Re: Reduce heap tuple header size II

On Fri, 21 Jun 2002 12:45:48 -0400 (EDT), Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> wrote:
>> > Yes, there are some good ones there, but the idea that somehow they are
>> > all going to hit in the same release seems unlikely. I say let's do
>> > some now, some later, and move ahead.

I (strongly :-)) agree.

>Well, that is a different argument than initially. So, it is a valid
>patch, but we have to decide when to apply it.
>
>We can easily hold it until we near release of 7.3. If pg_upgrade is in
>good shape _and_ no other format changes are required, we can hold it
>for 7.4. What happens if 7.4 doesn't have any format changes?
>
>However, if we have other changes or pg_upgrade isn't going to work, we
>can apply it in August.

But what, if the patch causes or reveals a well hidden bug, possibly
somewhere else in the code? I'd vote for applying it now, so that in
August it already has undergone some testing. You can always patch -R
before going beta...

>(Manfred, you can be sure I will not lose this patch.)

Thanks. Anyway, lose it! Here is a new version.

>So, we have to decide if we apply it now or delay it for later in 7.3,
>or for >=7.4.

Why not let the users decide? With this new version of the patch they
can
configure --enable-pg72format
if this patch is the only thing that stops pg_upgrade from working and
if they want to use pg_upgrade.

>My personal vote is that we apply it now, and perhaps try some of the
>other format changes we were going to make.

And with #ifdef PG72FORMAT we can introduce them without very much
risk. One thing that's still missing is we'd need two entries in
catversion.h.

Servus
Manfred

diff -u ../base/INSTALL ./INSTALL
--- ../base/INSTALL 2002-01-31 01:46:26.000000000 +0100
+++ ./INSTALL 2002-06-25 15:59:03.000000000 +0200
@@ -283,6 +283,13 @@
Enables single-byte character set recode support. See the
Administrator's Guide about this feature.

+ --enable-pg72format
+
+ Enables version 7.2 page format, giving you a better chance of
+ converting existing databases by pg_upgrade. Do not use this
+ feature, if you are just starting to use PostgreSQL or if you
+ plan to upgrade via pg_dump/restore.
+
--enable-multibyte

Allows the use of multibyte character encodings (including
Common subdirectories: ../base/config and ./config
diff -u ../base/configure ./configure
--- ../base/configure 2002-05-29 14:42:20.000000000 +0200
+++ ./configure 2002-06-25 15:51:18.000000000 +0200
@@ -1652,6 +1652,44 @@


#
+# Version 7.2 page format (--enable-pg72format)
+#
+echo "$as_me:$LINENO: checking whether to build with version 7.2 page format" >&5
+echo $ECHO_N "checking whether to build with version 7.2 page format... $ECHO_C" >&6
+
+
+# Check whether --enable-pg72format or --disable-pg72format was given.
+if test "${enable_pg72format+set}" = set; then
+ enableval="$enable_pg72format"
+
+ case $enableval in
+ yes)
+
+cat >>confdefs.h <<\_ACEOF
+#define PG72FORMAT 1
+_ACEOF
+
+ ;;
+ no)
+ :
+ ;;
+ *)
+ { { echo "$as_me:$LINENO: error: no argument expected for --enable-pg72format option" >&5
+echo "$as_me: error: no argument expected for --enable-pg72format option" >&2;}
+ { (exit 1); exit 1; }; }
+ ;;
+ esac
+
+else
+ enable_pg72format=no
+
+fi;
+
+echo "$as_me:$LINENO: result: $enable_pg72format" >&5
+echo "${ECHO_T}$enable_pg72format" >&6
+
+
+#
# Multibyte support
#
MULTIBYTE=SQL_ASCII
diff -u ../base/configure.in ./configure.in
--- ../base/configure.in 2002-05-29 14:42:20.000000000 +0200
+++ ./configure.in 2002-06-25 15:51:15.000000000 +0200
@@ -162,6 +162,16 @@


