/plpgsql/src/plpgsql.h | 3 +-
src/pl/plpgsql/src/sql/plpgsql_foreach.sql | 252 +++++++++++++++
10 files changed, 1016 insertions(+), 97 deletions(-)
create mode 100644 src/pl/plpgsql/src/expected/plpgsql_foreach.out
create mode 100644 src/pl/plpgsql/src/sql/plpgsql_foreach.sql
diff --git a/doc/src/sgml/plpgsql.sgml b/doc/src/sgml/plpgsql.sgml
index 561f6e50d63..6bc9fb02e1e 100644
--- a/doc/src/sgml/plpgsql.sgml
+++ b/doc/src/sgml/plpgsql.sgml
@@ -2697,12 +2697,12 @@ END LOOP <optional> <replaceable>label</replaceable> </optional>;
</sect2>
<sect2 id="plpgsql-foreach-array">
- <title>Looping through Arrays</title>
+ <title>Looping through Arrays or Jsonb arrays</title>
<para>
The <literal>FOREACH</literal> loop is much like a <literal>FOR</literal> loop,
but instead of iterating through the rows returned by an SQL query,
- it iterates through the elements of an array value.
+ it iterates through the elements of an array value or of jsonb array value.
(In general, <literal>FOREACH</literal> is meant for looping through
components of a composite-valued expression; variants for looping
through composites besides arrays may be added in future.)
@@ -2778,6 +2778,64 @@ NOTICE: row = {7,8,9}
NOTICE: row = {10,11,12}
</programlisting>
</para>
+
+ <para>
+ The <literal>SLICE</literal> higher than zero cannot be used when iterates
+ through jsonb arrays.
+ </para>
+
+ <para>
+ The <literal>FOREACH</literal> loop over jsonb arrays uses
+ same syntax like <literal>FOREACH</literal> loop over arrays,
+ but instead of iterating through elements of the array,
+ it iterates through the elements of a Jsonb array value.
+ </para>
+
+ <para>
+ The target can be a scalar variable, a composite variable, or a list
+ of scalar variables. When variable is not scalar, then assigned value
+ should be a JSON object and the JSON attributes are assigned by names.
+
+<programlisting>
+CREATE FUNCTION print_elements(jsonb) RETURNS void AS $$
+DECLARE
+ x int;
+BEGIN
+ FOREACH x IN ARRAY $1
+ LOOP
+ RAISE NOTICE 'row = %', x;
+ END LOOP;
+END;
+$$ LANGUAGE plpgsql;
+
+SELECT print_elements('[1,2,3]');
+NOTICE: row = 1
+NOTICE: row = 2
+NOTICE: row = 3
+
+CREATE FUNCTION print_fields(jsonb) RETURNS void AS $$
+DECLARE
+ x int; y varchar;
+BEGIN
+ FOREACH x, y IN ARRAY $1
+ LOOP
+ RAISE NOTICE 'x: %, y: %', x, y;
+ END LOOP;
+END;
+$$ LANGUAGE plpgsql;
+
+SELECT print_fields('[{},{"x":10},{"y":"Hi"},{"y":"Hi", "x":1000}]');
+NOTICE: x: <NULL>, y: <NULL>
+NOTICE: x: 10, y: <NULL>
+NOTICE: x: <NULL>, y: Hi
+NOTICE: x: 1000, y: Hi
+</programlisting>
+ </para>
+
+ <para>
+ The target variable can be of type <literal>RECORD</literal>, but the real structure has to be
+ assigned before usage in the <literal>FOREACH</literal> statement.
+ </para>
</sect2>
<sect2 id="plpgsql-error-trapping">
diff --git a/src/backend/utils/adt/arraysubs.c b/src/backend/utils/adt/arraysubs.c
index 2bf9e9509fb..a42248ed633 100644
--- a/src/backend/utils/adt/arraysubs.c
+++ b/src/backend/utils/adt/arraysubs.c
@@ -23,6 +23,7 @@
#include "parser/parse_coerce.h"
#include "parser/parse_expr.h"
#include "utils/array.h"
+#include "utils/builtins.h"
#include "utils/fmgrprotos.h"
#include "utils/lsyscache.h"
@@ -46,6 +47,96 @@ typedef struct ArraySubWorkspace
int lowerindex[MAXDIM];
} ArraySubWorkspace;
+typedef struct
+{
+ ForeachAIterator pub;
+ ArrayIterator it;
+ Oid result_typid;
+ int32 result_typmod;
+} ForeachAArrayIterState;
+
+static bool
+foreach_a_array_iterate(ForeachAIterator *self,
+ Datum *value, bool *isnull,
+ Oid *typid, int32 *typmod)
+{
+ ForeachAArrayIterState *iter = (ForeachAArrayIterState *) self;
+
+ *typid = iter->result_typid;
+ *typmod = iter->result_typmod;
+
+ return array_iterate(iter->it, value, isnull);
+}
+
+/*
+ * Used by plpgsql FOREACH IN ARRAY when input expression is an array
+ */
+static ForeachAIterator *
+create_foreach_a_array_iterator(Datum value, Oid typid, int32 typmod,
+ int slice, Oid target_typid, int32 target_typmod)
+{
+ ForeachAArrayIterState *iter = palloc0(sizeof(ForeachAArrayIterState));
+ ArrayType *arr;
+ Oid target_elem_typid;
+
+ /* check the type of the expression - must be an array */
+ if (!OidIsValid(get_element_type(typid)))
+ ereport(ERROR,
+ (errcode(ERRCODE_DATATYPE_MISMATCH),
+ errmsg("FOREACH expression must yield an array, not type %s",
+ format_type_be(typid))));
+
+ /*
+ * We must copy the array into current context, because input expression
+ * is evaluated in context cleaned by exec_eval_cleanup.
+ */
+ arr = DatumGetArrayTypePCopy(value);
+
+ /* Slice dimension must be less than or equal to array dimension */
+ if (slice < 0 || slice > ARR_NDIM(arr))
+ ereport(ERROR,
+ (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
+ errmsg("slice dimension (%d) is out of the valid range 0..%d",
+ slice, ARR_NDIM(arr))));
+
+ /*
+ * Sanity-check the target type. We don't try very hard here, and
+ * should not be too picky since it's possible that exec_assign_value can
+ * coerce values of different types. But it seems worthwhile to complain
+ * if the array-ness of the loop variable is not right.
+ */
+ target_elem_typid = get_element_type(target_typid);
+
+ if (slice > 0 && target_elem_typid == InvalidOid)
+ ereport(ERROR,
+ (errcode(ERRCODE_DATATYPE_MISMATCH),
+ errmsg("FOREACH ... SLICE loop variable must be of an array type")));
+ if (slice == 0 && target_elem_typid != InvalidOid)
+ ereport(ERROR,
+ (errcode(ERRCODE_DATATYPE_MISMATCH),
+ errmsg("FOREACH loop variable must not be of an array type")));
+
+ /* Identify iterator result type */
+ if (slice > 0)
+ {
+ /* When slicing, nominal type of result is same as array type */
+ iter->result_typid = typid;
+ iter->result_typmod = typmod;
+ }
+ else
+ {
+ /* Without slicing, results are individual array elements */
+ iter->result_typid = ARR_ELEMTYPE(arr);
+ iter->result_typmod = typmod;
+ }
+
+ /* Create an iterator to step through the array */
+ iter->it = array_create_iterator(arr, slice, NULL);
+
+ iter->pub.iterate = foreach_a_array_iterate;
+
+ return (ForeachAIterator *) iter;
+}
/*
* Finish parse analysis of a SubscriptingRef expression for an array.
@@ -545,7 +636,8 @@ array_subscript_handler(PG_FUNCTION_ARGS)
.exec_setup = array_exec_setup,
.fetch_strict = true, /* fetch returns NULL for NULL inputs */
.fetch_leakproof = true, /* fetch returns NULL for bad subscript */
- .store_leakproof = false /* ... but assignment throws error */
+ .store_leakproof = false, /* ... but assignment throws error */
+ .create_foreach_a_iterator = create_foreach_a_array_iterator
};
PG_RETURN_POINTER(&sbsroutines);
@@ -572,7 +664,8 @@ raw_array_subscript_handler(PG_FUNCTION_ARGS)
.exec_setup = array_exec_setup,
.fetch_strict = true, /* fetch returns NULL for NULL inputs */
.fetch_leakproof = true, /* fetch returns NULL for bad subscript */
- .store_leakproof = false /* ... but assignment throws error */
+ .store_leakproof = false, /* ... but assignment throws error */
+ .create_foreach_a_iterator = create_foreach_a_array_iterator
};
PG_RETURN_POINTER(&sbsroutines);
diff --git a/src/backend/utils/adt/jsonbsubs.c b/src/backend/utils/adt/jsonbsubs.c
index f2745b29a3f..ad2edf525de 100644
--- a/src/backend/utils/adt/jsonbsubs.c
+++ b/src/backend/utils/adt/jsonbsubs.c
@@ -22,6 +22,7 @@
#include "parser/parse_expr.h"
#include "utils/builtins.h"
#include "utils/jsonb.h"
+#include "utils/jsonfuncs.h"
/* SubscriptingRefState.workspace for jsonb subscripting execution */
@@ -33,6 +34,17 @@ typedef struct JsonbSubWorkspace
Datum *index; /* Subscript values in Datum format */
} JsonbSubWorkspace;
+typedef struct
+{
+ ForeachAIterator pub;
+ JsonbIterator *it;
+ bool skip_nested;
+ Oid target_typid;
+ int32 target_typmod;
+
+ MemoryContext cache_mcxt;
+ void *cache;
+} ForeachAJsonbIterState;
/*
* Finish parse analysis of a SubscriptingRef expression for a jsonb.
@@ -394,6 +406,172 @@ jsonb_exec_setup(const SubscriptingRef *sbsref,
methods->sbs_fetch_old = jsonb_subscript_fetch_old;
}
+/*
+ * Convert JsonbValue to Datum. This function is used in
+ * generic array iterator, that is used by FOREACH plpgsql
+ * statement. Against other cases, the result should not be
+ * necessary of expected_typid, because the value can be
+ * converted later when the value is assigned to PL/pgSQL
+ * variable. This can be more effective than generic IO
+ * cast used by json_populate_type.
+ */
+static Datum
+JsonbValueToDatum(JsonbValue *jbv,
+ Oid *typid, int32 *typmod, bool *isnull,
+ Oid expected_typid, int32 expected_typmod,
+ void **cache, MemoryContext mcxt)
+{
+ Datum result;
+
+ *isnull = false;
+ *typmod = -1;
+
+ /*
+ * These types can holds JSON null, so must be processed
+ * before processing jbvNull. We don't want to convert
+ * JSON null, to SQL null, when targer is of JSON.
+ */
+ if (expected_typid == JSONBOID || expected_typid == JSONOID)
+ {
+ Jsonb *jb = JsonbValueToJsonb(jbv);
+
+ if (expected_typid == JSONOID)
+ {
+ char *str;
+
+ str = JsonbToCString(NULL, &jb->root, VARSIZE(jb));
+ result = PointerGetDatum(cstring_to_text(str));
+ }
+ else
+ result = PointerGetDatum(jb);
+
+ *typid = expected_typid;
+ }
+
+ /*
+ * For special cases we can skip conversion to Jsonb
+ * and possibly IO cast.
+ */
+ else if (jbv->type == jbvNull)
+ {
+ result = (Datum) 0;
+ *isnull = true;
+ *typid = expected_typid;
+ }
+ else if (jbv->type == jbvString)
+ {
+ text *txt = cstring_to_text_with_len(jbv->val.string.val,
+ jbv->val.string.len);
+
+ result = PointerGetDatum(txt);
+ *typid = TEXTOID;
+ }
+ else if (jbv->type == jbvNumeric)
+ {
+ result = PointerGetDatum(jbv->val.numeric);
+ *typid = NUMERICOID;
+ }
+ else if (jbv->type == jbvBool)
+ {
+ result = BoolGetDatum(jbv->val.boolean);
+ *typid = BOOLOID;
+ }
+
+ /* generic conversion */
+ else
+ {
+ Jsonb *jb = JsonbValueToJsonb(jbv);
+
+ result = json_populate_type(PointerGetDatum(jb), JSONBOID,
+ expected_typid, expected_typmod,
+ cache, mcxt,
+ isnull, false, NULL);
+
+ *typid = expected_typid;
+ *typmod = expected_typmod;
+ }
+
+ return result;
+}
+
+static bool
+foreach_a_jsonb_iterate(ForeachAIterator *self,
+ Datum *value, bool *isnull,
+ Oid *typid, int32 *typmod)
+{
+ ForeachAJsonbIterState *iter = (ForeachAJsonbIterState *) self;
+ JsonbIteratorToken r;
+ JsonbValue jbv;
+
+ while ((r = JsonbIteratorNext(&iter->it, &jbv, iter->skip_nested)) != WJB_DONE)
+ {
+ iter->skip_nested = true;
+
+ if (r == WJB_ELEM)
+ {
+ *value = JsonbValueToDatum(&jbv, typid, typmod, isnull,
+ iter->target_typid, iter->target_typmod,
+ &iter->cache, iter->cache_mcxt);
+
+ return true;
+ }
+ }
+
+ return false;
+}
+
+/*
+ * Create foreach array iterator for jsonb array
+ */
+static ForeachAIterator *
+create_foreach_a_jsonb_iterator(Datum value, Oid typid, int32 typmod,
+ int slice, Oid target_typid, int32 target_typmod)
+{
+ ForeachAJsonbIterState *iter = palloc0(sizeof(ForeachAJsonbIterState));
+ Jsonb *jb;
+
+ if (typid != JSONBOID)
+ elog(ERROR, "unexpected source type");
+
+ if (slice > 0)
+ ereport(ERROR,
+ (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+ errmsg("jsonb array iterator doesn't support slicing")));
+
+ /*
+ * We must copy the JSON into current context, because input expression
+ * is evaluated in context cleaned by exec_eval_cleanup.
+ */
+ jb = DatumGetJsonbPCopy(value);
+
+ /*
+ * Jsonb iterator is designed like jsonb_array_element. Input value
+ * must be json array.
+ */
+ if (JB_ROOT_IS_SCALAR(jb))
+ ereport(ERROR,
+ (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+ errmsg("FOREACH expression must evaluate to a JSON array"),
+ errhint("Cannot iterate over a scalar value.")));
+ else if (JB_ROOT_IS_OBJECT(jb))
+ ereport(ERROR,
+ (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+ errmsg("FOREACH expression must evaluate to a JSON array"),
+ errdetail("Cannot iterate over an object value.")));
+
+ Assert(JB_ROOT_IS_ARRAY(jb));
+
+ iter->it = JsonbIteratorInit(&jb->root);
+
+ iter->target_typid = target_typid;
+ iter->target_typmod = target_typmod;
+ iter->cache_mcxt = CurrentMemoryContext;
+
+ iter->pub.iterate = foreach_a_jsonb_iterate;
+
+ return (ForeachAIterator *) iter;
+}
+
/*
* jsonb_subscript_handler
* Subscripting handler for jsonb.
@@ -407,7 +585,8 @@ jsonb_subscript_handler(PG_FUNCTION_ARGS)
.exec_setup = jsonb_exec_setup,
.fetch_strict = true, /* fetch returns NULL for NULL inputs */
.fetch_leakproof = true, /* fetch returns NULL for bad subscript */
- .store_leakproof = false /* ... but assignment throws error */
+ .store_leakproof = false, /* ... but assignment throws error */
+ .create_foreach_a_iterator = create_foreach_a_jsonb_iterator
};
PG_RETURN_POINTER(&sbsroutines);
diff --git a/src/include/nodes/subscripting.h b/src/include/nodes/subscripting.h
index 301f21dac2f..08bfe59ede4 100644
--- a/src/include/nodes/subscripting.h
+++ b/src/include/nodes/subscripting.h
@@ -154,6 +154,32 @@ typedef void (*SubscriptExecSetup) (const SubscriptingRef *sbsref,
SubscriptingRefState *sbsrefstate,
SubscriptExecSteps *methods);
+typedef struct _ForeachAIterator ForeachAIterator;
+
+/*
+ * ForeachAIiterator is used by PLpgSQL FOREACH IN ARRAY statement.
+ * Input value should not be null, and inside CreateForeachAIterator
+ * routine must be copied to current (statement) context. "iterate"
+ * routine is called under short life memory context, that is resetted
+ * after any call.
