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/*
* PL/Proxy - easy access to partitioned database.
*
* Copyright (c) 2006 Sven Suursoho, Skype Technologies OÜ
* Copyright (c) 2007 Marko Kreen, Skype Technologies OÜ
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
/*
* Conversion from PGresult to Datum.
*
* Functions here are called with CurrentMemoryContext == query context
* so that palloc()-ed memory stays valid after return to postgres.
*/
#include "plproxy.h"
static bool
name_matches(ProxyFunction *func, const char *aname, PGresult *res, int col)
{
const char *fname = PQfname(res, col);
if (fname == NULL)
plproxy_error(func, "Unnamed result column %d", col + 1);
if (strcmp(aname, fname) == 0)
return true;
return false;
}
/* fill func->result_map */
static void
map_results(ProxyFunction *func, PGresult *res)
{
int i, /* non-dropped column index */
xi, /* tupdesc index */
j, /* result column index */
natts,
nfields = PQnfields(res);
Form_pg_attribute a;
const char *aname;
if (func->ret_scalar)
{
if (nfields != 1)
plproxy_error(func,
"single field function but got record");
return;
}
natts = func->ret_composite->tupdesc->natts;
if (nfields < func->ret_composite->nfields)
plproxy_error(func, "Got too few fields from remote end");
if (nfields > func->ret_composite->nfields)
plproxy_error(func, "Got too many fields from remote end");
for (i = -1, xi = 0; xi < natts; xi++)
{
/* ->name_list has quoted names, take unquoted from ->tupdesc */
a = func->ret_composite->tupdesc->attrs[xi];
func->result_map[xi] = -1;
if (a->attisdropped)
continue;
i++;
aname = NameStr(a->attname);
if (name_matches(func, aname, res, i))
/* fast case: 1:1 mapping */
func->result_map[xi] = i;
else
{
/* slow case: messed up ordering */
for (j = 0; j < nfields; j++)
{
/* already tried this one */
if (j == i)
continue;
/*
* fixme: somehow remember the ones that are already mapped?
*/
if (name_matches(func, aname, res, j))
{
func->result_map[xi] = j;
break;
}
}
}
if (func->result_map[xi] < 0)
plproxy_error(func,
"Field %s does not exists in result", aname);
}
}
/* Return connection where are unreturned rows */
static ProxyConnection *
walk_results(ProxyFunction *func, ProxyCluster *cluster)
{
ProxyConnection *conn;
for (; cluster->ret_cur_conn < cluster->active_count;
cluster->ret_cur_conn++)
{
conn = cluster->active_list[cluster->ret_cur_conn];
if (conn->res == NULL)
continue;
if (conn->pos == PQntuples(conn->res))
continue;
/* first time on this connection? */
if (conn->pos == 0)
map_results(func, conn->res);
return conn;
}
plproxy_error(func, "bug: no result");
return NULL;
}
/* Return a tuple */
static Datum
return_composite(ProxyFunction *func, ProxyConnection *conn, FunctionCallInfo fcinfo)
{
int i,
col;
char **values;
int *fmts;
int *lengths;
HeapTuple tup;
ProxyComposite *meta = func->ret_composite;
values = palloc(meta->tupdesc->natts * sizeof(char *));
fmts = palloc(meta->tupdesc->natts * sizeof(int));
lengths = palloc(meta->tupdesc->natts * sizeof(int));
for (i = 0; i < meta->tupdesc->natts; i++)
{
col = func->result_map[i];
if (col < 0 || PQgetisnull(conn->res, conn->pos, col))
{
values[i] = NULL;
lengths[i] = 0;
fmts[i] = 0;
}
else
{
values[i] = PQgetvalue(conn->res, conn->pos, col);
lengths[i] = PQgetlength(conn->res, conn->pos, col);
fmts[i] = PQfformat(conn->res, col);
}
}
tup = plproxy_recv_composite(meta, values, lengths, fmts);
pfree(lengths);
pfree(fmts);
pfree(values);
return HeapTupleGetDatum(tup);
}
/* Return scalar value */
static Datum
return_scalar(ProxyFunction *func, ProxyConnection *conn, FunctionCallInfo fcinfo)
{
Datum dat;
char *val;
PGresult *res = conn->res;
int row = conn->pos;
if (func->ret_scalar->type_oid == VOIDOID)
{
dat = (Datum) NULL;
}
else if (PQgetisnull(res, row, 0))
{
fcinfo->isnull = true;
dat = (Datum) NULL;
}
else
{
val = PQgetvalue(res, row, 0);
if (val == NULL)
plproxy_error(func, "unexcpected NULL");
dat = plproxy_recv_type(func->ret_scalar, val,
PQgetlength(res, row, 0),
PQfformat(res, 0));
}
return dat;
}
/* Return next result Datum */
Datum
plproxy_result(ProxyFunction *func, FunctionCallInfo fcinfo)
{
Datum dat;
ProxyCluster *cluster = func->cur_cluster;
ProxyConnection *conn;
conn = walk_results(func, cluster);
if (func->ret_composite)
dat = return_composite(func, conn, fcinfo);
else
dat = return_scalar(func, conn, fcinfo);
cluster->ret_total--;
conn->pos++;
return dat;
}
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