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-rw-r--r--src/backend/rewrite/rewriteDefine.c255
1 files changed, 255 insertions, 0 deletions
diff --git a/src/backend/rewrite/rewriteDefine.c b/src/backend/rewrite/rewriteDefine.c
new file mode 100644
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+++ b/src/backend/rewrite/rewriteDefine.c
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+/*-------------------------------------------------------------------------
+ *
+ * rewriteDefine.c--
+ * routines for defining a rewrite rule
+ *
+ * Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ * $Header: /cvsroot/pgsql/src/backend/rewrite/rewriteDefine.c,v 1.1.1.1 1996/07/09 06:21:51 scrappy Exp $
+ *
+ *-------------------------------------------------------------------------
+ */
+#include <stdio.h>
+#include <string.h>
+#include "postgres.h"
+
+#include "utils/rel.h" /* for Relation stuff */
+#include "access/heapam.h" /* access methods like amopenr */
+#include "utils/builtins.h"
+#include "utils/elog.h" /* for elog */
+#include "utils/palloc.h"
+#include "utils/lsyscache.h" /* for get_typlen */
+#include "nodes/pg_list.h" /* for Lisp support */
+#include "nodes/parsenodes.h"
+#include "parser/catalog_utils.h"
+#include "rewrite/locks.h"
+#include "rewrite/rewriteRemove.h"
+#include "rewrite/rewriteSupport.h"
+#include "tcop/tcopprot.h"
+
+Oid LastOidProcessed = InvalidOid;
+
+/*
+ * This is too small for many rule plans, but it'll have to do for now.
+ * Rule plans, etc will eventually have to be large objects.
+ *
+ * should this be smaller?
+ */
+#define RULE_PLAN_SIZE 8192
+
+static void
+strcpyq(char *dest, char *source)
+{
+ char *current=source,*destp= dest;
+
+ for(current=source; *current; current++) {
+ if (*current == '\"') {
+ *destp = '\\';
+ destp++;
+ }
+ *destp = *current;
+ destp++;
+ }
+ *destp = '\0';
+}
+
+/*
+ * InsertRule -
+ * takes the arguments and inserts them as attributes into the system
+ * relation "pg_rewrite"
+ *
+ * MODS : changes the value of LastOidProcessed as a side
+ * effect of inserting the rule tuple
+ *
+ * ARGS : rulname - name of the rule
+ * evtype - one of RETRIEVE,REPLACE,DELETE,APPEND
+ * evobj - name of relation
+ * evslot - comma delimited list of slots
+ * if null => multi-attr rule
+ * evinstead - is an instead rule
+ * actiontree - parsetree(s) of rule action
+ */
+static Oid
+InsertRule(char *rulname,
+ int evtype,
+ char *evobj,
+ char *evslot,
+ char *evqual,
+ bool evinstead,
+ char *actiontree)
+{
+ static char rulebuf[RULE_PLAN_SIZE];
+ static char actionbuf[RULE_PLAN_SIZE];
+ static char qualbuf[RULE_PLAN_SIZE];
+ Oid eventrel_oid = InvalidOid;
+ AttrNumber evslot_index = InvalidAttrNumber;
+ Relation eventrel = NULL;
+ char *is_instead = "f";
+ extern void eval_as_new_xact();
+ char *template;
+
+ eventrel = heap_openr(evobj);
+ if (eventrel == NULL) {
+ elog(WARN, "rules cannot be defined on relations not in schema");
+ }
+ eventrel_oid = RelationGetRelationId(eventrel);
+
+ /*
+ * if the slotname is null, we know that this is a multi-attr
+ * rule
+ */
+ if (evslot == NULL)
+ evslot_index = -1;
+ else
+ evslot_index = varattno(eventrel, (char*)evslot);
+ heap_close(eventrel);
+
+ if (evinstead)
+ is_instead = "t";
+
+ if (evqual == NULL)
+ evqual = "nil";
+
+ if (IsDefinedRewriteRule(rulname))
+ elog(WARN, "Attempt to insert rule '%s' failed: already exists",
+ rulname);
+ strcpyq(actionbuf,actiontree);
+ strcpyq(qualbuf, evqual);
+
+ template = "INSERT INTO pg_rewrite \
+(rulename, ev_type, ev_class, ev_attr, action, ev_qual, is_instead) VALUES \
