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dblink.c
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1 /*
2  * dblink.c
3  *
4  * Functions returning results from a remote database
5  *
6  * Joe Conway <mail@joeconway.com>
7  * And contributors:
8  * Darko Prenosil <Darko.Prenosil@finteh.hr>
9  * Shridhar Daithankar <shridhar_daithankar@persistent.co.in>
10  *
11  * contrib/dblink/dblink.c
12  * Copyright (c) 2001-2017, PostgreSQL Global Development Group
13  * ALL RIGHTS RESERVED;
14  *
15  * Permission to use, copy, modify, and distribute this software and its
16  * documentation for any purpose, without fee, and without a written agreement
17  * is hereby granted, provided that the above copyright notice and this
18  * paragraph and the following two paragraphs appear in all copies.
19  *
20  * IN NO EVENT SHALL THE AUTHOR OR DISTRIBUTORS BE LIABLE TO ANY PARTY FOR
21  * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, INCLUDING
22  * LOST PROFITS, ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS
23  * DOCUMENTATION, EVEN IF THE AUTHOR OR DISTRIBUTORS HAVE BEEN ADVISED OF THE
24  * POSSIBILITY OF SUCH DAMAGE.
25  *
26  * THE AUTHOR AND DISTRIBUTORS SPECIFICALLY DISCLAIMS ANY WARRANTIES,
27  * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
28  * AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
29  * ON AN "AS IS" BASIS, AND THE AUTHOR AND DISTRIBUTORS HAS NO OBLIGATIONS TO
30  * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
31  *
32  */
33 #include "postgres.h"
34 
35 #include <limits.h>
36 
37 #include "libpq-fe.h"
38 
39 #include "access/htup_details.h"
40 #include "access/reloptions.h"
41 #include "catalog/indexing.h"
42 #include "catalog/namespace.h"
45 #include "catalog/pg_type.h"
47 #include "executor/spi.h"
48 #include "foreign/foreign.h"
49 #include "funcapi.h"
50 #include "lib/stringinfo.h"
51 #include "mb/pg_wchar.h"
52 #include "miscadmin.h"
53 #include "parser/scansup.h"
54 #include "utils/acl.h"
55 #include "utils/builtins.h"
56 #include "utils/fmgroids.h"
57 #include "utils/guc.h"
58 #include "utils/lsyscache.h"
59 #include "utils/memutils.h"
60 #include "utils/rel.h"
61 #include "utils/tqual.h"
62 #include "utils/varlena.h"
63 
65 
66 typedef struct remoteConn
67 {
68  PGconn *conn; /* Hold the remote connection */
69  int openCursorCount; /* The number of open cursors */
70  bool newXactForCursor; /* Opened a transaction for a cursor */
71 } remoteConn;
72 
73 typedef struct storeInfo
74 {
79  char **cstrs;
80  /* temp storage for results to avoid leaks on exception */
83 } storeInfo;
84 
85 /*
86  * Internal declarations
87  */
88 static Datum dblink_record_internal(FunctionCallInfo fcinfo, bool is_async);
89 static void prepTuplestoreResult(FunctionCallInfo fcinfo);
90 static void materializeResult(FunctionCallInfo fcinfo, PGconn *conn,
91  PGresult *res);
92 static void materializeQueryResult(FunctionCallInfo fcinfo,
93  PGconn *conn,
94  const char *conname,
95  const char *sql,
96  bool fail);
97 static PGresult *storeQueryResult(volatile storeInfo *sinfo, PGconn *conn, const char *sql);
98 static void storeRow(volatile storeInfo *sinfo, PGresult *res, bool first);
99 static remoteConn *getConnectionByName(const char *name);
100 static HTAB *createConnHash(void);
101 static void createNewConnection(const char *name, remoteConn *rconn);
102 static void deleteConnection(const char *name);
103 static char **get_pkey_attnames(Relation rel, int16 *numatts);
104 static char **get_text_array_contents(ArrayType *array, int *numitems);
105 static char *get_sql_insert(Relation rel, int *pkattnums, int pknumatts, char **src_pkattvals, char **tgt_pkattvals);
106 static char *get_sql_delete(Relation rel, int *pkattnums, int pknumatts, char **tgt_pkattvals);
107 static char *get_sql_update(Relation rel, int *pkattnums, int pknumatts, char **src_pkattvals, char **tgt_pkattvals);
108 static char *quote_ident_cstr(char *rawstr);
109 static int get_attnum_pk_pos(int *pkattnums, int pknumatts, int key);
110 static HeapTuple get_tuple_of_interest(Relation rel, int *pkattnums, int pknumatts, char **src_pkattvals);
111 static Relation get_rel_from_relname(text *relname_text, LOCKMODE lockmode, AclMode aclmode);
112 static char *generate_relation_name(Relation rel);
113 static void dblink_connstr_check(const char *connstr);
114 static void dblink_security_check(PGconn *conn, remoteConn *rconn);
115 static void dblink_res_error(PGconn *conn, const char *conname, PGresult *res,
116  const char *dblink_context_msg, bool fail);
117 static char *get_connect_string(const char *servername);
118 static char *escape_param_str(const char *from);
119 static void validate_pkattnums(Relation rel,
120  int2vector *pkattnums_arg, int32 pknumatts_arg,
121  int **pkattnums, int *pknumatts);
123  const char *option, Oid context);
124 static int applyRemoteGucs(PGconn *conn);
125 static void restoreLocalGucs(int nestlevel);
126 
127 /* Global */
128 static remoteConn *pconn = NULL;
129 static HTAB *remoteConnHash = NULL;
130 
131 /*
132  * Following is list that holds multiple remote connections.
133  * Calling convention of each dblink function changes to accept
134  * connection name as the first parameter. The connection list is
135  * much like ecpg e.g. a mapping between a name and a PGconn object.
136  */
137 
138 typedef struct remoteConnHashEnt
139 {
143 
144 /* initial number of connection hashes */
145 #define NUMCONN 16
146 
147 static char *
148 xpstrdup(const char *in)
149 {
150  if (in == NULL)
151  return NULL;
152  return pstrdup(in);
153 }
154 
155 static void
157 dblink_res_internalerror(PGconn *conn, PGresult *res, const char *p2)
158 {
159  char *msg = pchomp(PQerrorMessage(conn));
160 
161  if (res)
162  PQclear(res);
163  elog(ERROR, "%s: %s", p2, msg);
164 }
165 
166 static void
168 dblink_conn_not_avail(const char *conname)
169 {
170  if (conname)
171  ereport(ERROR,
172  (errcode(ERRCODE_CONNECTION_DOES_NOT_EXIST),
173  errmsg("connection \"%s\" not available", conname)));
174  else
175  ereport(ERROR,
176  (errcode(ERRCODE_CONNECTION_DOES_NOT_EXIST),
177  errmsg("connection not available")));
178 }
179 
180 static void
181 dblink_get_conn(char *conname_or_str,
182  PGconn *volatile *conn_p, char **conname_p, volatile bool *freeconn_p)
183 {
184  remoteConn *rconn = getConnectionByName(conname_or_str);
185  PGconn *conn;
186  char *conname;
187  bool freeconn;
188 
189  if (rconn)
190  {
191  conn = rconn->conn;
192  conname = conname_or_str;
193  freeconn = false;
194  }
195  else
196  {
197  const char *connstr;
198 
199  connstr = get_connect_string(conname_or_str);
200  if (connstr == NULL)
201  connstr = conname_or_str;
202  dblink_connstr_check(connstr);
203  conn = PQconnectdb(connstr);
204  if (PQstatus(conn) == CONNECTION_BAD)
205  {
206  char *msg = pchomp(PQerrorMessage(conn));
207 
208  PQfinish(conn);
209  ereport(ERROR,
210  (errcode(ERRCODE_SQLCLIENT_UNABLE_TO_ESTABLISH_SQLCONNECTION),
211  errmsg("could not establish connection"),
212  errdetail_internal("%s", msg)));
213  }
214  dblink_security_check(conn, rconn);
215  if (PQclientEncoding(conn) != GetDatabaseEncoding())
217  freeconn = true;
218  conname = NULL;
219  }
220 
221  *conn_p = conn;
222  *conname_p = conname;
223  *freeconn_p = freeconn;
224 }
225 
226 static PGconn *
227 dblink_get_named_conn(const char *conname)
228 {
229  remoteConn *rconn = getConnectionByName(conname);
230 
231  if (rconn)
232  return rconn->conn;
233 
234  dblink_conn_not_avail(conname);
235  return NULL; /* keep compiler quiet */
236 }
237 
238 static void
240 {
241  if (!pconn)
242  {
244  pconn->conn = NULL;
245  pconn->openCursorCount = 0;
246  pconn->newXactForCursor = FALSE;
247  }
248 }
249 
250 /*
251  * Create a persistent connection to another database
252  */
254 Datum
256 {
257  char *conname_or_str = NULL;
258  char *connstr = NULL;
259  char *connname = NULL;
260  char *msg;
261  PGconn *conn = NULL;
262  remoteConn *rconn = NULL;
263 
264  dblink_init();
265 
266  if (PG_NARGS() == 2)
267  {
268  conname_or_str = text_to_cstring(PG_GETARG_TEXT_PP(1));
269  connname = text_to_cstring(PG_GETARG_TEXT_PP(0));
270  }
271  else if (PG_NARGS() == 1)
272  conname_or_str = text_to_cstring(PG_GETARG_TEXT_PP(0));
273 
274  if (connname)
276  sizeof(remoteConn));
277 
278  /* first check for valid foreign data server */
279  connstr = get_connect_string(conname_or_str);
280  if (connstr == NULL)
281  connstr = conname_or_str;
282 
283  /* check password in connection string if not superuser */
284  dblink_connstr_check(connstr);
285  conn = PQconnectdb(connstr);
286 
287  if (PQstatus(conn) == CONNECTION_BAD)
288  {
289  msg = pchomp(PQerrorMessage(conn));
290  PQfinish(conn);
291  if (rconn)
292  pfree(rconn);
293 
294  ereport(ERROR,
295  (errcode(ERRCODE_SQLCLIENT_UNABLE_TO_ESTABLISH_SQLCONNECTION),
296  errmsg("could not establish connection"),
297  errdetail_internal("%s", msg)));
298  }
299 
300  /* check password actually used if not superuser */
301  dblink_security_check(conn, rconn);
302 
303  /* attempt to set client encoding to match server encoding, if needed */
304  if (PQclientEncoding(conn) != GetDatabaseEncoding())
306 
307  if (connname)
308  {
309  rconn->conn = conn;
310  createNewConnection(connname, rconn);
311  }
312  else
313  {
314  if (pconn->conn)
315  PQfinish(pconn->conn);
316  pconn->conn = conn;
317  }
318 
320 }
321 
322 /*
323  * Clear a persistent connection to another database
324  */
326 Datum
328 {
329  char *conname = NULL;
330  remoteConn *rconn = NULL;
331  PGconn *conn = NULL;
332 
333  dblink_init();
334 
335  if (PG_NARGS() == 1)
336  {
337  conname = text_to_cstring(PG_GETARG_TEXT_PP(0));
338  rconn = getConnectionByName(conname);
339  if (rconn)
340  conn = rconn->conn;
341  }
342  else
343  conn = pconn->conn;
344 
345  if (!conn)
346  dblink_conn_not_avail(conname);
347 
348  PQfinish(conn);
349  if (rconn)
350  {
351  deleteConnection(conname);
352  pfree(rconn);
353  }
354  else
355  pconn->conn = NULL;
356 
358 }
359 
360 /*
361  * opens a cursor using a persistent connection
362  */
364 Datum
366 {
367  PGresult *res = NULL;
368  PGconn *conn;
369  char *curname = NULL;
370  char *sql = NULL;
371  char *conname = NULL;
373  remoteConn *rconn = NULL;
374  bool fail = true; /* default to backward compatible behavior */
375 
376  dblink_init();
377  initStringInfo(&buf);
378 
379  if (PG_NARGS() == 2)
380  {
381  /* text,text */
382  curname = text_to_cstring(PG_GETARG_TEXT_PP(0));
384  rconn = pconn;
385  }
386  else if (PG_NARGS() == 3)
387  {
388  /* might be text,text,text or text,text,bool */
389  if (get_fn_expr_argtype(fcinfo->flinfo, 2) == BOOLOID)
390  {
391  curname = text_to_cstring(PG_GETARG_TEXT_PP(0));
393  fail = PG_GETARG_BOOL(2);
394  rconn = pconn;
395  }
396  else
397  {
398  conname = text_to_cstring(PG_GETARG_TEXT_PP(0));
399  curname = text_to_cstring(PG_GETARG_TEXT_PP(1));
401  rconn = getConnectionByName(conname);
402  }
403  }
404  else if (PG_NARGS() == 4)
405  {
406  /* text,text,text,bool */
407  conname = text_to_cstring(PG_GETARG_TEXT_PP(0));
408  curname = text_to_cstring(PG_GETARG_TEXT_PP(1));
410  fail = PG_GETARG_BOOL(3);
411  rconn = getConnectionByName(conname);
412  }
413 
414  if (!rconn || !rconn->conn)
415  dblink_conn_not_avail(conname);
416 
417  conn = rconn->conn;
418 
419  /* If we are not in a transaction, start one */
420  if (PQtransactionStatus(conn) == PQTRANS_IDLE)
421  {
422  res = PQexec(conn, "BEGIN");
423  if (PQresultStatus(res) != PGRES_COMMAND_OK)
424  dblink_res_internalerror(conn, res, "begin error");
425  PQclear(res);
426  rconn->newXactForCursor = TRUE;
427 
428  /*
429  * Since transaction state was IDLE, we force cursor count to
430  * initially be 0. This is needed as a previous ABORT might have wiped
431  * out our transaction without maintaining the cursor count for us.
