diff --git a/src/backend/catalog/pg_attribute.h b/src/backend/catalog/pg_attribute.h
index 4de5884005299f06833d36aca8d48b62fd4ff71d..1629462199143a2bf9c6edfc25f517a24e7e9bab 100644
--- a/src/backend/catalog/pg_attribute.h
+++ b/src/backend/catalog/pg_attribute.h
@@ -7,7 +7,7 @@
*
* Copyright (c) 1994, Regents of the University of California
*
- * $Id: pg_attribute.h,v 1.2 1996/08/21 04:25:47 scrappy Exp $
+ * $Id: pg_attribute.h,v 1.3 1996/08/24 20:56:13 scrappy Exp $
*
* NOTES
* the genbki.sh script reads this file and generates .bki
@@ -44,13 +44,19 @@ CATALOG(pg_attribute) BOOTSTRAP {
Oid attrelid;
NameData attname;
Oid atttypid;
+ /* atttypid is the OID of the instance in Catalog Class pg_type that
+ defines the data type of this attribute (e.g. int4). Information in
+ that instance is redundant with the attlen, attbyval, and attalign
+ attributes of this instance, so they had better match or Postgres
+ will fail.
+ */
Oid attdefrel;
int4 attnvals;
Oid atttyparg; /* type arg for arrays/spquel/procs */
int2 attlen;
- /* attlen is the number of bytes we use to represent the value
- of this attribute, e.g. 4 for an int4. But for a variable length
- attribute, attlen is -1.
+ /* attlen is a copy of the typlen field from pg_type for this
+ attribute. See atttypid above. See struct TypeTupleFormData for
+ definition.
*/
int2 attnum;
/* attnum is the "attribute number" for the attribute: A
@@ -68,6 +74,10 @@ CATALOG(pg_attribute) BOOTSTRAP {
*/
int2 attbound;
bool attbyval;
+ /* attbyval is a copy of the typbyval field from pg_type for this
+ attribute. See atttypid above. See struct TypeTupleFormData for
+ definition.
+ */
bool attcanindex;
Oid attproc; /* spquel? */
int4 attnelems;
@@ -80,7 +90,11 @@ CATALOG(pg_attribute) BOOTSTRAP {
walking process.
*/
bool attisset;
- char attalign; /* alignment (c=char, s=short, i=int, d=double) */
+ char attalign;
+ /* attalign is a copy of the typalign field from pg_type for this
+ attribute. See atttypid above. See struct TypeTupleFormData for
+ definition.
+ */
} FormData_pg_attribute;
/*
diff --git a/src/backend/catalog/pg_type.h b/src/backend/catalog/pg_type.h
index 029c25a781f39418776ed6f76891f8a3e0547d8c..39ebdb6bdaf16096bb323cf9106926c5d518c9a9 100644
--- a/src/backend/catalog/pg_type.h
+++ b/src/backend/catalog/pg_type.h
@@ -7,7 +7,7 @@
*
* Copyright (c) 1994, Regents of the University of California
*
- * $Id: pg_type.h,v 1.3 1996/07/19 05:21:28 scrappy Exp $
+ * $Id: pg_type.h,v 1.4 1996/08/24 20:56:16 scrappy Exp $
*
* NOTES
* the genbki.sh script reads this file and generates .bki
@@ -30,14 +30,34 @@
/* ----------------
* pg_type definition. cpp turns this into
* typedef struct FormData_pg_type
+ *
+ * Some of the values in a pg_type instance are copied into
+ * pg_attribute intances. Some parts of Postgres use the pg_type copy,
+ * while others use the pg_attribute copy, so they must match.
+ * See struct FormData_pg_attribute for details.
* ----------------
*/
CATALOG(pg_type) BOOTSTRAP {
NameData typname;
Oid typowner;
int2 typlen;
+ /* typlen is the number of bytes we use to represent a value of
+ this type, e.g. 4 for an int4. But for a variable length
+ attribute, typlen is -1.
+ */
int2 typprtlen;
bool typbyval;
+ /* typbyval determines whether internal Postgres routines pass a value
+ of this type by value or by reference. Postgres uses a 4 byte
+ area for passing class data, so if the value is not 1, 2,
+ or 4 bytes long, Postgres does not have the option of passing by
+ value and ignores typbyval.
+
+ (I don't understand why this attribute exists. The above description
+ may be an oversimplification. Also, there appear to be bugs in which
+ Postgres doesn't ignore typbyval when it should, but I'm
+ afraid to change them until I see proof of damage. -BRYANH 96.08).
+ */
char typtype;
bool typisdefined;
char typdelim;
@@ -47,7 +67,23 @@ CATALOG(pg_type) BOOTSTRAP {
regproc typoutput;
regproc typreceive;
regproc typsend;
- char typalign; /* alignment (c=char, s=short, i=int, d=double) */
+ char typalign;
+ /* typalign is the alignment required when storing a value of this
+ type. It applies to storage on disk as well as most representations
+ of the value inside Postgres. When multiple values are stored
+ consecutively, such as in the representation of a complete tuple
+ on disk, padding is inserted before a datum of this type so that it
+ begins on the specified boundary. The alignment reference is the
+ beginning of the first datum in the sequence.
+
+ 'c' = 1 byte alignment.
+ 's' = 2 byte alignment.
+ 'i' = 4 byte alignment.
+ 'd' = 8 byte alignment.
+
+ (This might actually be flexible depending on machine architecture,
+ but I doubt it - BRYANH 96.08).
+ */
text typdefault; /* VARIABLE LENGTH FIELD */
} TypeTupleFormData;
@@ -87,6 +123,11 @@ typedef TypeTupleFormData *TypeTupleForm;
/* keep the following ordered by OID so that later changes can be made easier*/
+/* Make sure the typlen, typbyval, and typalign values here match the initial
+ values for attlen, attbyval, and attalign in both places in pg_attribute.h
+ for every instance.
+*/
+
/* OIDS 1 - 99 */
DATA(insert OID = 16 ( bool PGUID 1 1 t b t \054 0 0 boolin boolout boolin boolout c _null_ ));
@@ -95,7 +136,7 @@ DATA(insert OID = 16 ( bool PGUID 1 1 t b t \054 0 0 boolin boolout
DATA(insert OID = 17 ( bytea PGUID -1 -1 f b t \054 0 18 byteain byteaout byteain byteaout i _null_ ));
DATA(insert OID = 18 ( char PGUID 1 1 t b t \054 0 0 charin charout charin charout c _null_ ));
-DATA(insert OID = 19 ( name PGUID NAMEDATALEN NAMEDATALEN f b t \054 0 18 namein nameout namein nameout d _null_ ));
+DATA(insert OID = 19 ( name PGUID NAMEDATALEN NAMEDATALEN f b t \054 0 18 namein nameout namein nameout i _null_ ));
DATA(insert OID = 20 ( char16 PGUID 16 16 f b t \054 0 18 char16in char16out char16in char16out i _null_ ));
/*DATA(insert OID = 20 ( dt PGUID 4 10 t b t \054 0 0 dtin dtout dtin dtout i _null_ )); */
DATA(insert OID = 21 ( int2 PGUID 2 5 t b t \054 0 0 int2in int2out int2in int2out s _null_ ));