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This patch implements ORACLE's COMMENT SQL command.
>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)
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-21
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12 files changed

+287
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lines changed

‎src/backend/catalog/heap.c

Lines changed: 153 additions & 9 deletions
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
*
88
*
99
* IDENTIFICATION
10-
* $Header: /cvsroot/pgsql/src/backend/catalog/heap.c,v 1.103 1999/10/07 05:48:03 tgl Exp $
10+
* $Header: /cvsroot/pgsql/src/backend/catalog/heap.c,v 1.104 1999/10/15 01:49:39 momjian Exp $
1111
*
1212
*
1313
* INTERFACE ROUTINES
@@ -38,6 +38,7 @@
3838
#include "catalog/index.h"
3939
#include "catalog/indexing.h"
4040
#include "catalog/pg_attrdef.h"
41+
#include "catalog/pg_description.h"
4142
#include "catalog/pg_index.h"
4243
#include "catalog/pg_inherits.h"
4344
#include "catalog/pg_ipl.h"
@@ -67,6 +68,7 @@ static void AddNewRelationTuple(Relation pg_class_desc,
6768
Relation new_rel_desc, Oid new_rel_oid, unsigned natts,
6869
char relkind, char *temp_relname);
6970
static void AddToNoNameRelList(Relation r);
71+
7072
static void DeleteAttributeTuples(Relation rel);
7173
static void DeleteRelationTuple(Relation rel);
7274
static void DeleteTypeTuple(Relation rel);
@@ -861,10 +863,11 @@ heap_create_with_catalog(char *relname,
861863
* 2) remove inheritance information
862864
* 3) remove indexes
863865
* 4) remove pg_class tuple
864-
* 5) remove pg_attribute tuples
865-
* 6) remove pg_type tuples
866-
* 7) RemoveConstraints ()
867-
* 8) unlink relation
866+
* 5) remove pg_attribute tuples and related descriptions
867+
* 6) remove pg_description tuples
868+
* 7) remove pg_type tuples
869+
* 8) RemoveConstraints ()
870+
* 9) unlink relation
868871
*
869872
* old comments
870873
* Except for vital relations, removes relation from
@@ -1269,18 +1272,152 @@ DeleteAttributeTuples(Relation rel)
12691272
attnum++)
12701273
{
12711274
if (HeapTupleIsValid(tup = SearchSysCacheTupleCopy(ATTNUM,
1272-
ObjectIdGetDatum(RelationGetRelid(rel)),
1273-
Int16GetDatum(attnum),
1275+
ObjectIdGetDatum(RelationGetRelid(rel)),
1276+
Int16GetDatum(attnum),
12741277
0, 0)))
12751278
{
1276-
heap_delete(pg_attribute_desc, &tup->t_self, NULL);
1277-
pfree(tup);
1279+
DeleteComments(tup->t_data->t_oid);
1280+
heap_delete(pg_attribute_desc, &tup->t_self, NULL);
1281+
pfree(tup);
12781282
}
12791283
}
12801284