432  */
433  rconn->openCursorCount = 0;
434  }
435 
436  /* if we started a transaction, increment cursor count */
437  if (rconn->newXactForCursor)
438  (rconn->openCursorCount)++;
439 
440  appendStringInfo(&buf, "DECLARE %s CURSOR FOR %s", curname, sql);
441  res = PQexec(conn, buf.data);
442  if (!res || PQresultStatus(res) != PGRES_COMMAND_OK)
443  {
444  dblink_res_error(conn, conname, res, "could not open cursor", fail);
446  }
447 
448  PQclear(res);
450 }
451 
452 /*
453  * closes a cursor
454  */
456 Datum
458 {
459  PGconn *conn;
460  PGresult *res = NULL;
461  char *curname = NULL;
462  char *conname = NULL;
464  remoteConn *rconn = NULL;
465  bool fail = true; /* default to backward compatible behavior */
466 
467  dblink_init();
468  initStringInfo(&buf);
469 
470  if (PG_NARGS() == 1)
471  {
472  /* text */
473  curname = text_to_cstring(PG_GETARG_TEXT_PP(0));
474  rconn = pconn;
475  }
476  else if (PG_NARGS() == 2)
477  {
478  /* might be text,text or text,bool */
479  if (get_fn_expr_argtype(fcinfo->flinfo, 1) == BOOLOID)
480  {
481  curname = text_to_cstring(PG_GETARG_TEXT_PP(0));
482  fail = PG_GETARG_BOOL(1);
483  rconn = pconn;
484  }
485  else
486  {
487  conname = text_to_cstring(PG_GETARG_TEXT_PP(0));
488  curname = text_to_cstring(PG_GETARG_TEXT_PP(1));
489  rconn = getConnectionByName(conname);
490  }
491  }
492  if (PG_NARGS() == 3)
493  {
494  /* text,text,bool */
495  conname = text_to_cstring(PG_GETARG_TEXT_PP(0));
496  curname = text_to_cstring(PG_GETARG_TEXT_PP(1));
497  fail = PG_GETARG_BOOL(2);
498  rconn = getConnectionByName(conname);
499  }
500 
501  if (!rconn || !rconn->conn)
502  dblink_conn_not_avail(conname);
503 
504  conn = rconn->conn;
505 
506  appendStringInfo(&buf, "CLOSE %s", curname);
507 
508  /* close the cursor */
509  res = PQexec(conn, buf.data);
510  if (!res || PQresultStatus(res) != PGRES_COMMAND_OK)
511  {
512  dblink_res_error(conn, conname, res, "could not close cursor", fail);
514  }
515 
516  PQclear(res);
517 
518  /* if we started a transaction, decrement cursor count */
519  if (rconn->newXactForCursor)
520  {
521  (rconn->openCursorCount)--;
522 
523  /* if count is zero, commit the transaction */
524  if (rconn->openCursorCount == 0)
525  {
526  rconn->newXactForCursor = FALSE;
527 
528  res = PQexec(conn, "COMMIT");
529  if (PQresultStatus(res) != PGRES_COMMAND_OK)
530  dblink_res_internalerror(conn, res, "commit error");
531  PQclear(res);
532  }
533  }
534 
536 }
537 
538 /*
539  * Fetch results from an open cursor
540  */
542 Datum
544 {
545  PGresult *res = NULL;
546  char *conname = NULL;
547  remoteConn *rconn = NULL;
548  PGconn *conn = NULL;
550  char *curname = NULL;
551  int howmany = 0;
552  bool fail = true; /* default to backward compatible */
553 
554  prepTuplestoreResult(fcinfo);
555 
556  dblink_init();
557 
558  if (PG_NARGS() == 4)
559  {
560  /* text,text,int,bool */
561  conname = text_to_cstring(PG_GETARG_TEXT_PP(0));
562  curname = text_to_cstring(PG_GETARG_TEXT_PP(1));
563  howmany = PG_GETARG_INT32(2);
564  fail = PG_GETARG_BOOL(3);
565 
566  rconn = getConnectionByName(conname);
567  if (rconn)
568  conn = rconn->conn;
569  }
570  else if (PG_NARGS() == 3)
571  {
572  /* text,text,int or text,int,bool */
573  if (get_fn_expr_argtype(fcinfo->flinfo, 2) == BOOLOID)
574  {
575  curname = text_to_cstring(PG_GETARG_TEXT_PP(0));
576  howmany = PG_GETARG_INT32(1);
577  fail = PG_GETARG_BOOL(2);
578  conn = pconn->conn;
579  }
580  else
581  {
582  conname = text_to_cstring(PG_GETARG_TEXT_PP(0));
583  curname = text_to_cstring(PG_GETARG_TEXT_PP(1));
584  howmany = PG_GETARG_INT32(2);
585 
586  rconn = getConnectionByName(conname);
587  if (rconn)
588  conn = rconn->conn;
589  }
590  }
591  else if (PG_NARGS() == 2)
592  {
593  /* text,int */
594  curname = text_to_cstring(PG_GETARG_TEXT_PP(0));
595  howmany = PG_GETARG_INT32(1);
596  conn = pconn->conn;
597  }
598 
599  if (!conn)
600  dblink_conn_not_avail(conname);
601 
602  initStringInfo(&buf);
603  appendStringInfo(&buf, "FETCH %d FROM %s", howmany, curname);
604 
605  /*
606  * Try to execute the query. Note that since libpq uses malloc, the
607  * PGresult will be long-lived even though we are still in a short-lived
608  * memory context.
609  */
610  res = PQexec(conn, buf.data);
611  if (!res ||
612  (PQresultStatus(res) != PGRES_COMMAND_OK &&
614  {
615  dblink_res_error(conn, conname, res,
616  "could not fetch from cursor", fail);
617  return (Datum) 0;
618  }
619  else if (PQresultStatus(res) == PGRES_COMMAND_OK)
620  {
621  /* cursor does not exist - closed already or bad name */
622  PQclear(res);
623  ereport(ERROR,
624  (errcode(ERRCODE_INVALID_CURSOR_NAME),
625  errmsg("cursor \"%s\" does not exist", curname)));
626  }
627 
628  materializeResult(fcinfo, conn, res);
629  return (Datum) 0;
630 }
631 
632 /*
633  * Note: this is the new preferred version of dblink
634  */
636 Datum
638 {
639  return dblink_record_internal(fcinfo, false);
640 }
641 
643 Datum
645 {
646  PGconn *conn;
647  char *sql;
648  int retval;
649 
650  if (PG_NARGS() == 2)
651  {
654  }
655  else
656  /* shouldn't happen */
657  elog(ERROR, "wrong number of arguments");
658 
659  /* async query send */
660  retval = PQsendQuery(conn, sql);
661  if (retval != 1)
662  elog(NOTICE, "could not send query: %s", pchomp(PQerrorMessage(conn)));
663 
664  PG_RETURN_INT32(retval);
665 }
666 
668 Datum
670 {
671  return dblink_record_internal(fcinfo, true);
672 }
673 
674 static Datum
676 {
677  PGconn *volatile conn = NULL;
678  volatile bool freeconn = false;
679 
680  prepTuplestoreResult(fcinfo);
681 
682  dblink_init();
683 
684  PG_TRY();
685  {
686  char *sql = NULL;
687  char *conname = NULL;
688  bool fail = true; /* default to backward compatible */
689 
690  if (!is_async)
691  {
692  if (PG_NARGS() == 3)
693  {
694  /* text,text,bool */
695  conname = text_to_cstring(PG_GETARG_TEXT_PP(0));
697  fail = PG_GETARG_BOOL(2);
698  dblink_get_conn(conname, &conn, &conname, &freeconn);
699  }
700  else if (PG_NARGS() == 2)
701  {
702  /* text,text or text,bool */
703  if (get_fn_expr_argtype(fcinfo->flinfo, 1) == BOOLOID)
704  {
706  fail = PG_GETARG_BOOL(1);
707  conn = pconn->conn;
708  }
709  else
710  {
711  conname = text_to_cstring(PG_GETARG_TEXT_PP(0));
713  dblink_get_conn(conname, &conn, &conname, &freeconn);
714  }
715  }
716  else if (PG_NARGS() == 1)
717  {
718  /* text */
719  conn = pconn->conn;
721  }
722  else
723  /* shouldn't happen */
724  elog(ERROR, "wrong number of arguments");
725  }
726  else /* is_async */
727  {
728  /* get async result */
729  conname = text_to_cstring(PG_GETARG_TEXT_PP(0));
730 
731  if (PG_NARGS() == 2)
732  {
733  /* text,bool */
734  fail = PG_GETARG_BOOL(1);
735  conn = dblink_get_named_conn(conname);
736  }
737  else if (PG_NARGS() == 1)
738  {
739  /* text */
740  conn = dblink_get_named_conn(conname);
741  }
742  else
743  /* shouldn't happen */
744  elog(ERROR, "wrong number of arguments");
745  }
746 
747  if (!conn)
748  dblink_conn_not_avail(conname);
749 
750  if (!is_async)
751  {
752  /* synchronous query, use efficient tuple collection method */
753  materializeQueryResult(fcinfo, conn, conname, sql, fail);
754  }
755  else
756  {
757  /* async result retrieval, do it the old way */
758  PGresult *res = PQgetResult(conn);
759 
760  /* NULL means we're all done with the async results */
761  if (res)
762  {
763  if (PQresultStatus(res) != PGRES_COMMAND_OK &&
765  {
766  dblink_res_error(conn, conname, res,
767  "could not execute query", fail);
768  /* if fail isn't set, we'll return an empty query result */
769  }
770  else
771  {
772  materializeResult(fcinfo, conn, res);
773  }
774  }
775  }
776  }
777  PG_CATCH();
778  {
779  /* if needed, close the connection to the database */
780  if (freeconn)
781  PQfinish(conn);
782  PG_RE_THROW();
783  }
784  PG_END_TRY();
785 
786  /* if needed, close the connection to the database */
787  if (freeconn)
788  PQfinish(conn);
789 
790  return (Datum) 0;
791 }
792 
793 /*
794  * Verify function caller can handle a tuplestore result, and set up for that.
795  *
796  * Note: if the caller returns without actually creating a tuplestore, the
797  * executor will treat the function result as an empty set.
