vacuumlo.c

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/*-------------------------------------------------------------------------
 *
 * vacuumlo.c
 *    This removes orphaned large objects from a database.
 *
 * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *    contrib/vacuumlo/vacuumlo.c
 *
 *-------------------------------------------------------------------------
 */
#include "postgres_fe.h"

#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#ifdef HAVE_TERMIOS_H
#include <termios.h>
#endif

#include "catalog/pg_class_d.h"
#include "common/connect.h"
#include "common/logging.h"
#include "common/string.h"
#include "getopt_long.h"
#include "libpq-fe.h"
#include "pg_getopt.h"

#define BUFSIZE         1024

enum trivalue
{
    TRI_DEFAULT,
    TRI_NO,
    TRI_YES
};

struct _param
{
    char       *pg_user;
    enum trivalue pg_prompt;
    char       *pg_port;
    char       *pg_host;
    const char *progname;
    int         verbose;
    int         dry_run;
    long        transaction_limit;
};

static int  vacuumlo(const char *database, const struct _param *param);
static void usage(const char *progname);



/*
 * This vacuums LOs of one database. It returns 0 on success, -1 on failure.
 */
static int
vacuumlo(const char *database, const struct _param *param)
{
    PGconn     *conn;
    PGresult   *res,
               *res2;
    char        buf[BUFSIZE];
    long        matched;
    long        deleted;
    int         i;
    bool        new_pass;
    bool        success = true;
    static char *password = NULL;

    /* Note: password can be carried over from a previous call */
    if (param->pg_prompt == TRI_YES && !password)
        password = simple_prompt("Password: ", false);

    /*
     * Start the connection.  Loop until we have a password if requested by
     * backend.
     */
    do
    {
#define PARAMS_ARRAY_SIZE      7

        const char *keywords[PARAMS_ARRAY_SIZE];
        const char *values[PARAMS_ARRAY_SIZE];

        keywords[0] = "host";
        values[0] = param->pg_host;
        keywords[1] = "port";
        values[1] = param->pg_port;
        keywords[2] = "user";
        values[2] = param->pg_user;
        keywords[3] = "password";
        values[3] = password;
        keywords[4] = "dbname";
        values[4] = database;
        keywords[5] = "fallback_application_name";
        values[5] = param->progname;
        keywords[6] = NULL;
        values[6] = NULL;

        new_pass = false;
        conn = PQconnectdbParams(keywords, values, true);
        if (!conn)
        {
            pg_log_error("connection to database \"%s\" failed", database);
            return -1;
        }

        if (PQstatus(conn) == CONNECTION_BAD &&
            PQconnectionNeedsPassword(conn) &&
            !password &&
            param->pg_prompt != TRI_NO)
        {
            PQfinish(conn);
            password = simple_prompt("Password: ", false);
            new_pass = true;
        }
    } while (new_pass);

    /* check to see that the backend connection was successfully made */
    if (PQstatus(conn) == CONNECTION_BAD)
    {
        pg_log_error("connection to database \"%s\" failed: %s",
                     database, PQerrorMessage(conn));
        PQfinish(conn);
        return -1;
    }

    if (param->verbose)
    {
        fprintf(stdout, "Connected to database \"%s\"\n", database);
        if (param->dry_run)
            fprintf(stdout, "Test run: no large objects will be removed!\n");
    }

    res = PQexec(conn, ALWAYS_SECURE_SEARCH_PATH_SQL);
    if (PQresultStatus(res) != PGRES_TUPLES_OK)
    {
        pg_log_error("failed to set search_path: %s", PQerrorMessage(conn));
        PQclear(res);
        PQfinish(conn);
        return -1;
    }
    PQclear(res);

    /*
     * First we create and populate the LO temp table
     */
    buf[0] = '\0';
    strcat(buf, "CREATE TEMP TABLE vacuum_l AS ");
    if (PQserverVersion(conn) >= 90000)
        strcat(buf, "SELECT oid AS lo FROM pg_largeobject_metadata");
    else
        strcat(buf, "SELECT DISTINCT loid AS lo FROM pg_largeobject");
    res = PQexec(conn, buf);
    if (PQresultStatus(res) != PGRES_COMMAND_OK)
    {
        pg_log_error("failed to create temp table: %s", PQerrorMessage(conn));
        PQclear(res);
        PQfinish(conn);
        return -1;
    }
    PQclear(res);

    /*
     * Analyze the temp table so that planner will generate decent plans for
     * the DELETEs below.
     */
    buf[0] = '\0';
    strcat(buf, "ANALYZE vacuum_l");
    res = PQexec(conn, buf);
    if (PQresultStatus(res) != PGRES_COMMAND_OK)
    {
        pg_log_error("failed to vacuum temp table: %s", PQerrorMessage(conn));
        PQclear(res);
        PQfinish(conn);
        return -1;
    }
    PQclear(res);

    /*
     * Now find any candidate tables that have columns of type oid.
     *
     * NOTE: we ignore system tables and temp tables by the expedient of
     * rejecting tables in schemas named 'pg_*'.  In particular, the temp
     * table formed above is ignored, and pg_largeobject will be too. If
     * either of these were scanned, obviously we'd end up with nothing to
     * delete...
     */
    buf[0] = '\0';
    strcat(buf, "SELECT s.nspname, c.relname, a.attname ");
    strcat(buf, "FROM pg_class c, pg_attribute a, pg_namespace s, pg_type t ");
    strcat(buf, "WHERE a.attnum > 0 AND NOT a.attisdropped ");
    strcat(buf, "      AND a.attrelid = c.oid ");
    strcat(buf, "      AND a.atttypid = t.oid ");
    strcat(buf, "      AND c.relnamespace = s.oid ");
    strcat(buf, "      AND t.typname in ('oid', 'lo') ");
    strcat(buf, "      AND c.relkind in (" CppAsString2(RELKIND_RELATION) ", " CppAsString2(RELKIND_MATVIEW) ")");
    strcat(buf, "      AND s.nspname !~ '^pg_'");
    res = PQexec(conn, buf);
    if (PQresultStatus(res) != PGRES_TUPLES_OK)
    {
        pg_log_error("failed to find OID columns: %s", PQerrorMessage(conn));
        PQclear(res);
        PQfinish(conn);
        return -1;
    }

    for (i = 0; i < PQntuples(res); i++)
    {
        char       *schema,
                   *table,
                   *field;

        schema = PQgetvalue(res, i, 0);
        table = PQgetvalue(res, i, 1);
        field = PQgetvalue(res, i, 2);

        if (param->verbose)
            fprintf(stdout, "Checking %s in %s.%s\n", field, schema, table);

        schema = PQescapeIdentifier(conn, schema, strlen(schema));
        table = PQescapeIdentifier(conn, table, strlen(table));
        field = PQescapeIdentifier(conn, field, strlen(field));

        if (!schema || !table || !field)
        {
            pg_log_error("%s", PQerrorMessage(conn));
            PQclear(res);
            PQfinish(conn);
            if (schema != NULL)
                PQfreemem(schema);
            if (table != NULL)
                PQfreemem(table);
            if (field != NULL)
                PQfreemem(field);
            return -1;
        }

        snprintf(buf, BUFSIZE,
                 "DELETE FROM vacuum_l "
                 "WHERE lo IN (SELECT %s FROM %s.%s)",
                 field, schema, table);
        res2 = PQexec(conn, buf);
        if (PQresultStatus(res2) != PGRES_COMMAND_OK)
        {
            pg_log_error("failed to check %s in table %s.%s: %s",
                         field, schema, table, PQerrorMessage(conn));
            PQclear(res2);
            PQclear(res);
            PQfinish(conn);
            PQfreemem(schema);
            PQfreemem(table);
            PQfreemem(field);
            return -1;
        }
        PQclear(res2);

        PQfreemem(schema);
        PQfreemem(table);
        PQfreemem(field);
    }
    PQclear(res);

    /*
     * Now, those entries remaining in vacuum_l are orphans.  Delete 'em.
     *
     * We don't want to run each delete as an individual transaction, because
     * the commit overhead would be high.  However, since 9.0 the backend will
     * acquire a lock per deleted LO, so deleting too many LOs per transaction
     * risks running out of room in the shared-memory lock table. Accordingly,
     * we delete up to transaction_limit LOs per transaction.
     */
    res = PQexec(conn, "begin");
    if (PQresultStatus(res) != PGRES_COMMAND_OK)
    {
        pg_log_error("failed to start transaction: %s", PQerrorMessage(conn));
        PQclear(res);
        PQfinish(conn);
        return -1;
    }
    PQclear(res);

    buf[0] = '\0';
    strcat(buf,
           "DECLARE myportal CURSOR WITH HOLD FOR SELECT lo FROM vacuum_l");
    res = PQexec(conn, buf);
    if (PQresultStatus(res) != PGRES_COMMAND_OK)
    {
        pg_log_error("DECLARE CURSOR failed: %s", PQerrorMessage(conn));
        PQclear(res);
        PQfinish(conn);
        return -1;
    }
    PQclear(res);

    snprintf(buf, BUFSIZE, "FETCH FORWARD %ld IN myportal",
             param->transaction_limit > 0 ? param->transaction_limit : 1000L);

    deleted = 0;

    do
    {
        res = PQexec(conn, buf);
        if (PQresultStatus(res) != PGRES_TUPLES_OK)
        {
            pg_log_error("FETCH FORWARD failed: %s", PQerrorMessage(conn));
            PQclear(res);
            PQfinish(conn);
            return -1;
        }

        matched = PQntuples(res);
        if (matched <= 0)
        {
            /* at end of resultset */
            PQclear(res);
            break;
        }

        for (i = 0; i < matched; i++)
        {
            Oid         lo = atooid(PQgetvalue(res, i, 0));

            if (param->verbose)
            {
                fprintf(stdout, "\rRemoving lo %6u   ", lo);
                fflush(stdout);
            }

            if (param->dry_run == 0)
            {
                if (lo_unlink(conn, lo) < 0)
                {
                    pg_log_error("failed to remove lo %u: %s", lo,
                                 PQerrorMessage(conn));
                    if (PQtransactionStatus(conn) == PQTRANS_INERROR)
                    {
                        success = false;
                        break;  /* out of inner for-loop */
                    }
                }
                else
                    deleted++;
            }
            else
                deleted++;

            if (param->transaction_limit > 0 &&
                (deleted % param->transaction_limit) == 0)
            {
                res2 = PQexec(conn, "commit");
                if (PQresultStatus(res2) != PGRES_COMMAND_OK)
                {
                    pg_log_error("failed to commit transaction: %s",
                                 PQerrorMessage(conn));
                    PQclear(res2);
                    PQclear(res);
                    PQfinish(conn);
                    return -1;
                }
                PQclear(res2);
                res2 = PQexec(conn, "begin");
                if (PQresultStatus(res2) != PGRES_COMMAND_OK)
                {
                    pg_log_error("failed to start transaction: %s",
                                 PQerrorMessage(conn));
                    PQclear(res2);
                    PQclear(res);
                    PQfinish(conn);
                    return -1;
                }
                PQclear(res2);
            }
        }

        PQclear(res);
    } while (success);

    /*
     * That's all folks!
     */
    res = PQexec(conn, "commit");
    if (PQresultStatus(res) != PGRES_COMMAND_OK)
    {
        pg_log_error("failed to commit transaction: %s",
                     PQerrorMessage(conn));
        PQclear(res);
        PQfinish(conn);
        return -1;
    }
    PQclear(res);

    PQfinish(conn);

    if (param->verbose)
    {
        if (param->dry_run)
            fprintf(stdout, "\rWould remove %ld large objects from database \"%s\".\n",
                    deleted, database);
        else if (success)
            fprintf(stdout,
                    "\rSuccessfully removed %ld large objects from database \"%s\".\n",
                    deleted, database);
        else
            fprintf(stdout, "\rRemoval from database \"%s\" failed at object %ld of %ld.\n",
                    database, deleted, matched);
    }

    return ((param->dry_run || success) ? 0 : -1);
}

static void
usage(const char *progname)
{
    printf("%s removes unreferenced large objects from databases.\n\n", progname);
    printf("Usage:\n  %s [OPTION]... DBNAME...\n\n", progname);
    printf("Options:\n");
    printf("  -l, --limit=LIMIT         commit after removing each LIMIT large objects\n");
    printf("  -n, --dry-run             don't remove large objects, just show what would be done\n");
    printf("  -v, --verbose             write a lot of progress messages\n");
    printf("  -V, --version             output version information, then exit\n");
    printf("  -?, --help                show this help, then exit\n");
    printf("\nConnection options:\n");
    printf("  -h, --host=HOSTNAME       database server host or socket directory\n");
    printf("  -p, --port=PORT           database server port\n");
    printf("  -U, --username=USERNAME   user name to connect as\n");
    printf("  -w, --no-password         never prompt for password\n");
    printf("  -W, --password            force password prompt\n");
    printf("\n");
    printf("Report bugs to <%s>.\n", PACKAGE_BUGREPORT);
    printf("%s home page: <%s>\n", PACKAGE_NAME, PACKAGE_URL);
}


int
main(int argc, char **argv)
{
    static struct option long_options[] = {
        {"host", required_argument, NULL, 'h'},
        {"limit", required_argument, NULL, 'l'},
        {"dry-run", no_argument, NULL, 'n'},
        {"port", required_argument, NULL, 'p'},
        {"username", required_argument, NULL, 'U'},
        {"verbose", no_argument, NULL, 'v'},
        {"version", no_argument, NULL, 'V'},
        {"no-password", no_argument, NULL, 'w'},
        {"password", no_argument, NULL, 'W'},
        {"help", no_argument, NULL, '?'},
        {NULL, 0, NULL, 0}
    };

    int         rc = 0;
    struct _param param;
    int         c;
    int         port;
    const char *progname;
    int         optindex;

    pg_logging_init(argv[0]);
    progname = get_progname(argv[0]);

    /* Set default parameter values */
    param.pg_user = NULL;
    param.pg_prompt = TRI_DEFAULT;
    param.pg_host = NULL;
    param.pg_port = NULL;
    param.progname = progname;
    param.verbose = 0;
    param.dry_run = 0;
    param.transaction_limit = 1000;

    /* Process command-line arguments */
    if (argc > 1)
    {
        if (strcmp(argv[1], "--help") == 0 || strcmp(argv[1], "-?") == 0)
        {
            usage(progname);
            exit(0);
        }
        if (strcmp(argv[1], "--version") == 0 || strcmp(argv[1], "-V") == 0)
        {
            puts("vacuumlo (PostgreSQL) " PG_VERSION);
            exit(0);
        }
    }

    while ((c = getopt_long(argc, argv, "h:l:np:U:vwW", long_options, &optindex)) != -1)
    {
        switch (c)
        {
            case '?':
                fprintf(stderr, _("Try \"%s --help\" for more information.\n"), progname);
                exit(1);
            case 'h':
                param.pg_host = pg_strdup(optarg);
                break;
            case 'l':
                param.transaction_limit = strtol(optarg, NULL, 10);
                if (param.transaction_limit < 0)
                {
                    pg_log_error("transaction limit must not be negative (0 disables)");
                    exit(1);
                }
                break;
            case 'n':
                param.dry_run = 1;
                param.verbose = 1;
                break;
            case 'p':
                port = strtol(optarg, NULL, 10);
                if ((port < 1) || (port > 65535))
                {
                    pg_log_error("invalid port number: %s", optarg);
                    exit(1);
                }
                param.pg_port = pg_strdup(optarg);
                break;
            case 'U':
                param.pg_user = pg_strdup(optarg);
                break;
            case 'v':
                param.verbose = 1;
                break;
            case 'w':
                param.pg_prompt = TRI_NO;
                break;
            case 'W':
                param.pg_prompt = TRI_YES;
                break;
            default:
                fprintf(stderr, _("Try \"%s --help\" for more information.\n"), progname);
                exit(1);
        }
    }

    /* No database given? Show usage */
    if (optind >= argc)
    {
        pg_log_error("missing required argument: database name");
        fprintf(stderr, _("Try \"%s --help\" for more information.\n"), progname);
        exit(1);
    }

    for (c = optind; c < argc; c++)
    {
        /* Work on selected database */
        rc += (vacuumlo(argv[c], &param) != 0);
    }

    return rc;
}