Make type Datum be 8 bytes wide everywhere.

This patch makes sizeof(Datum) be 8 on all platforms including
32-bit ones.  The objective is to allow USE_FLOAT8_BYVAL to be true
everywhere, and in consequence to remove a lot of code that is
specific to pass-by-reference handling of float8, int8, etc.  The
code for abbreviated sort keys can be simplified similarly.  In this
way we can reduce the maintenance effort involved in supporting 32-bit
platforms, without going so far as to actually desupport them.  Since
Datum is strictly an in-memory concept, this has no impact on on-disk
storage, though an initdb or pg_upgrade will be needed to fix affected
catalog entries.

We have required platforms to support [u]int64 for ages, so this
breaks no supported platform.  We can expect that this change will
make 32-bit builds a bit slower and more memory-hungry, although being
able to use pass-by-value handling of 8-byte types may buy back some
of that.  But we stopped optimizing for 32-bit cases a long time ago,
and this seems like just another step on that path.

This initial patch simply forces the correct type definition and
USE_FLOAT8_BYVAL setting, and cleans up a couple of minor compiler
complaints that ensued.  This is sufficient for testing purposes.
In the wake of a bunch of Datum-conversion cleanups by Peter
Eisentraut, this now compiles cleanly with gcc on a 32-bit platform.
(I'd only tested the previous version with clang, which it turns out
is less picky than gcc about width-changing coercions.)

There is a good deal of now-dead code that I'll remove in separate
follow-up patches.

A catversion bump is required because this affects initial catalog
contents (on 32-bit machines) in two ways: pg_type.typbyval changes
for some built-in types, and Const nodes in stored views/rules will
now have 8 bytes not 4 for pass-by-value types.

Author: Tom Lane <tgl@sss.pgh.pa.us>
Reviewed-by: Peter Eisentraut <peter@eisentraut.org>
Discussion: https://postgr.es/m/1749799.1752797397@sss.pgh.pa.us

1 files changed, 6 insertions, 2 deletions

diff --git a/src/include/nodes/nodes.h b/src/include/nodes/nodes.h
index fbe333d88fa..b2dc380b57b 100644
--- a/src/include/nodes/nodes.h
+++ b/src/include/nodes/nodes.h
@@ -188,6 +188,8 @@ castNodeImpl(NodeTag type, void *ptr)
  * ----------------------------------------------------------------
  */
 
+#ifndef FRONTEND
+
 /*
  * nodes/{outfuncs.c,print.c}
  */
@@ -198,7 +200,7 @@ extern void outNode(struct StringInfoData *str, const void *obj);
 extern void outToken(struct StringInfoData *str, const char *s);
 extern void outBitmapset(struct StringInfoData *str,
 						 const struct Bitmapset *bms);
-extern void outDatum(struct StringInfoData *str, uintptr_t value,
+extern void outDatum(struct StringInfoData *str, Datum value,
 					 int typlen, bool typbyval);
 extern char *nodeToString(const void *obj);
 extern char *nodeToStringWithLocations(const void *obj);
@@ -212,7 +214,7 @@ extern void *stringToNode(const char *str);
 extern void *stringToNodeWithLocations(const char *str);
 #endif
 extern struct Bitmapset *readBitmapset(void);
-extern uintptr_t readDatum(bool typbyval);
+extern Datum readDatum(bool typbyval);
 extern bool *readBoolCols(int numCols);
 extern int *readIntCols(int numCols);
 extern Oid *readOidCols(int numCols);
@@ -235,6 +237,8 @@ extern void *copyObjectImpl(const void *from);
  */
 extern bool equal(const void *a, const void *b);
 
+#endif							/* !FRONTEND */
+
 
 /*
  * Typedef for parse location.  This is just an int, but this way