798  */
799 static void
801 {
802  ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
803 
804  /* check to see if query supports us returning a tuplestore */
805  if (rsinfo == NULL || !IsA(rsinfo, ReturnSetInfo))
806  ereport(ERROR,
807  (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
808  errmsg("set-valued function called in context that cannot accept a set")));
809  if (!(rsinfo->allowedModes & SFRM_Materialize))
810  ereport(ERROR,
811  (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
812  errmsg("materialize mode required, but it is not allowed in this context")));
813 
814  /* let the executor know we're sending back a tuplestore */
815  rsinfo->returnMode = SFRM_Materialize;
816 
817  /* caller must fill these to return a non-empty result */
818  rsinfo->setResult = NULL;
819  rsinfo->setDesc = NULL;
820 }
821 
822 /*
823  * Copy the contents of the PGresult into a tuplestore to be returned
824  * as the result of the current function.
825  * The PGresult will be released in this function.
826  */
827 static void
829 {
830  ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
831 
832  /* prepTuplestoreResult must have been called previously */
833  Assert(rsinfo->returnMode == SFRM_Materialize);
834 
835  PG_TRY();
836  {
837  TupleDesc tupdesc;
838  bool is_sql_cmd;
839  int ntuples;
840  int nfields;
841 
842  if (PQresultStatus(res) == PGRES_COMMAND_OK)
843  {
844  is_sql_cmd = true;
845 
846  /*
847  * need a tuple descriptor representing one TEXT column to return
848  * the command status string as our result tuple
849  */
850  tupdesc = CreateTemplateTupleDesc(1, false);
851  TupleDescInitEntry(tupdesc, (AttrNumber) 1, "status",
852  TEXTOID, -1, 0);
853  ntuples = 1;
854  nfields = 1;
855  }
856  else
857  {
859 
860  is_sql_cmd = false;
861 
862  /* get a tuple descriptor for our result type */
863  switch (get_call_result_type(fcinfo, NULL, &tupdesc))
864  {
865  case TYPEFUNC_COMPOSITE:
866  /* success */
867  break;
868  case TYPEFUNC_RECORD:
869  /* failed to determine actual type of RECORD */
870  ereport(ERROR,
871  (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
872  errmsg("function returning record called in context "
873  "that cannot accept type record")));
874  break;
875  default:
876  /* result type isn't composite */
877  elog(ERROR, "return type must be a row type");
878  break;
879  }
880 
881  /* make sure we have a persistent copy of the tupdesc */
882  tupdesc = CreateTupleDescCopy(tupdesc);
883  ntuples = PQntuples(res);
884  nfields = PQnfields(res);
885  }
886 
887  /*
888  * check result and tuple descriptor have the same number of columns
889  */
890  if (nfields != tupdesc->natts)
891  ereport(ERROR,
892  (errcode(ERRCODE_DATATYPE_MISMATCH),
893  errmsg("remote query result rowtype does not match "
894  "the specified FROM clause rowtype")));
895 
896  if (ntuples > 0)
897  {
898  AttInMetadata *attinmeta;
899  int nestlevel = -1;
900  Tuplestorestate *tupstore;
901  MemoryContext oldcontext;
902  int row;
903  char **values;
904 
905  attinmeta = TupleDescGetAttInMetadata(tupdesc);
906 
907  /* Set GUCs to ensure we read GUC-sensitive data types correctly */
908  if (!is_sql_cmd)
909  nestlevel = applyRemoteGucs(conn);
910 
911  oldcontext = MemoryContextSwitchTo(
913  tupstore = tuplestore_begin_heap(true, false, work_mem);
914  rsinfo->setResult = tupstore;
915  rsinfo->setDesc = tupdesc;
916  MemoryContextSwitchTo(oldcontext);
917 
918  values = (char **) palloc(nfields * sizeof(char *));
919 
920  /* put all tuples into the tuplestore */
921  for (row = 0; row < ntuples; row++)
922  {
923  HeapTuple tuple;
924 
925  if (!is_sql_cmd)
926  {
927  int i;
928 
929  for (i = 0; i < nfields; i++)
930  {
931  if (PQgetisnull(res, row, i))
932  values[i] = NULL;
933  else
934  values[i] = PQgetvalue(res, row, i);
935  }
936  }
937  else
938  {
939  values[0] = PQcmdStatus(res);
940  }
941 
942  /* build the tuple and put it into the tuplestore. */
943  tuple = BuildTupleFromCStrings(attinmeta, values);
944  tuplestore_puttuple(tupstore, tuple);
945  }
946 
947  /* clean up GUC settings, if we changed any */
948  restoreLocalGucs(nestlevel);
949 
950  /* clean up and return the tuplestore */
951  tuplestore_donestoring(tupstore);
952  }
953 
954  PQclear(res);
955  }
956  PG_CATCH();
957  {
958  /* be sure to release the libpq result */
959  PQclear(res);
960  PG_RE_THROW();
961  }
962  PG_END_TRY();
963 }
964 
965 /*
966  * Execute the given SQL command and store its results into a tuplestore
967  * to be returned as the result of the current function.
968  *
969  * This is equivalent to PQexec followed by materializeResult, but we make
970  * use of libpq's single-row mode to avoid accumulating the whole result
971  * inside libpq before it gets transferred to the tuplestore.
972  */
973 static void
975  PGconn *conn,
976  const char *conname,
977  const char *sql,
978  bool fail)
979 {
980  ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
981  PGresult *volatile res = NULL;
982  volatile storeInfo sinfo;
983 
984  /* prepTuplestoreResult must have been called previously */
985  Assert(rsinfo->returnMode == SFRM_Materialize);
986 
987  /* initialize storeInfo to empty */
988  memset((void *) &sinfo, 0, sizeof(sinfo));
989  sinfo.fcinfo = fcinfo;
990 
991  PG_TRY();
992  {
993  /* Create short-lived memory context for data conversions */
994  sinfo.tmpcontext = AllocSetContextCreate(CurrentMemoryContext,
995  "dblink temporary context",
997 
998  /* execute query, collecting any tuples into the tuplestore */
999  res = storeQueryResult(&sinfo, conn, sql);
1000 
1001  if (!res ||
1002  (PQresultStatus(res) != PGRES_COMMAND_OK &&
1004  {
1005  /*
1006  * dblink_res_error will clear the passed PGresult, so we need
1007  * this ugly dance to avoid doing so twice during error exit
1008  */
1009  PGresult *res1 = res;
1010 
1011  res = NULL;
1012  dblink_res_error(conn, conname, res1,
1013  "could not execute query", fail);
1014  /* if fail isn't set, we'll return an empty query result */
1015  }
1016  else if (PQresultStatus(res) == PGRES_COMMAND_OK)
1017  {
1018  /*
1019  * storeRow didn't get called, so we need to convert the command
1020  * status string to a tuple manually
1021  */
1022  TupleDesc tupdesc;
1023  AttInMetadata *attinmeta;
1024  Tuplestorestate *tupstore;
1025  HeapTuple tuple;
1026  char *values[1];
1027  MemoryContext oldcontext;
1028 
1029  /*
1030  * need a tuple descriptor representing one TEXT column to return
1031  * the command status string as our result tuple
1032  */
1033  tupdesc = CreateTemplateTupleDesc(1, false);
1034  TupleDescInitEntry(tupdesc, (AttrNumber) 1, "status",
1035  TEXTOID, -1, 0);
1036  attinmeta = TupleDescGetAttInMetadata(tupdesc);
1037 
1038  oldcontext = MemoryContextSwitchTo(
1039  rsinfo->econtext->ecxt_per_query_memory);
1040  tupstore = tuplestore_begin_heap(true, false, work_mem);
1041  rsinfo->setResult = tupstore;
1042  rsinfo->setDesc = tupdesc;
1043  MemoryContextSwitchTo(oldcontext);
1044 
1045  values[0] = PQcmdStatus(res);
1046 
1047  /* build the tuple and put it into the tuplestore. */
1048  tuple = BuildTupleFromCStrings(attinmeta, values);
1049  tuplestore_puttuple(tupstore, tuple);
1050 
1051  PQclear(res);
1052  res = NULL;
1053  }
1054  else
1055  {
1057  /* storeRow should have created a tuplestore */
1058  Assert(rsinfo->setResult != NULL);
1059 
1060  PQclear(res);
1061  res = NULL;
1062  }
1063 
1064  /* clean up data conversion short-lived memory context */
1065  if (sinfo.tmpcontext != NULL)
1066  MemoryContextDelete(sinfo.tmpcontext);
1067  sinfo.tmpcontext = NULL;
1068 
1069  PQclear(sinfo.last_res);
1070  sinfo.last_res = NULL;
1071  PQclear(sinfo.cur_res);
1072  sinfo.cur_res = NULL;
1073  }
1074  PG_CATCH();
1075  {
1076  /* be sure to release any libpq result we collected */
1077  PQclear(res);
1078  PQclear(sinfo.last_res);
1079  PQclear(sinfo.cur_res);
1080  /* and clear out any pending data in libpq */
1081  while ((res = PQgetResult(conn)) != NULL)
1082  PQclear(res);
1083  PG_RE_THROW();
1084  }
1085  PG_END_TRY();
1086 }
1087 
1088 /*
1089  * Execute query, and send any result rows to sinfo->tuplestore.
1090  */
1091 static PGresult *
1092 storeQueryResult(volatile storeInfo *sinfo, PGconn *conn, const char *sql)
1093 {
1094  bool first = true;
1095  int nestlevel = -1;
1096  PGresult *res;
1097 
1098  if (!PQsendQuery(conn, sql))
1099  elog(ERROR, "could not send query: %s", pchomp(PQerrorMessage(conn)));
1100 
1101  if (!PQsetSingleRowMode(conn)) /* shouldn't fail */
1102  elog(ERROR, "failed to set single-row mode for dblink query");
1103 
1104  for (;;)
1105  {
1107 
1108  sinfo->cur_res = PQgetResult(conn);
1109  if (!sinfo->cur_res)
1110  break;
1111 
1112  if (PQresultStatus(sinfo->cur_res) == PGRES_SINGLE_TUPLE)
1113  {
1114  /* got one row from possibly-bigger resultset */
1115 
1116  /*
1117  * Set GUCs to ensure we read GUC-sensitive data types correctly.
1118  * We shouldn't do this until we have a row in hand, to ensure
1119  * libpq has seen any earlier ParameterStatus protocol messages.
1120  */
1121  if (first && nestlevel < 0)
1122  nestlevel = applyRemoteGucs(conn);
1123 
1124  storeRow(sinfo, sinfo->cur_res, first);
1125 
1126  PQclear(sinfo->cur_res);
1127  sinfo->cur_res = NULL;
1128  first = false;
1129  }
1130  else
1131  {
1132  /* if empty resultset, fill tuplestore header */
1133  if (first && PQresultStatus(sinfo->cur_res) == PGRES_TUPLES_OK)
1134  storeRow(sinfo, sinfo->cur_res, first);
1135 
1136  /* store completed result at last_res */
1137  PQclear(sinfo->last_res);
1138  sinfo->last_res = sinfo->cur_res;
1139  sinfo->cur_res = NULL;
1140  first = true;
1141  }
1142  }
1143 
1144  /* clean up GUC settings, if we changed any */
1145  restoreLocalGucs(nestlevel);
1146 
1147  /* return last_res */
1148  res = sinfo->last_res;
1149  sinfo->last_res = NULL;
1150  return res;
1151 }
1152 
1153 /*
1154  * Send single row to sinfo->tuplestore.
1155  *
1156  * If "first" is true, create the tuplestore using PGresult's metadata
1157  * (in this case the PGresult might contain either zero or one row).
1158  */
1159 static void
1160 storeRow(volatile storeInfo *sinfo, PGresult *res, bool first)
1161 {
1162  int nfields = PQnfields(res);
1163  HeapTuple tuple;
1164  int i;
1165  MemoryContext oldcontext;
1166 
1167  if (first)
1168  {
1169  /* Prepare for new result set */
1170  ReturnSetInfo *rsinfo = (ReturnSetInfo *) sinfo->fcinfo->resultinfo;
1171  TupleDesc tupdesc;
1172 
1173  /*
1174  * It's possible to get more than one result set if the query string
1175  * contained multiple SQL commands. In that case, we follow PQexec's
1176  * traditional behavior of throwing away all but the last result.
