From 5fecf226bc1a44bf2240199f7bd7c13fc9f3cc16 Mon Sep 17 00:00:00 2001 From: Michael Paquier Date: Wed, 13 Aug 2025 19:38:50 +0900 Subject: [PATCH v5 07/15] Split VARATT_EXTERNAL_GET_POINTER for indirect and OID TOAST pointers VARATT_EXTERNAL_GET_POINTER() is renamed to VARATT_INDIRECT_GET_POINTER() with the external on-disk TOAST pointers for OID values being now located within toast_external.c, splitting both concepts completely. --- src/include/access/detoast.h | 16 ++++++++-------- src/backend/access/common/detoast.c | 10 +++++----- src/backend/access/common/toast_external.c | 21 ++++++++++++++++++++- src/backend/utils/adt/expandeddatum.c | 2 +- 4 files changed, 34 insertions(+), 15 deletions(-) diff --git a/src/include/access/detoast.h b/src/include/access/detoast.h index b3ebad8b7cf9..31e9786848ef 100644 --- a/src/include/access/detoast.h +++ b/src/include/access/detoast.h @@ -13,17 +13,17 @@ #define DETOAST_H /* - * Macro to fetch the possibly-unaligned contents of an EXTERNAL datum - * into a local "varatt_external_*" toast pointer, as supported - * in toast_external.c and varatt.h. This should be just a memcpy, but - * some versions of gcc seem to produce broken code that assumes the datum - * contents are aligned. Introducing an explicit intermediate - * "varattrib_1b_e *" variable seems to fix it. + * Macro to fetch the possibly-unaligned contents of an indirect datum + * into a local "varatt_indirect" toast pointer, as supported + * in varatt.h. This should be just a memcpy, but some versions of gcc + * seem to produce broken code that assumes the datum contents are aligned. + * Introducing an explicit intermediate "varattrib_1b_e *" variable seems + * to fix it. */ -#define VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr) \ +#define VARATT_INDIRECT_GET_POINTER(toast_pointer, attr) \ do { \ varattrib_1b_e *attre = (varattrib_1b_e *) (attr); \ - Assert(VARATT_IS_EXTERNAL(attre)); \ + Assert(VARATT_IS_EXTERNAL_INDIRECT(attre)); \ Assert(VARSIZE_EXTERNAL(attre) == sizeof(toast_pointer) + VARHDRSZ_EXTERNAL); \ memcpy(&(toast_pointer), VARDATA_EXTERNAL(attre), sizeof(toast_pointer)); \ } while (0) diff --git a/src/backend/access/common/detoast.c b/src/backend/access/common/detoast.c index 8531c27439e4..b645988667f0 100644 --- a/src/backend/access/common/detoast.c +++ b/src/backend/access/common/detoast.c @@ -61,7 +61,7 @@ detoast_external_attr(struct varlena *attr) */ struct varatt_indirect redirect; - VARATT_EXTERNAL_GET_POINTER(redirect, attr); + VARATT_INDIRECT_GET_POINTER(redirect, attr); attr = (struct varlena *) redirect.pointer; /* nested indirect Datums aren't allowed */ @@ -138,7 +138,7 @@ detoast_attr(struct varlena *attr) */ struct varatt_indirect redirect; - VARATT_EXTERNAL_GET_POINTER(redirect, attr); + VARATT_INDIRECT_GET_POINTER(redirect, attr); attr = (struct varlena *) redirect.pointer; /* nested indirect Datums aren't allowed */ @@ -268,7 +268,7 @@ detoast_attr_slice(struct varlena *attr, { struct varatt_indirect redirect; - VARATT_EXTERNAL_GET_POINTER(redirect, attr); + VARATT_INDIRECT_GET_POINTER(redirect, attr); /* nested indirect Datums aren't allowed */ Assert(!VARATT_IS_EXTERNAL_INDIRECT(redirect.pointer)); @@ -561,7 +561,7 @@ toast_raw_datum_size(Datum value) { struct varatt_indirect toast_pointer; - VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr); + VARATT_INDIRECT_GET_POINTER(toast_pointer, attr); /* nested indirect Datums aren't allowed */ Assert(!VARATT_IS_EXTERNAL_INDIRECT(toast_pointer.pointer)); @@ -618,7 +618,7 @@ toast_datum_size(Datum value) { struct varatt_indirect toast_pointer; - VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr); + VARATT_INDIRECT_GET_POINTER(toast_pointer, attr); /* nested indirect Datums aren't allowed */ Assert(!VARATT_IS_EXTERNAL_INDIRECT(attr)); diff --git a/src/backend/access/common/toast_external.c b/src/backend/access/common/toast_external.c index d7bf2f7c69b2..8f58195051cf 100644 --- a/src/backend/access/common/toast_external.c +++ b/src/backend/access/common/toast_external.c @@ -26,6 +26,25 @@ static void ondisk_oid_to_external_data(struct varlena *attr, toast_external_data *data); static struct varlena *ondisk_oid_create_external_data(toast_external_data data); +/* + * Fetch the possibly-unaligned contents of an on-disk external TOAST with + * OID values into a local "varatt_external_oid" pointer. + * + * This should be just a memcpy, but some versions of gcc seem to produce + * broken code that assumes the datum contents are aligned. Introducing + * an explicit intermediate "varattrib_1b_e *" variable seems to fix it. + */ +static inline void +varatt_external_oid_get_pointer(varatt_external_oid *toast_pointer, + struct varlena *attr) +{ + varattrib_1b_e *attre = (varattrib_1b_e *) attr; + + Assert(VARATT_IS_EXTERNAL_ONDISK_OID(attre)); + Assert(VARSIZE_EXTERNAL(attre) == sizeof(varatt_external_oid) + VARHDRSZ_EXTERNAL); + memcpy(toast_pointer, VARDATA_EXTERNAL(attre), sizeof(varatt_external_oid)); +} + /* * Decompressed size of an on-disk varlena; but note argument is a struct * varatt_external_oid. @@ -168,7 +187,7 @@ ondisk_oid_to_external_data(struct varlena *attr, toast_external_data *data) { varatt_external_oid external; - VARATT_EXTERNAL_GET_POINTER(external, attr); + varatt_external_oid_get_pointer(&external, attr); data->rawsize = external.va_rawsize; /* diff --git a/src/backend/utils/adt/expandeddatum.c b/src/backend/utils/adt/expandeddatum.c index 6b4b8eaf005c..4c04671d23ed 100644 --- a/src/backend/utils/adt/expandeddatum.c +++ b/src/backend/utils/adt/expandeddatum.c @@ -23,7 +23,7 @@ * Given a Datum that is an expanded-object reference, extract the pointer. * * This is a bit tedious since the pointer may not be properly aligned; - * compare VARATT_EXTERNAL_GET_POINTER(). + * compare VARATT_INDIRECT_GET_POINTER(). */ ExpandedObjectHeader * DatumGetEOHP(Datum d) -- 2.50.0