Report all dependent objects to the server log when a shared object is dropped,

and only a truncated log of the objects in the current database to the client.
Also, instead of reporting object counts for all databases on which the user
might own objects, report only as many as fit in the predefined line count.

This is to avoid flooding the client when the user owns too many objects,
which could cause problems.

Per report from Ed L. on April 4th and subsequent discussion.

src/backend/catalog/pg_shdepend.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/catalog/pg_shdepend.c,v 1.18 2007/05/11 17:57:12 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/catalog/pg_shdepend.c,v 1.19 2007/05/14 16:50:36 alvherre Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -456,6 +456,9 @@ typedef struct
  * Check whether there are shared dependency entries for a given shared
  * object.	Returns a string containing a newline-separated list of object
  * descriptions that depend on the shared object, or NULL if none is found.
+ * The size of the returned string is limited to about MAX_REPORTED_DEPS lines;
+ * if there are more objects than that, the output is returned truncated at
+ * that point and the full message is logged to the postmaster log.
  *
  * We can find three different kinds of dependencies: dependencies on objects
  * of the current database; dependencies on shared objects; and dependencies
@@ -472,21 +475,26 @@ checkSharedDependencies(Oid classId, Oid objectId)
 	ScanKeyData key[2];
 	SysScanDesc scan;
 	HeapTuple	tup;
-	int			totalDeps = 0;
-	int			numLocalDeps = 0;
-	int			numSharedDeps = 0;
+	int			numNotReportedDeps = 0;
+	int			numReportedDeps = 0;
+	int			numNotReportedDbs = 0;
 	List	   *remDeps = NIL;
 	ListCell   *cell;
 	ObjectAddress object;
 	StringInfoData descs;
+	StringInfoData alldescs;
 
 	/*
-	 * We try to limit the number of reported dependencies to something sane,
-	 * both for the user's sake and to avoid blowing out memory.
+	 * We try to limit the number of dependencies reported to the client to
+	 * something sane, both for the user's sake and to avoid blowing out
+	 * memory.  The server log always gets a full report, which is collected
+	 * in a separate StringInfo if and only if we detect that the original
+	 * report is going to be truncated.
 	 */
 #define MAX_REPORTED_DEPS 100
 
 	initStringInfo(&descs);
+	initStringInfo(&alldescs);
 
 	sdepRel = heap_open(SharedDependRelationId, AccessShareLock);
 
@@ -531,17 +539,35 @@ checkSharedDependencies(Oid classId, Oid objectId)
 		 */
 		if (sdepForm->dbid == MyDatabaseId)
 		{
-			numLocalDeps++;
-			if (++totalDeps <= MAX_REPORTED_DEPS)
+			if (++numReportedDeps <= MAX_REPORTED_DEPS)
 				storeObjectDescription(&descs, LOCAL_OBJECT, &object,
 									   sdepForm->deptype, 0);
+			else
+			{
+				numNotReportedDeps++;
+				/* initialize the server-only log line */
+				if (alldescs.len == 0)
+					appendBinaryStringInfo(&alldescs, descs.data, descs.len);
+
+				storeObjectDescription(&alldescs, LOCAL_OBJECT, &object,
+									   sdepForm->deptype, 0);
+			}
 		}
 		else if (sdepForm->dbid == InvalidOid)
 		{
-			numSharedDeps++;
-			if (++totalDeps <= MAX_REPORTED_DEPS)
+			if (++numReportedDeps <= MAX_REPORTED_DEPS)
 				storeObjectDescription(&descs, SHARED_OBJECT, &object,
 									   sdepForm->deptype, 0);
+			else
+			{
+				numNotReportedDeps++;
+				/* initialize the server-only log line */
+				if (alldescs.len == 0)
+					appendBinaryStringInfo(&alldescs, descs.data, descs.len);
+
+				storeObjectDescription(&alldescs, SHARED_OBJECT, &object,
+									   sdepForm->deptype, 0);
+			}
 		}
 		else
 		{
@@ -571,7 +597,6 @@ checkSharedDependencies(Oid classId, Oid objectId)
 				dep->dbOid = sdepForm->dbid;
 				dep->count = 1;
 				remDeps = lappend(remDeps, dep);
-				totalDeps++;
 			}
 		}
 	}
@@ -580,28 +605,11 @@ checkSharedDependencies(Oid classId, Oid objectId)
 
 	heap_close(sdepRel, AccessShareLock);
 
