Reduce the alignment requirement of type "name" from int to char, and arrange

to suppress zero-padding of "name" entries in indexes.

The alignment change is unlikely to save any space, but it is really needed
anyway to make the world safe for our widespread practice of passing plain
old C strings to functions that are declared as taking Name.  In the previous
coding, the C compiler was entitled to assume that a Name pointer was
word-aligned; but we were failing to guarantee that.  I think the reason
we'd not seen failures is that usually the only thing that gets done with
such a pointer is strcmp(), which is hard to optimize in a way that exploits
word-alignment.  Still, some enterprising compiler guy will probably think
of a way eventually, or we might change our code in a way that exposes
more-obvious optimization opportunities.

The padding change is accomplished in one-liner fashion by declaring the
"name" index opclasses to use storage type "cstring" in pg_opclass.h.
Normally btree and hash don't allow a nondefault storage type, because they
don't have any provisions for converting the input datum to another type.
However, because name and cstring are effectively the same thing except for
padding, no conversion is needed --- we only need index_form_tuple() to treat
the datum as being cstring not name, and this is sufficient.  This seems to
make for about a one-third reduction in the typical sizes of system catalog
indexes that involve "name" columns, of which we have many.

These two changes are only weakly related, but the alignment change makes
me feel safer that the padding change won't introduce problems, so I'm
committing them together.

diff --git a/src/backend/bootstrap/bootstrap.c b/src/backend/bootstrap/bootstrap.c
index d8008c9811c4f17980789355220c6ddf1c9f284f..25eba1406fb7b8f16fc71415212d1d2bf6680fc9 100644 (file)
--- a/src/backend/bootstrap/bootstrap.c
+++ b/src/backend/bootstrap/bootstrap.c
@@ -8,7 +8,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/bootstrap/bootstrap.c,v 1.243 2008/05/12 00:00:46 alvherre Exp $
+ *       $PostgreSQL: pgsql/src/backend/bootstrap/bootstrap.c,v 1.244 2008/06/24 17:58:27 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -125,7 +125,7 @@ static const struct typinfo TypInfo[] = {
        F_INT4IN, F_INT4OUT},
        {"float4", FLOAT4OID, 0, 4, FLOAT4PASSBYVAL, 'i', 'p',
        F_FLOAT4IN, F_FLOAT4OUT},
-       {"name", NAMEOID, CHAROID, NAMEDATALEN, false, 'i', 'p',
+       {"name", NAMEOID, CHAROID, NAMEDATALEN, false, 'c', 'p',
        F_NAMEIN, F_NAMEOUT},
        {"regclass", REGCLASSOID, 0, 4, true, 'i', 'p',
        F_REGCLASSIN, F_REGCLASSOUT},

diff --git a/src/backend/utils/adt/name.c b/src/backend/utils/adt/name.c
index 96f398e5bb284e51f3065b0e17865748c5cf541b..701b0fd4a5c82a229fe5109d544ba2ed8d49d3cc 100644 (file)
--- a/src/backend/utils/adt/name.c
+++ b/src/backend/utils/adt/name.c
@@ -14,7 +14,7 @@
  *
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/utils/adt/name.c,v 1.62 2008/05/27 00:13:09 tgl Exp $
+ *       $PostgreSQL: pgsql/src/backend/utils/adt/name.c,v 1.63 2008/06/24 17:58:27 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -315,7 +315,7 @@ current_schemas(PG_FUNCTION_ARGS)
                                                        NAMEOID,
                                                        NAMEDATALEN,            /* sizeof(Name) */
                                                        false,          /* Name is not by-val */
-                                                       'i');           /* alignment of Name */
+                                                       'c');           /* alignment of Name */
 