+ */
+struct _ForeachAIterator
+{
+ bool (*iterate) (ForeachAIterator *self,
+ Datum *value,
+ bool *isnull,
+ Oid *typid,
+ int32 *typmod);
+ /* Private fields might appear beyond this point... */
+};
+
+typedef ForeachAIterator * (*CreateForeachAIterator) (Datum value,
+ Oid typid,
+ int32 typmod,
+ int slice,
+ Oid target_typid,
+ int32 target_typmod);
+
/* Struct returned by the SQL-visible subscript handler function */
typedef struct SubscriptRoutines
{
@@ -163,6 +189,9 @@ typedef struct SubscriptRoutines
bool fetch_leakproof; /* is fetch SubscriptingRef leakproof? */
bool store_leakproof; /* is assignment SubscriptingRef
* leakproof? */
+
+ /* returns iterator used by PL/pgSQL FOREACH statement */
+ CreateForeachAIterator create_foreach_a_iterator;
} SubscriptRoutines;
#endif /* SUBSCRIPTING_H */
diff --git a/src/pl/plpgsql/src/Makefile b/src/pl/plpgsql/src/Makefile
index 63cb96fae3e..5bd0cf31dfc 100644
--- a/src/pl/plpgsql/src/Makefile
+++ b/src/pl/plpgsql/src/Makefile
@@ -35,7 +35,7 @@ REGRESS_OPTS = --dbname=$(PL_TESTDB)
REGRESS = plpgsql_array plpgsql_cache plpgsql_call plpgsql_control \
plpgsql_copy plpgsql_domain plpgsql_misc \
plpgsql_record plpgsql_simple plpgsql_transaction \
- plpgsql_trap plpgsql_trigger plpgsql_varprops
+ plpgsql_trap plpgsql_trigger plpgsql_varprops plpgsql_foreach
# where to find gen_keywordlist.pl and subsidiary files
TOOLSDIR = $(top_srcdir)/src/tools
diff --git a/src/pl/plpgsql/src/expected/plpgsql_foreach.out b/src/pl/plpgsql/src/expected/plpgsql_foreach.out
new file mode 100644
index 00000000000..ddc571f3c79
--- /dev/null
+++ b/src/pl/plpgsql/src/expected/plpgsql_foreach.out
@@ -0,0 +1,297 @@
+-- input must be a JSON array
+do $$
+declare x numeric;
+begin
+ foreach x in array NULL::jsonb -- fail
+ loop
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+ERROR: FOREACH expression must not be null
+CONTEXT: PL/pgSQL function inline_code_block line 4 at FOREACH over array
+do $$
+declare x numeric;
+begin
+ foreach x in array jsonb '10' -- fail
+ loop
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+ERROR: FOREACH expression must evaluate to a JSON array
+HINT: Cannot iterate over a scalar value.
+CONTEXT: PL/pgSQL function inline_code_block line 4 at FOREACH over array
+do $$
+declare x numeric;
+begin
+ foreach x in array jsonb '{}' -- fail
+ loop
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+ERROR: FOREACH expression must evaluate to a JSON array
+DETAIL: Cannot iterate over an object value.
+CONTEXT: PL/pgSQL function inline_code_block line 4 at FOREACH over array
+-- numeric to numeric
+do $$
+declare x numeric;
+begin
+ foreach x in array jsonb '[10,20,30,3.14, null]'
+ loop
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+NOTICE: 10
+NOTICE: 20
+NOTICE: 30
+NOTICE: 3.14
+NOTICE: <NULL>
+-- numeric to int by cast
+do $$
+declare x int;
+begin
+ foreach x in array jsonb '[10,20,30,3.14, null]'
+ loop
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+NOTICE: 10
+NOTICE: 20
+NOTICE: 30
+NOTICE: 3
+NOTICE: <NULL>
+-- test of FOUND variable
+do $$
+declare x int;
+begin
+ foreach x in array jsonb '[10]'
+ loop
+ raise notice '%', x;
+ end loop;
+ raise notice 'FOUND: %', found;
+end;
+$$;
+NOTICE: 10
+NOTICE: FOUND: t
+-- test of FOUND variable
+do $$
+declare x int;
+begin
+ foreach x in array jsonb '[]'
+ loop
+ raise notice '%', x;
+ end loop;
+ raise notice 'FOUND: %', found;
+end;
+$$;
+NOTICE: FOUND: f
+-- conversion "3.14" to int should to fail due IO cast
+do $$
+declare x int;
+begin
+ foreach x in array jsonb '["10",20,30,"3.14"]'
+ loop
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+NOTICE: 10
+NOTICE: 20
+NOTICE: 30
+ERROR: invalid input syntax for type integer: "3.14"
+CONTEXT: PL/pgSQL function inline_code_block line 4 at FOREACH over array
+do $$
+declare x boolean;
+begin
+ foreach x in array jsonb '[true, false]'
+ loop
+ if x then
+ raise notice 'true';
+ else
+ raise notice 'false';
+ end if;
+ end loop;
+end;
+$$;
+NOTICE: true
+NOTICE: false
+-- jsonb to jsonb
+do $$
+declare x jsonb;
+begin
+ foreach x in array jsonb '[10,20,30,3.14, null, "Hi"]'
+ loop
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+NOTICE: 10
+NOTICE: 20
+NOTICE: 30
+NOTICE: 3.14
+NOTICE: null
+NOTICE: "Hi"
+-- jsonb to json
+do $$
+declare x json;
+begin
+ foreach x in array jsonb '[10,20,30,3.14, null, "Hi"]'
+ loop
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+NOTICE: 10
+NOTICE: 20
+NOTICE: 30
+NOTICE: 3.14
+NOTICE: null
+NOTICE: "Hi"
+-- iteration over composites
+do $$
+declare x int; y numeric; z varchar;
+begin
+ foreach x, y, z in array jsonb '[{}, {"z":"Hi"}, {"y": 3.14}, {"z":"Hi", "x":10, "y":3.14}]'
+ loop
+ raise notice 'x: %, y: %, z: %', x, y, z;
+ end loop;
+end;
+$$;
+NOTICE: x: <NULL>, y: <NULL>, z: <NULL>
+NOTICE: x: <NULL>, y: <NULL>, z: Hi
+NOTICE: x: <NULL>, y: 3.14, z: <NULL>
+NOTICE: x: 10, y: 3.14, z: Hi
+create type t3 as (x int, y numeric, z varchar);
+do $$
+declare c t3;
+begin
+ foreach c in array jsonb '[{}, {"z":"Hi"}, {"y": 3.14}, {"z":"Hi", "x":10, "y":3.14}]'
+ loop
+ raise notice 'x: %, y: %, z: %', c.x, c.y, c.z;
+ end loop;
+end;
+$$;
+NOTICE: x: <NULL>, y: <NULL>, z: <NULL>
+NOTICE: x: <NULL>, y: <NULL>, z: Hi
+NOTICE: x: <NULL>, y: 3.14, z: <NULL>
+NOTICE: x: 10, y: 3.14, z: Hi
+do $$
+declare c t3;
+begin
+ foreach c.x, c.y, c.z in array jsonb '[{}, {"z":"Hi"}, {"y": 3.14}, {"z":"Hi", "x":10, "y":3.14}]'
+ loop
+ raise notice 'x: %, y: %, z: %', c.x, c.y, c.z;
+ end loop;
+end;
+$$;
+NOTICE: x: <NULL>, y: <NULL>, z: <NULL>
+NOTICE: x: <NULL>, y: <NULL>, z: Hi
+NOTICE: x: <NULL>, y: 3.14, z: <NULL>
+NOTICE: x: 10, y: 3.14, z: Hi
+drop type t3;
+-- target can be a array
+do $$
+declare x int[];
+begin
+ foreach x in array jsonb '[[1,2,3],[4,5,6]]'
+ loop
+ raise notice '% % %', x[1], x[2], x[3];
+ end loop;
+end;
+$$;
+NOTICE: 1 2 3
+NOTICE: 4 5 6
+do $$
+declare x varchar[];
+begin
+ foreach x in array jsonb '[["Hi","Hello"],["Hello","Hi"]]'
+ loop
+ raise notice '% %', x[1], x[2];
+ end loop;
+end;
+$$;
+NOTICE: Hi Hello
+NOTICE: Hello Hi
+do $$
+declare x varchar[];
+begin
+ foreach x in array jsonb '[["Hi","Hello"],["Hello","Hi"]]'
+ loop
+ raise notice '% %', x[1], x[2];
+ end loop;
+end;
+$$;
+NOTICE: Hi Hello
+NOTICE: Hello Hi
+do $$
+declare x int[]; y varchar;
+begin
+ foreach x, y in array jsonb '[{"x":[1,2,3], "y":"Hi"}, {"x":[4,5,6], "y":"Hi"}]'
+ loop
+ raise notice '% % %, y: %', x[1], x[2], x[3], y;
+ end loop;
+end;
+$$;
+NOTICE: 1 2 3, y: Hi
+NOTICE: 4 5 6, y: Hi
+create type t2 as (x int[], y varchar);
+do $$
+declare c t2;
+begin
+ foreach c in array jsonb '[{"x":[1,2,3], "y":"Hi"}, {"x":[4,5,6], "y":"Hi"}]'
+ loop
+ raise notice '% % %, y: %', c.x[1], c.x[2], c.x[3], c.y;
+ end loop;
+end;
+$$;
+NOTICE: 1 2 3, y: Hi
+NOTICE: 4 5 6, y: Hi
+drop type t2;
+-- EXIT and CONTINUE can be triggered by LOOP_RC_PROCESSING
+do $$
+declare x int;
+begin
+ foreach x in array jsonb '[1,2,3,4,5]'
+ loop
+ exit when x = 3;
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+NOTICE: 1
+NOTICE: 2
+do $$
+declare x int;
+begin
+ foreach x in array jsonb '[1,2,3,4,5]'
+ loop
+ continue when x % 2 = 0;
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+NOTICE: 1
+NOTICE: 3
+NOTICE: 5
+-- Variable instead of string
+DO $$
+declare
+ x int;
+ arr jsonb;
+begin
+ select jsonb_agg(i) into arr
+ from generate_series(1,3) g(i);
+
+ foreach x in array arr
+ loop
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+NOTICE: 1
+NOTICE: 2
+NOTICE: 3
diff --git a/src/pl/plpgsql/src/meson.build b/src/pl/plpgsql/src/meson.build
index 6ff27006cfc..609eed7a28d 100644
--- a/src/pl/plpgsql/src/meson.build
+++ b/src/pl/plpgsql/src/meson.build
@@ -88,6 +88,7 @@ tests += {
'plpgsql_trap',
'plpgsql_trigger',
'plpgsql_varprops',
+ 'plpgsql_foreach',
],
},
}
diff --git a/src/pl/plpgsql/src/pl_exec.c b/src/pl/plpgsql/src/pl_exec.c
index 84552e32c87..331d64119c1 100644
--- a/src/pl/plpgsql/src/pl_exec.c
+++ b/src/pl/plpgsql/src/pl_exec.c
@@ -29,6 +29,7 @@
#include "mb/stringinfo_mb.h"
#include "miscadmin.h"
#include "nodes/nodeFuncs.h"
+#include "nodes/subscripting.h"
#include "nodes/supportnodes.h"
#include "optimizer/optimizer.h"
#include "parser/parse_coerce.h"
@@ -2994,40 +2995,49 @@ exec_stmt_forc(PLpgSQL_execstate *estate, PLpgSQL_stmt_forc *stmt)
return rc;
}
-
/* ----------
- * exec_stmt_foreach_a Loop over elements or slices of an array
- *
- * When looping over elements, the loop variable is the same type that the
- * array stores (eg: integer), when looping through slices, the loop variable
- * is an array of size and dimensions to match the size of the slice.
- * ----------
+ * exec_stmt_foreach_a Loop over elements in an array or jsonb array
+ * ----------
*/
static int
exec_stmt_foreach_a(PLpgSQL_execstate *estate, PLpgSQL_stmt_foreach_a *stmt)
{
- ArrayType *arr;
- Oid arrtype;
- int32 arrtypmod;
- PLpgSQL_datum *loop_var;
- Oid loop_var_elem_type;
- bool found = false;
+ Datum expr;
+ Oid expr_typid;
+ int32 expr_typmod;
+ bool isnull;
+ PLpgSQL_datum *target_var;
+ Oid target_typid;
+ int32 target_typmod;
+ Oid target_collation;
+ Datum value;
+ Oid typid;
+ int32 typmod;
int rc = PLPGSQL_RC_OK;
+ const struct SubscriptRoutines *sbroutines;
+ ForeachAIterator *iterator;
MemoryContext stmt_mcontext;
+ MemoryContext tmp_cxt;
MemoryContext oldcontext;
- ArrayIterator array_iterator;
- Oid iterator_result_type;
- int32 iterator_result_typmod;
- Datum value;
- bool isnull;
+ bool found = false;
- /* get the value of the array expression */
- value = exec_eval_expr(estate, stmt->expr, &isnull, &arrtype, &arrtypmod);
+ /* get the value of the expression */
+ expr = exec_eval_expr(estate, stmt->expr, &isnull,
+ &expr_typid, &expr_typmod);
if (isnull)
ereport(ERROR,
(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
errmsg("FOREACH expression must not be null")));
+ sbroutines = getSubscriptingRoutines(expr_typid, NULL);
+ if (!sbroutines)
+ ereport(ERROR,
+ (errcode(ERRCODE_DATATYPE_MISMATCH),
+ errmsg("cannot iterate over type %s because it does not support subscripting",
+ format_type_be(expr_typid))));
+
+ Assert(sbroutines->create_foreach_a_iterator);
+
/*
* Do as much as possible of the code below in stmt_mcontext, to avoid any
* leaks from called subroutines. We need a private stmt_mcontext since
@@ -3037,79 +3047,34 @@ exec_stmt_foreach_a(PLpgSQL_execstate *estate, PLpgSQL_stmt_foreach_a *stmt)
push_stmt_mcontext(estate);
oldcontext = MemoryContextSwitchTo(stmt_mcontext);
- /* check the type of the expression - must be an array */
- if (!OidIsValid(get_element_type(arrtype)))
- ereport(ERROR,
- (errcode(ERRCODE_DATATYPE_MISMATCH),
- errmsg("FOREACH expression must yield an array, not type %s",
- format_type_be(arrtype))));
+ /* Set up the target (loop) variable */
+ target_var = estate->datums[stmt->varno];
+
+ plpgsql_exec_get_datum_type_info(estate, target_var,
+ &target_typid, &target_typmod,
+ &target_collation);
/*
- * We must copy the array into stmt_mcontext, else it will disappear in
- * exec_eval_cleanup. This is annoying, but cleanup will certainly happen
- * while running the loop body, so we have little choice.
+ * inside iterator constroctor, the expr should be copied to
+ * current memory context (stmt_mcontext). Without it, it will be released
+ * by next exec_eval_cleanup. The iterator constructor should
+ * be called under stmt memory context.
*/
- arr = DatumGetArrayTypePCopy(value);
+ iterator = sbroutines->create_foreach_a_iterator(expr,
+ expr_typid, expr_typmod,
+ stmt->slice, target_typid,
+ target_typmod);
/* Clean up any leftover temporary memory */
exec_eval_cleanup(estate);
- /* Slice dimension must be less than or equal to array dimension */
- if (stmt->slice < 0 || stmt->slice > ARR_NDIM(arr))
- ereport(ERROR,
- (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
- errmsg("slice dimension (%d) is out of the valid range 0..%d",
- stmt->slice, ARR_NDIM(arr))));
-
- /* Set up the loop variable and see if it is of an array type */
- loop_var = estate->datums[stmt->varno];
- if (loop_var->dtype == PLPGSQL_DTYPE_REC ||
- loop_var->dtype == PLPGSQL_DTYPE_ROW)
- {
- /*
- * Record/row variable is certainly not of array type, and might not
- * be initialized at all yet, so don't try to get its type
- */
- loop_var_elem_type = InvalidOid;
- }
- else
- loop_var_elem_type = get_element_type(plpgsql_exec_get_datum_type(estate,
- loop_var));
+ tmp_cxt = AllocSetContextCreate(stmt_mcontext,
+ "FOREACH IN ARRAY temporary cxt",
+ ALLOCSET_DEFAULT_SIZES);
- /*
- * Sanity-check the loop variable type. We don't try very hard here, and
- * should not be too picky since it's possible that exec_assign_value can
- * coerce values of different types. But it seems worthwhile to complain
- * if the array-ness of the loop variable is not right.
- */
- if (stmt->slice > 0 && loop_var_elem_type == InvalidOid)
- ereport(ERROR,
- (errcode(ERRCODE_DATATYPE_MISMATCH),
- errmsg("FOREACH ... SLICE loop variable must be of an array type")));
- if (stmt->slice == 0 && loop_var_elem_type != InvalidOid)
- ereport(ERROR,
- (errcode(ERRCODE_DATATYPE_MISMATCH),
- errmsg("FOREACH loop variable must not be of an array type")));
+ MemoryContextSwitchTo(tmp_cxt);
- /* Create an iterator to step through the array */
- array_iterator = array_create_iterator(arr, stmt->slice, NULL);
-
- /* Identify iterator result type */
- if (stmt->slice > 0)
- {
- /* When slicing, nominal type of result is same as array type */
- iterator_result_type = arrtype;
- iterator_result_typmod = arrtypmod;
- }
- else
- {
- /* Without slicing, results are individual array elements */
- iterator_result_type = ARR_ELEMTYPE(arr);
- iterator_result_typmod = arrtypmod;
- }
-
- /* Iterate over the array elements or slices */
- while (array_iterate(array_iterator, &value, &isnull))
+ while (iterator->iterate(iterator, &value, &isnull, &typid, &typmod))
{
found = true; /* looped at least once */
@@ -3117,12 +3082,9 @@ exec_stmt_foreach_a(PLpgSQL_execstate *estate, PLpgSQL_stmt_foreach_a *stmt)
MemoryContextSwitchTo(oldcontext);
/* Assign current element/slice to the loop variable */
- exec_assign_value(estate, loop_var, value, isnull,
- iterator_result_type, iterator_result_typmod);
+ exec_assign_value(estate, target_var, value, isnull, typid, typmod);
- /* In slice case, value is temporary; must free it to avoid leakage */
- if (stmt->slice > 0)
- pfree(DatumGetPointer(value));
+ MemoryContextReset(tmp_cxt);
/*
* Execute the statements
@@ -3131,7 +3093,7 @@ exec_stmt_foreach_a(PLpgSQL_execstate *estate, PLpgSQL_stmt_foreach_a *stmt)
LOOP_RC_PROCESSING(stmt->label, break);
- MemoryContextSwitchTo(stmt_mcontext);
+ MemoryContextSwitchTo(tmp_cxt);
}
/* Restore memory context state */
@@ -5537,6 +5499,53 @@ plpgsql_exec_get_datum_type_info(PLpgSQL_execstate *estate,
break;
}
+ case PLPGSQL_DTYPE_ROW:
+ {
+ PLpgSQL_row *row = (PLpgSQL_row *) datum;
+
+ if (!row->rowtupdesc)
+ {
+ int i;
+
+ row->rowtupdesc = CreateTemplateTupleDesc(row->nfields);
+
+ for (i = 0; i < row->nfields; i++)
+ {
+ PLpgSQL_datum *var = estate->datums[row->varnos[i]];
+ Oid vartypid;
+ int32 vartypmod;
+ Oid varcollation;
+
+ /*
+ * We cannot use fieldnames for tupdescentry, because
+ * these names can be suffixed by name of row variable.
