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This patch implements ORACLE's COMMENT SQL command.

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>From the ORACLE 7 SQL Language Reference Manual:
-----------------------------------------------------
COMMENT

Purpose:

To add a comment about a table, view, snapshot, or
column into the data dictionary.

Prerequisites:

The table, view, or snapshot must be in your own
schema
or you must have COMMENT ANY TABLE system privilege.

Syntax:

COMMENT ON [ TABLE table ] |
           [ COLUMN table.column] IS 'text'

You can effectively drop a comment from the database
by setting it to the empty string ''.
-----------------------------------------------------

Example:

COMMENT ON TABLE workorders IS
   'Maintains base records for workorder information';

COMMENT ON COLUMN workorders.hours IS
   'Number of hours the engineer worked on the task';

to drop a comment:

COMMENT ON COLUMN workorders.hours IS '';

The current patch will simply perform the insert into
pg_description, as per the TODO. And, of course, when
the table is dropped, any comments relating to it
or any of its attributes are also dropped. I haven't
looked at the ODBC source yet, but I do know from
an ODBC client standpoint that the standard does
support the notion of table and column comments.
Hopefully the ODBC driver is already fetching these
values from pg_description, but if not, it should be
trivial.

Hope this makes the grade,

Mike Mascari
(mascarim@yahoo.com)
This commit is contained in:
Bruce Momjian
1999-10-15 01:49:49 +00:00
parent 55fa71a9e9
commit 7acc237744
12 changed files with 287 additions and 21 deletions
Download Patch File Download Diff File Expand all files Collapse all files