        PG_RETURN_POINTER(array);
 }

diff --git a/src/include/c.h b/src/include/c.h
index 16ccb4cf4e3097783dca4c038d19f4321c1f0ad5..d8fa1d25d20fcb505f510b151c5646d17a8bb935 100644 (file)
--- a/src/include/c.h
+++ b/src/include/c.h
@@ -12,7 +12,7 @@
  * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/c.h,v 1.227 2008/06/17 16:09:06 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/c.h,v 1.228 2008/06/24 17:58:27 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -442,16 +442,12 @@ typedef struct
 } oidvector;                                   /* VARIABLE LENGTH STRUCT */
 
 /*
- * We want NameData to have length NAMEDATALEN and int alignment,
- * because that's how the data type 'name' is defined in pg_type.
- * Use a union to make sure the compiler agrees.  Note that NAMEDATALEN
- * must be a multiple of sizeof(int), else sizeof(NameData) will probably
- * not come out equal to NAMEDATALEN.
+ * Representation of a Name: effectively just a C string, but null-padded to
+ * exactly NAMEDATALEN bytes.  The use of a struct is historical.
  */
-typedef union nameData
+typedef struct nameData
 {
        char            data[NAMEDATALEN];
-       int                     alignmentDummy;
 } NameData;
 typedef NameData *Name;
 

diff --git a/src/include/catalog/catversion.h b/src/include/catalog/catversion.h
index 5b434df51564e37f68b06def9d642d75a8db9b5d..a49beccd54f1b337f985589df4fe71a688d69cb8 100644 (file)
--- a/src/include/catalog/catversion.h
+++ b/src/include/catalog/catversion.h
@@ -37,7 +37,7 @@
  * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/catalog/catversion.h,v 1.463 2008/06/17 19:10:56 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/catalog/catversion.h,v 1.464 2008/06/24 17:58:27 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -53,6 +53,6 @@
  */
 
 /*                                                     yyyymmddN */
-#define CATALOG_VERSION_NO     200806171
+#define CATALOG_VERSION_NO     200806241
 
 #endif

diff --git a/src/include/catalog/pg_attribute.h b/src/include/catalog/pg_attribute.h
index 1378f109f6ef2d3764075331f0de25b2c3e746db..278b7387a506463fc1463bafba21f27fb5fe7285 100644 (file)
--- a/src/include/catalog/pg_attribute.h
+++ b/src/include/catalog/pg_attribute.h
@@ -8,7 +8,7 @@
  * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/catalog/pg_attribute.h,v 1.137 2008/04/21 00:26:46 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/catalog/pg_attribute.h,v 1.138 2008/06/24 17:58:27 tgl Exp $
  *
  * NOTES
  *       the genbki.sh script reads this file and generates .bki
@@ -217,7 +217,7 @@ typedef FormData_pg_attribute *Form_pg_attribute;
  * ----------------
  */
 #define Schema_pg_type \
-{ 1247, {"typname"},      19, -1, NAMEDATALEN, 1, 0, -1, -1, false, 'p', 'i', true, false, false, true, 0 }, \
+{ 1247, {"typname"},      19, -1, NAMEDATALEN, 1, 0, -1, -1, false, 'p', 'c', true, false, false, true, 0 }, \
 { 1247, {"typnamespace"},  26, -1,     4,      2, 0, -1, -1, true, 'p', 'i', true, false, false, true, 0 }, \
 { 1247, {"typowner"},     26, -1,      4,      3, 0, -1, -1, true, 'p', 'i', true, false, false, true, 0 }, \
 { 1247, {"typlen"},               21, -1,      2,      4, 0, -1, -1, true, 'p', 's', true, false, false, true, 0 }, \
@@ -244,7 +244,7 @@ typedef FormData_pg_attribute *Form_pg_attribute;
 { 1247, {"typdefaultbin"}, 25, -1, -1, 25, 0, -1, -1, false, 'x', 'i', false, false, false, true, 0 }, \
 { 1247, {"typdefault"},    25, -1, -1, 26, 0, -1, -1, false, 'x', 'i', false, false, false, true, 0 }
 