+ * Unfortunately, the PLpgSQL_recfield is not casted to
+ * PLpgSQL_variable.
+ */
+ plpgsql_exec_get_datum_type_info(estate, var,
+ &vartypid, &vartypmod,
+ &varcollation);
+
+ TupleDescInitEntry(row->rowtupdesc, i + 1,
+ var->refname, vartypid, vartypmod,
+ 0);
+ TupleDescInitEntryCollation(row->rowtupdesc, i + 1,
+ varcollation);
+ }
+
+ TupleDescFinalize(row->rowtupdesc);
+
+ /* Make sure we have a valid type/typmod setting */
+ BlessTupleDesc(row->rowtupdesc);
+ }
+
+ *typeId = row->rowtupdesc->tdtypeid;
+ *typMod = row->rowtupdesc->tdtypmod;
+ /* composite types are never collatable */
+ *collation = InvalidOid;
+ break;
+ }
+
case PLPGSQL_DTYPE_REC:
{
PLpgSQL_rec *rec = (PLpgSQL_rec *) datum;
diff --git a/src/pl/plpgsql/src/plpgsql.h b/src/pl/plpgsql/src/plpgsql.h
index addb14a9959..5cbdb4ecd9d 100644
--- a/src/pl/plpgsql/src/plpgsql.h
+++ b/src/pl/plpgsql/src/plpgsql.h
@@ -299,6 +299,7 @@ typedef struct PLpgSQL_datum
{
PLpgSQL_datum_type dtype;
int dno;
+ char *refname;
} PLpgSQL_datum;
/*
@@ -444,9 +445,9 @@ typedef struct PLpgSQL_recfield
{
PLpgSQL_datum_type dtype;
int dno;
+ char *fieldname; /* name of field */
/* end of PLpgSQL_datum fields */
- char *fieldname; /* name of field */
int recparentno; /* dno of parent record */
int nextfield; /* dno of next child, or -1 if none */
uint64 rectupledescid; /* record's tupledesc ID as of last lookup */
diff --git a/src/pl/plpgsql/src/sql/plpgsql_foreach.sql b/src/pl/plpgsql/src/sql/plpgsql_foreach.sql
new file mode 100644
index 00000000000..a64004417af
--- /dev/null
+++ b/src/pl/plpgsql/src/sql/plpgsql_foreach.sql
@@ -0,0 +1,252 @@
+-- input must be a JSON array
+do $$
+declare x numeric;
+begin
+ foreach x in array NULL::jsonb -- fail
+ loop
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+
+do $$
+declare x numeric;
+begin
+ foreach x in array jsonb '10' -- fail
+ loop
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+
+do $$
+declare x numeric;
+begin
+ foreach x in array jsonb '{}' -- fail
+ loop
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+
+-- numeric to numeric
+do $$
+declare x numeric;
+begin
+ foreach x in array jsonb '[10,20,30,3.14, null]'
+ loop
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+
+-- numeric to int by cast
+do $$
+declare x int;
+begin
+ foreach x in array jsonb '[10,20,30,3.14, null]'
+ loop
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+
+-- test of FOUND variable
+do $$
+declare x int;
+begin
+ foreach x in array jsonb '[10]'
+ loop
+ raise notice '%', x;
+ end loop;
+ raise notice 'FOUND: %', found;
+end;
+$$;
+
+-- test of FOUND variable
+do $$
+declare x int;
+begin
+ foreach x in array jsonb '[]'
+ loop
+ raise notice '%', x;
+ end loop;
+ raise notice 'FOUND: %', found;
+end;
+$$;
+
+-- conversion "3.14" to int should to fail due IO cast
+do $$
+declare x int;
+begin
+ foreach x in array jsonb '["10",20,30,"3.14"]'
+ loop
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+
+do $$
+declare x boolean;
+begin
+ foreach x in array jsonb '[true, false]'
+ loop
+ if x then
+ raise notice 'true';
+ else
+ raise notice 'false';
+ end if;
+ end loop;
+end;
+$$;
+
+-- jsonb to jsonb
+do $$
+declare x jsonb;
+begin
+ foreach x in array jsonb '[10,20,30,3.14, null, "Hi"]'
+ loop
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+
+-- jsonb to json
+do $$
+declare x json;
+begin
+ foreach x in array jsonb '[10,20,30,3.14, null, "Hi"]'
+ loop
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+
+-- iteration over composites
+do $$
+declare x int; y numeric; z varchar;
+begin
+ foreach x, y, z in array jsonb '[{}, {"z":"Hi"}, {"y": 3.14}, {"z":"Hi", "x":10, "y":3.14}]'
+ loop
+ raise notice 'x: %, y: %, z: %', x, y, z;
+ end loop;
+end;
+$$;
+
+create type t3 as (x int, y numeric, z varchar);
+
+do $$
+declare c t3;
+begin
+ foreach c in array jsonb '[{}, {"z":"Hi"}, {"y": 3.14}, {"z":"Hi", "x":10, "y":3.14}]'
+ loop
+ raise notice 'x: %, y: %, z: %', c.x, c.y, c.z;
+ end loop;
+end;
+$$;
+
+do $$
+declare c t3;
+begin
+ foreach c.x, c.y, c.z in array jsonb '[{}, {"z":"Hi"}, {"y": 3.14}, {"z":"Hi", "x":10, "y":3.14}]'
+ loop
+ raise notice 'x: %, y: %, z: %', c.x, c.y, c.z;
+ end loop;
+end;
+$$;
+
+drop type t3;
+
+-- target can be a array
+do $$
+declare x int[];
+begin
+ foreach x in array jsonb '[[1,2,3],[4,5,6]]'
+ loop
+ raise notice '% % %', x[1], x[2], x[3];
+ end loop;
+end;
+$$;
+
+do $$
+declare x varchar[];
+begin
+ foreach x in array jsonb '[["Hi","Hello"],["Hello","Hi"]]'
+ loop
+ raise notice '% %', x[1], x[2];
+ end loop;
+end;
+$$;
+
+do $$
+declare x varchar[];
+begin
+ foreach x in array jsonb '[["Hi","Hello"],["Hello","Hi"]]'
+ loop
+ raise notice '% %', x[1], x[2];
+ end loop;
+end;
+$$;
+
+do $$
+declare x int[]; y varchar;
+begin
+ foreach x, y in array jsonb '[{"x":[1,2,3], "y":"Hi"}, {"x":[4,5,6], "y":"Hi"}]'
+ loop
+ raise notice '% % %, y: %', x[1], x[2], x[3], y;
+ end loop;
+end;
+$$;
+
+create type t2 as (x int[], y varchar);
+
+do $$
+declare c t2;
+begin
+ foreach c in array jsonb '[{"x":[1,2,3], "y":"Hi"}, {"x":[4,5,6], "y":"Hi"}]'
+ loop
+ raise notice '% % %, y: %', c.x[1], c.x[2], c.x[3], c.y;
+ end loop;
+end;
+$$;
+
+drop type t2;
+
+-- EXIT and CONTINUE can be triggered by LOOP_RC_PROCESSING
+do $$
+declare x int;
+begin
+ foreach x in array jsonb '[1,2,3,4,5]'
+ loop
+ exit when x = 3;
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+
+do $$
+declare x int;
+begin
+ foreach x in array jsonb '[1,2,3,4,5]'
+ loop
+ continue when x % 2 = 0;
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+
+-- Variable instead of string
+DO $$
+declare
+ x int;
+ arr jsonb;
+begin
+ select jsonb_agg(i) into arr
+ from generate_series(1,3) g(i);
+
+ foreach x in array arr
+ loop
+ raise notice '%', x;
+ end loop;
+end;
+$$;
--
2.53.0
^ permalink raw reply [nested|flat] 6+ messages in thread
* Re: POC: PLpgSQL FOREACH IN JSON ARRAY
2026-02-28 07:10 POC: PLpgSQL FOREACH IN JSON ARRAY Pavel Stehule <[email protected]>
2026-03-11 20:57 ` Re: POC: PLpgSQL FOREACH IN JSON ARRAY Peter Eisentraut <[email protected]>
2026-03-12 07:00 ` Re: POC: PLpgSQL FOREACH IN JSON ARRAY Pavel Stehule <[email protected]>
2026-03-17 06:58 ` Re: POC: PLpgSQL FOREACH IN JSON ARRAY Pavel Stehule <[email protected]>
@ 2026-03-21 18:40 ` Pavel Stehule <[email protected]>
2026-05-26 06:51 ` Re: POC: PLpgSQL FOREACH IN JSON ARRAY Pavel Stehule <[email protected]>
0 siblings, 1 reply; 6+ messages in thread
From: Pavel Stehule @ 2026-03-21 18:40 UTC (permalink / raw)
To: Tom Lane <[email protected]>; +Cc: Peter Eisentraut <[email protected]>; PostgreSQL Hackers <[email protected]>
Hi
only rebase
Regards
Pavel
Attachments:
[text/x-patch] v20260321-8-0001-FOREACH-scalar-IN-ARRAY-jsonb_expr.patch (37.0K, 3-v20260321-8-0001-FOREACH-scalar-IN-ARRAY-jsonb_expr.patch)
download | inline diff:
From a08a1205caaf0b546b7f21a1a6251551db2a0196 Mon Sep 17 00:00:00 2001
From: "[email protected]" <[email protected]>
Date: Mon, 23 Feb 2026 12:53:44 +0100
Subject: [PATCH] FOREACH scalar IN ARRAY jsonb_expr
this patch introduce support FOREACH scalar_var IN ARRAY expr, when the
result of the expression can be Jsonb. The design is based
on behave of jsonb_array_elements functions. In this case, FOREACH enforce
casting to target type (because we know target type) and try to reduce
IO casting. Attention: IO casting can be more strict, then casting based
on cast functions.
DECLARE t int;
BEGIN
-- this can work because we use cast numeric -> int
FOREACH t IN ARRAY '[1,2,3.14]'::jsonb
LOOP
-- this fails, because IO cast is used, and integer input function
-- allows only digits
FOREAC t IN JSON ARRAY '[1,2,3,"3.14"]'::jsonb
LOOP
Conceptual question is if casting should be strict like "old" PostgreSQL
json function or lax as "new" SQL/JSON functions? I can imagine lax mode
as default with possibility to switch to strict mode (this is not implemented
now):
FOREACH t IN ARRAY '[1,2,3]' ERROR ON EMPTY ERROR ON ERROR
LOOP
...
Because we use "old" syntax - FOREACH IN ARRAY, I prefer "old" behaviour,
that is more similar to iteration over an array.
The performance (best case for iteration over 1000 fields array) is about
4x better than when FOR IN SELECT jsonb_array_elements is used.
---
doc/src/sgml/plpgsql.sgml | 62 +++-
src/backend/utils/adt/arraysubs.c | 97 +++++-
src/backend/utils/adt/jsonbsubs.c | 181 ++++++++++-
src/include/nodes/subscripting.h | 29 ++
src/pl/plpgsql/src/Makefile | 2 +-
.../plpgsql/src/expected/plpgsql_foreach.out | 297 ++++++++++++++++++
src/pl/plpgsql/src/meson.build | 1 +
src/pl/plpgsql/src/pl_exec.c | 189 +++++------
src/pl/plpgsql/src/plpgsql.h | 3 +-
src/pl/plpgsql/src/sql/plpgsql_foreach.sql | 252 +++++++++++++++
10 files changed, 1016 insertions(+), 97 deletions(-)
create mode 100644 src/pl/plpgsql/src/expected/plpgsql_foreach.out
create mode 100644 src/pl/plpgsql/src/sql/plpgsql_foreach.sql
diff --git a/doc/src/sgml/plpgsql.sgml b/doc/src/sgml/plpgsql.sgml
index 561f6e50d63..6bc9fb02e1e 100644
--- a/doc/src/sgml/plpgsql.sgml
+++ b/doc/src/sgml/plpgsql.sgml
@@ -2697,12 +2697,12 @@ END LOOP <optional> <replaceable>label</replaceable> </optional>;
</sect2>
<sect2 id="plpgsql-foreach-array">
- <title>Looping through Arrays</title>
+ <title>Looping through Arrays or Jsonb arrays</title>
<para>
The <literal>FOREACH</literal> loop is much like a <literal>FOR</literal> loop,
but instead of iterating through the rows returned by an SQL query,
- it iterates through the elements of an array value.
+ it iterates through the elements of an array value or of jsonb array value.
(In general, <literal>FOREACH</literal> is meant for looping through
components of a composite-valued expression; variants for looping
through composites besides arrays may be added in future.)
@@ -2778,6 +2778,64 @@ NOTICE: row = {7,8,9}
NOTICE: row = {10,11,12}
</programlisting>
</para>
+
+ <para>
+ The <literal>SLICE</literal> higher than zero cannot be used when iterates
+ through jsonb arrays.
+ </para>
+
+ <para>
+ The <literal>FOREACH</literal> loop over jsonb arrays uses
+ same syntax like <literal>FOREACH</literal> loop over arrays,
+ but instead of iterating through elements of the array,
+ it iterates through the elements of a Jsonb array value.
+ </para>
+
+ <para>
+ The target can be a scalar variable, a composite variable, or a list
+ of scalar variables. When variable is not scalar, then assigned value
+ should be a JSON object and the JSON attributes are assigned by names.
+
+<programlisting>
+CREATE FUNCTION print_elements(jsonb) RETURNS void AS $$
+DECLARE
+ x int;
+BEGIN
+ FOREACH x IN ARRAY $1
+ LOOP
+ RAISE NOTICE 'row = %', x;
+ END LOOP;
+END;
+$$ LANGUAGE plpgsql;
+
+SELECT print_elements('[1,2,3]');
+NOTICE: row = 1
+NOTICE: row = 2
+NOTICE: row = 3
+
+CREATE FUNCTION print_fields(jsonb) RETURNS void AS $$
+DECLARE
+ x int; y varchar;
+BEGIN
+ FOREACH x, y IN ARRAY $1
+ LOOP
+ RAISE NOTICE 'x: %, y: %', x, y;
+ END LOOP;
+END;
+$$ LANGUAGE plpgsql;
+
+SELECT print_fields('[{},{"x":10},{"y":"Hi"},{"y":"Hi", "x":1000}]');
+NOTICE: x: <NULL>, y: <NULL>
+NOTICE: x: 10, y: <NULL>
+NOTICE: x: <NULL>, y: Hi
+NOTICE: x: 1000, y: Hi
+</programlisting>
+ </para>
+
+ <para>
+ The target variable can be of type <literal>RECORD</literal>, but the real structure has to be
+ assigned before usage in the <literal>FOREACH</literal> statement.
+ </para>
</sect2>
<sect2 id="plpgsql-error-trapping">
diff --git a/src/backend/utils/adt/arraysubs.c b/src/backend/utils/adt/arraysubs.c
index 2bf9e9509fb..a42248ed633 100644
--- a/src/backend/utils/adt/arraysubs.c
+++ b/src/backend/utils/adt/arraysubs.c
@@ -23,6 +23,7 @@
#include "parser/parse_coerce.h"
#include "parser/parse_expr.h"
#include "utils/array.h"
+#include "utils/builtins.h"
#include "utils/fmgrprotos.h"
#include "utils/lsyscache.h"
@@ -46,6 +47,96 @@ typedef struct ArraySubWorkspace
int lowerindex[MAXDIM];
} ArraySubWorkspace;
+typedef struct
+{
+ ForeachAIterator pub;
+ ArrayIterator it;
+ Oid result_typid;
+ int32 result_typmod;
+} ForeachAArrayIterState;
+
+static bool
+foreach_a_array_iterate(ForeachAIterator *self,
+ Datum *value, bool *isnull,
+ Oid *typid, int32 *typmod)
+{
+ ForeachAArrayIterState *iter = (ForeachAArrayIterState *) self;
+
+ *typid = iter->result_typid;
+ *typmod = iter->result_typmod;
+
+ return array_iterate(iter->it, value, isnull);
+}
+
+/*
+ * Used by plpgsql FOREACH IN ARRAY when input expression is an array
+ */
+static ForeachAIterator *
+create_foreach_a_array_iterator(Datum value, Oid typid, int32 typmod,
+ int slice, Oid target_typid, int32 target_typmod)
+{
+ ForeachAArrayIterState *iter = palloc0(sizeof(ForeachAArrayIterState));
+ ArrayType *arr;
+ Oid target_elem_typid;
+
+ /* check the type of the expression - must be an array */
+ if (!OidIsValid(get_element_type(typid)))
+ ereport(ERROR,
+ (errcode(ERRCODE_DATATYPE_MISMATCH),
+ errmsg("FOREACH expression must yield an array, not type %s",
+ format_type_be(typid))));
+
+ /*
+ * We must copy the array into current context, because input expression
+ * is evaluated in context cleaned by exec_eval_cleanup.
