On Wed, 20 Sep 2006, Tomasz Ostrowski wrote:
> I've made some experiments with attached program and
> came up that for inserting 1kB of data this program needs about
> 5120kB of virtual memory, 1MB - 10MB, 10MB - 55MB.
Forgot to attach it.
Pozdrawiam
Tometzky
--
Best of prhn - najzabawniejsze teksty polskiego UseNet-u
http://prhn.dnsalias.org/
Chaos zawsze pokonuje porządek, gdyż jest lepiej zorganizowany.
[ Terry Pratchett ]
#include <libpq-fe.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
int main(int argc, char* argv[]) {
int data_fd;
char* query_buf;
unsigned char* data_cache;
size_t query_buf_len, query_buf_off;
ssize_t readbytes;
assert(argc == 2);
PGconn* pgconn = PQconnectdb("");
if ( PQstatus(pgconn) != CONNECTION_OK ) { fprintf(stderr, "Cannot
connect: %s\n", PQerrorMessage(pgconn)); exit(-1); };
if ( ( data_fd = open(argv[1],O_RDONLY) ) == -1 ) { perror("Cannot open
data file"); exit(-1); };
/* allocate query buffer */
#define QUERYSTART "create temporary table test (data bytea); insert
into test values ('"
#define QUERYEND "')"
{
struct stat statbuf;
if ( fstat(data_fd, &statbuf) == -1 ) { perror("Cannot stat
data file"); exit(-1); };
/* query_buf_len = maximum needed size of query buffer */
query_buf_len =
statbuf.st_size*5+sizeof(QUERYSTART)+sizeof(QUERYEND);
}
if ( ! (query_buf = malloc(query_buf_len)) ) { perror(NULL); exit(-1);
};
/* fill query buffer with QUERYSTART without null termination */
memcpy(query_buf, QUERYSTART, sizeof(QUERYSTART)-1);
query_buf_off = sizeof(QUERYSTART)-1; /* Offset in the query buffer */
/* allocate cache for file data */
#define CACHESIZE (0x7fff) /* minimum POSIX limit for read cache size */
if ( ! ( data_cache = malloc(CACHESIZE) ) ) { perror(NULL); exit(-1); };
/* read file */
while ( ( readbytes = read(data_fd, data_cache, CACHESIZE) ) > 0 ) {
size_t esc_data_cache_len;
unsigned char* esc_data_cache;
/* escape data */
if ( ! ( esc_data_cache = PQescapeByteaConn(pgconn, data_cache,
readbytes, &esc_data_cache_len) ) ) { fprintf(stderr, "Cannot escape data:
%s\n", PQerrorMessage(pgconn)); exit(-1); };
/* copy escaped data without null termination to query buffer */
assert( query_buf_off + esc_data_cache_len < query_buf_len );
memcpy(query_buf+query_buf_off, esc_data_cache,
esc_data_cache_len-1);
query_buf_off += esc_data_cache_len-1;
/* free escaped data */
PQfreemem(esc_data_cache);
}
if ( readbytes == -1 ) { perror("Cannot read from data file");
exit(-1); }
/* deallocate cache for file data */
free(data_cache);
/* fill query buffer with QUERYEND with null termination */
assert(query_buf_off+sizeof(QUERYEND) <= query_buf_len);
memcpy(query_buf+query_buf_off, QUERYEND, sizeof(QUERYEND));
/* fprintf(stderr, "%s\n", query_buf); */
PQexec(pgconn, query_buf);
/* deallocate query buffer */
free(query_buf);
PQfinish(pgconn);
return 0;
}
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