12811285
heap_close(pg_attribute_desc, RowExclusiveLock);
12821286
}
12831287

1288+
/* ----------------------------------------------------------
1289+
* CreateComments
1290+
*
1291+
* This routine is handed the oid and the command associated
1292+
* with that id and will insert, update, or delete (if the
1293+
* comment is an empty string or a NULL pointer) the associated
1294+
* comment from the system cataloge, pg_description.
1295+
*
1296+
* ----------------------------------------------------------
1297+
*/
1298+
1299+
void
1300+
CreateComments(Oid oid, char *comment)
1301+
{
1302+
1303+
Relation description;
1304+
TupleDesc tupDesc;
1305+
HeapScanDesc scan;
1306+
ScanKeyData entry;
1307+
HeapTuple desctuple, searchtuple;
1308+
Datum values[Natts_pg_description];
1309+
char nulls[Natts_pg_description];
1310+
char replaces[Natts_pg_description];
1311+
bool modified = false;
1312+
int i;
1313+
1314+
/*** Open pg_description, form a new tuple, if necessary ***/
1315+
1316+
description = heap_openr(DescriptionRelationName, RowExclusiveLock);
1317+
tupDesc = description->rd_att;
1318+
if ((comment != NULL) && (strlen(comment) > 0)) {
1319+
for (i = 0; i < Natts_pg_description; i++) {
1320+
nulls[i] = ' ';
1321+
replaces[i] = 'r';
1322+
values[i] = (Datum) NULL;
1323+
}
1324+
i = 0;
1325+
values[i++] = ObjectIdGetDatum(oid);
1326+
values[i++] = (Datum) fmgr(F_TEXTIN, comment);
1327+
}
1328+
1329+
/*** Now, open pg_description and attempt to find the old tuple ***/
1330+
1331+
ScanKeyEntryInitialize(&entry, 0x0, Anum_pg_description_objoid, F_OIDEQ,
1332+
ObjectIdGetDatum(oid));
1333+
scan = heap_beginscan(description, false, SnapshotNow, 1, &entry);
1334+
searchtuple = heap_getnext(scan, 0);
1335+
1336+
/*** If a previous tuple exists, either delete it or prepare a replacement ***/
1337+
1338+
if (HeapTupleIsValid(searchtuple)) {
1339+
1340+
/*** If the comment is blank, call heap_delete, else heap_replace ***/
1341+
1342+
if ((comment == NULL) || (strlen(comment) == 0)) {
1343+
heap_delete(description, &searchtuple->t_self, NULL);
1344+
} else {
1345+
desctuple = heap_modifytuple(searchtuple, description, values, nulls, replaces);
1346+
setheapoverride(true);
1347+
heap_replace(description, &searchtuple->t_self, desctuple, NULL);
1348+
setheapoverride(false);
1349+
modified = TRUE;
1350+
}
1351+
1352+
} else {
1353+
desctuple = heap_formtuple(tupDesc, values, nulls);
1354+
heap_insert(description, desctuple);
1355+
modified = TRUE;
1356+
}
1357+
1358+
/*** Complete the scan, update indices, if necessary ***/
1359+
1360+
heap_endscan(scan);
1361+
1362+
if (modified) {
1363+
if (RelationGetForm(description)->relhasindex) {
1364+
Relation idescs[Num_pg_description_indices];
1365+
1366+
CatalogOpenIndices(Num_pg_description_indices, Name_pg_description_indices, idescs);
1367+
CatalogIndexInsert(idescs, Num_pg_description_indices, description, desctuple);
1368+
CatalogCloseIndices(Num_pg_description_indices, idescs);
1369+
}
1370+
pfree(desctuple);
1371+
1372+
}
1373+
1374+
heap_close(description, RowExclusiveLock);
1375+
1376+
}
1377+
1378+
/* --------------------------------
1379+
* DeleteComments
1380+
*
1381+
* This routine is used to purge any comments
1382+
* associated with the Oid handed to this routine,
1383+
* regardless of the actual object type. It is
1384+
* called, for example, when a relation is destroyed.
1385+
* --------------------------------
1386+
*/
1387+
1388+
void
1389+
DeleteComments(Oid oid)
1390+
{
1391+
1392+
Relation description;
1393+
TupleDesc tupDesc;
1394+
ScanKeyData entry;
1395+
HeapScanDesc scan;
1396+
HeapTuple searchtuple;
1397+
1398+
description = heap_openr(DescriptionRelationName, RowExclusiveLock);
1399+
tupDesc = description->rd_att;
1400+
1401+
/*** Now, open pg_description and attempt to find the old tuple ***/
1402+
1403+
ScanKeyEntryInitialize(&entry, 0x0, Anum_pg_description_objoid, F_OIDEQ,
1404+
ObjectIdGetDatum(oid));
1405+
scan = heap_beginscan(description, false, SnapshotNow, 1, &entry);
1406+
searchtuple = heap_getnext(scan, 0);
1407+
1408+
/*** If a previous tuple exists, delete it ***/
1409+
1410+
if (HeapTupleIsValid(searchtuple)) {
1411+
heap_delete(description, &searchtuple->t_self, NULL);
1412+
}
1413+
1414+
/*** Complete the scan, update indices, if necessary ***/
1415+
1416+
heap_endscan(scan);
1417+
heap_close(description, RowExclusiveLock);
1418+
1419+
}
1420+
12841421
/* --------------------------------
12851422
* DeleteTypeTuple
12861423
*
@@ -1471,6 +1608,13 @@ heap_destroy_with_catalog(char *relname)
14711608
*/
14721609
DeleteAttributeTuples(rel);
14731610