+ */
+ arr = DatumGetArrayTypePCopy(value);
+
+ /* Slice dimension must be less than or equal to array dimension */
+ if (slice < 0 || slice > ARR_NDIM(arr))
+ ereport(ERROR,
+ (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
+ errmsg("slice dimension (%d) is out of the valid range 0..%d",
+ slice, ARR_NDIM(arr))));
+
+ /*
+ * Sanity-check the target type. We don't try very hard here, and
+ * should not be too picky since it's possible that exec_assign_value can
+ * coerce values of different types. But it seems worthwhile to complain
+ * if the array-ness of the loop variable is not right.
+ */
+ target_elem_typid = get_element_type(target_typid);
+
+ if (slice > 0 && target_elem_typid == InvalidOid)
+ ereport(ERROR,
+ (errcode(ERRCODE_DATATYPE_MISMATCH),
+ errmsg("FOREACH ... SLICE loop variable must be of an array type")));
+ if (slice == 0 && target_elem_typid != InvalidOid)
+ ereport(ERROR,
+ (errcode(ERRCODE_DATATYPE_MISMATCH),
+ errmsg("FOREACH loop variable must not be of an array type")));
+
+ /* Identify iterator result type */
+ if (slice > 0)
+ {
+ /* When slicing, nominal type of result is same as array type */
+ iter->result_typid = typid;
+ iter->result_typmod = typmod;
+ }
+ else
+ {
+ /* Without slicing, results are individual array elements */
+ iter->result_typid = ARR_ELEMTYPE(arr);
+ iter->result_typmod = typmod;
+ }
+
+ /* Create an iterator to step through the array */
+ iter->it = array_create_iterator(arr, slice, NULL);
+
+ iter->pub.iterate = foreach_a_array_iterate;
+
+ return (ForeachAIterator *) iter;
+}
/*
* Finish parse analysis of a SubscriptingRef expression for an array.
@@ -545,7 +636,8 @@ array_subscript_handler(PG_FUNCTION_ARGS)
.exec_setup = array_exec_setup,
.fetch_strict = true, /* fetch returns NULL for NULL inputs */
.fetch_leakproof = true, /* fetch returns NULL for bad subscript */
- .store_leakproof = false /* ... but assignment throws error */
+ .store_leakproof = false, /* ... but assignment throws error */
+ .create_foreach_a_iterator = create_foreach_a_array_iterator
};
PG_RETURN_POINTER(&sbsroutines);
@@ -572,7 +664,8 @@ raw_array_subscript_handler(PG_FUNCTION_ARGS)
.exec_setup = array_exec_setup,
.fetch_strict = true, /* fetch returns NULL for NULL inputs */
.fetch_leakproof = true, /* fetch returns NULL for bad subscript */
- .store_leakproof = false /* ... but assignment throws error */
+ .store_leakproof = false, /* ... but assignment throws error */
+ .create_foreach_a_iterator = create_foreach_a_array_iterator
};
PG_RETURN_POINTER(&sbsroutines);
diff --git a/src/backend/utils/adt/jsonbsubs.c b/src/backend/utils/adt/jsonbsubs.c
index f2745b29a3f..ad2edf525de 100644
--- a/src/backend/utils/adt/jsonbsubs.c
+++ b/src/backend/utils/adt/jsonbsubs.c
@@ -22,6 +22,7 @@
#include "parser/parse_expr.h"
#include "utils/builtins.h"
#include "utils/jsonb.h"
+#include "utils/jsonfuncs.h"
/* SubscriptingRefState.workspace for jsonb subscripting execution */
@@ -33,6 +34,17 @@ typedef struct JsonbSubWorkspace
Datum *index; /* Subscript values in Datum format */
} JsonbSubWorkspace;
+typedef struct
+{
+ ForeachAIterator pub;
+ JsonbIterator *it;
+ bool skip_nested;
+ Oid target_typid;
+ int32 target_typmod;
+
+ MemoryContext cache_mcxt;
+ void *cache;
+} ForeachAJsonbIterState;
/*
* Finish parse analysis of a SubscriptingRef expression for a jsonb.
@@ -394,6 +406,172 @@ jsonb_exec_setup(const SubscriptingRef *sbsref,
methods->sbs_fetch_old = jsonb_subscript_fetch_old;
}
+/*
+ * Convert JsonbValue to Datum. This function is used in
+ * generic array iterator, that is used by FOREACH plpgsql
+ * statement. Against other cases, the result should not be
+ * necessary of expected_typid, because the value can be
+ * converted later when the value is assigned to PL/pgSQL
+ * variable. This can be more effective than generic IO
+ * cast used by json_populate_type.
+ */
+static Datum
+JsonbValueToDatum(JsonbValue *jbv,
+ Oid *typid, int32 *typmod, bool *isnull,
+ Oid expected_typid, int32 expected_typmod,
+ void **cache, MemoryContext mcxt)
+{
+ Datum result;
+
+ *isnull = false;
+ *typmod = -1;
+
+ /*
+ * These types can holds JSON null, so must be processed
+ * before processing jbvNull. We don't want to convert
+ * JSON null, to SQL null, when targer is of JSON.
+ */
+ if (expected_typid == JSONBOID || expected_typid == JSONOID)
+ {
+ Jsonb *jb = JsonbValueToJsonb(jbv);
+
+ if (expected_typid == JSONOID)
+ {
+ char *str;
+
+ str = JsonbToCString(NULL, &jb->root, VARSIZE(jb));
+ result = PointerGetDatum(cstring_to_text(str));
+ }
+ else
+ result = PointerGetDatum(jb);
+
+ *typid = expected_typid;
+ }
+
+ /*
+ * For special cases we can skip conversion to Jsonb
+ * and possibly IO cast.
+ */
+ else if (jbv->type == jbvNull)
+ {
+ result = (Datum) 0;
+ *isnull = true;
+ *typid = expected_typid;
+ }
+ else if (jbv->type == jbvString)
+ {
+ text *txt = cstring_to_text_with_len(jbv->val.string.val,
+ jbv->val.string.len);
+
+ result = PointerGetDatum(txt);
+ *typid = TEXTOID;
+ }
+ else if (jbv->type == jbvNumeric)
+ {
+ result = PointerGetDatum(jbv->val.numeric);
+ *typid = NUMERICOID;
+ }
+ else if (jbv->type == jbvBool)
+ {
+ result = BoolGetDatum(jbv->val.boolean);
+ *typid = BOOLOID;
+ }
+
+ /* generic conversion */
+ else
+ {
+ Jsonb *jb = JsonbValueToJsonb(jbv);
+
+ result = json_populate_type(PointerGetDatum(jb), JSONBOID,
+ expected_typid, expected_typmod,
+ cache, mcxt,
+ isnull, false, NULL);
+
+ *typid = expected_typid;
+ *typmod = expected_typmod;
+ }
+
+ return result;
+}
+
+static bool
+foreach_a_jsonb_iterate(ForeachAIterator *self,
+ Datum *value, bool *isnull,
+ Oid *typid, int32 *typmod)
+{
+ ForeachAJsonbIterState *iter = (ForeachAJsonbIterState *) self;
+ JsonbIteratorToken r;
+ JsonbValue jbv;
+
+ while ((r = JsonbIteratorNext(&iter->it, &jbv, iter->skip_nested)) != WJB_DONE)
+ {
+ iter->skip_nested = true;
+
+ if (r == WJB_ELEM)
+ {
+ *value = JsonbValueToDatum(&jbv, typid, typmod, isnull,
+ iter->target_typid, iter->target_typmod,
+ &iter->cache, iter->cache_mcxt);
+
+ return true;
+ }
+ }
+
+ return false;
+}
+
+/*
+ * Create foreach array iterator for jsonb array
+ */
+static ForeachAIterator *
+create_foreach_a_jsonb_iterator(Datum value, Oid typid, int32 typmod,
+ int slice, Oid target_typid, int32 target_typmod)
+{
+ ForeachAJsonbIterState *iter = palloc0(sizeof(ForeachAJsonbIterState));
+ Jsonb *jb;
+
+ if (typid != JSONBOID)
+ elog(ERROR, "unexpected source type");
+
+ if (slice > 0)
+ ereport(ERROR,
+ (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+ errmsg("jsonb array iterator doesn't support slicing")));
+
+ /*
+ * We must copy the JSON into current context, because input expression
+ * is evaluated in context cleaned by exec_eval_cleanup.
+ */
+ jb = DatumGetJsonbPCopy(value);
+
+ /*
+ * Jsonb iterator is designed like jsonb_array_element. Input value
+ * must be json array.
+ */
+ if (JB_ROOT_IS_SCALAR(jb))
+ ereport(ERROR,
+ (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+ errmsg("FOREACH expression must evaluate to a JSON array"),
+ errhint("Cannot iterate over a scalar value.")));
+ else if (JB_ROOT_IS_OBJECT(jb))
+ ereport(ERROR,
+ (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+ errmsg("FOREACH expression must evaluate to a JSON array"),
+ errdetail("Cannot iterate over an object value.")));
+
+ Assert(JB_ROOT_IS_ARRAY(jb));
+
+ iter->it = JsonbIteratorInit(&jb->root);
+
+ iter->target_typid = target_typid;
+ iter->target_typmod = target_typmod;
+ iter->cache_mcxt = CurrentMemoryContext;
+
+ iter->pub.iterate = foreach_a_jsonb_iterate;
+
+ return (ForeachAIterator *) iter;
+}
+
/*
* jsonb_subscript_handler
* Subscripting handler for jsonb.
@@ -407,7 +585,8 @@ jsonb_subscript_handler(PG_FUNCTION_ARGS)
.exec_setup = jsonb_exec_setup,
.fetch_strict = true, /* fetch returns NULL for NULL inputs */
.fetch_leakproof = true, /* fetch returns NULL for bad subscript */
- .store_leakproof = false /* ... but assignment throws error */
+ .store_leakproof = false, /* ... but assignment throws error */
+ .create_foreach_a_iterator = create_foreach_a_jsonb_iterator
};
PG_RETURN_POINTER(&sbsroutines);
diff --git a/src/include/nodes/subscripting.h b/src/include/nodes/subscripting.h
index 301f21dac2f..08bfe59ede4 100644
--- a/src/include/nodes/subscripting.h
+++ b/src/include/nodes/subscripting.h
@@ -154,6 +154,32 @@ typedef void (*SubscriptExecSetup) (const SubscriptingRef *sbsref,
SubscriptingRefState *sbsrefstate,
SubscriptExecSteps *methods);
+typedef struct _ForeachAIterator ForeachAIterator;
+
+/*
+ * ForeachAIiterator is used by PLpgSQL FOREACH IN ARRAY statement.
+ * Input value should not be null, and inside CreateForeachAIterator
+ * routine must be copied to current (statement) context. "iterate"
+ * routine is called under short life memory context, that is resetted
+ * after any call.
+ */
+struct _ForeachAIterator
+{
+ bool (*iterate) (ForeachAIterator *self,
+ Datum *value,
+ bool *isnull,
+ Oid *typid,
+ int32 *typmod);
+ /* Private fields might appear beyond this point... */
+};
+
+typedef ForeachAIterator * (*CreateForeachAIterator) (Datum value,
+ Oid typid,
+ int32 typmod,
+ int slice,
+ Oid target_typid,
+ int32 target_typmod);
+
/* Struct returned by the SQL-visible subscript handler function */
typedef struct SubscriptRoutines
{
@@ -163,6 +189,9 @@ typedef struct SubscriptRoutines
bool fetch_leakproof; /* is fetch SubscriptingRef leakproof? */
bool store_leakproof; /* is assignment SubscriptingRef
* leakproof? */
+
+ /* returns iterator used by PL/pgSQL FOREACH statement */
+ CreateForeachAIterator create_foreach_a_iterator;
} SubscriptRoutines;
#endif /* SUBSCRIPTING_H */
diff --git a/src/pl/plpgsql/src/Makefile b/src/pl/plpgsql/src/Makefile
index 63cb96fae3e..5bd0cf31dfc 100644
--- a/src/pl/plpgsql/src/Makefile
+++ b/src/pl/plpgsql/src/Makefile
@@ -35,7 +35,7 @@ REGRESS_OPTS = --dbname=$(PL_TESTDB)
REGRESS = plpgsql_array plpgsql_cache plpgsql_call plpgsql_control \
plpgsql_copy plpgsql_domain plpgsql_misc \
plpgsql_record plpgsql_simple plpgsql_transaction \
- plpgsql_trap plpgsql_trigger plpgsql_varprops
+ plpgsql_trap plpgsql_trigger plpgsql_varprops plpgsql_foreach
# where to find gen_keywordlist.pl and subsidiary files
TOOLSDIR = $(top_srcdir)/src/tools
diff --git a/src/pl/plpgsql/src/expected/plpgsql_foreach.out b/src/pl/plpgsql/src/expected/plpgsql_foreach.out
new file mode 100644
index 00000000000..ddc571f3c79
--- /dev/null
+++ b/src/pl/plpgsql/src/expected/plpgsql_foreach.out
@@ -0,0 +1,297 @@
+-- input must be a JSON array
+do $$
+declare x numeric;
+begin
+ foreach x in array NULL::jsonb -- fail
+ loop
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+ERROR: FOREACH expression must not be null
+CONTEXT: PL/pgSQL function inline_code_block line 4 at FOREACH over array
+do $$
+declare x numeric;
+begin
+ foreach x in array jsonb '10' -- fail
+ loop
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+ERROR: FOREACH expression must evaluate to a JSON array
+HINT: Cannot iterate over a scalar value.
+CONTEXT: PL/pgSQL function inline_code_block line 4 at FOREACH over array
+do $$
+declare x numeric;
+begin
+ foreach x in array jsonb '{}' -- fail
+ loop
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+ERROR: FOREACH expression must evaluate to a JSON array
+DETAIL: Cannot iterate over an object value.