-DATA(insert ( 1247 typname                     19 -1 NAMEDATALEN       1 0 -1 -1 f p i t f f t 0));
+DATA(insert ( 1247 typname                     19 -1 NAMEDATALEN       1 0 -1 -1 f p c t f f t 0));
 DATA(insert ( 1247 typnamespace                26 -1 4   2 0 -1 -1 t p i t f f t 0));
 DATA(insert ( 1247 typowner                    26 -1 4   3 0 -1 -1 t p i t f f t 0));
 DATA(insert ( 1247 typlen                      21 -1 2   4 0 -1 -1 t p s t f f t 0));
@@ -283,7 +283,7 @@ DATA(insert ( 1247 tableoid                 26 0  4  -7 0 -1 -1 t p i t f f t 0));
  * ----------------
  */
 #define Schema_pg_proc \
-{ 1255, {"proname"},                   19, -1, NAMEDATALEN,  1, 0, -1, -1, false, 'p', 'i', true, false, false, true, 0 }, \
+{ 1255, {"proname"},                   19, -1, NAMEDATALEN,  1, 0, -1, -1, false, 'p', 'c', true, false, false, true, 0 }, \
 { 1255, {"pronamespace"},              26, -1, 4,      2, 0, -1, -1, true, 'p', 'i', true, false, false, true, 0 }, \
 { 1255, {"proowner"},                  26, -1, 4,      3, 0, -1, -1, true, 'p', 'i', true, false, false, true, 0 }, \
 { 1255, {"prolang"},                   26, -1, 4,      4, 0, -1, -1, true, 'p', 'i', true, false, false, true, 0 }, \
@@ -305,7 +305,7 @@ DATA(insert ( 1247 tableoid                 26 0  4  -7 0 -1 -1 t p i t f f t 0));
 { 1255, {"proconfig"},           1009, -1, -1, 20, 1, -1, -1, false, 'x', 'i', false, false, false, true, 0 }, \
 { 1255, {"proacl"},                      1034, -1, -1, 21, 1, -1, -1, false, 'x', 'i', false, false, false, true, 0 }
 
-DATA(insert ( 1255 proname                     19 -1 NAMEDATALEN       1 0 -1 -1 f p i t f f t 0));
+DATA(insert ( 1255 proname                     19 -1 NAMEDATALEN       1 0 -1 -1 f p c t f f t 0));
 DATA(insert ( 1255 pronamespace                26 -1 4   2 0 -1 -1 t p i t f f t 0));
 DATA(insert ( 1255 proowner                    26 -1 4   3 0 -1 -1 t p i t f f t 0));
 DATA(insert ( 1255 prolang                     26 -1 4   4 0 -1 -1 t p i t f f t 0));
@@ -340,7 +340,7 @@ DATA(insert ( 1255 tableoid                 26 0  4  -7 0 -1 -1 t p i t f f t 0));
  */
 #define Schema_pg_attribute \
 { 1249, {"attrelid"},    26, -1,       4,      1, 0, -1, -1, true, 'p', 'i', true, false, false, true, 0 }, \
-{ 1249, {"attname"},     19, -1, NAMEDATALEN,  2, 0, -1, -1, false, 'p', 'i', true, false, false, true, 0 }, \
+{ 1249, {"attname"},     19, -1, NAMEDATALEN,  2, 0, -1, -1, false, 'p', 'c', true, false, false, true, 0 }, \
 { 1249, {"atttypid"},    26, -1,       4,      3, 0, -1, -1, true, 'p', 'i', true, false, false, true, 0 }, \
 { 1249, {"attstattarget"}, 23, -1,     4,      4, 0, -1, -1, true, 'p', 'i', true, false, false, true, 0 }, \
 { 1249, {"attlen"},              21, -1,       2,      5, 0, -1, -1, true, 'p', 's', true, false, false, true, 0 }, \
@@ -358,7 +358,7 @@ DATA(insert ( 1255 tableoid                 26 0  4  -7 0 -1 -1 t p i t f f t 0));
 { 1249, {"attinhcount"},  23, -1,      4, 17, 0, -1, -1, true, 'p', 'i', true, false, false, true, 0 }
 