1611+
/* ----------------
1612+
* delete comments
1613+
* ----------------
1614+
*/
1615+
1616+
DeleteComments(RelationGetRelid(rel));
1617+
14741618
if (istemp)
14751619
remove_temp_relation(rid);
14761620

‎src/backend/catalog/indexing.c

Lines changed: 4 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $Header: /cvsroot/pgsql/src/backend/catalog/indexing.c,v 1.47 1999/09/30 10:31:42 wieck Exp $
11+
* $Header: /cvsroot/pgsql/src/backend/catalog/indexing.c,v 1.48 1999/10/15 01:49:39 momjian Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -55,6 +55,9 @@ char *Name_pg_trigger_indices[Num_pg_trigger_indices] = {TriggerRelidIndex,
5555
TriggerConstrNameIndex,
5656
TriggerConstrRelidIndex};
5757

58+
char *Name_pg_description_indices[Num_pg_description_indices] = {DescriptionObjIndex};
59+
60+
5861

5962
static HeapTuple CatalogIndexFetchTuple(Relation heapRelation,
6063
Relation idesc,

‎src/backend/commands/creatinh.c

Lines changed: 49 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
*
88
*
99
* IDENTIFICATION
10-
* $Header: /cvsroot/pgsql/src/backend/commands/Attic/creatinh.c,v 1.48 1999/10/03 23:55:27 tgl Exp $
10+
* $Header: /cvsroot/pgsql/src/backend/commands/Attic/creatinh.c,v 1.49 1999/10/15 01:49:39 momjian Exp $
1111
*
1212
*-------------------------------------------------------------------------
1313
*/
@@ -16,10 +16,12 @@
1616

1717
#include "access/heapam.h"
1818
#include "catalog/catname.h"
19+
#include "catalog/indexing.h"
1920
#include "catalog/heap.h"
2021
#include "catalog/pg_inherits.h"
2122
#include "catalog/pg_ipl.h"
2223
#include "catalog/pg_type.h"
24+
#include "catalog/pg_description.h"
2325
#include "commands/creatinh.h"
2426
#include "utils/syscache.h"
2527

@@ -232,6 +234,52 @@ TruncateRelation(char *name)
232234
heap_truncate(name);
233235
}
234236

237+
/*------------------------------------------------------------------
238+
* CommentRelation --
239+
* Adds a comment to pg_description for the associated
240+
* relation or relation attribute.
241+
*
242+
* Note:
243+
* The comment is dropped on the relation or attribute if
244+
* the comment is an empty string.
245+
*------------------------------------------------------------------
246+
*/
247+
void
248+
CommentRelation(char *relname, char *attrname, char *comments)
249+
{
250+
251+
Relation relation;
252+
HeapTuple attrtuple;
253+
Oid oid;
254+
255+
/*** First ensure relname is valid ***/
256+
257+
relation = heap_openr(relname, AccessShareLock);
258+
259+
/*** Now, if an attribute was specified, fetch its oid, else use relation's oid ***/
260+
261+
if (attrname != NULL) {
262+
attrtuple = SearchSysCacheTuple(ATTNAME, ObjectIdGetDatum(relation->rd_id),
263+
PointerGetDatum(attrname), 0, 0);
264+
if (!HeapTupleIsValid(attrtuple)) {
265+
elog(ERROR, "CommentRelation: attribute \"%s\" is not an attribute of relation \"%s\"",
266+
attrname, relname);
267+
}
268+
oid = attrtuple->t_data->t_oid;
269+
} else {
270+
oid = RelationGetRelid(relation);
271+
}
272+
273+
/*** Call CreateComments() to create/drop the comments ***/
274+
275+
CreateComments(oid, comments);
276+
277+
/*** Now, close the heap relation ***/
278+
279+
heap_close(relation, AccessShareLock);
280+
281+
}
282+
235283
/*
236284
* MergeAttributes
237285
* Returns new schema given initial schema and supers.