+CONTEXT: PL/pgSQL function inline_code_block line 4 at FOREACH over array
+-- numeric to numeric
+do $$
+declare x numeric;
+begin
+ foreach x in array jsonb '[10,20,30,3.14, null]'
+ loop
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+NOTICE: 10
+NOTICE: 20
+NOTICE: 30
+NOTICE: 3.14
+NOTICE: <NULL>
+-- numeric to int by cast
+do $$
+declare x int;
+begin
+ foreach x in array jsonb '[10,20,30,3.14, null]'
+ loop
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+NOTICE: 10
+NOTICE: 20
+NOTICE: 30
+NOTICE: 3
+NOTICE: <NULL>
+-- test of FOUND variable
+do $$
+declare x int;
+begin
+ foreach x in array jsonb '[10]'
+ loop
+ raise notice '%', x;
+ end loop;
+ raise notice 'FOUND: %', found;
+end;
+$$;
+NOTICE: 10
+NOTICE: FOUND: t
+-- test of FOUND variable
+do $$
+declare x int;
+begin
+ foreach x in array jsonb '[]'
+ loop
+ raise notice '%', x;
+ end loop;
+ raise notice 'FOUND: %', found;
+end;
+$$;
+NOTICE: FOUND: f
+-- conversion "3.14" to int should to fail due IO cast
+do $$
+declare x int;
+begin
+ foreach x in array jsonb '["10",20,30,"3.14"]'
+ loop
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+NOTICE: 10
+NOTICE: 20
+NOTICE: 30
+ERROR: invalid input syntax for type integer: "3.14"
+CONTEXT: PL/pgSQL function inline_code_block line 4 at FOREACH over array
+do $$
+declare x boolean;
+begin
+ foreach x in array jsonb '[true, false]'
+ loop
+ if x then
+ raise notice 'true';
+ else
+ raise notice 'false';
+ end if;
+ end loop;
+end;
+$$;
+NOTICE: true
+NOTICE: false
+-- jsonb to jsonb
+do $$
+declare x jsonb;
+begin
+ foreach x in array jsonb '[10,20,30,3.14, null, "Hi"]'
+ loop
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+NOTICE: 10
+NOTICE: 20
+NOTICE: 30
+NOTICE: 3.14
+NOTICE: null
+NOTICE: "Hi"
+-- jsonb to json
+do $$
+declare x json;
+begin
+ foreach x in array jsonb '[10,20,30,3.14, null, "Hi"]'
+ loop
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+NOTICE: 10
+NOTICE: 20
+NOTICE: 30
+NOTICE: 3.14
+NOTICE: null
+NOTICE: "Hi"
+-- iteration over composites
+do $$
+declare x int; y numeric; z varchar;
+begin
+ foreach x, y, z in array jsonb '[{}, {"z":"Hi"}, {"y": 3.14}, {"z":"Hi", "x":10, "y":3.14}]'
+ loop
+ raise notice 'x: %, y: %, z: %', x, y, z;
+ end loop;
+end;
+$$;
+NOTICE: x: <NULL>, y: <NULL>, z: <NULL>
+NOTICE: x: <NULL>, y: <NULL>, z: Hi
+NOTICE: x: <NULL>, y: 3.14, z: <NULL>
+NOTICE: x: 10, y: 3.14, z: Hi
+create type t3 as (x int, y numeric, z varchar);
+do $$
+declare c t3;
+begin
+ foreach c in array jsonb '[{}, {"z":"Hi"}, {"y": 3.14}, {"z":"Hi", "x":10, "y":3.14}]'
+ loop
+ raise notice 'x: %, y: %, z: %', c.x, c.y, c.z;
+ end loop;
+end;
+$$;
+NOTICE: x: <NULL>, y: <NULL>, z: <NULL>
+NOTICE: x: <NULL>, y: <NULL>, z: Hi
+NOTICE: x: <NULL>, y: 3.14, z: <NULL>
+NOTICE: x: 10, y: 3.14, z: Hi
+do $$
+declare c t3;
+begin
+ foreach c.x, c.y, c.z in array jsonb '[{}, {"z":"Hi"}, {"y": 3.14}, {"z":"Hi", "x":10, "y":3.14}]'
+ loop
+ raise notice 'x: %, y: %, z: %', c.x, c.y, c.z;
+ end loop;
+end;
+$$;
+NOTICE: x: <NULL>, y: <NULL>, z: <NULL>
+NOTICE: x: <NULL>, y: <NULL>, z: Hi
+NOTICE: x: <NULL>, y: 3.14, z: <NULL>
+NOTICE: x: 10, y: 3.14, z: Hi
+drop type t3;
+-- target can be a array
+do $$
+declare x int[];
+begin
+ foreach x in array jsonb '[[1,2,3],[4,5,6]]'
+ loop
+ raise notice '% % %', x[1], x[2], x[3];
+ end loop;
+end;
+$$;
+NOTICE: 1 2 3
+NOTICE: 4 5 6
+do $$
+declare x varchar[];
+begin
+ foreach x in array jsonb '[["Hi","Hello"],["Hello","Hi"]]'
+ loop
+ raise notice '% %', x[1], x[2];
+ end loop;
+end;
+$$;
+NOTICE: Hi Hello
+NOTICE: Hello Hi
+do $$
+declare x varchar[];
+begin
+ foreach x in array jsonb '[["Hi","Hello"],["Hello","Hi"]]'
+ loop
+ raise notice '% %', x[1], x[2];
+ end loop;
+end;
+$$;
+NOTICE: Hi Hello
+NOTICE: Hello Hi
+do $$
+declare x int[]; y varchar;
+begin
+ foreach x, y in array jsonb '[{"x":[1,2,3], "y":"Hi"}, {"x":[4,5,6], "y":"Hi"}]'
+ loop
+ raise notice '% % %, y: %', x[1], x[2], x[3], y;
+ end loop;
+end;
+$$;
+NOTICE: 1 2 3, y: Hi
+NOTICE: 4 5 6, y: Hi
+create type t2 as (x int[], y varchar);
+do $$
+declare c t2;
+begin
+ foreach c in array jsonb '[{"x":[1,2,3], "y":"Hi"}, {"x":[4,5,6], "y":"Hi"}]'
+ loop
+ raise notice '% % %, y: %', c.x[1], c.x[2], c.x[3], c.y;
+ end loop;
+end;
+$$;
+NOTICE: 1 2 3, y: Hi
+NOTICE: 4 5 6, y: Hi
+drop type t2;
+-- EXIT and CONTINUE can be triggered by LOOP_RC_PROCESSING
+do $$
+declare x int;
+begin
+ foreach x in array jsonb '[1,2,3,4,5]'
+ loop
+ exit when x = 3;
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+NOTICE: 1
+NOTICE: 2
+do $$
+declare x int;
+begin
+ foreach x in array jsonb '[1,2,3,4,5]'
+ loop
+ continue when x % 2 = 0;
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+NOTICE: 1
+NOTICE: 3
+NOTICE: 5
+-- Variable instead of string
+DO $$
+declare
+ x int;
+ arr jsonb;
+begin
+ select jsonb_agg(i) into arr
+ from generate_series(1,3) g(i);
+
+ foreach x in array arr
+ loop
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+NOTICE: 1
+NOTICE: 2
+NOTICE: 3
diff --git a/src/pl/plpgsql/src/meson.build b/src/pl/plpgsql/src/meson.build
index 6ff27006cfc..609eed7a28d 100644
--- a/src/pl/plpgsql/src/meson.build
+++ b/src/pl/plpgsql/src/meson.build
@@ -88,6 +88,7 @@ tests += {
'plpgsql_trap',
'plpgsql_trigger',
'plpgsql_varprops',
+ 'plpgsql_foreach',
],
},
}
diff --git a/src/pl/plpgsql/src/pl_exec.c b/src/pl/plpgsql/src/pl_exec.c
index 45d667428f4..9ed346f13ab 100644
--- a/src/pl/plpgsql/src/pl_exec.c
+++ b/src/pl/plpgsql/src/pl_exec.c
@@ -29,6 +29,7 @@
#include "mb/stringinfo_mb.h"
#include "miscadmin.h"
#include "nodes/nodeFuncs.h"
+#include "nodes/subscripting.h"
#include "nodes/supportnodes.h"
#include "optimizer/optimizer.h"
#include "parser/parse_coerce.h"
@@ -3026,40 +3027,49 @@ exec_stmt_forc(PLpgSQL_execstate *estate, PLpgSQL_stmt_forc *stmt)
return rc;
}
-
/* ----------
- * exec_stmt_foreach_a Loop over elements or slices of an array
- *
- * When looping over elements, the loop variable is the same type that the
- * array stores (eg: integer), when looping through slices, the loop variable
- * is an array of size and dimensions to match the size of the slice.
- * ----------
+ * exec_stmt_foreach_a Loop over elements in an array or jsonb array
+ * ----------
*/
static int
exec_stmt_foreach_a(PLpgSQL_execstate *estate, PLpgSQL_stmt_foreach_a *stmt)
{
- ArrayType *arr;
- Oid arrtype;
- int32 arrtypmod;
- PLpgSQL_datum *loop_var;
- Oid loop_var_elem_type;
- bool found = false;
+ Datum expr;
+ Oid expr_typid;
+ int32 expr_typmod;
+ bool isnull;
+ PLpgSQL_datum *target_var;
+ Oid target_typid;
+ int32 target_typmod;
+ Oid target_collation;
+ Datum value;
+ Oid typid;
+ int32 typmod;
int rc = PLPGSQL_RC_OK;
+ const struct SubscriptRoutines *sbroutines;
+ ForeachAIterator *iterator;
MemoryContext stmt_mcontext;
+ MemoryContext tmp_cxt;
MemoryContext oldcontext;
- ArrayIterator array_iterator;
- Oid iterator_result_type;
- int32 iterator_result_typmod;
- Datum value;
- bool isnull;
+ bool found = false;
- /* get the value of the array expression */
- value = exec_eval_expr(estate, stmt->expr, &isnull, &arrtype, &arrtypmod);
+ /* get the value of the expression */
+ expr = exec_eval_expr(estate, stmt->expr, &isnull,
+ &expr_typid, &expr_typmod);
if (isnull)
ereport(ERROR,
(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
errmsg("FOREACH expression must not be null")));
+ sbroutines = getSubscriptingRoutines(expr_typid, NULL);
+ if (!sbroutines)
+ ereport(ERROR,
+ (errcode(ERRCODE_DATATYPE_MISMATCH),
+ errmsg("cannot iterate over type %s because it does not support subscripting",
+ format_type_be(expr_typid))));
+
+ Assert(sbroutines->create_foreach_a_iterator);
+
/*
* Do as much as possible of the code below in stmt_mcontext, to avoid any
* leaks from called subroutines. We need a private stmt_mcontext since
@@ -3069,79 +3079,34 @@ exec_stmt_foreach_a(PLpgSQL_execstate *estate, PLpgSQL_stmt_foreach_a *stmt)
push_stmt_mcontext(estate);
oldcontext = MemoryContextSwitchTo(stmt_mcontext);
- /* check the type of the expression - must be an array */
- if (!OidIsValid(get_element_type(arrtype)))
- ereport(ERROR,
- (errcode(ERRCODE_DATATYPE_MISMATCH),
- errmsg("FOREACH expression must yield an array, not type %s",
- format_type_be(arrtype))));
+ /* Set up the target (loop) variable */
+ target_var = estate->datums[stmt->varno];
+
+ plpgsql_exec_get_datum_type_info(estate, target_var,
+ &target_typid, &target_typmod,
+ &target_collation);
/*
- * We must copy the array into stmt_mcontext, else it will disappear in
- * exec_eval_cleanup. This is annoying, but cleanup will certainly happen
- * while running the loop body, so we have little choice.
+ * inside iterator constroctor, the expr should be copied to
+ * current memory context (stmt_mcontext). Without it, it will be released
+ * by next exec_eval_cleanup. The iterator constructor should
+ * be called under stmt memory context.
*/
- arr = DatumGetArrayTypePCopy(value);
+ iterator = sbroutines->create_foreach_a_iterator(expr,
+ expr_typid, expr_typmod,
+ stmt->slice, target_typid,
+ target_typmod);
/* Clean up any leftover temporary memory */
exec_eval_cleanup(estate);
- /* Slice dimension must be less than or equal to array dimension */
- if (stmt->slice < 0 || stmt->slice > ARR_NDIM(arr))
- ereport(ERROR,
- (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
- errmsg("slice dimension (%d) is out of the valid range 0..%d",
- stmt->slice, ARR_NDIM(arr))));
-
- /* Set up the loop variable and see if it is of an array type */
- loop_var = estate->datums[stmt->varno];
- if (loop_var->dtype == PLPGSQL_DTYPE_REC ||
- loop_var->dtype == PLPGSQL_DTYPE_ROW)
- {
- /*
- * Record/row variable is certainly not of array type, and might not
- * be initialized at all yet, so don't try to get its type
- */
- loop_var_elem_type = InvalidOid;
- }
- else
- loop_var_elem_type = get_element_type(plpgsql_exec_get_datum_type(estate,
- loop_var));
+ tmp_cxt = AllocSetContextCreate(stmt_mcontext,
+ "FOREACH IN ARRAY temporary cxt",
+ ALLOCSET_DEFAULT_SIZES);
- /*
- * Sanity-check the loop variable type. We don't try very hard here, and
- * should not be too picky since it's possible that exec_assign_value can
- * coerce values of different types. But it seems worthwhile to complain
- * if the array-ness of the loop variable is not right.
- */
- if (stmt->slice > 0 && loop_var_elem_type == InvalidOid)
- ereport(ERROR,
- (errcode(ERRCODE_DATATYPE_MISMATCH),
- errmsg("FOREACH ... SLICE loop variable must be of an array type")));
- if (stmt->slice == 0 && loop_var_elem_type != InvalidOid)
- ereport(ERROR,
- (errcode(ERRCODE_DATATYPE_MISMATCH),
- errmsg("FOREACH loop variable must not be of an array type")));
+ MemoryContextSwitchTo(tmp_cxt);
- /* Create an iterator to step through the array */
- array_iterator = array_create_iterator(arr, stmt->slice, NULL);
-
- /* Identify iterator result type */
- if (stmt->slice > 0)
- {
- /* When slicing, nominal type of result is same as array type */
- iterator_result_type = arrtype;
- iterator_result_typmod = arrtypmod;
- }
- else
- {
- /* Without slicing, results are individual array elements */
- iterator_result_type = ARR_ELEMTYPE(arr);
- iterator_result_typmod = arrtypmod;
- }
-
- /* Iterate over the array elements or slices */
- while (array_iterate(array_iterator, &value, &isnull))
+ while (iterator->iterate(iterator, &value, &isnull, &typid, &typmod))
{
found = true; /* looped at least once */
@@ -3149,12 +3114,9 @@ exec_stmt_foreach_a(PLpgSQL_execstate *estate, PLpgSQL_stmt_foreach_a *stmt)
MemoryContextSwitchTo(oldcontext);
/* Assign current element/slice to the loop variable */
- exec_assign_value(estate, loop_var, value, isnull,
- iterator_result_type, iterator_result_typmod);
+ exec_assign_value(estate, target_var, value, isnull, typid, typmod);
- /* In slice case, value is temporary; must free it to avoid leakage */
- if (stmt->slice > 0)
- pfree(DatumGetPointer(value));
+ MemoryContextReset(tmp_cxt);
/*
* Execute the statements
@@ -3163,7 +3125,7 @@ exec_stmt_foreach_a(PLpgSQL_execstate *estate, PLpgSQL_stmt_foreach_a *stmt)
LOOP_RC_PROCESSING(stmt->label, break);
- MemoryContextSwitchTo(stmt_mcontext);
+ MemoryContextSwitchTo(tmp_cxt);
}
/* Restore memory context state */
@@ -5637,6 +5599,53 @@ plpgsql_exec_get_datum_type_info(PLpgSQL_execstate *estate,
break;
}
+ case PLPGSQL_DTYPE_ROW:
+ {
+ PLpgSQL_row *row = (PLpgSQL_row *) datum;
+
+ if (!row->rowtupdesc)
+ {
+ int i;
+
+ row->rowtupdesc = CreateTemplateTupleDesc(row->nfields);
+
+ for (i = 0; i < row->nfields; i++)
+ {
+ PLpgSQL_datum *var = estate->datums[row->varnos[i]];
+ Oid vartypid;
+ int32 vartypmod;
+ Oid varcollation;
+
+ /*
+ * We cannot use fieldnames for tupdescentry, because
+ * these names can be suffixed by name of row variable.
+ * Unfortunately, the PLpgSQL_recfield is not casted to
+ * PLpgSQL_variable.
