diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/include/fmgr.h | 9 | ||||
| -rw-r--r-- | src/include/postgres.h | 9 |
2 files changed, 16 insertions, 2 deletions
diff --git a/src/include/fmgr.h b/src/include/fmgr.h index 298cd12c775..32cadeb6b54 100644 --- a/src/include/fmgr.h +++ b/src/include/fmgr.h @@ -11,7 +11,7 @@ * Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * - * $PostgreSQL: pgsql/src/include/fmgr.h,v 1.50 2007/04/06 04:21:44 tgl Exp $ + * $PostgreSQL: pgsql/src/include/fmgr.h,v 1.51 2007/05/15 17:39:54 momjian Exp $ * *------------------------------------------------------------------------- */ @@ -158,6 +158,12 @@ extern void fmgr_info_copy(FmgrInfo *dstinfo, FmgrInfo *srcinfo, * The resulting datum can be accessed using VARSIZE_ANY() and VARDATA_ANY() * (beware of multiple evaluations in those macros!) * + * WARNING: It is only safe to use PG_DETOAST_DATUM_UNPACKED() and + * VARDATA_ANY() if you really don't care about the alignment. Either because + * you're working with something like text where the alignment doesn't matter + * or because you're not going to access its constituent parts and just use + * things like memcpy on it anyways. + * * Note: it'd be nice if these could be macros, but I see no way to do that * without evaluating the arguments multiple times, which is NOT acceptable. */ @@ -174,6 +180,7 @@ extern struct varlena *pg_detoast_datum_packed(struct varlena * datum); #define PG_DETOAST_DATUM_SLICE(datum,f,c) \ pg_detoast_datum_slice((struct varlena *) DatumGetPointer(datum), \ (int32) f, (int32) c) +/* WARNING -- unaligned pointer */ #define PG_DETOAST_DATUM_PACKED(datum) \ pg_detoast_datum_packed((struct varlena *) DatumGetPointer(datum)) diff --git a/src/include/postgres.h b/src/include/postgres.h index 27c21e2bcc8..3f65d646312 100644 --- a/src/include/postgres.h +++ b/src/include/postgres.h @@ -10,7 +10,7 @@ * Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group * Portions Copyright (c) 1995, Regents of the University of California * - * $PostgreSQL: pgsql/src/include/postgres.h,v 1.80 2007/05/04 02:01:02 tgl Exp $ + * $PostgreSQL: pgsql/src/include/postgres.h,v 1.81 2007/05/15 17:39:54 momjian Exp $ * *------------------------------------------------------------------------- */ @@ -235,6 +235,12 @@ typedef struct * use VARSIZE_ANY/VARSIZE_ANY_EXHDR/VARDATA_ANY. The other macros here * should usually be used only by tuple assembly/disassembly code and * code that specifically wants to work with still-toasted Datums. + * + * WARNING: It is only safe to use VARDATA_ANY() -- typically with + * PG_DETOAST_DATUM_UNPACKED() -- if you really don't care about the alignment. + * Either because you're working with something like text where the alignment + * doesn't matter or because you're not going to access its constituent parts + * and just use things like memcpy on it anyways. */ #define VARDATA(PTR) VARDATA_4B(PTR) #define VARSIZE(PTR) VARSIZE_4B(PTR) @@ -265,6 +271,7 @@ typedef struct VARSIZE_4B(PTR)-4)) /* caution: this will not work on an external or compressed-in-line Datum */ +/* caution: this will return a possibly unaligned pointer */ #define VARDATA_ANY(PTR) \ (VARATT_IS_1B(PTR) ? VARDATA_1B(PTR) : VARDATA_4B(PTR)) |