On Tue, 30 Jan 2024 13:47:45 +0800
jian he <jian.universal...@gmail.com> wrote:
> On Tue, Jan 30, 2024 at 12:35 PM Yugo NAGATA <nag...@sraoss.co.jp> wrote:
> >
> >
> > Sorry, I also attached a wrong file.
> > Attached is the correct one.
> I think you attached the wrong file again. also please name it as v4.
Opps..sorry, again.
I attached the correct one, v4.
Regards,
Yugo Nagata
--
Yugo NAGATA <nag...@sraoss.co.jp>
>From 8c0f9993c49d1d4ed1bb3e10ba26652da98cd41e Mon Sep 17 00:00:00 2001
From: Yugo Nagata <nag...@sraoss.co.jp>
Date: Wed, 29 Mar 2023 09:59:25 +0900
Subject: [PATCH v4] Add pg_column_toast_chunk_id function
This function returns the chunk_id of an on-disk TOASTed value, or
NULL if the value is un-TOASTed or not on disk. This enables users to
know which columns are actually TOASTed. This function is also useful
to identify a problematic row when an error like
"ERROR: unexpected chunk number ... (expected ...) for toast value"
occurs.
---
doc/src/sgml/func.sgml | 17 ++++++++
src/backend/utils/adt/varlena.c | 41 ++++++++++++++++++++
src/include/catalog/pg_proc.dat | 3 ++
src/test/regress/expected/misc_functions.out | 18 +++++++++
src/test/regress/sql/misc_functions.sql | 18 +++++++++
5 files changed, 97 insertions(+)
diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index 210c7c0b02..2d82331323 100644
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -28078,6 +28078,23 @@ postgres=# SELECT '0/0'::pg_lsn + pd.segment_number * ps.setting::int + :offset
</para></entry>
</row>
+ <row>
+ <entry role="func_table_entry"><para role="func_signature">
+ <indexterm>
+ <primary>pg_column_toast_chunk_id</primary>
+ </indexterm>
+ <function>pg_column_toast_chunk_id</function> ( <type>"any"</type> )
+ <returnvalue>oid</returnvalue>
+ </para>
+ <para>
+ Shows the <structfield>chunk_id</structfield> of an on-disk
+ <acronym>TOAST</acronym>ed value. Returns <literal>NULL</literal>
+ if the value is un-<acronym>TOAST</acronym>ed or not on-disk.
+ See <xref linkend="storage-toast-ondisk"/> for details about
+ <acronym>TOAST</acronym>.
+ </para></entry>
+ </row>
+
<row>
<entry role="func_table_entry"><para role="func_signature">
<indexterm>
diff --git a/src/backend/utils/adt/varlena.c b/src/backend/utils/adt/varlena.c
index 543afb66e5..84d36781a4 100644
--- a/src/backend/utils/adt/varlena.c
+++ b/src/backend/utils/adt/varlena.c
@@ -5105,6 +5105,47 @@ pg_column_compression(PG_FUNCTION_ARGS)
PG_RETURN_TEXT_P(cstring_to_text(result));
}
+/*
+ * Return the chunk_id of the on-disk TOASTed value.
+ * Return NULL if the value is unTOASTed or not on disk.
+ */
+Datum
+pg_column_toast_chunk_id(PG_FUNCTION_ARGS)
+{
+ int typlen;
+ struct varlena *attr;
+ struct varatt_external toast_pointer;
+
+ /* On first call, get the input type's typlen, and save at *fn_extra */
+ if (fcinfo->flinfo->fn_extra == NULL)
+ {
+ /* Lookup the datatype of the supplied argument */
+ Oid argtypeid = get_fn_expr_argtype(fcinfo->flinfo, 0);
+
+ typlen = get_typlen(argtypeid);
+ if (typlen == 0) /* should not happen */
+ elog(ERROR, "cache lookup failed for type %u", argtypeid);
+
+ fcinfo->flinfo->fn_extra = MemoryContextAlloc(fcinfo->flinfo->fn_mcxt,
+ sizeof(int));
+ *((int *) fcinfo->flinfo->fn_extra) = typlen;
+ }
+ else
+ typlen = *((int *) fcinfo->flinfo->fn_extra);
+
+ if (typlen != -1)
+ PG_RETURN_NULL();
+
+ attr = (struct varlena *) DatumGetPointer(PG_GETARG_DATUM(0));
+
+ if (!VARATT_IS_EXTERNAL_ONDISK(attr))
+ PG_RETURN_NULL();
+
+ VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
+
+ PG_RETURN_OID(toast_pointer.va_valueid);
+}
+
/*
* string_agg - Concatenates values and returns string.