+ */
+ plpgsql_exec_get_datum_type_info(estate, var,
+ &vartypid, &vartypmod,
+ &varcollation);
+
+ TupleDescInitEntry(row->rowtupdesc, i + 1,
+ var->refname, vartypid, vartypmod,
+ 0);
+ TupleDescInitEntryCollation(row->rowtupdesc, i + 1,
+ varcollation);
+ }
+
+ TupleDescFinalize(row->rowtupdesc);
+
+ /* Make sure we have a valid type/typmod setting */
+ BlessTupleDesc(row->rowtupdesc);
+ }
+
+ *typeId = row->rowtupdesc->tdtypeid;
+ *typMod = row->rowtupdesc->tdtypmod;
+ /* composite types are never collatable */
+ *collation = InvalidOid;
+ break;
+ }
+
case PLPGSQL_DTYPE_REC:
{
PLpgSQL_rec *rec = (PLpgSQL_rec *) datum;
diff --git a/src/pl/plpgsql/src/plpgsql.h b/src/pl/plpgsql/src/plpgsql.h
index addb14a9959..5cbdb4ecd9d 100644
--- a/src/pl/plpgsql/src/plpgsql.h
+++ b/src/pl/plpgsql/src/plpgsql.h
@@ -299,6 +299,7 @@ typedef struct PLpgSQL_datum
{
PLpgSQL_datum_type dtype;
int dno;
+ char *refname;
} PLpgSQL_datum;
/*
@@ -444,9 +445,9 @@ typedef struct PLpgSQL_recfield
{
PLpgSQL_datum_type dtype;
int dno;
+ char *fieldname; /* name of field */
/* end of PLpgSQL_datum fields */
- char *fieldname; /* name of field */
int recparentno; /* dno of parent record */
int nextfield; /* dno of next child, or -1 if none */
uint64 rectupledescid; /* record's tupledesc ID as of last lookup */
diff --git a/src/pl/plpgsql/src/sql/plpgsql_foreach.sql b/src/pl/plpgsql/src/sql/plpgsql_foreach.sql
new file mode 100644
index 00000000000..a64004417af
--- /dev/null
+++ b/src/pl/plpgsql/src/sql/plpgsql_foreach.sql
@@ -0,0 +1,252 @@
+-- input must be a JSON array
+do $$
+declare x numeric;
+begin
+ foreach x in array NULL::jsonb -- fail
+ loop
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+
+do $$
+declare x numeric;
+begin
+ foreach x in array jsonb '10' -- fail
+ loop
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+
+do $$
+declare x numeric;
+begin
+ foreach x in array jsonb '{}' -- fail
+ loop
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+
+-- numeric to numeric
+do $$
+declare x numeric;
+begin
+ foreach x in array jsonb '[10,20,30,3.14, null]'
+ loop
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+
+-- numeric to int by cast
+do $$
+declare x int;
+begin
+ foreach x in array jsonb '[10,20,30,3.14, null]'
+ loop
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+
+-- test of FOUND variable
+do $$
+declare x int;
+begin
+ foreach x in array jsonb '[10]'
+ loop
+ raise notice '%', x;
+ end loop;
+ raise notice 'FOUND: %', found;
+end;
+$$;
+
+-- test of FOUND variable
+do $$
+declare x int;
+begin
+ foreach x in array jsonb '[]'
+ loop
+ raise notice '%', x;
+ end loop;
+ raise notice 'FOUND: %', found;
+end;
+$$;
+
+-- conversion "3.14" to int should to fail due IO cast
+do $$
+declare x int;
+begin
+ foreach x in array jsonb '["10",20,30,"3.14"]'
+ loop
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+
+do $$
+declare x boolean;
+begin
+ foreach x in array jsonb '[true, false]'
+ loop
+ if x then
+ raise notice 'true';
+ else
+ raise notice 'false';
+ end if;
+ end loop;
+end;
+$$;
+
+-- jsonb to jsonb
+do $$
+declare x jsonb;
+begin
+ foreach x in array jsonb '[10,20,30,3.14, null, "Hi"]'
+ loop
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+
+-- jsonb to json
+do $$
+declare x json;
+begin
+ foreach x in array jsonb '[10,20,30,3.14, null, "Hi"]'
+ loop
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+
+-- iteration over composites
+do $$
+declare x int; y numeric; z varchar;
+begin
+ foreach x, y, z in array jsonb '[{}, {"z":"Hi"}, {"y": 3.14}, {"z":"Hi", "x":10, "y":3.14}]'
+ loop
+ raise notice 'x: %, y: %, z: %', x, y, z;
+ end loop;
+end;
+$$;
+
+create type t3 as (x int, y numeric, z varchar);
+
+do $$
+declare c t3;
+begin
+ foreach c in array jsonb '[{}, {"z":"Hi"}, {"y": 3.14}, {"z":"Hi", "x":10, "y":3.14}]'
+ loop
+ raise notice 'x: %, y: %, z: %', c.x, c.y, c.z;
+ end loop;
+end;
+$$;
+
+do $$
+declare c t3;
+begin
+ foreach c.x, c.y, c.z in array jsonb '[{}, {"z":"Hi"}, {"y": 3.14}, {"z":"Hi", "x":10, "y":3.14}]'
+ loop
+ raise notice 'x: %, y: %, z: %', c.x, c.y, c.z;
+ end loop;
+end;
+$$;
+
+drop type t3;
+
+-- target can be a array
+do $$
+declare x int[];
+begin
+ foreach x in array jsonb '[[1,2,3],[4,5,6]]'
+ loop
+ raise notice '% % %', x[1], x[2], x[3];
+ end loop;
+end;
+$$;
+
+do $$
+declare x varchar[];
+begin
+ foreach x in array jsonb '[["Hi","Hello"],["Hello","Hi"]]'
+ loop
+ raise notice '% %', x[1], x[2];
+ end loop;
+end;
+$$;
+
+do $$
+declare x varchar[];
+begin
+ foreach x in array jsonb '[["Hi","Hello"],["Hello","Hi"]]'
+ loop
+ raise notice '% %', x[1], x[2];
+ end loop;
+end;
+$$;
+
+do $$
+declare x int[]; y varchar;
+begin
+ foreach x, y in array jsonb '[{"x":[1,2,3], "y":"Hi"}, {"x":[4,5,6], "y":"Hi"}]'
+ loop
+ raise notice '% % %, y: %', x[1], x[2], x[3], y;
+ end loop;
+end;
+$$;
+
+create type t2 as (x int[], y varchar);
+
+do $$
+declare c t2;
+begin
+ foreach c in array jsonb '[{"x":[1,2,3], "y":"Hi"}, {"x":[4,5,6], "y":"Hi"}]'
+ loop
+ raise notice '% % %, y: %', c.x[1], c.x[2], c.x[3], c.y;
+ end loop;
+end;
+$$;
+
+drop type t2;
+
+-- EXIT and CONTINUE can be triggered by LOOP_RC_PROCESSING
+do $$
+declare x int;
+begin
+ foreach x in array jsonb '[1,2,3,4,5]'
+ loop
+ exit when x = 3;
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+
+do $$
+declare x int;
+begin
+ foreach x in array jsonb '[1,2,3,4,5]'
+ loop
+ continue when x % 2 = 0;
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+
+-- Variable instead of string
+DO $$
+declare
+ x int;
+ arr jsonb;
+begin
+ select jsonb_agg(i) into arr
+ from generate_series(1,3) g(i);
+
+ foreach x in array arr
+ loop
+ raise notice '%', x;
+ end loop;
+end;
+$$;
--
2.53.0
^ permalink raw reply [nested|flat] 6+ messages in thread
* Re: POC: PLpgSQL FOREACH IN JSON ARRAY
2026-02-28 07:10 POC: PLpgSQL FOREACH IN JSON ARRAY Pavel Stehule <[email protected]>
2026-03-11 20:57 ` Re: POC: PLpgSQL FOREACH IN JSON ARRAY Peter Eisentraut <[email protected]>
2026-03-12 07:00 ` Re: POC: PLpgSQL FOREACH IN JSON ARRAY Pavel Stehule <[email protected]>
2026-03-17 06:58 ` Re: POC: PLpgSQL FOREACH IN JSON ARRAY Pavel Stehule <[email protected]>
2026-03-21 18:40 ` Re: POC: PLpgSQL FOREACH IN JSON ARRAY Pavel Stehule <[email protected]>
@ 2026-05-26 06:51 ` Pavel Stehule <[email protected]>
0 siblings, 0 replies; 6+ messages in thread
From: Pavel Stehule @ 2026-05-26 06:51 UTC (permalink / raw)
To: Tom Lane <[email protected]>; +Cc: Peter Eisentraut <[email protected]>; PostgreSQL Hackers <[email protected]>
Hi
fresh rebase
Regards
Pavel
Attachments:
[text/x-patch] v20260526-0001-FOREACH-scalar-IN-ARRAY-jsonb_expr.patch (37.0K, 3-v20260526-0001-FOREACH-scalar-IN-ARRAY-jsonb_expr.patch)
download | inline diff:
From 78a4eb85d8a4cf9b2aaa6082bcbadc46a7472e60 Mon Sep 17 00:00:00 2001
From: "[email protected]" <[email protected]>
Date: Mon, 23 Feb 2026 12:53:44 +0100
Subject: [PATCH] FOREACH scalar IN ARRAY jsonb_expr
this patch introduce support FOREACH scalar_var IN ARRAY expr, when the
result of the expression can be Jsonb. The design is based
on behave of jsonb_array_elements functions. In this case, FOREACH enforce
casting to target type (because we know target type) and try to reduce
IO casting. Attention: IO casting can be more strict, then casting based
on cast functions.
DECLARE t int;
BEGIN
-- this can work because we use cast numeric -> int
FOREACH t IN ARRAY '[1,2,3.14]'::jsonb
LOOP
-- this fails, because IO cast is used, and integer input function
-- allows only digits
FOREAC t IN JSON ARRAY '[1,2,3,"3.14"]'::jsonb
LOOP
Conceptual question is if casting should be strict like "old" PostgreSQL
json function or lax as "new" SQL/JSON functions? I can imagine lax mode
as default with possibility to switch to strict mode (this is not implemented
now):
FOREACH t IN ARRAY '[1,2,3]' ERROR ON EMPTY ERROR ON ERROR
LOOP
...
Because we use "old" syntax - FOREACH IN ARRAY, I prefer "old" behaviour,
that is more similar to iteration over an array.
The performance (best case for iteration over 1000 fields array) is about
4x better than when FOR IN SELECT jsonb_array_elements is used.
---
doc/src/sgml/plpgsql.sgml | 62 +++-
src/backend/utils/adt/arraysubs.c | 97 +++++-
src/backend/utils/adt/jsonbsubs.c | 181 ++++++++++-
src/include/nodes/subscripting.h | 29 ++
src/pl/plpgsql/src/Makefile | 2 +-
.../plpgsql/src/expected/plpgsql_foreach.out | 297 ++++++++++++++++++
src/pl/plpgsql/src/meson.build | 1 +
src/pl/plpgsql/src/pl_exec.c | 189 +++++------
src/pl/plpgsql/src/plpgsql.h | 3 +-
src/pl/plpgsql/src/sql/plpgsql_foreach.sql | 252 +++++++++++++++
10 files changed, 1016 insertions(+), 97 deletions(-)
create mode 100644 src/pl/plpgsql/src/expected/plpgsql_foreach.out
create mode 100644 src/pl/plpgsql/src/sql/plpgsql_foreach.sql
diff --git a/doc/src/sgml/plpgsql.sgml b/doc/src/sgml/plpgsql.sgml
index 561f6e50d63..6bc9fb02e1e 100644
--- a/doc/src/sgml/plpgsql.sgml
+++ b/doc/src/sgml/plpgsql.sgml
@@ -2697,12 +2697,12 @@ END LOOP <optional> <replaceable>label</replaceable> </optional>;
</sect2>
<sect2 id="plpgsql-foreach-array">
- <title>Looping through Arrays</title>
+ <title>Looping through Arrays or Jsonb arrays</title>
<para>
The <literal>FOREACH</literal> loop is much like a <literal>FOR</literal> loop,
but instead of iterating through the rows returned by an SQL query,
- it iterates through the elements of an array value.
+ it iterates through the elements of an array value or of jsonb array value.
(In general, <literal>FOREACH</literal> is meant for looping through
components of a composite-valued expression; variants for looping
through composites besides arrays may be added in future.)
@@ -2778,6 +2778,64 @@ NOTICE: row = {7,8,9}
NOTICE: row = {10,11,12}
</programlisting>
</para>
+
+ <para>
+ The <literal>SLICE</literal> higher than zero cannot be used when iterates
+ through jsonb arrays.
+ </para>
+
+ <para>
+ The <literal>FOREACH</literal> loop over jsonb arrays uses
+ same syntax like <literal>FOREACH</literal> loop over arrays,
+ but instead of iterating through elements of the array,
+ it iterates through the elements of a Jsonb array value.
+ </para>
+
+ <para>
+ The target can be a scalar variable, a composite variable, or a list
+ of scalar variables. When variable is not scalar, then assigned value
+ should be a JSON object and the JSON attributes are assigned by names.
+
+<programlisting>
+CREATE FUNCTION print_elements(jsonb) RETURNS void AS $$
+DECLARE
+ x int;
+BEGIN
+ FOREACH x IN ARRAY $1
+ LOOP
+ RAISE NOTICE 'row = %', x;
+ END LOOP;
+END;
+$$ LANGUAGE plpgsql;
+
+SELECT print_elements('[1,2,3]');
+NOTICE: row = 1
+NOTICE: row = 2
+NOTICE: row = 3
+
+CREATE FUNCTION print_fields(jsonb) RETURNS void AS $$
+DECLARE
+ x int; y varchar;
+BEGIN
+ FOREACH x, y IN ARRAY $1
+ LOOP
+ RAISE NOTICE 'x: %, y: %', x, y;
+ END LOOP;
+END;
+$$ LANGUAGE plpgsql;
+
+SELECT print_fields('[{},{"x":10},{"y":"Hi"},{"y":"Hi", "x":1000}]');
+NOTICE: x: <NULL>, y: <NULL>
+NOTICE: x: 10, y: <NULL>
+NOTICE: x: <NULL>, y: Hi
+NOTICE: x: 1000, y: Hi
+</programlisting>
+ </para>
+
+ <para>
+ The target variable can be of type <literal>RECORD</literal>, but the real structure has to be
+ assigned before usage in the <literal>FOREACH</literal> statement.
+ </para>
</sect2>
<sect2 id="plpgsql-error-trapping">
diff --git a/src/backend/utils/adt/arraysubs.c b/src/backend/utils/adt/arraysubs.c
index 2bf9e9509fb..a42248ed633 100644
--- a/src/backend/utils/adt/arraysubs.c
+++ b/src/backend/utils/adt/arraysubs.c
@@ -23,6 +23,7 @@
#include "parser/parse_coerce.h"
#include "parser/parse_expr.h"
#include "utils/array.h"
+#include "utils/builtins.h"
#include "utils/fmgrprotos.h"
#include "utils/lsyscache.h"
@@ -46,6 +47,96 @@ typedef struct ArraySubWorkspace
int lowerindex[MAXDIM];
} ArraySubWorkspace;
+typedef struct
+{
+ ForeachAIterator pub;
+ ArrayIterator it;
+ Oid result_typid;
+ int32 result_typmod;
+} ForeachAArrayIterState;
+
+static bool
+foreach_a_array_iterate(ForeachAIterator *self,
+ Datum *value, bool *isnull,
+ Oid *typid, int32 *typmod)
+{
+ ForeachAArrayIterState *iter = (ForeachAArrayIterState *) self;
+
+ *typid = iter->result_typid;
+ *typmod = iter->result_typmod;
+
+ return array_iterate(iter->it, value, isnull);
+}
+
+/*
+ * Used by plpgsql FOREACH IN ARRAY when input expression is an array
+ */
+static ForeachAIterator *
+create_foreach_a_array_iterator(Datum value, Oid typid, int32 typmod,
+ int slice, Oid target_typid, int32 target_typmod)
+{
+ ForeachAArrayIterState *iter = palloc0(sizeof(ForeachAArrayIterState));
+ ArrayType *arr;
+ Oid target_elem_typid;
+
+ /* check the type of the expression - must be an array */
+ if (!OidIsValid(get_element_type(typid)))
+ ereport(ERROR,
+ (errcode(ERRCODE_DATATYPE_MISMATCH),
+ errmsg("FOREACH expression must yield an array, not type %s",
+ format_type_be(typid))));
+
+ /*
+ * We must copy the array into current context, because input expression
+ * is evaluated in context cleaned by exec_eval_cleanup.
+ */
+ arr = DatumGetArrayTypePCopy(value);
+
+ /* Slice dimension must be less than or equal to array dimension */
+ if (slice < 0 || slice > ARR_NDIM(arr))
+ ereport(ERROR,
+ (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
+ errmsg("slice dimension (%d) is out of the valid range 0..%d",
+ slice, ARR_NDIM(arr))));
+
+ /*
+ * Sanity-check the target type. We don't try very hard here, and
+ * should not be too picky since it's possible that exec_assign_value can
+ * coerce values of different types. But it seems worthwhile to complain
+ * if the array-ness of the loop variable is not right.
+ */
+ target_elem_typid = get_element_type(target_typid);
+
+ if (slice > 0 && target_elem_typid == InvalidOid)
+ ereport(ERROR,
+ (errcode(ERRCODE_DATATYPE_MISMATCH),
+ errmsg("FOREACH ... SLICE loop variable must be of an array type")));
+ if (slice == 0 && target_elem_typid != InvalidOid)
+ ereport(ERROR,
+ (errcode(ERRCODE_DATATYPE_MISMATCH),
+ errmsg("FOREACH loop variable must not be of an array type")));
+
+ /* Identify iterator result type */
+ if (slice > 0)
+ {
+ /* When slicing, nominal type of result is same as array type */
+ iter->result_typid = typid;
+ iter->result_typmod = typmod;
+ }
+ else
+ {
+ /* Without slicing, results are individual array elements */
+ iter->result_typid = ARR_ELEMTYPE(arr);
+ iter->result_typmod = typmod;
+ }
+
+ /* Create an iterator to step through the array */
+ iter->it = array_create_iterator(arr, slice, NULL);
+
+ iter->pub.iterate = foreach_a_array_iterate;
+
+ return (ForeachAIterator *) iter;
+}
/*
* Finish parse analysis of a SubscriptingRef expression for an array.
@@ -545,7 +636,8 @@ array_subscript_handler(PG_FUNCTION_ARGS)
.exec_setup = array_exec_setup,
.fetch_strict = true, /* fetch returns NULL for NULL inputs */
.fetch_leakproof = true, /* fetch returns NULL for bad subscript */
- .store_leakproof = false /* ... but assignment throws error */
+ .store_leakproof = false, /* ... but assignment throws error */
+ .create_foreach_a_iterator = create_foreach_a_array_iterator
};
PG_RETURN_POINTER(&sbsroutines);
@@ -572,7 +664,8 @@ raw_array_subscript_handler(PG_FUNCTION_ARGS)
.exec_setup = array_exec_setup,
.fetch_strict = true, /* fetch returns NULL for NULL inputs */
.fetch_leakproof = true, /* fetch returns NULL for bad subscript */
- .store_leakproof = false /* ... but assignment throws error */
+ .store_leakproof = false, /* ... but assignment throws error */
+ .create_foreach_a_iterator = create_foreach_a_array_iterator
};
PG_RETURN_POINTER(&sbsroutines);
diff --git a/src/backend/utils/adt/jsonbsubs.c b/src/backend/utils/adt/jsonbsubs.c
index f2745b29a3f..ad2edf525de 100644
--- a/src/backend/utils/adt/jsonbsubs.c
+++ b/src/backend/utils/adt/jsonbsubs.c
@@ -22,6 +22,7 @@
#include "parser/parse_expr.h"
#include "utils/builtins.h"
#include "utils/jsonb.h"
+#include "utils/jsonfuncs.h"
/* SubscriptingRefState.workspace for jsonb subscripting execution */
@@ -33,6 +34,17 @@ typedef struct JsonbSubWorkspace
Datum *index; /* Subscript values in Datum format */
} JsonbSubWorkspace;
+typedef struct
+{
+ ForeachAIterator pub;
+ JsonbIterator *it;
+ bool skip_nested;
+ Oid target_typid;
+ int32 target_typmod;
+
+ MemoryContext cache_mcxt;
+ void *cache;
+} ForeachAJsonbIterState;
/*
* Finish parse analysis of a SubscriptingRef expression for a jsonb.