162
src/backend/catalog/heap.c
View File

@@ -7,7 +7,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/catalog/heap.c,v 1.103 1999/10/07 05:48:03 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/catalog/heap.c,v 1.104 1999/10/15 01:49:39 momjian Exp $
*
*
* INTERFACE ROUTINES
@@ -38,6 +38,7 @@
#include "catalog/index.h"
#include "catalog/indexing.h"
#include "catalog/pg_attrdef.h"
#include "catalog/pg_description.h"
#include "catalog/pg_index.h"
#include "catalog/pg_inherits.h"
#include "catalog/pg_ipl.h"
@@ -67,6 +68,7 @@ static void AddNewRelationTuple(Relation pg_class_desc,
Relation new_rel_desc, Oid new_rel_oid, unsigned natts,
char relkind, char *temp_relname);
static void AddToNoNameRelList(Relation r);
static void DeleteAttributeTuples(Relation rel);
static void DeleteRelationTuple(Relation rel);
static void DeleteTypeTuple(Relation rel);
@@ -861,10 +863,11 @@ heap_create_with_catalog(char *relname,
* 2) remove inheritance information
* 3) remove indexes
* 4) remove pg_class tuple
* 5) remove pg_attribute tuples
* 6) remove pg_type tuples
* 7) RemoveConstraints ()
* 8) unlink relation
* 5) remove pg_attribute tuples and related descriptions
* 6) remove pg_description tuples
* 7) remove pg_type tuples
* 8) RemoveConstraints ()
* 9) unlink relation
*
* old comments
* Except for vital relations, removes relation from
@@ -1269,18 +1272,152 @@ DeleteAttributeTuples(Relation rel)
attnum++)
{
if (HeapTupleIsValid(tup = SearchSysCacheTupleCopy(ATTNUM,
ObjectIdGetDatum(RelationGetRelid(rel)),
Int16GetDatum(attnum),
ObjectIdGetDatum(RelationGetRelid(rel)),
Int16GetDatum(attnum),
0, 0)))
{
heap_delete(pg_attribute_desc, &tup->t_self, NULL);
pfree(tup);
DeleteComments(tup->t_data->t_oid);
heap_delete(pg_attribute_desc, &tup->t_self, NULL);
pfree(tup);
}
}
heap_close(pg_attribute_desc, RowExclusiveLock);
}
/* ----------------------------------------------------------
* CreateComments
*
* This routine is handed the oid and the command associated
* with that id and will insert, update, or delete (if the
* comment is an empty string or a NULL pointer) the associated
* comment from the system cataloge, pg_description.
*
* ----------------------------------------------------------
*/
void
CreateComments(Oid oid, char *comment)
{
Relation description;
TupleDesc tupDesc;
HeapScanDesc scan;
ScanKeyData entry;
HeapTuple desctuple, searchtuple;
Datum values[Natts_pg_description];
char nulls[Natts_pg_description];
char replaces[Natts_pg_description];
bool modified = false;
int i;
/*** Open pg_description, form a new tuple, if necessary ***/
description = heap_openr(DescriptionRelationName, RowExclusiveLock);
tupDesc = description->rd_att;
if ((comment != NULL) && (strlen(comment) > 0)) {
for (i = 0; i < Natts_pg_description; i++) {
nulls[i] = ' ';
replaces[i] = 'r';
values[i] = (Datum) NULL;
}
i = 0;
values[i++] = ObjectIdGetDatum(oid);
values[i++] = (Datum) fmgr(F_TEXTIN, comment);
}
/*** Now, open pg_description and attempt to find the old tuple ***/
ScanKeyEntryInitialize(&entry, 0x0, Anum_pg_description_objoid, F_OIDEQ,
ObjectIdGetDatum(oid));
scan = heap_beginscan(description, false, SnapshotNow, 1, &entry);
searchtuple = heap_getnext(scan, 0);
/*** If a previous tuple exists, either delete it or prepare a replacement ***/
if (HeapTupleIsValid(searchtuple)) {
/*** If the comment is blank, call heap_delete, else heap_replace ***/
if ((comment == NULL) || (strlen(comment) == 0)) {
heap_delete(description, &searchtuple->t_self, NULL);
} else {
desctuple = heap_modifytuple(searchtuple, description, values, nulls, replaces);
setheapoverride(true);
heap_replace(description, &searchtuple->t_self, desctuple, NULL);
setheapoverride(false);
modified = TRUE;
}
} else {
desctuple = heap_formtuple(tupDesc, values, nulls);
heap_insert(description, desctuple);
modified = TRUE;
}
/*** Complete the scan, update indices, if necessary ***/
heap_endscan(scan);
if (modified) {
if (RelationGetForm(description)->relhasindex) {
Relation idescs[Num_pg_description_indices];
CatalogOpenIndices(Num_pg_description_indices, Name_pg_description_indices, idescs);
CatalogIndexInsert(idescs, Num_pg_description_indices, description, desctuple);
CatalogCloseIndices(Num_pg_description_indices, idescs);
}
pfree(desctuple);
}
heap_close(description, RowExclusiveLock);
}
/* --------------------------------
* DeleteComments
*
* This routine is used to purge any comments
* associated with the Oid handed to this routine,
* regardless of the actual object type. It is
* called, for example, when a relation is destroyed.
* --------------------------------
*/
void
DeleteComments(Oid oid)
{
Relation description;
TupleDesc tupDesc;
ScanKeyData entry;
HeapScanDesc scan;
HeapTuple searchtuple;
description = heap_openr(DescriptionRelationName, RowExclusiveLock);
tupDesc = description->rd_att;
/*** Now, open pg_description and attempt to find the old tuple ***/
ScanKeyEntryInitialize(&entry, 0x0, Anum_pg_description_objoid, F_OIDEQ,
ObjectIdGetDatum(oid));
scan = heap_beginscan(description, false, SnapshotNow, 1, &entry);
searchtuple = heap_getnext(scan, 0);
/*** If a previous tuple exists, delete it ***/
if (HeapTupleIsValid(searchtuple)) {
heap_delete(description, &searchtuple->t_self, NULL);
}
/*** Complete the scan, update indices, if necessary ***/
heap_endscan(scan);
heap_close(description, RowExclusiveLock);
}
/* --------------------------------
* DeleteTypeTuple
*
@@ -1471,6 +1608,13 @@ heap_destroy_with_catalog(char *relname)
*/
DeleteAttributeTuples(rel);
/* ----------------
* delete comments
* ----------------
*/
DeleteComments(RelationGetRelid(rel));
if (istemp)
remove_temp_relation(rid);

5
src/backend/catalog/indexing.c
View File

@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/catalog/indexing.c,v 1.47 1999/09/30 10:31:42 wieck Exp $
* $Header: /cvsroot/pgsql/src/backend/catalog/indexing.c,v 1.48 1999/10/15 01:49:39 momjian Exp $
*
*-------------------------------------------------------------------------
*/
@@ -55,6 +55,9 @@ char *Name_pg_trigger_indices[Num_pg_trigger_indices] = {TriggerRelidIndex,
TriggerConstrNameIndex,
TriggerConstrRelidIndex};
char *Name_pg_description_indices[Num_pg_description_indices] = {DescriptionObjIndex};
static HeapTuple CatalogIndexFetchTuple(Relation heapRelation,
Relation idesc,