Postgres95 1.01 Distribution - Virgin SourcesPG95-1_01

1 files changed, 181 insertions, 0 deletions

diff --git a/src/backend/rewrite/rewriteRemove.c b/src/backend/rewrite/rewriteRemove.c
new file mode 100644
index 00000000000..9146d137c13
--- /dev/null
+++ b/src/backend/rewrite/rewriteRemove.c
@@ -0,0 +1,181 @@
+/*-------------------------------------------------------------------------
+ *
+ * rewriteRemove.c--
+ *    routines for removing rewrite rules
+ *
+ * Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *    $Header: /cvsroot/pgsql/src/backend/rewrite/rewriteRemove.c,v 1.1.1.1 1996/07/09 06:21:52 scrappy Exp $
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "access/skey.h"
+#include "catalog/pg_rewrite.h"
+#include "catalog/catname.h"	/* for RewriteRelationName */
+#include "utils/syscache.h"
+#include "utils/elog.h"		/* for elog stuff */
+#include "utils/palloc.h"
+#include "utils/tqual.h"	/* 'NowTimeQual' defined here.. */
+#include "access/heapam.h"	/* heap AM calls defined here */
+#include "fmgr.h"		/* for CHAR_16_EQ */
+
+#include "rewrite/rewriteRemove.h"	/* where the decls go */
+#include "rewrite/rewriteSupport.h"
+
+/*-----------------------------------------------------------------------
+ * RewriteGetRuleEventRel
+ *-----------------------------------------------------------------------
+ */
+char*
+RewriteGetRuleEventRel(char *rulename)
+{
+    HeapTuple htp;
+    Oid eventrel;
+    
+    htp = SearchSysCacheTuple(REWRITENAME, PointerGetDatum(rulename),
+			      0,0,0);
+    if (!HeapTupleIsValid(htp))
+	elog(WARN, "RewriteGetRuleEventRel: rule \"%s\" not found",
+	     rulename);
+    eventrel = ((Form_pg_rewrite) GETSTRUCT(htp))->ev_class;
+    htp = SearchSysCacheTuple(RELOID, PointerGetDatum(eventrel), 
+			      0,0,0);
+    if (!HeapTupleIsValid(htp))
+	elog(WARN, "RewriteGetRuleEventRel: class %d not found",
+	     eventrel);
+    return ((Form_pg_class) GETSTRUCT(htp))->relname.data;
+}
+
+/* ----------------------------------------------------------------
+ *
+ * RemoveRewriteRule
+ *
+ * Delete a rule given its rulename.
+ *
+ * There are three steps.
+ *   1) Find the corresponding tuple in 'pg_rewrite' relation.
+ *      Find the rule Id (i.e. the Oid of the tuple) and finally delete
+ *      the tuple.
+ *   3) Delete the locks from the 'pg_class' relation.
+ *
+ *
+ * ----------------------------------------------------------------
+ */
+void
+RemoveRewriteRule(char *ruleName)
+{
+    Relation RewriteRelation	= NULL;
+    HeapScanDesc scanDesc	= NULL;
+    ScanKeyData scanKeyData;
+    HeapTuple tuple		= NULL;
+    Oid ruleId			= (Oid)0;
+    Oid eventRelationOid	= (Oid)NULL;
+    Datum eventRelationOidDatum	= (Datum)NULL;
+    Buffer buffer		= (Buffer)NULL;
+    bool isNull		= false;
+
+    /*
+     * Open the pg_rewrite relation. 
+     */
+    RewriteRelation = heap_openr(RewriteRelationName);
+    
+    /*
+     * Scan the RuleRelation ('pg_rewrite') until we find a tuple
+     */
+    ScanKeyEntryInitialize(&scanKeyData, 0, Anum_pg_rewrite_rulename,
+			   F_CHAR16EQ, NameGetDatum(ruleName));
+    scanDesc = heap_beginscan(RewriteRelation,
+			      0, NowTimeQual, 1, &scanKeyData);
+    
+    tuple = heap_getnext(scanDesc, 0, (Buffer *)NULL);
+    
+    /*
+     * complain if no rule with such name existed
+     */
+    if (!HeapTupleIsValid(tuple)) {
+	heap_close(RewriteRelation);
+	elog(WARN, "No rule with name = '%s' was found.\n", ruleName);
+    }
+    
+    /*
+     * Store the OID of the rule (i.e. the tuple's OID)
+     * and the event relation's OID
+     */
+    ruleId = tuple->t_oid;
+    eventRelationOidDatum =
+	PointerGetDatum(heap_getattr(tuple,
+				     buffer,
+				     Anum_pg_rewrite_ev_class,
+		     RelationGetTupleDescriptor(RewriteRelation),
+				     &isNull));
+    if (isNull) {
+	/* XXX strange!!! */
+	elog(WARN, "RemoveRewriteRule: null event target relation!");
+    }
+    eventRelationOid = DatumGetObjectId(eventRelationOidDatum);
+    
+    /*
+     * Now delete the relation level locks from the updated relation.
+     * (Make sure we do this before we remove the rule from pg_rewrite.
+     * Otherwise, heap_openr on eventRelationOid which reads pg_rwrite
+     * for the rules will fail.)
+     */
+    prs2_deleteFromRelation(eventRelationOid, ruleId);
+
+    /*
+     * Now delete the tuple...
+     */
+    heap_delete(RewriteRelation, &(tuple->t_ctid));
+    heap_close(RewriteRelation);
+    heap_endscan(scanDesc);
+}
+
+/*
+ * RelationRemoveRules -
+ *    removes all rules associated with the relation when the relation is
+ *    being removed.
+ */
+void
+RelationRemoveRules(Oid relid)
+{
+    Relation RewriteRelation	= NULL;
+    HeapScanDesc scanDesc	= NULL;
+    ScanKeyData scanKeyData;
+    HeapTuple tuple		= NULL;
+
+    /*
+     * Open the pg_rewrite relation. 
+     */
+    RewriteRelation = heap_openr(RewriteRelationName);
+    
+    /*
+     * Scan the RuleRelation ('pg_rewrite') for all the tuples that
+     * has the same ev_class as relid (the relation to be removed).
+     */
+    ScanKeyEntryInitialize(&scanKeyData,
+			   0,
+			   Anum_pg_rewrite_ev_class,
+			   F_OIDEQ,
+			   ObjectIdGetDatum(relid));
+    scanDesc = heap_beginscan(RewriteRelation,
+			      0, NowTimeQual, 1, &scanKeyData);
+
+    for(;;) {
+	tuple = heap_getnext(scanDesc, 0, (Buffer *)NULL);
+    
+	if (!HeapTupleIsValid(tuple)) {
+	    break; /* we're done */
+	}
+    
+	/*
+	 * delete the tuple...
+	 */
+	heap_delete(RewriteRelation, &(tuple->t_ctid));
+    }
+
+    heap_endscan(scanDesc);
+    heap_close(RewriteRelation);
+}
+