1177  */
1178  if (sinfo->tuplestore)
1179  tuplestore_end(sinfo->tuplestore);
1180  sinfo->tuplestore = NULL;
1181 
1182  /* get a tuple descriptor for our result type */
1183  switch (get_call_result_type(sinfo->fcinfo, NULL, &tupdesc))
1184  {
1185  case TYPEFUNC_COMPOSITE:
1186  /* success */
1187  break;
1188  case TYPEFUNC_RECORD:
1189  /* failed to determine actual type of RECORD */
1190  ereport(ERROR,
1191  (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
1192  errmsg("function returning record called in context "
1193  "that cannot accept type record")));
1194  break;
1195  default:
1196  /* result type isn't composite */
1197  elog(ERROR, "return type must be a row type");
1198  break;
1199  }
1200 
1201  /* make sure we have a persistent copy of the tupdesc */
1202  tupdesc = CreateTupleDescCopy(tupdesc);
1203 
1204  /* check result and tuple descriptor have the same number of columns */
1205  if (nfields != tupdesc->natts)
1206  ereport(ERROR,
1207  (errcode(ERRCODE_DATATYPE_MISMATCH),
1208  errmsg("remote query result rowtype does not match "
1209  "the specified FROM clause rowtype")));
1210 
1211  /* Prepare attinmeta for later data conversions */
1212  sinfo->attinmeta = TupleDescGetAttInMetadata(tupdesc);
1213 
1214  /* Create a new, empty tuplestore */
1215  oldcontext = MemoryContextSwitchTo(rsinfo->econtext->ecxt_per_query_memory);
1216  sinfo->tuplestore = tuplestore_begin_heap(true, false, work_mem);
1217  rsinfo->setResult = sinfo->tuplestore;
1218  rsinfo->setDesc = tupdesc;
1219  MemoryContextSwitchTo(oldcontext);
1220 
1221  /* Done if empty resultset */
1222  if (PQntuples(res) == 0)
1223  return;
1224 
1225  /*
1226  * Set up sufficiently-wide string pointers array; this won't change
1227  * in size so it's easy to preallocate.
1228  */
1229  if (sinfo->cstrs)
1230  pfree(sinfo->cstrs);
1231  sinfo->cstrs = (char **) palloc(nfields * sizeof(char *));
1232  }
1233 
1234  /* Should have a single-row result if we get here */
1235  Assert(PQntuples(res) == 1);
1236 
1237  /*
1238  * Do the following work in a temp context that we reset after each tuple.
1239  * This cleans up not only the data we have direct access to, but any
1240  * cruft the I/O functions might leak.
1241  */
1242  oldcontext = MemoryContextSwitchTo(sinfo->tmpcontext);
1243 
1244  /*
1245  * Fill cstrs with null-terminated strings of column values.
1246  */
1247  for (i = 0; i < nfields; i++)
1248  {
1249  if (PQgetisnull(res, 0, i))
1250  sinfo->cstrs[i] = NULL;
1251  else
1252  sinfo->cstrs[i] = PQgetvalue(res, 0, i);
1253  }
1254 
1255  /* Convert row to a tuple, and add it to the tuplestore */
1256  tuple = BuildTupleFromCStrings(sinfo->attinmeta, sinfo->cstrs);
1257 
1258  tuplestore_puttuple(sinfo->tuplestore, tuple);
1259 
1260  /* Clean up */
1261  MemoryContextSwitchTo(oldcontext);
1263 }
1264 
1265 /*
1266  * List all open dblink connections by name.
1267  * Returns an array of all connection names.
1268  * Takes no params
1269  */
1271 Datum
1273 {
1275  remoteConnHashEnt *hentry;
1276  ArrayBuildState *astate = NULL;
1277 
1278  if (remoteConnHash)
1279  {
1280  hash_seq_init(&status, remoteConnHash);
1281  while ((hentry = (remoteConnHashEnt *) hash_seq_search(&status)) != NULL)
1282  {
1283  /* stash away current value */
1284  astate = accumArrayResult(astate,
1285  CStringGetTextDatum(hentry->name),
1286  false, TEXTOID, CurrentMemoryContext);
1287  }
1288  }
1289 
1290  if (astate)
1293  else
1294  PG_RETURN_NULL();
1295 }
1296 
1297 /*
1298  * Checks if a given remote connection is busy
1299  *
1300  * Returns 1 if the connection is busy, 0 otherwise
1301  * Params:
1302  * text connection_name - name of the connection to check
1303  *
1304  */
1306 Datum
1308 {
1309  PGconn *conn;
1310 
1311  dblink_init();
1313 
1314  PQconsumeInput(conn);
1315  PG_RETURN_INT32(PQisBusy(conn));
1316 }
1317 
1318 /*
1319  * Cancels a running request on a connection
1320  *
1321  * Returns text:
1322  * "OK" if the cancel request has been sent correctly,
1323  * an error message otherwise
1324  *
1325  * Params:
1326  * text connection_name - name of the connection to check
1327  *
1328  */
1330 Datum
1332 {
1333  int res;
1334  PGconn *conn;
1335  PGcancel *cancel;
1336  char errbuf[256];
1337 
1338  dblink_init();
1340  cancel = PQgetCancel(conn);
1341 
1342  res = PQcancel(cancel, errbuf, 256);
1343  PQfreeCancel(cancel);
1344 
1345  if (res == 1)
1347  else
1349 }
1350 
1351 
1352 /*
1353  * Get error message from a connection
1354  *
1355  * Returns text:
1356  * "OK" if no error, an error message otherwise
1357  *
1358  * Params:
1359  * text connection_name - name of the connection to check
1360  *
1361  */
1363 Datum
1365 {
1366  char *msg;
1367  PGconn *conn;
1368 
1369  dblink_init();
1371 
1372  msg = PQerrorMessage(conn);
1373  if (msg == NULL || msg[0] == '\0')
1375  else
1377 }
1378 
1379 /*
1380  * Execute an SQL non-SELECT command
1381  */
1383 Datum
1385 {
1386  text *volatile sql_cmd_status = NULL;
1387  PGconn *volatile conn = NULL;
1388  volatile bool freeconn = false;
1389 
1390  dblink_init();
1391 
1392  PG_TRY();
1393  {
1394  PGresult *res = NULL;
1395  char *sql = NULL;
1396  char *conname = NULL;
1397  bool fail = true; /* default to backward compatible behavior */
1398 
1399  if (PG_NARGS() == 3)
1400  {
1401  /* must be text,text,bool */
1402  conname = text_to_cstring(PG_GETARG_TEXT_PP(0));
1404  fail = PG_GETARG_BOOL(2);
1405  dblink_get_conn(conname, &conn, &conname, &freeconn);
1406  }
1407  else if (PG_NARGS() == 2)
1408  {
1409  /* might be text,text or text,bool */
1410  if (get_fn_expr_argtype(fcinfo->flinfo, 1) == BOOLOID)
1411  {
1413  fail = PG_GETARG_BOOL(1);
1414  conn = pconn->conn;
1415  }
1416  else
1417  {
1418  conname = text_to_cstring(PG_GETARG_TEXT_PP(0));
1420  dblink_get_conn(conname, &conn, &conname, &freeconn);
1421  }
1422  }
1423  else if (PG_NARGS() == 1)
1424  {
1425  /* must be single text argument */
1426  conn = pconn->conn;
1428  }
1429  else
1430  /* shouldn't happen */
1431  elog(ERROR, "wrong number of arguments");
1432 
1433  if (!conn)
1434  dblink_conn_not_avail(conname);
1435 
1436  res = PQexec(conn, sql);
1437  if (!res ||
1438  (PQresultStatus(res) != PGRES_COMMAND_OK &&
1440  {
1441  dblink_res_error(conn, conname, res,
1442  "could not execute command", fail);
1443 
1444  /*
1445  * and save a copy of the command status string to return as our
1446  * result tuple
1447  */
1448  sql_cmd_status = cstring_to_text("ERROR");
1449  }
1450  else if (PQresultStatus(res) == PGRES_COMMAND_OK)
1451  {
1452  /*
1453  * and save a copy of the command status string to return as our
1454  * result tuple
1455  */
1456  sql_cmd_status = cstring_to_text(PQcmdStatus(res));
1457  PQclear(res);
1458  }
1459  else
1460  {
1461  PQclear(res);
1462  ereport(ERROR,
1463  (errcode(ERRCODE_S_R_E_PROHIBITED_SQL_STATEMENT_ATTEMPTED),
1464  errmsg("statement returning results not allowed")));
1465  }
1466  }
1467  PG_CATCH();
1468  {
1469  /* if needed, close the connection to the database */
1470  if (freeconn)
1471  PQfinish(conn);
1472  PG_RE_THROW();
1473  }
1474  PG_END_TRY();
1475 
1476  /* if needed, close the connection to the database */
1477  if (freeconn)
1478  PQfinish(conn);
1479 
1480  PG_RETURN_TEXT_P(sql_cmd_status);
1481 }
1482 
1483 
1484 /*
1485  * dblink_get_pkey
1486  *
1487  * Return list of primary key fields for the supplied relation,
1488  * or NULL if none exists.
1489  */
1491 Datum
1493 {
1494  int16 numatts;
1495  char **results;
1496  FuncCallContext *funcctx;
1497  int32 call_cntr;
1498  int32 max_calls;
1499  AttInMetadata *attinmeta;
1500  MemoryContext oldcontext;
1501 
1502  /* stuff done only on the first call of the function */
1503  if (SRF_IS_FIRSTCALL())
1504  {
1505  Relation rel;
1506  TupleDesc tupdesc;
1507 
1508  /* create a function context for cross-call persistence */
1509  funcctx = SRF_FIRSTCALL_INIT();
1510 
1511  /*
1512  * switch to memory context appropriate for multiple function calls
1513  */
1514  oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
1515 
1516  /* open target relation */
1518 
1519  /* get the array of attnums */
1520  results = get_pkey_attnames(rel, &numatts);
1521 
1523 
1524  /*
1525  * need a tuple descriptor representing one INT and one TEXT column
1526  */
1527  tupdesc = CreateTemplateTupleDesc(2, false);
1528  TupleDescInitEntry(tupdesc, (AttrNumber) 1, "position",
1529  INT4OID, -1, 0);
1530  TupleDescInitEntry(tupdesc, (AttrNumber) 2, "colname",
1531  TEXTOID, -1, 0);
1532 
1533  /*
1534  * Generate attribute metadata needed later to produce tuples from raw
1535  * C strings
1536  */
1537  attinmeta = TupleDescGetAttInMetadata(tupdesc);
1538  funcctx->attinmeta = attinmeta;
1539 
1540  if ((results != NULL) && (numatts > 0))
1541  {
1542  funcctx->max_calls = numatts;
1543 
1544  /* got results, keep track of them */
1545  funcctx->user_fctx = results;
1546  }
1547  else
1548  {
1549  /* fast track when no results */
1550  MemoryContextSwitchTo(oldcontext);
1551  SRF_RETURN_DONE(funcctx);
1552  }
1553 
1554  MemoryContextSwitchTo(oldcontext);
1555  }
1556 
1557  /* stuff done on every call of the function */
1558  funcctx = SRF_PERCALL_SETUP();
1559 
1560  /*
1561  * initialize per-call variables
1562  */
1563  call_cntr = funcctx->call_cntr;
1564  max_calls = funcctx->max_calls;
1565 
1566  results = (char **) funcctx->user_fctx;
1567  attinmeta = funcctx->attinmeta;
1568 
1569  if (call_cntr < max_calls) /* do when there is more left to send */
1570  {
1571  char **values;
1572  HeapTuple tuple;
1573  Datum result;
1574 
1575  values = (char **) palloc(2 * sizeof(char *));
1576  values[0] = psprintf("%d", call_cntr + 1);
1577  values[1] = results[call_cntr];
1578 
1579  /* build the tuple */
1580  tuple = BuildTupleFromCStrings(attinmeta, values);
1581 
1582  /* make the tuple into a datum */
1583  result = HeapTupleGetDatum(tuple);
1584 
1585  SRF_RETURN_NEXT(funcctx, result);
1586  }
1587  else
1588  {
1589  /* do when there is no more left */
1590  SRF_RETURN_DONE(funcctx);
1591  }
1592 }
1593 
1594 
1595 /*
1596  * dblink_build_sql_insert
1597  *
1598  * Used to generate an SQL insert statement
1599  * based on an existing tuple in a local relation.