#
+# Version 7.2 page format (--enable-pg72format)
+#
+AC_MSG_CHECKING([whether to build with version 7.2 page format])
+PGAC_ARG_BOOL(enable, pg72format, no, [ --enable-pg72format enable version 7.2 page format],
+ [AC_DEFINE([PG72FORMAT], 1,
+ [Set to 1 if you want version 7.2 page format (--enable-pg72format)])])
+AC_MSG_RESULT([$enable_pg72format])
+
+
+#
# Multibyte support
#
MULTIBYTE=SQL_ASCII
diff -ru ../base/src/backend/access/heap/heapam.c src/backend/access/heap/heapam.c
--- ../base/src/backend/access/heap/heapam.c 2002-06-17 10:11:31.000000000 +0200
+++ src/backend/access/heap/heapam.c 2002-06-17 22:35:32.000000000 +0200
@@ -2204,7 +2204,7 @@
htup->t_infomask = HEAP_XMAX_INVALID | xlhdr.mask;
HeapTupleHeaderSetXmin(htup, record->xl_xid);
HeapTupleHeaderSetCmin(htup, FirstCommandId);
- HeapTupleHeaderSetXmax(htup, InvalidTransactionId);
+ HeapTupleHeaderSetXmaxInvalid(htup);
HeapTupleHeaderSetCmax(htup, FirstCommandId);

offnum = PageAddItem(page, (Item) htup, newlen, offnum,
diff -ru ../base/src/include/access/htup.h src/include/access/htup.h
--- ../base/src/include/access/htup.h 2002-06-17 10:11:32.000000000 +0200
+++ src/include/access/htup.h 2002-06-25 16:14:37.000000000 +0200
@@ -57,15 +57,33 @@
* Also note that we omit the nulls bitmap if t_infomask shows that there
* are no nulls in the tuple.
*/
+/*
+** We store five "virtual" fields Xmin, Cmin, Xmax, Cmax, and Xvac
+** in three physical fields t_xmin, t_cid, t_xmax:
+** CommandId Cmin; insert CID stamp
+** CommandId Cmax; delete CommandId stamp
+** TransactionId Xmin; insert XID stamp
+** TransactionId Xmax; delete XID stamp
+** TransactionId Xvac; used by VACCUUM
+**
+** This assumes, that a CommandId can be stored in a TransactionId.
+*/
typedef struct HeapTupleHeaderData
{
Oid t_oid; /* OID of this tuple -- 4 bytes */

+#ifdef PG72FORMAT
+ /* v7.2: Xvac is stored in t_cmin */
CommandId t_cmin; /* insert CID stamp -- 4 bytes each */
CommandId t_cmax; /* delete CommandId stamp */

TransactionId t_xmin; /* insert XID stamp -- 4 bytes each */
TransactionId t_xmax; /* delete XID stamp */
+#else
+ TransactionId t_xmin; /* Xmin -- 4 bytes each */
+ TransactionId t_cid; /* Cmin, Cmax, Xvac */
+ TransactionId t_xmax; /* Xmax, Cmax */
+#endif

ItemPointerData t_ctid; /* current TID of this or newer tuple */

@@ -75,7 +93,7 @@

uint8 t_hoff; /* sizeof header incl. bitmap, padding */

- /* ^ - 31 bytes - ^ */
+ /* ^ - 27 (v7.3) or 31 (v7.2) bytes - ^ */

bits8 t_bits[1]; /* bitmap of NULLs -- VARIABLE LENGTH */

@@ -96,6 +114,8 @@
* attribute(s) */
#define HEAP_HASEXTENDED 0x000C /* the two above combined */

+#define HEAP_XMIN_IS_XMAX 0x0040 /* created and deleted in the */
+ /* same transaction */
#define HEAP_XMAX_UNLOGGED 0x0080 /* to lock tuple for update */
/* without logging */
#define HEAP_XMIN_COMMITTED 0x0100 /* t_xmin committed */
@@ -108,6 +128,7 @@
* vacuum */
#define HEAP_MOVED_IN 0x8000 /* moved from another place by
* vacuum */
+#define HEAP_MOVED (HEAP_MOVED_OFF | HEAP_MOVED_IN)

#define HEAP_XACT_MASK 0xFFF0 /* visibility-related bits */

@@ -116,8 +137,11 @@
/* HeapTupleHeader accessor macros */

#define HeapTupleHeaderGetXmin(tup) \
- ((tup)->t_xmin)
+( \
+ (tup)->t_xmin \
+)

+#ifdef PG72FORMAT
#define HeapTupleHeaderGetXmax(tup) \
((tup)->t_xmax)

