vacuumlo deals with large objects not referenced by any tables and removes them.

contrib/vacuumlo/Makefile

+# $Header: /cvsroot/pgsql/contrib/vacuumlo/Makefile,v 1.1 1999/04/10 16:48:04 peter Exp $
+
+SRCDIR= ../../src
+
+include $(SRCDIR)/Makefile.global
+
+CONTRIBDIR=$(LIBDIR)/contrib
+
+CFLAGS+= -I$(HEADERDIR)
+
+TARGETS= vacuumlo
+CLEANFILES+= $(TARGETS)
+CURDIR=`pwd`
+
+all:: $(TARGETS)
+
+$(TARGETS): vacuumlo.o
+	$(CC) -o vacuumlo -L $(LIBDIR) -lpq -lcrypt vacuumlo.o
+
+clean: 
+	rm -f $(TARGETS) *.o
+
+dist:
+	tar cf vacuumlo.tar README Makefile vacuumlo.c

contrib/vacuumlo/README

+$Header: /cvsroot/pgsql/contrib/vacuumlo/Attic/README,v 1.1 1999/04/10 16:48:04 peter Exp $
+
+This is a simple utility that will remove any orphaned large objects out of a
+PostgreSQL database.
+
+Compiling
+--------
+
+Simply run make. A single executable "vacuumlo" is created.
+
+Useage
+------
+
+vacuumlo [-v] database [db2 ... dbn]
+
+The -v flag outputs some progress messages to stdout.
+
+Method
+------
+
+First, it builds a temporary table which contains all of the oid's of the
+large objects in that database.
+
+It then scans through any columns in the database that are of type 'oid', and
+removes any entries from the temporary table.
+
+Finally, it runs through the first table, and removes from the second table, any
+oid's it finds. What is left are the orphans, and these are removed.
+
+I decided to place this in contrib as it needs further testing, but hopefully,
+this (or a variant of it) would make it into the backed as a "vacuum lo" command
+in a later release.
+
+Peter Mount <peter@retep.org.uk>
+http://www.retep.org.uk
+March 21 1999
+
+Committed April 10 1999 Peter