1600  * This is useful for selectively replicating data
1601  * to another server via dblink.
1602  *
1603  * API:
1604  * <relname> - name of local table of interest
1605  * <pkattnums> - an int2vector of attnums which will be used
1606  * to identify the local tuple of interest
1607  * <pknumatts> - number of attnums in pkattnums
1608  * <src_pkattvals_arry> - text array of key values which will be used
1609  * to identify the local tuple of interest
1610  * <tgt_pkattvals_arry> - text array of key values which will be used
1611  * to build the string for execution remotely. These are substituted
1612  * for their counterparts in src_pkattvals_arry
1613  */
1615 Datum
1617 {
1618  text *relname_text = PG_GETARG_TEXT_PP(0);
1619  int2vector *pkattnums_arg = (int2vector *) PG_GETARG_POINTER(1);
1620  int32 pknumatts_arg = PG_GETARG_INT32(2);
1621  ArrayType *src_pkattvals_arry = PG_GETARG_ARRAYTYPE_P(3);
1622  ArrayType *tgt_pkattvals_arry = PG_GETARG_ARRAYTYPE_P(4);
1623  Relation rel;
1624  int *pkattnums;
1625  int pknumatts;
1626  char **src_pkattvals;
1627  char **tgt_pkattvals;
1628  int src_nitems;
1629  int tgt_nitems;
1630  char *sql;
1631 
1632  /*
1633  * Open target relation.
1634  */
1635  rel = get_rel_from_relname(relname_text, AccessShareLock, ACL_SELECT);
1636 
1637  /*
1638  * Process pkattnums argument.
1639  */
1640  validate_pkattnums(rel, pkattnums_arg, pknumatts_arg,
1641  &pkattnums, &pknumatts);
1642 
1643  /*
1644  * Source array is made up of key values that will be used to locate the
1645  * tuple of interest from the local system.
1646  */
1647  src_pkattvals = get_text_array_contents(src_pkattvals_arry, &src_nitems);
1648 
1649  /*
1650  * There should be one source array key value for each key attnum
1651  */
1652  if (src_nitems != pknumatts)
1653  ereport(ERROR,
1654  (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
1655  errmsg("source key array length must match number of key " \
1656  "attributes")));
1657 
1658  /*
1659  * Target array is made up of key values that will be used to build the
1660  * SQL string for use on the remote system.
1661  */
1662  tgt_pkattvals = get_text_array_contents(tgt_pkattvals_arry, &tgt_nitems);
1663 
1664  /*
1665  * There should be one target array key value for each key attnum
1666  */
1667  if (tgt_nitems != pknumatts)
1668  ereport(ERROR,
1669  (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
1670  errmsg("target key array length must match number of key " \
1671  "attributes")));
1672 
1673  /*
1674  * Prep work is finally done. Go get the SQL string.
1675  */
1676  sql = get_sql_insert(rel, pkattnums, pknumatts, src_pkattvals, tgt_pkattvals);
1677 
1678  /*
1679  * Now we can close the relation.
1680  */
1682 
1683  /*
1684  * And send it
1685  */
1687 }
1688 
1689 
1690 /*
1691  * dblink_build_sql_delete
1692  *
1693  * Used to generate an SQL delete statement.
1694  * This is useful for selectively replicating a
1695  * delete to another server via dblink.
1696  *
1697  * API:
1698  * <relname> - name of remote table of interest
1699  * <pkattnums> - an int2vector of attnums which will be used
1700  * to identify the remote tuple of interest
1701  * <pknumatts> - number of attnums in pkattnums
1702  * <tgt_pkattvals_arry> - text array of key values which will be used
1703  * to build the string for execution remotely.
1704  */
1706 Datum
1708 {
1709  text *relname_text = PG_GETARG_TEXT_PP(0);
1710  int2vector *pkattnums_arg = (int2vector *) PG_GETARG_POINTER(1);
1711  int32 pknumatts_arg = PG_GETARG_INT32(2);
1712  ArrayType *tgt_pkattvals_arry = PG_GETARG_ARRAYTYPE_P(3);
1713  Relation rel;
1714  int *pkattnums;
1715  int pknumatts;
1716  char **tgt_pkattvals;
1717  int tgt_nitems;
1718  char *sql;
1719 
1720  /*
1721  * Open target relation.
1722  */
1723  rel = get_rel_from_relname(relname_text, AccessShareLock, ACL_SELECT);
1724 
1725  /*
1726  * Process pkattnums argument.
1727  */
1728  validate_pkattnums(rel, pkattnums_arg, pknumatts_arg,
1729  &pkattnums, &pknumatts);
1730 
1731  /*
1732  * Target array is made up of key values that will be used to build the
1733  * SQL string for use on the remote system.
1734  */
1735  tgt_pkattvals = get_text_array_contents(tgt_pkattvals_arry, &tgt_nitems);
1736 
1737  /*
1738  * There should be one target array key value for each key attnum
1739  */
1740  if (tgt_nitems != pknumatts)
1741  ereport(ERROR,
1742  (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
1743  errmsg("target key array length must match number of key " \
1744  "attributes")));
1745 
1746  /*
1747  * Prep work is finally done. Go get the SQL string.
1748  */
1749  sql = get_sql_delete(rel, pkattnums, pknumatts, tgt_pkattvals);
1750 
1751  /*
1752  * Now we can close the relation.
1753  */
1755 
1756  /*
1757  * And send it
1758  */
1760 }
1761 
1762 
1763 /*
1764  * dblink_build_sql_update
1765  *
1766  * Used to generate an SQL update statement
1767  * based on an existing tuple in a local relation.
1768  * This is useful for selectively replicating data
1769  * to another server via dblink.
1770  *
1771  * API:
1772  * <relname> - name of local table of interest
1773  * <pkattnums> - an int2vector of attnums which will be used
1774  * to identify the local tuple of interest
1775  * <pknumatts> - number of attnums in pkattnums
1776  * <src_pkattvals_arry> - text array of key values which will be used
1777  * to identify the local tuple of interest
1778  * <tgt_pkattvals_arry> - text array of key values which will be used
1779  * to build the string for execution remotely. These are substituted
1780  * for their counterparts in src_pkattvals_arry
1781  */
1783 Datum
1785 {
1786  text *relname_text = PG_GETARG_TEXT_PP(0);
1787  int2vector *pkattnums_arg = (int2vector *) PG_GETARG_POINTER(1);
1788  int32 pknumatts_arg = PG_GETARG_INT32(2);
1789  ArrayType *src_pkattvals_arry = PG_GETARG_ARRAYTYPE_P(3);
1790  ArrayType *tgt_pkattvals_arry = PG_GETARG_ARRAYTYPE_P(4);
1791  Relation rel;
1792  int *pkattnums;
1793  int pknumatts;
1794  char **src_pkattvals;
1795  char **tgt_pkattvals;
1796  int src_nitems;
1797  int tgt_nitems;
1798  char *sql;
1799 
1800  /*
1801  * Open target relation.
1802  */
1803  rel = get_rel_from_relname(relname_text, AccessShareLock, ACL_SELECT);
1804 
1805  /*
1806  * Process pkattnums argument.
1807  */
1808  validate_pkattnums(rel, pkattnums_arg, pknumatts_arg,
1809  &pkattnums, &pknumatts);
1810 
1811  /*
1812  * Source array is made up of key values that will be used to locate the
1813  * tuple of interest from the local system.
1814  */
1815  src_pkattvals = get_text_array_contents(src_pkattvals_arry, &src_nitems);
1816 
1817  /*
1818  * There should be one source array key value for each key attnum
1819  */
1820  if (src_nitems != pknumatts)
1821  ereport(ERROR,
1822  (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
1823  errmsg("source key array length must match number of key " \
1824  "attributes")));
1825 
1826  /*
1827  * Target array is made up of key values that will be used to build the
1828  * SQL string for use on the remote system.
1829  */
1830  tgt_pkattvals = get_text_array_contents(tgt_pkattvals_arry, &tgt_nitems);
1831 
1832  /*
1833  * There should be one target array key value for each key attnum
1834  */
1835  if (tgt_nitems != pknumatts)
1836  ereport(ERROR,
1837  (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
1838  errmsg("target key array length must match number of key " \
1839  "attributes")));
1840 
1841  /*
1842  * Prep work is finally done. Go get the SQL string.
1843  */
1844  sql = get_sql_update(rel, pkattnums, pknumatts, src_pkattvals, tgt_pkattvals);
1845 
1846  /*
1847  * Now we can close the relation.
1848  */
1850 
1851  /*
1852  * And send it
1853  */
1855 }
1856 
1857 /*
1858  * dblink_current_query
1859  * return the current query string
1860  * to allow its use in (among other things)
1861  * rewrite rules
1862  */
1864 Datum
1866 {
1867  /* This is now just an alias for the built-in function current_query() */
1868  PG_RETURN_DATUM(current_query(fcinfo));
1869 }
1870 
1871 /*
1872  * Retrieve async notifications for a connection.
1873  *
1874  * Returns a setof record of notifications, or an empty set if none received.
1875  * Can optionally take a named connection as parameter, but uses the unnamed
1876  * connection per default.
1877  *
1878  */
1879 #define DBLINK_NOTIFY_COLS 3
1880 
1882 Datum
1884 {
1885  PGconn *conn;
1886  PGnotify *notify;
1887  ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
1888  TupleDesc tupdesc;
1889  Tuplestorestate *tupstore;
1890  MemoryContext per_query_ctx;
1891  MemoryContext oldcontext;
1892 
1893  prepTuplestoreResult(fcinfo);
1894 
1895  dblink_init();
1896  if (PG_NARGS() == 1)
1898  else
1899  conn = pconn->conn;
1900 
1901  /* create the tuplestore in per-query memory */
1902  per_query_ctx = rsinfo->econtext->ecxt_per_query_memory;
1903  oldcontext = MemoryContextSwitchTo(per_query_ctx);
1904 
1905  tupdesc = CreateTemplateTupleDesc(DBLINK_NOTIFY_COLS, false);
1906  TupleDescInitEntry(tupdesc, (AttrNumber) 1, "notify_name",
1907  TEXTOID, -1, 0);
1908  TupleDescInitEntry(tupdesc, (AttrNumber) 2, "be_pid",
1909  INT4OID, -1, 0);
1910  TupleDescInitEntry(tupdesc, (AttrNumber) 3, "extra",
1911  TEXTOID, -1, 0);
1912 
1913  tupstore = tuplestore_begin_heap(true, false, work_mem);
1914  rsinfo->setResult = tupstore;
1915  rsinfo->setDesc = tupdesc;
1916 
1917  MemoryContextSwitchTo(oldcontext);
1918 
1919  PQconsumeInput(conn);
1920  while ((notify = PQnotifies(conn)) != NULL)
1921  {
1923  bool nulls[DBLINK_NOTIFY_COLS];
1924 
1925  memset(values, 0, sizeof(values));
1926  memset(nulls, 0, sizeof(nulls));
1927 
1928  if (notify->relname != NULL)
1929  values[0] = CStringGetTextDatum(notify->relname);
1930  else
1931  nulls[0] = true;
1932 
1933  values[1] = Int32GetDatum(notify->be_pid);
1934 
1935  if (notify->extra != NULL)
1936  values[2] = CStringGetTextDatum(notify->extra);
1937  else
1938  nulls[2] = true;
1939 
1940  tuplestore_putvalues(tupstore, tupdesc, values, nulls);
1941 
1942  PQfreemem(notify);
1943  PQconsumeInput(conn);
1944  }
1945 
1946  /* clean up and return the tuplestore */
1947  tuplestore_donestoring(tupstore);
1948 
1949  return (Datum) 0;
1950 }
1951 
1952 /*
1953  * Validate the options given to a dblink foreign server or user mapping.
1954  * Raise an error if any option is invalid.
1955  *
1956  * We just check the names of options here, so semantic errors in options,
1957  * such as invalid numeric format, will be detected at the attempt to connect.
1958  */
1960 Datum
1962 {
1963  List *options_list = untransformRelOptions(PG_GETARG_DATUM(0));
1964  Oid context = PG_GETARG_OID(1);
1965  ListCell *cell;
1966 
1967  static const PQconninfoOption *options = NULL;
1968 
1969  /*
1970  * Get list of valid libpq options.