@@ -394,6 +406,172 @@ jsonb_exec_setup(const SubscriptingRef *sbsref,
methods->sbs_fetch_old = jsonb_subscript_fetch_old;
}
+/*
+ * Convert JsonbValue to Datum. This function is used in
+ * generic array iterator, that is used by FOREACH plpgsql
+ * statement. Against other cases, the result should not be
+ * necessary of expected_typid, because the value can be
+ * converted later when the value is assigned to PL/pgSQL
+ * variable. This can be more effective than generic IO
+ * cast used by json_populate_type.
+ */
+static Datum
+JsonbValueToDatum(JsonbValue *jbv,
+ Oid *typid, int32 *typmod, bool *isnull,
+ Oid expected_typid, int32 expected_typmod,
+ void **cache, MemoryContext mcxt)
+{
+ Datum result;
+
+ *isnull = false;
+ *typmod = -1;
+
+ /*
+ * These types can holds JSON null, so must be processed
+ * before processing jbvNull. We don't want to convert
+ * JSON null, to SQL null, when targer is of JSON.
+ */
+ if (expected_typid == JSONBOID || expected_typid == JSONOID)
+ {
+ Jsonb *jb = JsonbValueToJsonb(jbv);
+
+ if (expected_typid == JSONOID)
+ {
+ char *str;
+
+ str = JsonbToCString(NULL, &jb->root, VARSIZE(jb));
+ result = PointerGetDatum(cstring_to_text(str));
+ }
+ else
+ result = PointerGetDatum(jb);
+
+ *typid = expected_typid;
+ }
+
+ /*
+ * For special cases we can skip conversion to Jsonb
+ * and possibly IO cast.
+ */
+ else if (jbv->type == jbvNull)
+ {
+ result = (Datum) 0;
+ *isnull = true;
+ *typid = expected_typid;
+ }
+ else if (jbv->type == jbvString)
+ {
+ text *txt = cstring_to_text_with_len(jbv->val.string.val,
+ jbv->val.string.len);
+
+ result = PointerGetDatum(txt);
+ *typid = TEXTOID;
+ }
+ else if (jbv->type == jbvNumeric)
+ {
+ result = PointerGetDatum(jbv->val.numeric);
+ *typid = NUMERICOID;
+ }
+ else if (jbv->type == jbvBool)
+ {
+ result = BoolGetDatum(jbv->val.boolean);
+ *typid = BOOLOID;
+ }
+
+ /* generic conversion */
+ else
+ {
+ Jsonb *jb = JsonbValueToJsonb(jbv);
+
+ result = json_populate_type(PointerGetDatum(jb), JSONBOID,
+ expected_typid, expected_typmod,
+ cache, mcxt,
+ isnull, false, NULL);
+
+ *typid = expected_typid;
+ *typmod = expected_typmod;
+ }
+
+ return result;
+}
+
+static bool
+foreach_a_jsonb_iterate(ForeachAIterator *self,
+ Datum *value, bool *isnull,
+ Oid *typid, int32 *typmod)
+{
+ ForeachAJsonbIterState *iter = (ForeachAJsonbIterState *) self;
+ JsonbIteratorToken r;
+ JsonbValue jbv;
+
+ while ((r = JsonbIteratorNext(&iter->it, &jbv, iter->skip_nested)) != WJB_DONE)
+ {
+ iter->skip_nested = true;
+
+ if (r == WJB_ELEM)
+ {
+ *value = JsonbValueToDatum(&jbv, typid, typmod, isnull,
+ iter->target_typid, iter->target_typmod,
+ &iter->cache, iter->cache_mcxt);
+
+ return true;
+ }
+ }
+
+ return false;
+}
+
+/*
+ * Create foreach array iterator for jsonb array
+ */
+static ForeachAIterator *
+create_foreach_a_jsonb_iterator(Datum value, Oid typid, int32 typmod,
+ int slice, Oid target_typid, int32 target_typmod)
+{
+ ForeachAJsonbIterState *iter = palloc0(sizeof(ForeachAJsonbIterState));
+ Jsonb *jb;
+
+ if (typid != JSONBOID)
+ elog(ERROR, "unexpected source type");
+
+ if (slice > 0)
+ ereport(ERROR,
+ (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+ errmsg("jsonb array iterator doesn't support slicing")));
+
+ /*
+ * We must copy the JSON into current context, because input expression
+ * is evaluated in context cleaned by exec_eval_cleanup.
+ */
+ jb = DatumGetJsonbPCopy(value);
+
+ /*
+ * Jsonb iterator is designed like jsonb_array_element. Input value
+ * must be json array.
+ */
+ if (JB_ROOT_IS_SCALAR(jb))
+ ereport(ERROR,
+ (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+ errmsg("FOREACH expression must evaluate to a JSON array"),
+ errhint("Cannot iterate over a scalar value.")));
+ else if (JB_ROOT_IS_OBJECT(jb))
+ ereport(ERROR,
+ (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+ errmsg("FOREACH expression must evaluate to a JSON array"),
+ errdetail("Cannot iterate over an object value.")));
+
+ Assert(JB_ROOT_IS_ARRAY(jb));
+
+ iter->it = JsonbIteratorInit(&jb->root);
+
+ iter->target_typid = target_typid;
+ iter->target_typmod = target_typmod;
+ iter->cache_mcxt = CurrentMemoryContext;
+
+ iter->pub.iterate = foreach_a_jsonb_iterate;
+
+ return (ForeachAIterator *) iter;
+}
+
/*
* jsonb_subscript_handler
* Subscripting handler for jsonb.
@@ -407,7 +585,8 @@ jsonb_subscript_handler(PG_FUNCTION_ARGS)
.exec_setup = jsonb_exec_setup,
.fetch_strict = true, /* fetch returns NULL for NULL inputs */
.fetch_leakproof = true, /* fetch returns NULL for bad subscript */
- .store_leakproof = false /* ... but assignment throws error */
+ .store_leakproof = false, /* ... but assignment throws error */
+ .create_foreach_a_iterator = create_foreach_a_jsonb_iterator
};
PG_RETURN_POINTER(&sbsroutines);
diff --git a/src/include/nodes/subscripting.h b/src/include/nodes/subscripting.h
index 301f21dac2f..08bfe59ede4 100644
--- a/src/include/nodes/subscripting.h
+++ b/src/include/nodes/subscripting.h
@@ -154,6 +154,32 @@ typedef void (*SubscriptExecSetup) (const SubscriptingRef *sbsref,
SubscriptingRefState *sbsrefstate,
SubscriptExecSteps *methods);
+typedef struct _ForeachAIterator ForeachAIterator;
+
+/*
+ * ForeachAIiterator is used by PLpgSQL FOREACH IN ARRAY statement.
+ * Input value should not be null, and inside CreateForeachAIterator
+ * routine must be copied to current (statement) context. "iterate"
+ * routine is called under short life memory context, that is resetted
+ * after any call.
+ */
+struct _ForeachAIterator
+{
+ bool (*iterate) (ForeachAIterator *self,
+ Datum *value,
+ bool *isnull,
+ Oid *typid,
+ int32 *typmod);
+ /* Private fields might appear beyond this point... */
+};
+
+typedef ForeachAIterator * (*CreateForeachAIterator) (Datum value,
+ Oid typid,
+ int32 typmod,
+ int slice,
+ Oid target_typid,
+ int32 target_typmod);
+
/* Struct returned by the SQL-visible subscript handler function */
typedef struct SubscriptRoutines
{
@@ -163,6 +189,9 @@ typedef struct SubscriptRoutines
bool fetch_leakproof; /* is fetch SubscriptingRef leakproof? */
bool store_leakproof; /* is assignment SubscriptingRef
* leakproof? */
+
+ /* returns iterator used by PL/pgSQL FOREACH statement */
+ CreateForeachAIterator create_foreach_a_iterator;
} SubscriptRoutines;
#endif /* SUBSCRIPTING_H */
diff --git a/src/pl/plpgsql/src/Makefile b/src/pl/plpgsql/src/Makefile
index 63cb96fae3e..5bd0cf31dfc 100644
--- a/src/pl/plpgsql/src/Makefile
+++ b/src/pl/plpgsql/src/Makefile
@@ -35,7 +35,7 @@ REGRESS_OPTS = --dbname=$(PL_TESTDB)
REGRESS = plpgsql_array plpgsql_cache plpgsql_call plpgsql_control \
plpgsql_copy plpgsql_domain plpgsql_misc \
plpgsql_record plpgsql_simple plpgsql_transaction \
- plpgsql_trap plpgsql_trigger plpgsql_varprops
+ plpgsql_trap plpgsql_trigger plpgsql_varprops plpgsql_foreach
# where to find gen_keywordlist.pl and subsidiary files
TOOLSDIR = $(top_srcdir)/src/tools
diff --git a/src/pl/plpgsql/src/expected/plpgsql_foreach.out b/src/pl/plpgsql/src/expected/plpgsql_foreach.out
new file mode 100644
index 00000000000..ddc571f3c79
--- /dev/null
+++ b/src/pl/plpgsql/src/expected/plpgsql_foreach.out
@@ -0,0 +1,297 @@
+-- input must be a JSON array
+do $$
+declare x numeric;
+begin
+ foreach x in array NULL::jsonb -- fail
+ loop
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+ERROR: FOREACH expression must not be null
+CONTEXT: PL/pgSQL function inline_code_block line 4 at FOREACH over array
+do $$
+declare x numeric;
+begin
+ foreach x in array jsonb '10' -- fail
+ loop
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+ERROR: FOREACH expression must evaluate to a JSON array
+HINT: Cannot iterate over a scalar value.
+CONTEXT: PL/pgSQL function inline_code_block line 4 at FOREACH over array
+do $$
+declare x numeric;
+begin
+ foreach x in array jsonb '{}' -- fail
+ loop
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+ERROR: FOREACH expression must evaluate to a JSON array
+DETAIL: Cannot iterate over an object value.
+CONTEXT: PL/pgSQL function inline_code_block line 4 at FOREACH over array
+-- numeric to numeric
+do $$
+declare x numeric;
+begin
+ foreach x in array jsonb '[10,20,30,3.14, null]'
+ loop
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+NOTICE: 10
+NOTICE: 20
+NOTICE: 30
+NOTICE: 3.14
+NOTICE: <NULL>
+-- numeric to int by cast
+do $$
+declare x int;
+begin
+ foreach x in array jsonb '[10,20,30,3.14, null]'
+ loop
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+NOTICE: 10
+NOTICE: 20
+NOTICE: 30
+NOTICE: 3
+NOTICE: <NULL>
+-- test of FOUND variable
+do $$
+declare x int;
+begin
+ foreach x in array jsonb '[10]'
+ loop
+ raise notice '%', x;
+ end loop;
+ raise notice 'FOUND: %', found;
+end;
+$$;
+NOTICE: 10
+NOTICE: FOUND: t
+-- test of FOUND variable
+do $$
+declare x int;
+begin
+ foreach x in array jsonb '[]'
+ loop
+ raise notice '%', x;
+ end loop;
+ raise notice 'FOUND: %', found;
+end;
+$$;
+NOTICE: FOUND: f
+-- conversion "3.14" to int should to fail due IO cast
+do $$
+declare x int;
+begin
+ foreach x in array jsonb '["10",20,30,"3.14"]'
+ loop
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+NOTICE: 10
+NOTICE: 20
+NOTICE: 30
+ERROR: invalid input syntax for type integer: "3.14"
+CONTEXT: PL/pgSQL function inline_code_block line 4 at FOREACH over array
+do $$
+declare x boolean;
+begin
+ foreach x in array jsonb '[true, false]'
+ loop
+ if x then
+ raise notice 'true';
+ else
+ raise notice 'false';
+ end if;
+ end loop;
+end;
+$$;
+NOTICE: true
+NOTICE: false
+-- jsonb to jsonb
+do $$
+declare x jsonb;
+begin
+ foreach x in array jsonb '[10,20,30,3.14, null, "Hi"]'
+ loop
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+NOTICE: 10
+NOTICE: 20
+NOTICE: 30
+NOTICE: 3.14
+NOTICE: null
+NOTICE: "Hi"
+-- jsonb to json
+do $$
+declare x json;
+begin
+ foreach x in array jsonb '[10,20,30,3.14, null, "Hi"]'
+ loop
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+NOTICE: 10
+NOTICE: 20
+NOTICE: 30
+NOTICE: 3.14
+NOTICE: null
+NOTICE: "Hi"
+-- iteration over composites
+do $$
+declare x int; y numeric; z varchar;
+begin
+ foreach x, y, z in array jsonb '[{}, {"z":"Hi"}, {"y": 3.14}, {"z":"Hi", "x":10, "y":3.14}]'
+ loop
+ raise notice 'x: %, y: %, z: %', x, y, z;
+ end loop;
+end;
+$$;
+NOTICE: x: <NULL>, y: <NULL>, z: <NULL>
+NOTICE: x: <NULL>, y: <NULL>, z: Hi
+NOTICE: x: <NULL>, y: 3.14, z: <NULL>
+NOTICE: x: 10, y: 3.14, z: Hi
+create type t3 as (x int, y numeric, z varchar);
+do $$
+declare c t3;
+begin
+ foreach c in array jsonb '[{}, {"z":"Hi"}, {"y": 3.14}, {"z":"Hi", "x":10, "y":3.14}]'
+ loop
+ raise notice 'x: %, y: %, z: %', c.x, c.y, c.z;
+ end loop;
+end;
+$$;
+NOTICE: x: <NULL>, y: <NULL>, z: <NULL>
+NOTICE: x: <NULL>, y: <NULL>, z: Hi
+NOTICE: x: <NULL>, y: 3.14, z: <NULL>
+NOTICE: x: 10, y: 3.14, z: Hi
+do $$
+declare c t3;
+begin
+ foreach c.x, c.y, c.z in array jsonb '[{}, {"z":"Hi"}, {"y": 3.14}, {"z":"Hi", "x":10, "y":3.14}]'
+ loop
+ raise notice 'x: %, y: %, z: %', c.x, c.y, c.z;
+ end loop;
+end;
+$$;
+NOTICE: x: <NULL>, y: <NULL>, z: <NULL>
+NOTICE: x: <NULL>, y: <NULL>, z: Hi
+NOTICE: x: <NULL>, y: 3.14, z: <NULL>
+NOTICE: x: 10, y: 3.14, z: Hi
+drop type t3;
+-- target can be a array
+do $$
+declare x int[];
+begin
+ foreach x in array jsonb '[[1,2,3],[4,5,6]]'
+ loop
+ raise notice '% % %', x[1], x[2], x[3];
+ end loop;
+end;
+$$;
+NOTICE: 1 2 3
+NOTICE: 4 5 6
+do $$
+declare x varchar[];
+begin
+ foreach x in array jsonb '[["Hi","Hello"],["Hello","Hi"]]'
+ loop
+ raise notice '% %', x[1], x[2];
+ end loop;
+end;
+$$;
+NOTICE: Hi Hello
+NOTICE: Hello Hi
+do $$
+declare x varchar[];
+begin
+ foreach x in array jsonb '[["Hi","Hello"],["Hello","Hi"]]'
+ loop
+ raise notice '% %', x[1], x[2];
+ end loop;
+end;
+$$;
+NOTICE: Hi Hello
+NOTICE: Hello Hi
+do $$
+declare x int[]; y varchar;
+begin
+ foreach x, y in array jsonb '[{"x":[1,2,3], "y":"Hi"}, {"x":[4,5,6], "y":"Hi"}]'
+ loop
+ raise notice '% % %, y: %', x[1], x[2], x[3], y;
+ end loop;
+end;
+$$;
+NOTICE: 1 2 3, y: Hi
+NOTICE: 4 5 6, y: Hi
+create type t2 as (x int[], y varchar);
+do $$
+declare c t2;
+begin
+ foreach c in array jsonb '[{"x":[1,2,3], "y":"Hi"}, {"x":[4,5,6], "y":"Hi"}]'
+ loop
+ raise notice '% % %, y: %', c.x[1], c.x[2], c.x[3], c.y;
+ end loop;
+end;
+$$;
+NOTICE: 1 2 3, y: Hi
+NOTICE: 4 5 6, y: Hi
+drop type t2;
+-- EXIT and CONTINUE can be triggered by LOOP_RC_PROCESSING
+do $$
+declare x int;
+begin
+ foreach x in array jsonb '[1,2,3,4,5]'
+ loop
+ exit when x = 3;
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+NOTICE: 1
+NOTICE: 2
+do $$
+declare x int;
+begin
+ foreach x in array jsonb '[1,2,3,4,5]'
+ loop
+ continue when x % 2 = 0;
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+NOTICE: 1
+NOTICE: 3
+NOTICE: 5
+-- Variable instead of string
+DO $$
+declare
+ x int;
+ arr jsonb;
+begin
+ select jsonb_agg(i) into arr
+ from generate_series(1,3) g(i);
+
+ foreach x in array arr
+ loop
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+NOTICE: 1
+NOTICE: 2
+NOTICE: 3
diff --git a/src/pl/plpgsql/src/meson.build b/src/pl/plpgsql/src/meson.build
index 6ff27006cfc..609eed7a28d 100644
--- a/src/pl/plpgsql/src/meson.build
+++ b/src/pl/plpgsql/src/meson.build
@@ -88,6 +88,7 @@ tests += {
'plpgsql_trap',
'plpgsql_trigger',
'plpgsql_varprops',
+ 'plpgsql_foreach',
],
},
}
diff --git a/src/pl/plpgsql/src/pl_exec.c b/src/pl/plpgsql/src/pl_exec.c
index 65b0fd0790f..1c1d98157df 100644
--- a/src/pl/plpgsql/src/pl_exec.c
+++ b/src/pl/plpgsql/src/pl_exec.c
@@ -29,6 +29,7 @@
#include "mb/stringinfo_mb.h"
#include "miscadmin.h"
#include "nodes/nodeFuncs.h"
+#include "nodes/subscripting.h"
#include "nodes/supportnodes.h"
#include "optimizer/optimizer.h"
#include "parser/parse_coerce.h"
@@ -3026,40 +3027,49 @@ exec_stmt_forc(PLpgSQL_execstate *estate, PLpgSQL_stmt_forc *stmt)
return rc;
}
-
/* ----------
- * exec_stmt_foreach_a Loop over elements or slices of an array
- *
- * When looping over elements, the loop variable is the same type that the
- * array stores (eg: integer), when looping through slices, the loop variable
- * is an array of size and dimensions to match the size of the slice.
