I attach a version of my toast-slicing patch, against current CVS

(current as of a few hours ago.)

This patch:

1. Adds PG_GETARG_xxx_P_SLICE() macros and associated support routines.

2. Adds routines in src/backend/access/tuptoaster.c for fetching only
necessary chunks of a toasted value. (Modelled on latest changes to
assume chunks are returned in order).

3. Amends text_substr and bytea_substr to use new methods. It now
handles multibyte cases -and should still lead to a performance
improvement in the multibyte case where the substring is near the
beginning of the string.

4. Added new command: ALTER TABLE tabname ALTER COLUMN colname SET
STORAGE {PLAIN | EXTERNAL | EXTENDED | MAIN} to parser and documented in
alter-table.sgml. (NB I used ColId as the item type for the storage
mode string, rather than a new production - I hope this makes sense!).
All this does is sets attstorage for the specified column.

4. AlterTableAlterColumnStatistics is now AlterTableAlterColumnFlags and
handles both statistics and storage (it uses the subtype code to
distinguish). The previous version of my patch also re-arranged other
code in backend/commands/command.c but I have dropped that from this
patch.(I plan to return to it separately).

5. Documented new macros (and also the PG_GETARG_xxx_P_COPY macros) in
xfunc.sgml. ref/alter_table.sgml also contains documentation for ALTER
COLUMN SET STORAGE.

John Gray

2 files changed, 16 insertions, 3 deletions

diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 9ff44e9d930..dfc8898653c 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -11,7 +11,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/parser/gram.y,v 2.283 2002/03/02 21:39:27 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/parser/gram.y,v 2.284 2002/03/05 05:33:14 momjian Exp $
  *
  * HISTORY
  *	  AUTHOR			DATE			MAJOR EVENT
@@ -364,7 +364,7 @@ static void doNegateFloat(Value *v);
 		OFFSET, OIDS, OPERATOR, OWNER, PASSWORD, PROCEDURAL,
 		REINDEX, RENAME, RESET, RETURNS, ROW, RULE,
 		SEQUENCE, SETOF, SHARE, SHOW, START, STATEMENT,
-		STATISTICS, STDIN, STDOUT, SYSID,
+		STATISTICS, STDIN, STDOUT, STORAGE, SYSID,
 		TEMP, TEMPLATE, TOAST, TRUNCATE, TRUSTED, 
 		UNLISTEN, UNTIL, VACUUM, VALID, VERBOSE, VERSION
 
@@ -1117,6 +1117,17 @@ AlterTableStmt:
 					n->def = (Node *) makeInteger($9);
 					$$ = (Node *)n;
 				}
+/* ALTER TABLE <relation> ALTER [COLUMN] <colname> SET STORAGE <storagemode> */
+        | ALTER TABLE relation_expr ALTER opt_column ColId SET STORAGE ColId
+                {
+					AlterTableStmt *n = makeNode(AlterTableStmt);
+					n->subtype = 'M';
+					n->relname = $3->relname;
+					n->inhOpt = $3->inhOpt;
+					n->name = $6;
+					n->def = (Node *) makeString($9);
+					$$ = (Node *)n;
+				}
 /* ALTER TABLE <relation> DROP [COLUMN] <colname> {RESTRICT|CASCADE} */
 		| ALTER TABLE relation_expr DROP opt_column ColId drop_behavior
 				{
@@ -5959,6 +5970,7 @@ unreserved_keyword:
 		| STATISTICS					{ $$ = "statistics"; }
 		| STDIN							{ $$ = "stdin"; }
 		| STDOUT						{ $$ = "stdout"; }
+        | STORAGE                       { $$ = "storage"; }
 		| SYSID							{ $$ = "sysid"; }
 		| TEMP							{ $$ = "temp"; }
 		| TEMPLATE						{ $$ = "template"; }
diff --git a/src/backend/parser/keywords.c b/src/backend/parser/keywords.c
index 12b05c6bcd1..eaa0f7fa2b0 100644
--- a/src/backend/parser/keywords.c
+++ b/src/backend/parser/keywords.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/parser/keywords.c,v 1.100 2002/02/18 23:11:18 petere Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/parser/keywords.c,v 1.101 2002/03/05 05:33:15 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -243,6 +243,7 @@ static ScanKeyword ScanKeywords[] = {
 	{"statistics", STATISTICS},
 	{"stdin", STDIN},
 	{"stdout", STDOUT},
+	{"storage", STORAGE},
 	{"substring", SUBSTRING},
 	{"sysid", SYSID},
 	{"table", TABLE},