1971  *
1972  * To avoid unnecessary work, we get the list once and use it throughout
1973  * the lifetime of this backend process. We don't need to care about
1974  * memory context issues, because PQconndefaults allocates with malloc.
1975  */
1976  if (!options)
1977  {
1978  options = PQconndefaults();
1979  if (!options) /* assume reason for failure is OOM */
1980  ereport(ERROR,
1981  (errcode(ERRCODE_FDW_OUT_OF_MEMORY),
1982  errmsg("out of memory"),
1983  errdetail("could not get libpq's default connection options")));
1984  }
1985 
1986  /* Validate each supplied option. */
1987  foreach(cell, options_list)
1988  {
1989  DefElem *def = (DefElem *) lfirst(cell);
1990 
1991  if (!is_valid_dblink_option(options, def->defname, context))
1992  {
1993  /*
1994  * Unknown option, or invalid option for the context specified, so
1995  * complain about it. Provide a hint with list of valid options
1996  * for the context.
1997  */
1999  const PQconninfoOption *opt;
2000 
2001  initStringInfo(&buf);
2002  for (opt = options; opt->keyword; opt++)
2003  {
2004  if (is_valid_dblink_option(options, opt->keyword, context))
2005  appendStringInfo(&buf, "%s%s",
2006  (buf.len > 0) ? ", " : "",
2007  opt->keyword);
2008  }
2009  ereport(ERROR,
2010  (errcode(ERRCODE_FDW_OPTION_NAME_NOT_FOUND),
2011  errmsg("invalid option \"%s\"", def->defname),
2012  errhint("Valid options in this context are: %s",
2013  buf.data)));
2014  }
2015  }
2016 
2017  PG_RETURN_VOID();
2018 }
2019 
2020 
2021 /*************************************************************
2022  * internal functions
2023  */
2024 
2025 
2026 /*
2027  * get_pkey_attnames
2028  *
2029  * Get the primary key attnames for the given relation.
2030  * Return NULL, and set numatts = 0, if no primary key exists.
2031  */
2032 static char **
2034 {
2035  Relation indexRelation;
2036  ScanKeyData skey;
2037  SysScanDesc scan;
2038  HeapTuple indexTuple;
2039  int i;
2040  char **result = NULL;
2041  TupleDesc tupdesc;
2042 
2043  /* initialize numatts to 0 in case no primary key exists */
2044  *numatts = 0;
2045 
2046  tupdesc = rel->rd_att;
2047 
2048  /* Prepare to scan pg_index for entries having indrelid = this rel. */
2049  indexRelation = heap_open(IndexRelationId, AccessShareLock);
2050  ScanKeyInit(&skey,
2052  BTEqualStrategyNumber, F_OIDEQ,
2054 
2055  scan = systable_beginscan(indexRelation, IndexIndrelidIndexId, true,
2056  NULL, 1, &skey);
2057 
2058  while (HeapTupleIsValid(indexTuple = systable_getnext(scan)))
2059  {
2060  Form_pg_index index = (Form_pg_index) GETSTRUCT(indexTuple);
2061 
2062  /* we're only interested if it is the primary key */
2063  if (index->indisprimary)
2064  {
2065  *numatts = index->indnatts;
2066  if (*numatts > 0)
2067  {
2068  result = (char **) palloc(*numatts * sizeof(char *));
2069 
2070  for (i = 0; i < *numatts; i++)
2071  result[i] = SPI_fname(tupdesc, index->indkey.values[i]);
2072  }
2073  break;
2074  }
2075  }
2076 
2077  systable_endscan(scan);
2078  heap_close(indexRelation, AccessShareLock);
2079 
2080  return result;
2081 }
2082 
2083 /*
2084  * Deconstruct a text[] into C-strings (note any NULL elements will be
2085  * returned as NULL pointers)
2086  */
2087 static char **
2088 get_text_array_contents(ArrayType *array, int *numitems)
2089 {
2090  int ndim = ARR_NDIM(array);
2091  int *dims = ARR_DIMS(array);
2092  int nitems;
2093  int16 typlen;
2094  bool typbyval;
2095  char typalign;
2096  char **values;
2097  char *ptr;
2098  bits8 *bitmap;
2099  int bitmask;
2100  int i;
2101 
2102  Assert(ARR_ELEMTYPE(array) == TEXTOID);
2103 
2104  *numitems = nitems = ArrayGetNItems(ndim, dims);
2105 
2107  &typlen, &typbyval, &typalign);
2108 
2109  values = (char **) palloc(nitems * sizeof(char *));
2110 
2111  ptr = ARR_DATA_PTR(array);
2112  bitmap = ARR_NULLBITMAP(array);
2113  bitmask = 1;
2114 
2115  for (i = 0; i < nitems; i++)
2116  {
2117  if (bitmap && (*bitmap & bitmask) == 0)
2118  {
2119  values[i] = NULL;
2120  }
2121  else
2122  {
2123  values[i] = TextDatumGetCString(PointerGetDatum(ptr));
2124  ptr = att_addlength_pointer(ptr, typlen, ptr);
2125  ptr = (char *) att_align_nominal(ptr, typalign);
2126  }
2127 
2128  /* advance bitmap pointer if any */
2129  if (bitmap)
2130  {
2131  bitmask <<= 1;
2132  if (bitmask == 0x100)
2133  {
2134  bitmap++;
2135  bitmask = 1;
2136  }
2137  }
2138  }
2139 
2140  return values;
2141 }
2142 
2143 static char *
2144 get_sql_insert(Relation rel, int *pkattnums, int pknumatts, char **src_pkattvals, char **tgt_pkattvals)
2145 {
2146  char *relname;
2147  HeapTuple tuple;
2148  TupleDesc tupdesc;
2149  int natts;
2151  char *val;
2152  int key;
2153  int i;
2154  bool needComma;
2155 
2156  initStringInfo(&buf);
2157 
2158  /* get relation name including any needed schema prefix and quoting */
2159  relname = generate_relation_name(rel);
2160 
2161  tupdesc = rel->rd_att;
2162  natts = tupdesc->natts;
2163 
2164  tuple = get_tuple_of_interest(rel, pkattnums, pknumatts, src_pkattvals);
2165  if (!tuple)
2166  ereport(ERROR,
2167  (errcode(ERRCODE_CARDINALITY_VIOLATION),
2168  errmsg("source row not found")));
2169 
2170  appendStringInfo(&buf, "INSERT INTO %s(", relname);
2171 
2172  needComma = false;
2173  for (i = 0; i < natts; i++)
2174  {
2175  Form_pg_attribute att = TupleDescAttr(tupdesc, i);
2176 
2177  if (att->attisdropped)
2178  continue;
2179 
2180  if (needComma)
2181  appendStringInfoChar(&buf, ',');
2182 
2184  quote_ident_cstr(NameStr(att->attname)));
2185  needComma = true;
2186  }
2187 
2188  appendStringInfoString(&buf, ") VALUES(");
2189 
2190  /*
2191  * Note: i is physical column number (counting from 0).
2192  */
2193  needComma = false;
2194  for (i = 0; i < natts; i++)
2195  {
2196  if (TupleDescAttr(tupdesc, i)->attisdropped)
2197  continue;
2198 
2199  if (needComma)
2200  appendStringInfoChar(&buf, ',');
2201 
2202  key = get_attnum_pk_pos(pkattnums, pknumatts, i);
2203 
2204  if (key >= 0)
2205  val = tgt_pkattvals[key] ? pstrdup(tgt_pkattvals[key]) : NULL;
2206  else
2207  val = SPI_getvalue(tuple, tupdesc, i + 1);
2208 
2209  if (val != NULL)
2210  {
2212  pfree(val);
2213  }
2214  else
2215  appendStringInfoString(&buf, "NULL");
2216  needComma = true;
2217  }
2218  appendStringInfoChar(&buf, ')');
2219 
2220  return buf.data;
2221 }
2222 
2223 static char *
2224 get_sql_delete(Relation rel, int *pkattnums, int pknumatts, char **tgt_pkattvals)
2225 {
2226  char *relname;
2227  TupleDesc tupdesc;
2229  int i;
2230 
2231  initStringInfo(&buf);
2232 
2233  /* get relation name including any needed schema prefix and quoting */
2234  relname = generate_relation_name(rel);
2235 
2236  tupdesc = rel->rd_att;
2237 
2238  appendStringInfo(&buf, "DELETE FROM %s WHERE ", relname);
2239  for (i = 0; i < pknumatts; i++)
2240  {
2241  int pkattnum = pkattnums[i];
2242  Form_pg_attribute attr = TupleDescAttr(tupdesc, pkattnum);
2243 
2244  if (i > 0)
2245  appendStringInfoString(&buf, " AND ");
2246 
2248  quote_ident_cstr(NameStr(attr->attname)));
2249 
2250  if (tgt_pkattvals[i] != NULL)
2251  appendStringInfo(&buf, " = %s",
2252  quote_literal_cstr(tgt_pkattvals[i]));
2253  else
2254  appendStringInfoString(&buf, " IS NULL");
2255  }
2256 
2257  return buf.data;
2258 }
2259 
2260 static char *
2261 get_sql_update(Relation rel, int *pkattnums, int pknumatts, char **src_pkattvals, char **tgt_pkattvals)
2262 {
2263  char *relname;
2264  HeapTuple tuple;
2265  TupleDesc tupdesc;
2266  int natts;
2268  char *val;
2269  int key;
2270  int i;
2271  bool needComma;
2272 
2273  initStringInfo(&buf);
2274 
2275  /* get relation name including any needed schema prefix and quoting */
2276  relname = generate_relation_name(rel);
2277 
2278  tupdesc = rel->rd_att;
2279  natts = tupdesc->natts;
2280 
2281  tuple = get_tuple_of_interest(rel, pkattnums, pknumatts, src_pkattvals);
2282  if (!tuple)
2283  ereport(ERROR,
2284  (errcode(ERRCODE_CARDINALITY_VIOLATION),
2285  errmsg("source row not found")));
2286 
2287  appendStringInfo(&buf, "UPDATE %s SET ", relname);
2288 
2289  /*
2290  * Note: i is physical column number (counting from 0).
2291  */
2292  needComma = false;
2293  for (i = 0; i < natts; i++)
2294  {
2295  Form_pg_attribute attr = TupleDescAttr(tupdesc, i);
2296 
2297  if (attr->attisdropped)
2298  continue;
2299 
2300  if (needComma)
2301  appendStringInfoString(&buf, ", ");
2302 
2303  appendStringInfo(&buf, "%s = ",
2304  quote_ident_cstr(NameStr(attr->attname)));
2305 
2306  key = get_attnum_pk_pos(pkattnums, pknumatts, i);
2307 
2308  if (key >= 0)
2309  val = tgt_pkattvals[key] ? pstrdup(tgt_pkattvals[key]) : NULL;
2310  else
2311  val = SPI_getvalue(tuple, tupdesc, i + 1);
2312 
2313  if (val != NULL)
2314  {
2316  pfree(val);
2317  }
2318  else
2319  appendStringInfoString(&buf, "NULL");
2320  needComma = true;
2321  }
2322 
2323  appendStringInfoString(&buf, " WHERE ");
2324 
2325  for (i = 0; i < pknumatts; i++)
2326  {
2327  int pkattnum = pkattnums[i];
2328  Form_pg_attribute attr = TupleDescAttr(tupdesc, pkattnum);
2329 
2330  if (i > 0)
2331  appendStringInfoString(&buf, " AND ");
2332 
2334  quote_ident_cstr(NameStr(attr->attname)));
2335 
2336  val = tgt_pkattvals[i];
2337 
2338  if (val != NULL)
2339  appendStringInfo(&buf, " = %s", quote_literal_cstr(val));
2340  else
2341  appendStringInfoString(&buf, " IS NULL");
2342  }
2343 
2344  return buf.data;
2345 }
2346 
2347 /*
2348  * Return a properly quoted identifier.