contrib/vacuumlo/vacuumlo.c

+/*-------------------------------------------------------------------------
+ *
+ * vacuumlo.c
+ *	  This removes orphaned large objects from a database.
+ *
+ * Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *	  $Header: /cvsroot/pgsql/contrib/vacuumlo/vacuumlo.c,v 1.1 1999/04/10 16:48:05 peter Exp $
+ *
+ *-------------------------------------------------------------------------
+ */
+#include <stdio.h>
+#include <stdlib.h>
+#include <strings.h>
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+
+#include "libpq-fe.h"
+#include "libpq/libpq-fs.h"
+
+#define BUFSIZE			1024
+
+int vacuumlo(char *,int);
+
+
+/*
+ * This vacuums a database. It returns 1 on success, -1 on failure.
+ */
+int vacuumlo(char *database,int verbose)
+{
+    PGconn     *conn;
+    PGresult   *res, *res2;
+    char buf[BUFSIZE];
+    int matched=0;	/* Number matched per scan */
+    int i;
+    
+    conn = PQsetdb(NULL, NULL, NULL, NULL, database);
+    
+    /* check to see that the backend connection was successfully made */
+    if (PQstatus(conn) == CONNECTION_BAD)
+	{
+	    fprintf(stderr, "Connection to database '%s' failed.\n", database);
+	    fprintf(stderr, "%s", PQerrorMessage(conn));
+	    return -1;
+	}
+    
+    if(verbose)
+	fprintf(stdout,"Connected to %s\n",database);
+    
+    /*
+     * First we create and populate the lo temp table
+     */
+    buf[0]='\0';
+    strcat(buf,"SELECT oid AS lo ");
+    strcat(buf,"INTO TEMP TABLE vacuum_l ");
+    strcat(buf,"FROM pg_class ");
+    strcat(buf,"WHERE relkind='l'");
+    if(!(res = PQexec(conn,buf))) {
+	fprintf(stderr,"Failed to create temp table.\n");
+	PQfinish(conn);
+	return -1;
+    }
+    PQclear(res);
+    
+    /*
+     * Now find any candidate tables who have columns of type oid (the column
+     * oid is ignored, as it has attnum < 1)
+     */
+    buf[0]='\0';
+    strcat(buf,"SELECT c.relname, a.attname ");
+    strcat(buf,"FROM pg_class c, pg_attribute a, pg_type t ");
+    strcat(buf,"WHERE a.attnum > 0 ");
+    strcat(buf,"      AND a.attrelid = c.oid ");
+    strcat(buf,"      AND a.atttypid = t.oid ");
+    strcat(buf,"      AND t.typname = 'oid' ");
+    strcat(buf,"      AND c.relname NOT LIKE 'pg_%'");
+    if(!(res = PQexec(conn,buf))) {
+	fprintf(stderr,"Failed to create temp table.\n");
+	PQfinish(conn);
+	return -1;
+    }
+    for(i=0;i<PQntuples(res);i++)
+	{
+	    char *table,*field;
+	    
+	    table = PQgetvalue(res,i,0);
+	    field = PQgetvalue(res,i,1);
+	    
+	    if(verbose) {
+		fprintf(stdout,"Checking %s in %s: ",field,table);
+		fflush(stdout);
+	    }
+	    
+	    res2 = PQexec(conn, "begin");
+	    PQclear(res2);
+	    
+	    buf[0] = '\0';
+	    strcat(buf,"DELETE FROM vacuum_l ");
+	    strcat(buf,"WHERE lo IN (");
+	    strcat(buf,"SELECT ");
+	    strcat(buf,field);
+	    strcat(buf," FROM ");
+	    strcat(buf,table);
+	    strcat(buf,");");
+	    if(!(res2 = PQexec(conn,buf))) {
+		fprintf(stderr,"Failed to check %s in table %s\n",field,table);
+		PQclear(res);
+		PQfinish(conn);
+		return -1;
+	    }
+	    if(PQresultStatus(res2)!=PGRES_COMMAND_OK) {
+		fprintf(stderr,
+			"Failed to check %s in table %s\n%s\n",
+			field,table,
+			PQerrorMessage(conn)
+			);
+		PQclear(res2);
+		PQclear(res);
+		PQfinish(conn);
+		return -1;
+	    }
+	    PQclear(res2);
+
+	    res2 = PQexec(conn, "end");
+	    PQclear(res2);
+	    
+	}
+    PQclear(res);
+    
+    /* Start the transaction */
+    res = PQexec(conn, "begin");
+    PQclear(res);
+    
+    /*
+     * Finally, those entries remaining in vacuum_l are orphans.
+     */
+    buf[0]='\0';
+    strcat(buf,"SELECT lo ");
+    strcat(buf,"FROM vacuum_l");
+    if(!(res = PQexec(conn,buf))) {
+	fprintf(stderr,"Failed to read temp table.\n");
+	PQfinish(conn);
+	return -1;
+    }
+    matched=PQntuples(res);
+    for(i=0;i<matched;i++)
+	{
+	    Oid lo = (Oid) atoi(PQgetvalue(res,i,0));
+	    
+	    if(verbose) {
+		fprintf(stdout,"\rRemoving lo %6d \n",lo);
+		fflush(stdout);
+	    }
+	    
+	    if(lo_unlink(conn,lo)<0) {
+		fprintf(stderr,"Failed to remove lo %d\n",lo);
+	    }
+	}
+    PQclear(res);
+    
+    /*
+     * That's all folks!
+     */
+    res = PQexec(conn, "end");
+    PQclear(res);
+    PQfinish(conn);
+    
+    if(verbose)
+	fprintf(stdout,"\rRemoved %d large objects from %s.\n",matched,database);
+    
+    return 0;
+}
+
+int
+main(int argc, char **argv)
+{
+    int verbose = 0;
+    int arg;
+    int rc=0;
+    
+    if (argc < 2)
+	{
+	    fprintf(stderr, "Usage: %s [-v] database_name [db2 ... dbn]\n",
+		    argv[0]);
+	    exit(1);
+	}
+    
+    for(arg=1;arg<argc;arg++) {
+	if(strcmp("-v",argv[arg])==0)
+	    verbose=!verbose;
+	else
+	    rc += vacuumlo(argv[arg],verbose);
+    }
+    
+    return rc;
+}