*
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 58811a6530..1d4521ac1f 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -7454,6 +7454,9 @@
{ oid => '2121', descr => 'compression method for the compressed datum',
proname => 'pg_column_compression', provolatile => 's', prorettype => 'text',
proargtypes => 'any', prosrc => 'pg_column_compression' },
+{ oid => '8393', descr => 'chunk ID of on-disk TOASTed value',
+ proname => 'pg_column_toast_chunk_id', provolatile => 's', prorettype => 'oid',
+ proargtypes => 'any', prosrc => 'pg_column_toast_chunk_id' },
{ oid => '2322',
descr => 'total disk space usage for the specified tablespace',
proname => 'pg_tablespace_size', provolatile => 'v', prorettype => 'int8',
diff --git a/src/test/regress/expected/misc_functions.out b/src/test/regress/expected/misc_functions.out
index 9302134077..6a1fcc22f5 100644
--- a/src/test/regress/expected/misc_functions.out
+++ b/src/test/regress/expected/misc_functions.out
@@ -670,3 +670,21 @@ FROM pg_walfile_name_offset('0/0'::pg_lsn + :segment_size - 1),
0 | t
(1 row)
+-- Test pg_column_toast_chunk_id:
+-- Check if the returned chunk_id exists in the TOAST table
+CREATE TABLE test_chunk_id (v1 text, v2 text);
+INSERT INTO test_chunk_id VALUES (
+ repeat('0123456789', 10), -- v1: small enough not to be TOASTed
+ repeat('0123456789', 100000)); -- v2: large enough to be TOASTed
+DO $$
+ DECLARE result text;
+ BEGIN
+ EXECUTE format(
+ 'SELECT ''ok'' FROM test_chunk_id
+ WHERE pg_column_toast_chunk_id(v1) IS NULL AND
+ pg_column_toast_chunk_id(v2) IN (SELECT chunk_id FROM pg_toast.pg_toast_%s)',
+ regclass('test_chunk_id')::int::text) INTO result;
+ RAISE INFO '%', result;
+END; $$;
+INFO: ok
+DROP TABLE test_chunk_id;
diff --git a/src/test/regress/sql/misc_functions.sql b/src/test/regress/sql/misc_functions.sql
index d3dc591173..fe3b6c26c6 100644
--- a/src/test/regress/sql/misc_functions.sql
+++ b/src/test/regress/sql/misc_functions.sql
@@ -250,3 +250,21 @@ FROM pg_walfile_name_offset('0/0'::pg_lsn + :segment_size + 1),
SELECT segment_number, file_offset = :segment_size - 1
FROM pg_walfile_name_offset('0/0'::pg_lsn + :segment_size - 1),
pg_split_walfile_name(file_name);
+
+-- Test pg_column_toast_chunk_id:
+-- Check if the returned chunk_id exists in the TOAST table
+CREATE TABLE test_chunk_id (v1 text, v2 text);
+INSERT INTO test_chunk_id VALUES (
+ repeat('0123456789', 10), -- v1: small enough not to be TOASTed
+ repeat('0123456789', 100000)); -- v2: large enough to be TOASTed
+DO $$
+ DECLARE result text;
+ BEGIN
+ EXECUTE format(
+ 'SELECT ''ok'' FROM test_chunk_id
+ WHERE pg_column_toast_chunk_id(v1) IS NULL AND
+ pg_column_toast_chunk_id(v2) IN (SELECT chunk_id FROM pg_toast.pg_toast_%s)',
+ regclass('test_chunk_id')::int::text) INTO result;
+ RAISE INFO '%', result;
+END; $$;
+DROP TABLE test_chunk_id;
--
2.25.1