 DATA(insert ( 1249 attrelid                    26 -1  4   1 0 -1 -1 t p i t f f t 0));
-DATA(insert ( 1249 attname                     19 -1 NAMEDATALEN  2 0 -1 -1 f p i t f f t 0));
+DATA(insert ( 1249 attname                     19 -1 NAMEDATALEN  2 0 -1 -1 f p c t f f t 0));
 DATA(insert ( 1249 atttypid                    26 -1  4   3 0 -1 -1 t p i t f f t 0));
 DATA(insert ( 1249 attstattarget       23 -1  4   4 0 -1 -1 t p i t f f t 0));
 DATA(insert ( 1249 attlen                      21 -1  2   5 0 -1 -1 t p s t f f t 0));
@@ -387,7 +387,7 @@ DATA(insert ( 1249 tableoid                 26 0  4  -7 0 -1 -1 t p i t f f t 0));
  * ----------------
  */
 #define Schema_pg_class \
-{ 1259, {"relname"},      19, -1, NAMEDATALEN, 1, 0, -1, -1, false, 'p', 'i', true, false, false, true, 0 }, \
+{ 1259, {"relname"},      19, -1, NAMEDATALEN, 1, 0, -1, -1, false, 'p', 'c', true, false, false, true, 0 }, \
 { 1259, {"relnamespace"},  26, -1,     4,      2, 0, -1, -1, true, 'p', 'i', true, false, false, true, 0 }, \
 { 1259, {"reltype"},      26, -1,      4,      3, 0, -1, -1, true, 'p', 'i', true, false, false, true, 0 }, \
 { 1259, {"relowner"},     26, -1,      4,      4, 0, -1, -1, true, 'p', 'i', true, false, false, true, 0 }, \
@@ -415,7 +415,7 @@ DATA(insert ( 1249 tableoid                 26 0  4  -7 0 -1 -1 t p i t f f t 0));
 { 1259, {"relacl"},             1034, -1, -1, 26, 1, -1, -1, false, 'x', 'i', false, false, false, true, 0 }, \
 { 1259, {"reloptions"},  1009, -1, -1, 27, 1, -1, -1, false, 'x', 'i', false, false, false, true, 0 }
 
-DATA(insert ( 1259 relname                     19 -1 NAMEDATALEN       1 0 -1 -1 f p i t f f t 0));
+DATA(insert ( 1259 relname                     19 -1 NAMEDATALEN       1 0 -1 -1 f p c t f f t 0));
 DATA(insert ( 1259 relnamespace                26 -1 4   2 0 -1 -1 t p i t f f t 0));
 DATA(insert ( 1259 reltype                     26 -1 4   3 0 -1 -1 t p i t f f t 0));
 DATA(insert ( 1259 relowner                    26 -1 4   4 0 -1 -1 t p i t f f t 0));

