Re: Parsing speed (was Re: pgstats_initstats() cost)

Gavin Sherry <swm(at)linuxworld(dot)com(dot)au> writes:
> On Tue, 12 Aug 2003, Tom Lane wrote:
>> I'm beginning to think that was a serious omission. I'm tempted to fix
>> it, even though we're past feature freeze for 7.4. Comments?

> Can you give an example of this usage of this API? I am wondering whether
> releasing this specific feature would be eclipsed by a generalised bound
> variables solution in a future release... still, that's a nice speed up
> :-).

Attached is the test code I was using to compare speeds. It won't do
you much good without the accompanying libpq mods, but it's enough to
illustrate the usage. (This is a hacked version of example program 3 from
the 7.4 libpq docs.)

regards, tom lane

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include "libpq-fe.h"

/* for ntohl/htonl */
#include <netinet/in.h>
#include <arpa/inet.h>

static void
exit_nicely(PGconn *conn)
{
PQfinish(conn);
exit(1);
}

int
main(int argc, char **argv)
{
const char *conninfo;
PGconn *conn;
PGresult *res;
const char *paramValues[3];
int tries, ntries;

/*
* If the user supplies a parameter on the command line, use it as the
* conninfo string; otherwise default to setting dbname=template1 and
* using environment variables or defaults for all other connection
* parameters.
*/
if (argc > 1)
conninfo = argv[1];
else
conninfo = "dbname = template1";

if (argc > 2)
ntries = atoi(argv[2]);
else
ntries = 10;

/* Make a connection to the database */
conn = PQconnectdb(conninfo);

/* Check to see that the backend connection was successfully made */
if (PQstatus(conn) != CONNECTION_OK)
{
fprintf(stderr, "Connection to database '%s' failed.\n", PQdb(conn));
fprintf(stderr, "%s", PQerrorMessage(conn));
exit_nicely(conn);
}

res = PQexec(conn, "PREPARE mystmt(text,int,float8) AS insert into abc values($1,$2,$3)");
if (PQresultStatus(res) != PGRES_COMMAND_OK)
{
fprintf(stderr, "PREPARE failed: %s", PQerrorMessage(conn));
PQclear(res);
exit_nicely(conn);
}
PQclear(res);

res = PQexec(conn, "BEGIN");
if (PQresultStatus(res) != PGRES_COMMAND_OK)
{
fprintf(stderr, "BEGIN failed: %s", PQerrorMessage(conn));
PQclear(res);
exit_nicely(conn);
}
PQclear(res);

for (tries = 0; tries < ntries; tries++)
{
#if 0
res = PQexec(conn, "insert into abc values('joe''s place',22,123.4)");
#endif

#if 0
/* Here are our out-of-line parameter values */
paramValues[0] = "joe's place";
paramValues[1] = "22";
paramValues[2] = "123.4";

res = PQexecParams(conn,
"insert into abc values($1,$2,$3)",
3, /* 3 params */
NULL, /* let the backend deduce param type */
paramValues,
NULL, /* don't need param lengths since text */
NULL, /* default to all text params */
1); /* ask for binary results */
#endif

#if 1
/* Here are our out-of-line parameter values */
paramValues[0] = "joe's place";
paramValues[1] = "22";
paramValues[2] = "123.4";

res = PQexecPrepared(conn,
"mystmt",
3, /* 3 params */
paramValues,
NULL, /* don't need param lengths since text */
NULL, /* default to all text params */
1); /* ask for binary results */
#endif

if (PQresultStatus(res) != PGRES_COMMAND_OK)
{
fprintf(stderr, "INSERT failed: %s", PQerrorMessage(conn));
PQclear(res);
exit_nicely(conn);
}

PQclear(res);
}

res = PQexec(conn, "COMMIT");
if (PQresultStatus(res) != PGRES_COMMAND_OK)
{
fprintf(stderr, "COMMIT failed: %s", PQerrorMessage(conn));
PQclear(res);
exit_nicely(conn);
}
PQclear(res);

/* close the connection to the database and cleanup */
PQfinish(conn);

return 0;
}