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BUG #1756: PQexec eats huge amounts of memory

From: "Denis Vlasenko" <vda(at)ilport(dot)com(dot)ua>
To: pgsql-bugs(at)postgresql(dot)org
Subject: BUG #1756: PQexec eats huge amounts of memory
Date: 2005-07-06 11:35:28
Message-ID: 20050706113528.000E3F0B01@svr2.postgresql.org (view raw or flat)
Thread:
Lists: pgsql-bugs
The following bug has been logged online:

Bug reference:      1756
Logged by:          Denis Vlasenko
Email address:      vda(at)ilport(dot)com(dot)ua
PostgreSQL version: 8.0.1
Operating system:   Linux
Description:        PQexec eats huge amounts of memory
Details: 

Verbatim from http://bugs.php.net/bug.php?id=33587:

Description:
------------
Seen on php-4.3.4RC2. Since I was just testing how good
PG fares compared to Oracle, and I am not feeling any
real pain from this (IOW: not my itch to scratch),
I do not research this in depth, apart from submitting
bug report. Sorry.

Symptom: even the simplest query
$result = pg_query($db, "SELECT * FROM big_table");
eats enormous amounts of memory on server
(proportional to table size).

I think this is a problem with PostgreSQL client libs.
php's source is included for easy reference.

PHP_FUNCTION(pg_query)
{

...
        pgsql_result = PQexec(pgsql, Z_STRVAL_PP(query));
        if ((PGG(auto_reset_persistent) & 2) && PQstatus(pgsql) !=
CONNECTION_OK) {
                PQclear(pgsql_result);
                PQreset(pgsql);
                pgsql_result = PQexec(pgsql, Z_STRVAL_PP(query));
        }

        if (pgsql_result) {
                status = PQresultStatus(pgsql_result);
        } else {
                status = (ExecStatusType) PQstatus(pgsql);
        }

        switch (status) {
                case PGRES_EMPTY_QUERY:
                case PGRES_BAD_RESPONSE:
                case PGRES_NONFATAL_ERROR:
                case PGRES_FATAL_ERROR:
                        php_error_docref(NULL TSRMLS_CC, E_WARNING,
"Query failed: %s.", PQerrorMessage(pgsql));
                        PQclear(pgsql_result);
                        RETURN_FALSE;
                        break;
                case PGRES_COMMAND_OK: /* successful command that did
not return rows */
                default:
                        if (pgsql_result) {
                                pg_result = (pgsql_result_handle *)
emalloc(sizeof(pgsql_result_handle));
                                pg_result->conn = pgsql;
                                pg_result->result = pgsql_result;
                                pg_result->row = 0;
                                ZEND_REGISTER_RESOURCE(return_value,
pg_result, le_result);
                        } else {
                                PQclear(pgsql_result);
                                RETURN_FALSE;
                        }
                        break;
        }
}

Responses

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Next:From: Michael FuhrDate: 2005-07-06 13:34:27
Subject: Re: Creating trigger function with argument(s) gets backend crash.
Previous:From: Satoshi NagayasuDate: 2005-07-06 08:59:24
Subject: Creating trigger function with argument(s) gets backend crash.

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