diff --git a/src/include/catalog/pg_opclass.h b/src/include/catalog/pg_opclass.h
index 13f66c01baf9b41e96988011a3267bd4103aa032..f0cb23e27085e9957087f7c511b77cdfe69d63a5 100644 (file)
--- a/src/include/catalog/pg_opclass.h
+++ b/src/include/catalog/pg_opclass.h
@@ -28,7 +28,7 @@
  * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/catalog/pg_opclass.h,v 1.81 2008/05/27 00:13:09 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/catalog/pg_opclass.h,v 1.82 2008/06/24 17:58:27 tgl Exp $
  *
  * NOTES
  *       the genbki.sh script reads this file and generates .bki
@@ -121,8 +121,15 @@ DATA(insert (      403             interval_ops            PGNSP PGUID 1982 1186 t 0 ));
 DATA(insert (  405             interval_ops            PGNSP PGUID 1983 1186 t 0 ));
 DATA(insert (  403             macaddr_ops                     PGNSP PGUID 1984  829 t 0 ));
 DATA(insert (  405             macaddr_ops                     PGNSP PGUID 1985  829 t 0 ));
-DATA(insert (  403             name_ops                        PGNSP PGUID 1986   19 t 0 ));
-DATA(insert (  405             name_ops                        PGNSP PGUID 1987   19 t 0 ));
+/*
+ * Here's an ugly little hack to save space in the system catalog indexes.
+ * btree and hash don't ordinarily allow a storage type different from input
+ * type; but cstring and name are the same thing except for trailing padding,
+ * and we can safely omit that within an index entry.  So we declare the
+ * opclasses for name as using cstring storage type.
+ */
+DATA(insert (  403             name_ops                        PGNSP PGUID 1986   19 t 2275 ));
+DATA(insert (  405             name_ops                        PGNSP PGUID 1987   19 t 2275 ));
 DATA(insert (  403             numeric_ops                     PGNSP PGUID 1988 1700 t 0 ));
 DATA(insert (  405             numeric_ops                     PGNSP PGUID 1998 1700 t 0 ));
 DATA(insert OID = 1981 ( 403   oid_ops         PGNSP PGUID 1989   26 t 0 ));

diff --git a/src/include/catalog/pg_type.h b/src/include/catalog/pg_type.h
index 5687332e2a90c5e1d07416bb8a53eaebee089507..82798a7951e467f434d80243485ee2c15d64d8d8 100644 (file)
--- a/src/include/catalog/pg_type.h
+++ b/src/include/catalog/pg_type.h
@@ -8,7 +8,7 @@
  * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/catalog/pg_type.h,v 1.195 2008/04/21 00:26:47 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/catalog/pg_type.h,v 1.196 2008/06/24 17:58:27 tgl Exp $
  *
  * NOTES
  *       the genbki.sh script reads this file and generates .bki
@@ -267,7 +267,7 @@ DATA(insert OID = 18 (      char       PGNSP PGUID  1 t b t \054 0   0 1002 charin charout
 DESCR("single character");
 #define CHAROID                        18
 
-DATA(insert OID = 19 ( name       PGNSP PGUID NAMEDATALEN f b t \054 0 18 1003 namein nameout namerecv namesend - - - i p f 0 -1 0 _null_ _null_ ));
+DATA(insert OID = 19 ( name       PGNSP PGUID NAMEDATALEN f b t \054 0 18 1003 namein nameout namerecv namesend - - - c p f 0 -1 0 _null_ _null_ ));
 DESCR("63-character type for storing system identifiers");
 #define NAMEOID                        19
 

diff --git a/src/include/pg_config_manual.h b/src/include/pg_config_manual.h
index b56902d6fab94b424634d7b2d143317d7f59a445..3ee0d6d91b6c4a74aeb3326696bca796982e2bce 100644 (file)
--- a/src/include/pg_config_manual.h
+++ b/src/include/pg_config_manual.h
@@ -6,14 +6,14 @@
  * for developers.     If you edit any of these, be sure to do a *full*
  * rebuild (and an initdb if noted).
  *
- * $PostgreSQL: pgsql/src/include/pg_config_manual.h,v 1.33 2008/05/02 19:52:37 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/pg_config_manual.h,v 1.34 2008/06/24 17:58:27 tgl Exp $
  *------------------------------------------------------------------------
  */
 
 /*
  * Maximum length for identifiers (e.g. table names, column names,
- * function names).  It must be a multiple of sizeof(int) (typically
- * 4).
+ * function names).  Names actually are limited to one less byte than this,
+ * because the length must include a trailing zero byte.
  *
  * Changing this requires an initdb.
  */