2349  * Uses quote_ident in quote.c
2350  */
2351 static char *
2352 quote_ident_cstr(char *rawstr)
2353 {
2354  text *rawstr_text;
2355  text *result_text;
2356  char *result;
2357 
2358  rawstr_text = cstring_to_text(rawstr);
2360  PointerGetDatum(rawstr_text)));
2361  result = text_to_cstring(result_text);
2362 
2363  return result;
2364 }
2365 
2366 static int
2367 get_attnum_pk_pos(int *pkattnums, int pknumatts, int key)
2368 {
2369  int i;
2370 
2371  /*
2372  * Not likely a long list anyway, so just scan for the value
2373  */
2374  for (i = 0; i < pknumatts; i++)
2375  if (key == pkattnums[i])
2376  return i;
2377 
2378  return -1;
2379 }
2380 
2381 static HeapTuple
2382 get_tuple_of_interest(Relation rel, int *pkattnums, int pknumatts, char **src_pkattvals)
2383 {
2384  char *relname;
2385  TupleDesc tupdesc;
2386  int natts;
2388  int ret;
2389  HeapTuple tuple;
2390  int i;
2391 
2392  /*
2393  * Connect to SPI manager
2394  */
2395  if ((ret = SPI_connect()) < 0)
2396  /* internal error */
2397  elog(ERROR, "SPI connect failure - returned %d", ret);
2398 
2399  initStringInfo(&buf);
2400 
2401  /* get relation name including any needed schema prefix and quoting */
2402  relname = generate_relation_name(rel);
2403 
2404  tupdesc = rel->rd_att;
2405  natts = tupdesc->natts;
2406 
2407  /*
2408  * Build sql statement to look up tuple of interest, ie, the one matching
2409  * src_pkattvals. We used to use "SELECT *" here, but it's simpler to
2410  * generate a result tuple that matches the table's physical structure,
2411  * with NULLs for any dropped columns. Otherwise we have to deal with two
2412  * different tupdescs and everything's very confusing.
2413  */
2414  appendStringInfoString(&buf, "SELECT ");
2415 
2416  for (i = 0; i < natts; i++)
2417  {
2418  Form_pg_attribute attr = TupleDescAttr(tupdesc, i);
2419 
2420  if (i > 0)
2421  appendStringInfoString(&buf, ", ");
2422 
2423  if (attr->attisdropped)
2424  appendStringInfoString(&buf, "NULL");
2425  else
2427  quote_ident_cstr(NameStr(attr->attname)));
2428  }
2429 
2430  appendStringInfo(&buf, " FROM %s WHERE ", relname);
2431 
2432  for (i = 0; i < pknumatts; i++)
2433  {
2434  int pkattnum = pkattnums[i];
2435  Form_pg_attribute attr = TupleDescAttr(tupdesc, pkattnum);
2436 
2437  if (i > 0)
2438  appendStringInfoString(&buf, " AND ");
2439 
2441  quote_ident_cstr(NameStr(attr->attname)));
2442 
2443  if (src_pkattvals[i] != NULL)
2444  appendStringInfo(&buf, " = %s",
2445  quote_literal_cstr(src_pkattvals[i]));
2446  else
2447  appendStringInfoString(&buf, " IS NULL");
2448  }
2449 
2450  /*
2451  * Retrieve the desired tuple
2452  */
2453  ret = SPI_exec(buf.data, 0);
2454  pfree(buf.data);
2455 
2456  /*
2457  * Only allow one qualifying tuple
2458  */
2459  if ((ret == SPI_OK_SELECT) && (SPI_processed > 1))
2460  ereport(ERROR,
2461  (errcode(ERRCODE_CARDINALITY_VIOLATION),
2462  errmsg("source criteria matched more than one record")));
2463 
2464  else if (ret == SPI_OK_SELECT && SPI_processed == 1)
2465  {
2466  SPITupleTable *tuptable = SPI_tuptable;
2467 
2468  tuple = SPI_copytuple(tuptable->vals[0]);
2469  SPI_finish();
2470 
2471  return tuple;
2472  }
2473  else
2474  {
2475  /*
2476  * no qualifying tuples
2477  */
2478  SPI_finish();
2479 
2480  return NULL;
2481  }
2482 
2483  /*
2484  * never reached, but keep compiler quiet
2485  */
2486  return NULL;
2487 }
2488 
2489 /*
2490  * Open the relation named by relname_text, acquire specified type of lock,
2491  * verify we have specified permissions.
2492  * Caller must close rel when done with it.
2493  */
2494 static Relation
2495 get_rel_from_relname(text *relname_text, LOCKMODE lockmode, AclMode aclmode)
2496 {
2497  RangeVar *relvar;
2498  Relation rel;
2499  AclResult aclresult;
2500 
2501  relvar = makeRangeVarFromNameList(textToQualifiedNameList(relname_text));
2502  rel = heap_openrv(relvar, lockmode);
2503 
2504  aclresult = pg_class_aclcheck(RelationGetRelid(rel), GetUserId(),
2505  aclmode);
2506  if (aclresult != ACLCHECK_OK)
2507  aclcheck_error(aclresult, ACL_KIND_CLASS,
2509 
2510  return rel;
2511 }
2512 
2513 /*
2514  * generate_relation_name - copied from ruleutils.c
2515  * Compute the name to display for a relation
2516  *
2517  * The result includes all necessary quoting and schema-prefixing.
2518  */
2519 static char *
2521 {
2522  char *nspname;
2523  char *result;
2524 
2525  /* Qualify the name if not visible in search path */
2527  nspname = NULL;
2528  else
2529  nspname = get_namespace_name(rel->rd_rel->relnamespace);
2530 
2531  result = quote_qualified_identifier(nspname, RelationGetRelationName(rel));
2532 
2533  return result;
2534 }
2535 
2536 
2537 static remoteConn *
2539 {
2540  remoteConnHashEnt *hentry;
2541  char *key;
2542 
2543  if (!remoteConnHash)
2544  remoteConnHash = createConnHash();
2545 
2546  key = pstrdup(name);
2547  truncate_identifier(key, strlen(key), false);
2548  hentry = (remoteConnHashEnt *) hash_search(remoteConnHash,
2549  key, HASH_FIND, NULL);
2550 
2551  if (hentry)
2552  return hentry->rconn;
2553 
2554  return NULL;
2555 }
2556 
2557 static HTAB *
2559 {
2560  HASHCTL ctl;
2561 
2562  ctl.keysize = NAMEDATALEN;
2563  ctl.entrysize = sizeof(remoteConnHashEnt);
2564 
2565  return hash_create("Remote Con hash", NUMCONN, &ctl, HASH_ELEM);
2566 }
2567 
2568 static void
2570 {
2571  remoteConnHashEnt *hentry;
2572  bool found;
2573  char *key;
2574 
2575  if (!remoteConnHash)
2576  remoteConnHash = createConnHash();
2577 
2578  key = pstrdup(name);
2579  truncate_identifier(key, strlen(key), true);
2580  hentry = (remoteConnHashEnt *) hash_search(remoteConnHash, key,
2581  HASH_ENTER, &found);
2582 
2583  if (found)
2584  {
2585  PQfinish(rconn->conn);
2586  pfree(rconn);
2587 
2588  ereport(ERROR,
2590  errmsg("duplicate connection name")));
2591  }
2592 
2593  hentry->rconn = rconn;
2594  strlcpy(hentry->name, name, sizeof(hentry->name));
2595 }
2596 
2597 static void
2599 {
2600  remoteConnHashEnt *hentry;
2601  bool found;
2602  char *key;
2603 
2604  if (!remoteConnHash)
2605  remoteConnHash = createConnHash();
2606 
2607  key = pstrdup(name);
2608  truncate_identifier(key, strlen(key), false);
2609  hentry = (remoteConnHashEnt *) hash_search(remoteConnHash,
2610  key, HASH_REMOVE, &found);
2611 
2612  if (!hentry)
2613  ereport(ERROR,
2614  (errcode(ERRCODE_UNDEFINED_OBJECT),
2615  errmsg("undefined connection name")));
2616 
2617 }
2618 
2619 static void
2621 {
2622  if (!superuser())
2623  {
2624  if (!PQconnectionUsedPassword(conn))
2625  {
2626  PQfinish(conn);
2627  if (rconn)
2628  pfree(rconn);
2629 
2630  ereport(ERROR,
2631  (errcode(ERRCODE_S_R_E_PROHIBITED_SQL_STATEMENT_ATTEMPTED),
2632  errmsg("password is required"),
2633  errdetail("Non-superuser cannot connect if the server does not request a password."),
2634  errhint("Target server's authentication method must be changed.")));
2635  }
2636  }
2637 }
2638 
2639 /*
2640  * For non-superusers, insist that the connstr specify a password. This
2641  * prevents a password from being picked up from .pgpass, a service file,
2642  * the environment, etc. We don't want the postgres user's passwords
2643  * to be accessible to non-superusers.
2644  */
2645 static void
2647 {
2648  if (!superuser())
2649  {
2652  bool connstr_gives_password = false;
2653 
2654  options = PQconninfoParse(connstr, NULL);
2655  if (options)
2656  {
2657  for (option = options; option->keyword != NULL; option++)
2658  {
2659  if (strcmp(option->keyword, "password") == 0)
2660  {
2661  if (option->val != NULL && option->val[0] != '\0')
2662  {
2663  connstr_gives_password = true;
2664  break;
2665  }
2666  }
2667  }
2668  PQconninfoFree(options);
2669  }
2670 
2671  if (!connstr_gives_password)
2672  ereport(ERROR,
2673  (errcode(ERRCODE_S_R_E_PROHIBITED_SQL_STATEMENT_ATTEMPTED),
2674  errmsg("password is required"),
2675  errdetail("Non-superusers must provide a password in the connection string.")));
2676  }
2677 }
2678 
2679 static void
2680 dblink_res_error(PGconn *conn, const char *conname, PGresult *res,
2681  const char *dblink_context_msg, bool fail)
2682 {
2683  int level;
2684  char *pg_diag_sqlstate = PQresultErrorField(res, PG_DIAG_SQLSTATE);
2685  char *pg_diag_message_primary = PQresultErrorField(res, PG_DIAG_MESSAGE_PRIMARY);
2686  char *pg_diag_message_detail = PQresultErrorField(res, PG_DIAG_MESSAGE_DETAIL);
2687  char *pg_diag_message_hint = PQresultErrorField(res, PG_DIAG_MESSAGE_HINT);
2688  char *pg_diag_context = PQresultErrorField(res, PG_DIAG_CONTEXT);
2689  int sqlstate;
2690  char *message_primary;
2691  char *message_detail;
2692  char *message_hint;
2693  char *message_context;
2694  const char *dblink_context_conname = "unnamed";
2695 
2696  if (fail)
2697  level = ERROR;
2698  else
2699  level = NOTICE;
2700 
2701  if (pg_diag_sqlstate)
2702  sqlstate = MAKE_SQLSTATE(pg_diag_sqlstate[0],
2703  pg_diag_sqlstate[1],
2704  pg_diag_sqlstate[2],
2705  pg_diag_sqlstate[3],
2706  pg_diag_sqlstate[4]);
2707  else
2708  sqlstate = ERRCODE_CONNECTION_FAILURE;
2709 
2710  message_primary = xpstrdup(pg_diag_message_primary);
2711  message_detail = xpstrdup(pg_diag_message_detail);
2712  message_hint = xpstrdup(pg_diag_message_hint);
2713  message_context = xpstrdup(pg_diag_context);
2714 
2715  /*
2716  * If we don't get a message from the PGresult, try the PGconn. This is
2717  * needed because for connection-level failures, PQexec may just return
2718  * NULL, not a PGresult at all.
2719  */
2720  if (message_primary == NULL)
2721  message_primary = pchomp(PQerrorMessage(conn));
2722 
2723  if (res)
2724  PQclear(res);
2725 
2726  if (conname)
2727  dblink_context_conname = conname;
2728 
2729  ereport(level,
2730  (errcode(sqlstate),
2731  message_primary ? errmsg_internal("%s", message_primary) :
2732  errmsg("could not obtain message string for remote error"),
2733  message_detail ? errdetail_internal("%s", message_detail) : 0,
2734  message_hint ? errhint("%s", message_hint) : 0,
2735  message_context ? errcontext("%s", message_context) : 0,
2736  errcontext("Error occurred on dblink connection named \"%s\": %s.",
2737  dblink_context_conname, dblink_context_msg)));
2738 }
2739 
2740 /*
2741  * Obtain connection string for a foreign server
2742  */
2743 static char *
2744 get_connect_string(const char *servername)
2745 {
2746  ForeignServer *foreign_server = NULL;
2747  UserMapping *user_mapping;
2748  ListCell *cell;
2750  ForeignDataWrapper *fdw;
2751  AclResult aclresult;
2752  char *srvname;
2753 
2754  static const PQconninfoOption *options = NULL;
2755 
2756  initStringInfo(&buf);
2757 
2758  /*
2759  * Get list of valid libpq options.