+('%s', %d::char, %d::oid, %d::int2, '%s'::text, '%s'::text, \
+ '%s'::bool);";
+ if (strlen(template) + strlen(rulname) + strlen(actionbuf) +
+ strlen(qualbuf) + 20 /* fudge fac */ > RULE_PLAN_SIZE) {
+ elog(WARN, "DefineQueryRewrite: rule plan string too big.");
+ }
+ sprintf(rulebuf, template,
+ rulname, evtype, eventrel_oid, evslot_index, actionbuf,
+ qualbuf, is_instead);
+
+ pg_eval(rulebuf, (char **) NULL, (Oid *) NULL, 0);
+
+ return (LastOidProcessed);
+}
+
+/*
+ * for now, event_object must be a single attribute
+ */
+static void
+ValidateRule(int event_type,
+ char *eobj_string,
+ char *eslot_string,
+ Node *event_qual,
+ List **action,
+ int is_instead,
+ Oid event_attype)
+{
+ if (((event_type == CMD_INSERT) || (event_type == CMD_DELETE)) &&
+ eslot_string) {
+ elog(WARN,
+ "rules not allowed for insert or delete events to an attribute");
+ }
+
+ if (event_qual && !*action && is_instead)
+ elog(WARN,
+ "event_quals on 'instead nothing' rules not currently supported");
+
+#if 0
+ /* on retrieve to class.attribute do instead nothing is converted
+ * to 'on retrieve to class.attribute do instead
+ * retrieve (attribute = NULL)'
+ * --- this is also a terrible hack that works well -- glass*/
+ if (is_instead && !*action && eslot_string && event_type == CMD_SELECT) {
+ char *temp_buffer = (char *) palloc(strlen(template)+80);
+ sprintf(temp_buffer, template, event_attype,
+ get_typlen(event_attype), eslot_string,
+ event_attype);
+
+ *action = (List*) stringToNode(temp_buffer);
+
+ pfree(temp_buffer);
+ }
+#endif
+}
+
+void
+DefineQueryRewrite(RuleStmt *stmt)
+{
+ CmdType event_type = stmt->event;
+ Attr *event_obj = stmt->object;
+ Node *event_qual = stmt->whereClause;
+ bool is_instead = stmt->instead;
+ List *action = stmt->actions;
+ Relation event_relation = NULL ;
+ Oid ruleId;
+ Oid ev_relid = 0;
+ char *eslot_string = NULL;
+ int event_attno = 0;
+ Oid event_attype = 0;
+ char *actionP, *event_qualP;
+
+ extern Oid att_typeid();
+
+ if (event_obj->attrs)
+ eslot_string = strVal(lfirst(event_obj->attrs));
+ else
+ eslot_string = NULL;
+
+ event_relation = heap_openr(event_obj->relname);
+ if ( event_relation == NULL ) {
+ elog(WARN, "virtual relations not supported yet");
+ }
+ ev_relid = RelationGetRelationId(event_relation);
+
+ if (eslot_string == NULL) {
+ event_attno = -1;
+ event_attype = -1; /* XXX - don't care */
+ } else {
+ event_attno = varattno(event_relation, eslot_string);
+ event_attype = att_typeid(event_relation,event_attno);
+ }
+ heap_close(event_relation);
+
+ /* fix bug about instead nothing */
+ ValidateRule(event_type, event_obj->relname,
+ eslot_string, event_qual, &action,
+ is_instead,event_attype);
+
+ if (action == NULL) {
+ if (!is_instead) return; /* doesn't do anything */
+
+ event_qualP = nodeToString(event_qual);
+
+ ruleId = InsertRule(stmt->rulename,
+ event_type,
+ event_obj->relname,
+ eslot_string,
+ event_qualP,
+ true,
+ "nil");
+ prs2_addToRelation(ev_relid, ruleId, event_type, event_attno, TRUE,
+ event_qual, NIL);
+
+ } else {
+ event_qualP = nodeToString(event_qual);
+ actionP = nodeToString(action);
+
+ ruleId = InsertRule(stmt->rulename,
+ event_type,
+ event_obj->relname,
+ eslot_string,
+ event_qualP,
+ is_instead,
+ actionP);
+
+ /* what is the max size of type text? XXX -- glass */
+ if (length(action) > 15 )
+ elog(WARN,"max # of actions exceeded");
+ prs2_addToRelation(ev_relid, ruleId, event_type, event_attno,
+ is_instead, event_qual, action);
+ }
+}
+
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