‎src/backend/parser/gram.y

Lines changed: 32 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -10,7 +10,7 @@
1010
*
1111
*
1212
* IDENTIFICATION
13-
* $Header: /cvsroot/pgsql/src/backend/parser/gram.y,v 2.108 1999/10/07 04:23:12 tgl Exp $
13+
* $Header: /cvsroot/pgsql/src/backend/parser/gram.y,v 2.109 1999/10/15 01:49:41 momjian Exp $
1414
*
1515
* HISTORY
1616
* AUTHOR DATE MAJOR EVENT
@@ -118,7 +118,7 @@ Oid param_type(int t); /* used in parse_expr.c */
118118
%type <node> stmt,
119119
AddAttrStmt, ClosePortalStmt,
120120
CopyStmt, CreateStmt, CreateAsStmt, CreateSeqStmt, DefineStmt, DestroyStmt,
121-
TruncateStmt,
121+
TruncateStmt, CommentStmt,
122122
ExtendStmt, FetchStmt, GrantStmt, CreateTrigStmt, DropTrigStmt,
123123
CreatePLangStmt, DropPLangStmt,
124124
IndexStmt, ListenStmt, UnlistenStmt, LockStmt, OptimizableStmt,
@@ -314,7 +314,7 @@ Oid param_type(int t); /* used in parse_expr.c */
314314
*/
315315
%token ABORT_TRANS, ACCESS, AFTER, AGGREGATE, ANALYZE,
316316
BACKWARD, BEFORE, BINARY,
317-
CACHE, CLUSTER, COPY, CREATEDB, CREATEUSER, CYCLE,
317+
CACHE, CLUSTER, COMMENT, COPY, CREATEDB, CREATEUSER, CYCLE,
318318
DATABASE, DELIMITERS, DO,
319319
EACH, ENCODING, EXCLUSIVE, EXPLAIN, EXTEND,
320320
FORWARD, FUNCTION, HANDLER,
@@ -402,6 +402,7 @@ stmt : AddAttrStmt
402402
| DefineStmt
403403
| DestroyStmt
404404
| TruncateStmt
405+
| CommentStmt
405406
| DropPLangStmt
406407
| DropTrigStmt
407408
| DropUserStmt
@@ -1539,6 +1540,32 @@ TruncateStmt: TRUNCATE TABLE relation_name
15391540
}
15401541
;
15411542

1543+
/*****************************************************************************
1544+
*
1545+
* QUERY:
1546+
* comment on [ table <relname> | column <relname>.<attribute> ]
1547+
* is 'text'
1548+
*
1549+
*****************************************************************************/
1550+
1551+
CommentStmt: COMMENT ON COLUMN relation_name '.' attr_name IS Sconst
1552+
{
1553+
CommentStmt *n = makeNode(CommentStmt);
1554+
n->relname = $4;
1555+
n->attrname = $6;
1556+
n->comment = $8;
1557+
$$ = (Node *) n;
1558+
}
1559+
| COMMENT ON TABLE relation_name IS Sconst
1560+
{
1561+
CommentStmt *n = makeNode(CommentStmt);
1562+
n->relname = $4;
1563+
n->attrname = NULL;
1564+
n->comment = $6;
1565+
$$ = (Node *) n;
1566+
}
1567+
;
1568+
15421569
/*****************************************************************************
15431570
*
15441571
* QUERY:
@@ -5011,6 +5038,7 @@ ColId: IDENT { $$ = $1; }
50115038
| BACKWARD { $$ = "backward"; }
50125039
| BEFORE { $$ = "before"; }
50135040
| CACHE { $$ = "cache"; }
5041+
| COMMENT { $$ = "comment"; }
50145042
| COMMITTED { $$ = "committed"; }
50155043
| CONSTRAINTS { $$ = "constraints"; }
50165044
| CREATEDB { $$ = "createdb"; }
@@ -5081,6 +5109,7 @@ ColId: IDENT { $$ = $1; }
50815109
| TIMEZONE_HOUR { $$ = "timezone_hour"; }
50825110
| TIMEZONE_MINUTE { $$ = "timezone_minute"; }
50835111
| TRIGGER { $$ = "trigger"; }
5112+
| TRUNCATE { $$ = "truncate"; }
50845113
| TRUSTED { $$ = "trusted"; }
50855114
| TYPE_P { $$ = "type"; }
50865115
| VALID { $$ = "valid"; }

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