-	if (totalDeps > MAX_REPORTED_DEPS)
-	{
-		/*
-		 * Report seems unreasonably long, so reduce it to per-database info
-		 *
-		 * Note: we don't ever suppress per-database totals, which should be
-		 * OK as long as there aren't too many databases ...
-		 */
-		resetStringInfo(&descs);
-
-		if (numLocalDeps > 0)
-		{
-			appendStringInfo(&descs, _("%d objects in this database"),
-							 numLocalDeps);
-			if (numSharedDeps > 0)
-				appendStringInfoChar(&descs, '\n');
-		}
-		if (numSharedDeps > 0)
-			appendStringInfo(&descs, _("%d shared objects"),
-							 numSharedDeps);
-	}
-
+	/*
+	 * Report dependencies on remote databases.  If we're truncating the
+	 * output already, don't put a line per database, but a single one for all
+	 * of them.  Otherwise add as many as fit in MAX_REPORTED_DEPS.
+	 */
 	foreach(cell, remDeps)
 	{
 		remoteDep  *dep = lfirst(cell);
@@ -610,8 +618,35 @@ checkSharedDependencies(Oid classId, Oid objectId)
 		object.objectId = dep->dbOid;
 		object.objectSubId = 0;
 
-		storeObjectDescription(&descs, REMOTE_OBJECT, &object,
-							   SHARED_DEPENDENCY_INVALID, dep->count);
+		if (alldescs.len != 0)
+		{
+			numNotReportedDbs++;
+			storeObjectDescription(&alldescs, REMOTE_OBJECT, &object,
+								   SHARED_DEPENDENCY_INVALID, dep->count);
+		}
+		else
+		{
+			if (numReportedDeps <= MAX_REPORTED_DEPS)
+			{
+				numReportedDeps++;
+				storeObjectDescription(&descs, REMOTE_OBJECT, &object,
+									   SHARED_DEPENDENCY_INVALID, dep->count);
+			}
+			else
+			{
+				/* initialize the server-only log line */
+				numNotReportedDbs++;
+				appendBinaryStringInfo(&alldescs, descs.data, descs.len);
+				storeObjectDescription(&alldescs, REMOTE_OBJECT, &object,
+									   SHARED_DEPENDENCY_INVALID, dep->count);
+			}
+		}
+	}
+
+	if (numNotReportedDbs > 0)
+	{
+		appendStringInfo(&descs, "\nand objects in other %d databases",
+						 numNotReportedDbs);
 	}
 
 	list_free_deep(remDeps);
@@ -619,9 +654,27 @@ checkSharedDependencies(Oid classId, Oid objectId)
 	if (descs.len == 0)
 	{
 		pfree(descs.data);
+		pfree(alldescs.data);
 		return NULL;
 	}
 
+	if (numNotReportedDbs + numNotReportedDeps > 0)
+	{
+		ObjectAddress	obj;
+
+		obj.classId = classId;
+		obj.objectId = objectId;
+		obj.objectSubId = 0;
+		ereport(LOG,
+				(errmsg("objects dependent on %s", getObjectDescription(&obj)),
+				 errdetail(alldescs.data)));
+
+		if (numNotReportedDeps > 0)
+			appendStringInfo(&descs, "\nand other %d objects",
+							 numNotReportedDeps);
+	}
+	pfree(alldescs.data);
+
 	return descs.data;
 }
 
@@ -977,8 +1030,12 @@ storeObjectDescription(StringInfo descs, objectType type,
 			break;
 
 		case REMOTE_OBJECT:
-			/* translator: %s will always be "database %s" */
-			appendStringInfo(descs, _("%d objects in %s"), count, objdesc);
+			if (count == 1)
+				/* translator: %s will always be "database %s" */
+				appendStringInfo(descs, _("one object in %s"), objdesc);
+			else
+				/* translator: %s will always be "database %s" */
+				appendStringInfo(descs, _("%d objects in %s"), count, objdesc);
 			break;
 
 		default: