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vacuumlo: Use a cursor to limit client-side memory usage. 

This prevents the client from gobbling up too much memory when the
number of large objects to be removed is very large.

Andrew Dunstan, reviewed by Josh Kupershmidt
This commit is contained in:
Robert Haas 2013-07-15 10:48:44 -04:00
parent 03010366b6
commit 67ccbb080d
1 changed files with 70 additions and 43 deletions
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113
contrib/vacuumlo/vacuumlo.c
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@ -290,74 +290,101 @@ vacuumlo(const char *database, const struct _param * param)
PQclear(res);
buf[0] = '\0';
strcat(buf, "SELECT lo FROM vacuum_l");
strcat(buf,
"DECLARE myportal CURSOR WITH HOLD FOR SELECT lo FROM vacuum_l");
res = PQexec(conn, buf);
if (PQresultStatus(res) != PGRES_TUPLES_OK)
if (PQresultStatus(res) != PGRES_COMMAND_OK)
{
fprintf(stderr, "Failed to read temp table:\n");
fprintf(stderr, "%s", PQerrorMessage(conn));
fprintf(stderr, "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);
matched = PQntuples(res);
deleted = 0;
for (i = 0; i < matched; i++)
{
Oid lo = atooid(PQgetvalue(res, i, 0));
if (param->verbose)
while (1)
{
res = PQexec(conn, buf);
if (PQresultStatus(res) != PGRES_TUPLES_OK)
{
fprintf(stdout, "\rRemoving lo %6u ", lo);
fflush(stdout);
fprintf(stderr, "FETCH FORWARD failed: %s", PQerrorMessage(conn));
PQclear(res);
PQfinish(conn);
return -1;
}
if (param->dry_run == 0)
matched = PQntuples(res);
if (matched <= 0)
{
if (lo_unlink(conn, lo) < 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(stderr, "\nFailed to remove lo %u: ", lo);
fprintf(stderr, "%s", PQerrorMessage(conn));
if (PQtransactionStatus(conn) == PQTRANS_INERROR)
fprintf(stdout, "\rRemoving lo %6u ", lo);
fflush(stdout);
}
if (param->dry_run == 0)
{
if (lo_unlink(conn, lo) < 0)
{
success = false;
break;
fprintf(stderr, "\nFailed to remove lo %u: ", lo);
fprintf(stderr, "%s", PQerrorMessage(conn));
if (PQtransactionStatus(conn) == PQTRANS_INERROR)
{
success = false;
PQclear(res);
break;
}
}
else
deleted++;
}
else
deleted++;
}
else
deleted++;
if (param->transaction_limit > 0 &&
(deleted % param->transaction_limit) == 0)
{
res2 = PQexec(conn, "commit");
if (PQresultStatus(res2) != PGRES_COMMAND_OK)
if (param->transaction_limit > 0 &&
(deleted % param->transaction_limit) == 0)
{
fprintf(stderr, "Failed to commit transaction:\n");
fprintf(stderr, "%s", PQerrorMessage(conn));
res2 = PQexec(conn, "commit");
if (PQresultStatus(res2) != PGRES_COMMAND_OK)
{
fprintf(stderr, "Failed to commit transaction:\n");
fprintf(stderr, "%s", PQerrorMessage(conn));
PQclear(res2);
PQclear(res);
PQfinish(conn);
return -1;
}
PQclear(res2);
PQclear(res);
PQfinish(conn);
return -1;
}
PQclear(res2);
res2 = PQexec(conn, "begin");
if (PQresultStatus(res2) != PGRES_COMMAND_OK)
{
fprintf(stderr, "Failed to start transaction:\n");
fprintf(stderr, "%s", PQerrorMessage(conn));
res2 = PQexec(conn, "begin");
if (PQresultStatus(res2) != PGRES_COMMAND_OK)
{
fprintf(stderr, "Failed to start transaction:\n");
fprintf(stderr, "%s", PQerrorMessage(conn));
PQclear(res2);
PQclear(res);
PQfinish(conn);
return -1;
}
PQclear(res2);
PQclear(res);
PQfinish(conn);
return -1;
}
PQclear(res2);
}
PQclear(res);
}
PQclear(res);
/*
* That's all folks!