@@ -163,6 +187,98 @@
AssertMacro((tup)->t_infomask & (HEAP_MOVED_IN | HEAP_MOVED_OFF)), \
TransactionIdStore((xid), (TransactionId *) &((tup)->t_cmin)) \
)
+#else
+#define HeapTupleHeaderGetXmax(tup) \
+( \
+ ((tup)->t_infomask & HEAP_XMIN_IS_XMAX) ? \
+ (tup)->t_xmin \
+ : \
+ (tup)->t_xmax \
+)
+
+/* no AssertMacro, because this is read as a system-defined attribute */
+#define HeapTupleHeaderGetCmin(tup) \
+( \
+ ((tup)->t_infomask & HEAP_MOVED) ? \
+ FirstCommandId \
+ : \
+ ( \
+ ((tup)->t_infomask & (HEAP_XMIN_IS_XMAX | HEAP_XMAX_INVALID)) ? \
+ (CommandId) (tup)->t_cid \
+ : \
+ FirstCommandId \
+ ) \
+)
+
+#define HeapTupleHeaderGetCmax(tup) \
+( \
+ ((tup)->t_infomask & HEAP_MOVED) ? \
+ FirstCommandId \
+ : \
+ ( \
+ ((tup)->t_infomask & (HEAP_XMIN_IS_XMAX | HEAP_XMAX_INVALID)) ? \
+ (CommandId) (tup)->t_xmax \
+ : \
+ (CommandId) (tup)->t_cid \
+ ) \
+)
+
+#define HeapTupleHeaderGetXvac(tup) \
+( \
+ AssertMacro((tup)->t_infomask & HEAP_MOVED), \
+ (tup)->t_cid \
+)
+
+
+#define HeapTupleHeaderSetXmin(tup, xid) \
+( \
+ TransactionIdStore((xid), &(tup)->t_xmin) \
+)
+
+#define HeapTupleHeaderSetXminInvalid(tup) \
+do { \
+ (tup)->t_infomask &= ~HEAP_XMIN_IS_XMAX; \
+ StoreInvalidTransactionId(&(tup)->t_xmin); \
+} while (0)
+
+#define HeapTupleHeaderSetXmax(tup, xid) \
+do { \
+ if (TransactionIdEquals((tup)->t_xmin, (xid))) \
+ (tup)->t_infomask |= HEAP_XMIN_IS_XMAX; \
+ else \
+ { \
+ (tup)->t_infomask &= ~HEAP_XMIN_IS_XMAX; \
+ TransactionIdStore((xid), &(tup)->t_xmax); \
+ } \
+} while (0)
+
+#define HeapTupleHeaderSetXmaxInvalid(tup) \
+do { \
+ (tup)->t_infomask &= ~HEAP_XMIN_IS_XMAX; \
+ StoreInvalidTransactionId(&(tup)->t_xmax); \
+} while (0)
+
+#define HeapTupleHeaderSetCmin(tup, cid) \
+do { \
+ Assert(!((tup)->t_infomask & HEAP_MOVED)); \
+ TransactionIdStore((TransactionId) (cid), &(tup)->t_cid); \
+} while (0)
+
+#define HeapTupleHeaderSetCmax(tup, cid) \
+do { \
+ Assert(!((tup)->t_infomask & HEAP_MOVED)); \
+ if ((tup)->t_infomask & HEAP_XMIN_IS_XMAX) \
+ TransactionIdStore((TransactionId) (cid), &(tup)->t_xmax); \
+ else \
+ TransactionIdStore((TransactionId) (cid), &(tup)->t_cid); \
+} while (0)
+
+#define HeapTupleHeaderSetXvac(tup, xid) \
+do { \
+ Assert((tup)->t_infomask & HEAP_MOVED); \
+ TransactionIdStore((xid), &(tup)->t_cid); \
+} while (0)
+#endif


/*
diff -ru ../base/src/include/pg_config.h.in src/include/pg_config.h.in
--- ../base/src/include/pg_config.h.in 2002-06-17 21:04:03.000000000 +0200
+++ src/include/pg_config.h.in 2002-06-25 16:02:40.000000000 +0200
@@ -39,6 +39,9 @@
/* Set to 1 if you want cyrillic recode (--enable-recode) */
#undef CYR_RECODE

+/* Set to 1 if you want version 7.2 page format (--enable-pg72format) */
+#undef PG72FORMAT
+
/* Set to 1 if you want to use multibyte characters (--enable-multibyte) */
#undef MULTIBYTE