From d1162cfda885c5a8cb9cebfc8eed9f1d76855e83 Mon Sep 17 00:00:00 2001 From: Nathan Bossart Date: Thu, 14 Mar 2024 10:58:00 -0500 Subject: [PATCH] Add pg_column_toast_chunk_id(). This function returns the chunk_id of an on-disk TOASTed value. If the value is un-TOASTed or not on-disk, it returns NULL. This is useful for identifying which values are actually TOASTed and for investigating "unexpected chunk number" errors. Bumps catversion. Author: Yugo Nagata Reviewed-by: Jian He Discussion: https://postgr.es/m/20230329105507.d764497456eeac1ca491b5bd%40sraoss.co.jp --- doc/src/sgml/func.sgml | 17 ++++++++ src/backend/utils/adt/varlena.c | 41 ++++++++++++++++++++ src/include/catalog/catversion.h | 2 +- src/include/catalog/pg_proc.dat | 3 ++ src/test/regress/expected/misc_functions.out | 16 ++++++++ src/test/regress/sql/misc_functions.sql | 12 ++++++ 6 files changed, 90 insertions(+), 1 deletion(-) diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml index 91f1e69359..72c5175e3b 100644 --- a/doc/src/sgml/func.sgml +++ b/doc/src/sgml/func.sgml @@ -28552,6 +28552,23 @@ postgres=# SELECT '0/0'::pg_lsn + pd.segment_number * ps.setting::int + :offset + + + + pg_column_toast_chunk_id + + pg_column_toast_chunk_id ( "any" ) + oid + + + Shows the chunk_id of an on-disk + TOASTed value. Returns NULL + if the value is un-TOASTed or not on-disk. See + for more information about + TOAST. + + + diff --git a/src/backend/utils/adt/varlena.c b/src/backend/utils/adt/varlena.c index 543afb66e5..8d28dd42ce 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 un-TOASTed 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/catversion.h b/src/include/catalog/catversion.h index 429989efd9..9cf6dae3d9 100644 --- a/src/include/catalog/catversion.h +++ b/src/include/catalog/catversion.h @@ -57,6 +57,6 @@ */ /* yyyymmddN */ -#define CATALOG_VERSION_NO 202403132 +#define CATALOG_VERSION_NO 202403141 #endif diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat index 4af5c2e847..700f7daf7b 100644 --- a/src/include/catalog/pg_proc.dat +++ b/src/include/catalog/pg_proc.dat @@ -7447,6 +7447,9 @@ { 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 d5f61dfad9..e0ba9fdafa 100644 --- a/src/test/regress/expected/misc_functions.out +++ b/src/test/regress/expected/misc_functions.out @@ -703,3 +703,19 @@ SELECT has_function_privilege('regress_current_logfile', (1 row) DROP ROLE regress_current_logfile; +-- pg_column_toast_chunk_id +CREATE TABLE test_chunk_id (a TEXT, b TEXT STORAGE EXTERNAL); +INSERT INTO test_chunk_id VALUES ('x', repeat('x', 8192)); +SELECT t.relname AS toastrel FROM pg_class c + LEFT JOIN pg_class t ON c.reltoastrelid = t.oid + WHERE c.relname = 'test_chunk_id' +\gset +SELECT pg_column_toast_chunk_id(a) IS NULL, + pg_column_toast_chunk_id(b) IN (SELECT chunk_id FROM pg_toast.:toastrel) + FROM test_chunk_id; + ?column? | ?column? +----------+---------- + t | t +(1 row) + +DROP TABLE test_chunk_id; diff --git a/src/test/regress/sql/misc_functions.sql b/src/test/regress/sql/misc_functions.sql index 928b04db7f..ff5ed5edde 100644 --- a/src/test/regress/sql/misc_functions.sql +++ b/src/test/regress/sql/misc_functions.sql @@ -265,3 +265,15 @@ GRANT pg_monitor TO regress_current_logfile; SELECT has_function_privilege('regress_current_logfile', 'pg_current_logfile()', 'EXECUTE'); DROP ROLE regress_current_logfile; + +-- pg_column_toast_chunk_id +CREATE TABLE test_chunk_id (a TEXT, b TEXT STORAGE EXTERNAL); +INSERT INTO test_chunk_id VALUES ('x', repeat('x', 8192)); +SELECT t.relname AS toastrel FROM pg_class c + LEFT JOIN pg_class t ON c.reltoastrelid = t.oid + WHERE c.relname = 'test_chunk_id' +\gset +SELECT pg_column_toast_chunk_id(a) IS NULL, + pg_column_toast_chunk_id(b) IN (SELECT chunk_id FROM pg_toast.:toastrel) + FROM test_chunk_id; +DROP TABLE test_chunk_id;