- * ----------
+ * exec_stmt_foreach_a Loop over elements in an array or jsonb array
+ * ----------
*/
static int
exec_stmt_foreach_a(PLpgSQL_execstate *estate, PLpgSQL_stmt_foreach_a *stmt)
{
- ArrayType *arr;
- Oid arrtype;
- int32 arrtypmod;
- PLpgSQL_datum *loop_var;
- Oid loop_var_elem_type;
- bool found = false;
+ Datum expr;
+ Oid expr_typid;
+ int32 expr_typmod;
+ bool isnull;
+ PLpgSQL_datum *target_var;
+ Oid target_typid;
+ int32 target_typmod;
+ Oid target_collation;
+ Datum value;
+ Oid typid;
+ int32 typmod;
int rc = PLPGSQL_RC_OK;
+ const struct SubscriptRoutines *sbroutines;
+ ForeachAIterator *iterator;
MemoryContext stmt_mcontext;
+ MemoryContext tmp_cxt;
MemoryContext oldcontext;
- ArrayIterator array_iterator;
- Oid iterator_result_type;
- int32 iterator_result_typmod;
- Datum value;
- bool isnull;
+ bool found = false;
- /* get the value of the array expression */
- value = exec_eval_expr(estate, stmt->expr, &isnull, &arrtype, &arrtypmod);
+ /* get the value of the expression */
+ expr = exec_eval_expr(estate, stmt->expr, &isnull,
+ &expr_typid, &expr_typmod);
if (isnull)
ereport(ERROR,
(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
errmsg("FOREACH expression must not be null")));
+ sbroutines = getSubscriptingRoutines(expr_typid, NULL);
+ if (!sbroutines)
+ ereport(ERROR,
+ (errcode(ERRCODE_DATATYPE_MISMATCH),
+ errmsg("cannot iterate over type %s because it does not support subscripting",
+ format_type_be(expr_typid))));
+
+ Assert(sbroutines->create_foreach_a_iterator);
+
/*
* Do as much as possible of the code below in stmt_mcontext, to avoid any
* leaks from called subroutines. We need a private stmt_mcontext since
@@ -3069,79 +3079,34 @@ exec_stmt_foreach_a(PLpgSQL_execstate *estate, PLpgSQL_stmt_foreach_a *stmt)
push_stmt_mcontext(estate);
oldcontext = MemoryContextSwitchTo(stmt_mcontext);
- /* check the type of the expression - must be an array */
- if (!OidIsValid(get_element_type(arrtype)))
- ereport(ERROR,
- (errcode(ERRCODE_DATATYPE_MISMATCH),
- errmsg("FOREACH expression must yield an array, not type %s",
- format_type_be(arrtype))));
+ /* Set up the target (loop) variable */
+ target_var = estate->datums[stmt->varno];
+
+ plpgsql_exec_get_datum_type_info(estate, target_var,
+ &target_typid, &target_typmod,
+ &target_collation);
/*
- * We must copy the array into stmt_mcontext, else it will disappear in
- * exec_eval_cleanup. This is annoying, but cleanup will certainly happen
- * while running the loop body, so we have little choice.
+ * inside iterator constroctor, the expr should be copied to
+ * current memory context (stmt_mcontext). Without it, it will be released
+ * by next exec_eval_cleanup. The iterator constructor should
+ * be called under stmt memory context.
*/
- arr = DatumGetArrayTypePCopy(value);
+ iterator = sbroutines->create_foreach_a_iterator(expr,
+ expr_typid, expr_typmod,
+ stmt->slice, target_typid,
+ target_typmod);
/* Clean up any leftover temporary memory */
exec_eval_cleanup(estate);
- /* Slice dimension must be less than or equal to array dimension */
- if (stmt->slice < 0 || stmt->slice > ARR_NDIM(arr))
- ereport(ERROR,
- (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
- errmsg("slice dimension (%d) is out of the valid range 0..%d",
- stmt->slice, ARR_NDIM(arr))));
-
- /* Set up the loop variable and see if it is of an array type */
- loop_var = estate->datums[stmt->varno];
- if (loop_var->dtype == PLPGSQL_DTYPE_REC ||
- loop_var->dtype == PLPGSQL_DTYPE_ROW)
- {
- /*
- * Record/row variable is certainly not of array type, and might not
- * be initialized at all yet, so don't try to get its type
- */
- loop_var_elem_type = InvalidOid;
- }
- else
- loop_var_elem_type = get_element_type(plpgsql_exec_get_datum_type(estate,
- loop_var));
+ tmp_cxt = AllocSetContextCreate(stmt_mcontext,
+ "FOREACH IN ARRAY temporary cxt",
+ ALLOCSET_DEFAULT_SIZES);
- /*
- * Sanity-check the loop variable type. We don't try very hard here, and
- * should not be too picky since it's possible that exec_assign_value can
- * coerce values of different types. But it seems worthwhile to complain
- * if the array-ness of the loop variable is not right.
- */
- if (stmt->slice > 0 && loop_var_elem_type == InvalidOid)
- ereport(ERROR,
- (errcode(ERRCODE_DATATYPE_MISMATCH),
- errmsg("FOREACH ... SLICE loop variable must be of an array type")));
- if (stmt->slice == 0 && loop_var_elem_type != InvalidOid)
- ereport(ERROR,
- (errcode(ERRCODE_DATATYPE_MISMATCH),
- errmsg("FOREACH loop variable must not be of an array type")));
+ MemoryContextSwitchTo(tmp_cxt);
- /* Create an iterator to step through the array */
- array_iterator = array_create_iterator(arr, stmt->slice, NULL);
-
- /* Identify iterator result type */
- if (stmt->slice > 0)
- {
- /* When slicing, nominal type of result is same as array type */
- iterator_result_type = arrtype;
- iterator_result_typmod = arrtypmod;
- }
- else
- {
- /* Without slicing, results are individual array elements */
- iterator_result_type = ARR_ELEMTYPE(arr);
- iterator_result_typmod = arrtypmod;
- }
-
- /* Iterate over the array elements or slices */
- while (array_iterate(array_iterator, &value, &isnull))
+ while (iterator->iterate(iterator, &value, &isnull, &typid, &typmod))
{
found = true; /* looped at least once */
@@ -3149,12 +3114,9 @@ exec_stmt_foreach_a(PLpgSQL_execstate *estate, PLpgSQL_stmt_foreach_a *stmt)
MemoryContextSwitchTo(oldcontext);
/* Assign current element/slice to the loop variable */
- exec_assign_value(estate, loop_var, value, isnull,
- iterator_result_type, iterator_result_typmod);
+ exec_assign_value(estate, target_var, value, isnull, typid, typmod);
- /* In slice case, value is temporary; must free it to avoid leakage */
- if (stmt->slice > 0)
- pfree(DatumGetPointer(value));
+ MemoryContextReset(tmp_cxt);
/*
* Execute the statements
@@ -3163,7 +3125,7 @@ exec_stmt_foreach_a(PLpgSQL_execstate *estate, PLpgSQL_stmt_foreach_a *stmt)
LOOP_RC_PROCESSING(stmt->label, break);
- MemoryContextSwitchTo(stmt_mcontext);
+ MemoryContextSwitchTo(tmp_cxt);
}
/* Restore memory context state */
@@ -5639,6 +5601,53 @@ plpgsql_exec_get_datum_type_info(PLpgSQL_execstate *estate,
break;
}
+ case PLPGSQL_DTYPE_ROW:
+ {
+ PLpgSQL_row *row = (PLpgSQL_row *) datum;
+
+ if (!row->rowtupdesc)
+ {
+ int i;
+
+ row->rowtupdesc = CreateTemplateTupleDesc(row->nfields);
+
+ for (i = 0; i < row->nfields; i++)
+ {
+ PLpgSQL_datum *var = estate->datums[row->varnos[i]];
+ Oid vartypid;
+ int32 vartypmod;
+ Oid varcollation;
+
+ /*
+ * We cannot use fieldnames for tupdescentry, because
+ * these names can be suffixed by name of row variable.
+ * Unfortunately, the PLpgSQL_recfield is not casted to
+ * PLpgSQL_variable.
+ */
+ plpgsql_exec_get_datum_type_info(estate, var,
+ &vartypid, &vartypmod,
+ &varcollation);
+
+ TupleDescInitEntry(row->rowtupdesc, i + 1,
+ var->refname, vartypid, vartypmod,
+ 0);
+ TupleDescInitEntryCollation(row->rowtupdesc, i + 1,
+ varcollation);
+ }
+
+ TupleDescFinalize(row->rowtupdesc);
+
+ /* Make sure we have a valid type/typmod setting */
+ BlessTupleDesc(row->rowtupdesc);
+ }
+
+ *typeId = row->rowtupdesc->tdtypeid;
+ *typMod = row->rowtupdesc->tdtypmod;
+ /* composite types are never collatable */
+ *collation = InvalidOid;
+ break;
+ }
+
case PLPGSQL_DTYPE_REC:
{
PLpgSQL_rec *rec = (PLpgSQL_rec *) datum;
diff --git a/src/pl/plpgsql/src/plpgsql.h b/src/pl/plpgsql/src/plpgsql.h
index addb14a9959..5cbdb4ecd9d 100644
--- a/src/pl/plpgsql/src/plpgsql.h
+++ b/src/pl/plpgsql/src/plpgsql.h
@@ -299,6 +299,7 @@ typedef struct PLpgSQL_datum
{
PLpgSQL_datum_type dtype;
int dno;
+ char *refname;
} PLpgSQL_datum;
/*
@@ -444,9 +445,9 @@ typedef struct PLpgSQL_recfield
{
PLpgSQL_datum_type dtype;
int dno;
+ char *fieldname; /* name of field */
/* end of PLpgSQL_datum fields */
- char *fieldname; /* name of field */
int recparentno; /* dno of parent record */
int nextfield; /* dno of next child, or -1 if none */
uint64 rectupledescid; /* record's tupledesc ID as of last lookup */
diff --git a/src/pl/plpgsql/src/sql/plpgsql_foreach.sql b/src/pl/plpgsql/src/sql/plpgsql_foreach.sql
new file mode 100644
index 00000000000..a64004417af
--- /dev/null
+++ b/src/pl/plpgsql/src/sql/plpgsql_foreach.sql
@@ -0,0 +1,252 @@
+-- input must be a JSON array
+do $$
+declare x numeric;
+begin
+ foreach x in array NULL::jsonb -- fail
+ loop
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+
+do $$
+declare x numeric;
+begin
+ foreach x in array jsonb '10' -- fail
+ loop
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+
+do $$
+declare x numeric;
+begin
+ foreach x in array jsonb '{}' -- fail
+ loop
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+
+-- numeric to numeric
+do $$
+declare x numeric;
+begin
+ foreach x in array jsonb '[10,20,30,3.14, null]'
+ loop
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+
+-- numeric to int by cast
+do $$
+declare x int;
+begin
+ foreach x in array jsonb '[10,20,30,3.14, null]'
+ loop
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+
+-- test of FOUND variable
+do $$
+declare x int;
+begin
+ foreach x in array jsonb '[10]'
+ loop
+ raise notice '%', x;
+ end loop;
+ raise notice 'FOUND: %', found;
+end;
+$$;
+
+-- test of FOUND variable
+do $$
+declare x int;
+begin
+ foreach x in array jsonb '[]'
+ loop
+ raise notice '%', x;
+ end loop;
+ raise notice 'FOUND: %', found;
+end;
+$$;
+
+-- conversion "3.14" to int should to fail due IO cast
+do $$
+declare x int;
+begin
+ foreach x in array jsonb '["10",20,30,"3.14"]'
+ loop
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+
+do $$
+declare x boolean;
+begin
+ foreach x in array jsonb '[true, false]'
+ loop
+ if x then
+ raise notice 'true';
+ else
+ raise notice 'false';
+ end if;
+ end loop;
+end;
+$$;
+
+-- jsonb to jsonb
+do $$
+declare x jsonb;
+begin
+ foreach x in array jsonb '[10,20,30,3.14, null, "Hi"]'
+ loop
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+
+-- jsonb to json
+do $$
+declare x json;
+begin
+ foreach x in array jsonb '[10,20,30,3.14, null, "Hi"]'
+ loop
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+
+-- iteration over composites
+do $$
+declare x int; y numeric; z varchar;
+begin
+ foreach x, y, z in array jsonb '[{}, {"z":"Hi"}, {"y": 3.14}, {"z":"Hi", "x":10, "y":3.14}]'
+ loop
+ raise notice 'x: %, y: %, z: %', x, y, z;
+ end loop;
+end;
+$$;
+
+create type t3 as (x int, y numeric, z varchar);
+
+do $$
+declare c t3;
+begin
+ foreach c in array jsonb '[{}, {"z":"Hi"}, {"y": 3.14}, {"z":"Hi", "x":10, "y":3.14}]'
+ loop
+ raise notice 'x: %, y: %, z: %', c.x, c.y, c.z;
+ end loop;
+end;
+$$;
+
+do $$
+declare c t3;
+begin
+ foreach c.x, c.y, c.z in array jsonb '[{}, {"z":"Hi"}, {"y": 3.14}, {"z":"Hi", "x":10, "y":3.14}]'
+ loop
+ raise notice 'x: %, y: %, z: %', c.x, c.y, c.z;
+ end loop;
+end;
+$$;
+
+drop type t3;
+
+-- target can be a array
+do $$
+declare x int[];
+begin
+ foreach x in array jsonb '[[1,2,3],[4,5,6]]'
+ loop
+ raise notice '% % %', x[1], x[2], x[3];
+ end loop;
+end;
+$$;
+
+do $$
+declare x varchar[];
+begin
+ foreach x in array jsonb '[["Hi","Hello"],["Hello","Hi"]]'
+ loop
+ raise notice '% %', x[1], x[2];
+ end loop;
+end;
+$$;
+
+do $$
+declare x varchar[];
+begin
+ foreach x in array jsonb '[["Hi","Hello"],["Hello","Hi"]]'
+ loop
+ raise notice '% %', x[1], x[2];
+ end loop;
+end;
+$$;
+
+do $$
+declare x int[]; y varchar;
+begin
+ foreach x, y in array jsonb '[{"x":[1,2,3], "y":"Hi"}, {"x":[4,5,6], "y":"Hi"}]'
+ loop
+ raise notice '% % %, y: %', x[1], x[2], x[3], y;
+ end loop;
+end;
+$$;
+
+create type t2 as (x int[], y varchar);
+
+do $$
+declare c t2;
+begin
+ foreach c in array jsonb '[{"x":[1,2,3], "y":"Hi"}, {"x":[4,5,6], "y":"Hi"}]'
+ loop
+ raise notice '% % %, y: %', c.x[1], c.x[2], c.x[3], c.y;
+ end loop;
+end;
+$$;
+
+drop type t2;
+
+-- EXIT and CONTINUE can be triggered by LOOP_RC_PROCESSING
+do $$
+declare x int;
+begin
+ foreach x in array jsonb '[1,2,3,4,5]'
+ loop
+ exit when x = 3;
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+
+do $$
+declare x int;
+begin
+ foreach x in array jsonb '[1,2,3,4,5]'
+ loop
+ continue when x % 2 = 0;
+ raise notice '%', x;
+ end loop;
+end;
+$$;
+
+-- Variable instead of string
+DO $$
+declare
+ x int;
+ arr jsonb;
+begin
+ select jsonb_agg(i) into arr
+ from generate_series(1,3) g(i);
+
+ foreach x in array arr
+ loop
+ raise notice '%', x;
+ end loop;
+end;
+$$;
--
2.54.0
^ permalink raw reply [nested|flat] 6+ messages in thread
end of thread, other threads:[~2026-05-26 06:51 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz follow: Atom feed)
-- links below jump to the message on this page --
2026-02-28 07:10 POC: PLpgSQL FOREACH IN JSON ARRAY Pavel Stehule <[email protected]>
2026-03-11 20:57 ` Peter Eisentraut <[email protected]>
2026-03-12 07:00 ` Pavel Stehule <[email protected]>
2026-03-17 06:58 ` Pavel Stehule <[email protected]>
2026-03-21 18:40 ` Pavel Stehule <[email protected]>
2026-05-26 06:51 ` Pavel Stehule <[email protected]>
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