2760  *
2761  * To avoid unnecessary work, we get the list once and use it throughout
2762  * the lifetime of this backend process. We don't need to care about
2763  * memory context issues, because PQconndefaults allocates with malloc.
2764  */
2765  if (!options)
2766  {
2767  options = PQconndefaults();
2768  if (!options) /* assume reason for failure is OOM */
2769  ereport(ERROR,
2770  (errcode(ERRCODE_FDW_OUT_OF_MEMORY),
2771  errmsg("out of memory"),
2772  errdetail("could not get libpq's default connection options")));
2773  }
2774 
2775  /* first gather the server connstr options */
2776  srvname = pstrdup(servername);
2777  truncate_identifier(srvname, strlen(srvname), false);
2778  foreign_server = GetForeignServerByName(srvname, true);
2779 
2780  if (foreign_server)
2781  {
2782  Oid serverid = foreign_server->serverid;
2783  Oid fdwid = foreign_server->fdwid;
2784  Oid userid = GetUserId();
2785 
2786  user_mapping = GetUserMapping(userid, serverid);
2787  fdw = GetForeignDataWrapper(fdwid);
2788 
2789  /* Check permissions, user must have usage on the server. */
2790  aclresult = pg_foreign_server_aclcheck(serverid, userid, ACL_USAGE);
2791  if (aclresult != ACLCHECK_OK)
2792  aclcheck_error(aclresult, ACL_KIND_FOREIGN_SERVER, foreign_server->servername);
2793 
2794  foreach(cell, fdw->options)
2795  {
2796  DefElem *def = lfirst(cell);
2797 
2799  appendStringInfo(&buf, "%s='%s' ", def->defname,
2800  escape_param_str(strVal(def->arg)));
2801  }
2802 
2803  foreach(cell, foreign_server->options)
2804  {
2805  DefElem *def = lfirst(cell);
2806 
2808  appendStringInfo(&buf, "%s='%s' ", def->defname,
2809  escape_param_str(strVal(def->arg)));
2810  }
2811 
2812  foreach(cell, user_mapping->options)
2813  {
2814 
2815  DefElem *def = lfirst(cell);
2816 
2818  appendStringInfo(&buf, "%s='%s' ", def->defname,
2819  escape_param_str(strVal(def->arg)));
2820  }
2821 
2822  return buf.data;
2823  }
2824  else
2825  return NULL;
2826 }
2827 
2828 /*
2829  * Escaping libpq connect parameter strings.
2830  *
2831  * Replaces "'" with "\'" and "\" with "\\".
2832  */
2833 static char *
2834 escape_param_str(const char *str)
2835 {
2836  const char *cp;
2838 
2839  initStringInfo(&buf);
2840 
2841  for (cp = str; *cp; cp++)
2842  {
2843  if (*cp == '\\' || *cp == '\'')
2844  appendStringInfoChar(&buf, '\\');
2845  appendStringInfoChar(&buf, *cp);
2846  }
2847 
2848  return buf.data;
2849 }
2850 
2851 /*
2852  * Validate the PK-attnums argument for dblink_build_sql_insert() and related
2853  * functions, and translate to the internal representation.
2854  *
2855  * The user supplies an int2vector of 1-based logical attnums, plus a count
2856  * argument (the need for the separate count argument is historical, but we
2857  * still check it). We check that each attnum corresponds to a valid,
2858  * non-dropped attribute of the rel. We do *not* prevent attnums from being
2859  * listed twice, though the actual use-case for such things is dubious.
2860  * Note that before Postgres 9.0, the user's attnums were interpreted as
2861  * physical not logical column numbers; this was changed for future-proofing.
2862  *
2863  * The internal representation is a palloc'd int array of 0-based physical
2864  * attnums.
2865  */
2866 static void
2868  int2vector *pkattnums_arg, int32 pknumatts_arg,
2869  int **pkattnums, int *pknumatts)
2870 {
2871  TupleDesc tupdesc = rel->rd_att;
2872  int natts = tupdesc->natts;
2873  int i;
2874 
2875  /* Don't take more array elements than there are */
2876  pknumatts_arg = Min(pknumatts_arg, pkattnums_arg->dim1);
2877 
2878  /* Must have at least one pk attnum selected */
2879  if (pknumatts_arg <= 0)
2880  ereport(ERROR,
2881  (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
2882  errmsg("number of key attributes must be > 0")));
2883 
2884  /* Allocate output array */
2885  *pkattnums = (int *) palloc(pknumatts_arg * sizeof(int));
2886  *pknumatts = pknumatts_arg;
2887 
2888  /* Validate attnums and convert to internal form */
2889  for (i = 0; i < pknumatts_arg; i++)
2890  {
2891  int pkattnum = pkattnums_arg->values[i];
2892  int lnum;
2893  int j;
2894 
2895  /* Can throw error immediately if out of range */
2896  if (pkattnum <= 0 || pkattnum > natts)
2897  ereport(ERROR,
2898  (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
2899  errmsg("invalid attribute number %d", pkattnum)));
2900 
2901  /* Identify which physical column has this logical number */
2902  lnum = 0;
2903  for (j = 0; j < natts; j++)
2904  {
2905  /* dropped columns don't count */
2906  if (TupleDescAttr(tupdesc, j)->attisdropped)
2907  continue;
2908 
2909  if (++lnum == pkattnum)
2910  break;
2911  }
2912 
2913  if (j < natts)
2914  (*pkattnums)[i] = j;
2915  else
2916  ereport(ERROR,
2917  (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
2918  errmsg("invalid attribute number %d", pkattnum)));
2919  }
2920 }
2921 
2922 /*
2923  * Check if the specified connection option is valid.
2924  *
2925  * We basically allow whatever libpq thinks is an option, with these
2926  * restrictions:
2927  * debug options: disallowed
2928  * "client_encoding": disallowed
2929  * "user": valid only in USER MAPPING options
2930  * secure options (eg password): valid only in USER MAPPING options
2931  * others: valid only in FOREIGN SERVER options
2932  *
2933  * We disallow client_encoding because it would be overridden anyway via
2934  * PQclientEncoding; allowing it to be specified would merely promote
2935  * confusion.
2936  */
2937 static bool
2939  Oid context)
2940 {
2941  const PQconninfoOption *opt;
2942 
2943  /* Look up the option in libpq result */
2944  for (opt = options; opt->keyword; opt++)
2945  {
2946  if (strcmp(opt->keyword, option) == 0)
2947  break;
2948  }
2949  if (opt->keyword == NULL)
2950  return false;
2951 
2952  /* Disallow debug options (particularly "replication") */
2953  if (strchr(opt->dispchar, 'D'))
2954  return false;
2955 
2956  /* Disallow "client_encoding" */
2957  if (strcmp(opt->keyword, "client_encoding") == 0)
2958  return false;
2959 
2960  /*
2961  * If the option is "user" or marked secure, it should be specified only
2962  * in USER MAPPING. Others should be specified only in SERVER.
2963  */
2964  if (strcmp(opt->keyword, "user") == 0 || strchr(opt->dispchar, '*'))
2965  {
2966  if (context != UserMappingRelationId)
2967  return false;
2968  }
2969  else
2970  {
2971  if (context != ForeignServerRelationId)
2972  return false;
2973  }
2974 
2975  return true;
2976 }
2977 
2978 /*
2979  * Copy the remote session's values of GUCs that affect datatype I/O
2980  * and apply them locally in a new GUC nesting level. Returns the new
2981  * nestlevel (which is needed by restoreLocalGucs to undo the settings),
2982  * or -1 if no new nestlevel was needed.
2983  *
2984  * We use the equivalent of a function SET option to allow the settings to
2985  * persist only until the caller calls restoreLocalGucs. If an error is
2986  * thrown in between, guc.c will take care of undoing the settings.
2987  */
2988 static int
2990 {
2991  static const char *const GUCsAffectingIO[] = {
2992  "DateStyle",
2993  "IntervalStyle"
2994  };
2995 
2996  int nestlevel = -1;
2997  int i;
2998 
2999  for (i = 0; i < lengthof(GUCsAffectingIO); i++)
3000  {
3001  const char *gucName = GUCsAffectingIO[i];
3002  const char *remoteVal = PQparameterStatus(conn, gucName);
3003  const char *localVal;
3004 
3005  /*
3006  * If the remote server is pre-8.4, it won't have IntervalStyle, but
3007  * that's okay because its output format won't be ambiguous. So just
3008  * skip the GUC if we don't get a value for it. (We might eventually
3009  * need more complicated logic with remote-version checks here.)
3010  */
3011  if (remoteVal == NULL)
3012  continue;
3013 
3014  /*
3015  * Avoid GUC-setting overhead if the remote and local GUCs already
3016  * have the same value.
3017  */
3018  localVal = GetConfigOption(gucName, false, false);
3019  Assert(localVal != NULL);
3020 
3021  if (strcmp(remoteVal, localVal) == 0)
3022  continue;
3023 
3024  /* Create new GUC nest level if we didn't already */
3025  if (nestlevel < 0)
3026  nestlevel = NewGUCNestLevel();
3027 
3028  /* Apply the option (this will throw error on failure) */
3029  (void) set_config_option(gucName, remoteVal,
3031  GUC_ACTION_SAVE, true, 0, false);
3032  }
3033 
3034  return nestlevel;
3035 }
3036 
3037 /*
3038  * Restore local GUCs after they have been overlaid with remote settings.
3039  */
3040 static void
3041 restoreLocalGucs(int nestlevel)
3042 {
3043  /* Do nothing if no new nestlevel was created */
3044  if (nestlevel > 0)
3045  AtEOXact_GUC(true, nestlevel);
3046 }
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Definition: tuplestore.c:750
const char * GetConfigOption(const char *name, bool missing_ok, bool restrict_superuser)
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Definition: lockdefs.h:26
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Size entrysize
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Definition: spi.c:41
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MemoryContext ecxt_per_query_memory
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#define ARR_NDIM(a)
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Definition: encode.c:521
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Definition: aclchk.c:4422
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Definition: execnodes.h:273
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Definition: bootstrap.c:164
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ExprContext * econtext
Definition: execnodes.h:266
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Definition: fe-connect.c:3906
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Definition: postgres.h:485
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Definition: guc.c:5075
FunctionCallInfo fcinfo
Definition: dblink.c:75
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Definition: execnodes.h:274
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Definition: mcxt.c:848
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Definition: namespace.c:682
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Definition: foreign.h:50
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PGresult * last_res
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Definition: elog.h:164
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Definition: c.h:493
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Definition: scankey.c:76
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Definition: foreign.c:166
#define CStringGetTextDatum(s)
Definition: builtins.h:91
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Definition: fe-exec.c:1897
Definition: c.h:433
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Definition: fmgr.h:158
char * defname
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Definition: miscadmin.h:98
#define elog
Definition: elog.h:219
static void static void status(const char *fmt,...) pg_attribute_printf(1
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Definition: fe-exec.c:3143
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Definition: fe-connect.c:6044
#define PG_TRY()
Definition: elog.h:284
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Definition: guc.c:5918
Definition: pg_list.h:45
List * options
Definition: foreign.h:53
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Definition: array.h:273
int16 AttrNumber
Definition: attnum.h:21
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Definition: fe-exec.c:3251
#define RelationGetRelid(relation)
Definition: rel.h:416
#define ARR_NULLBITMAP(a)
Definition: array.h:281
long val
Definition: informix.c:689
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Definition: fe-exec.c:1753
Oid serverid
Definition: foreign.h:47
#define PG_RETURN_NULL()
Definition: fmgr.h:305
#define PG_END_TRY()
Definition: elog.h:300
#define BTEqualStrategyNumber
Definition: stratnum.h:31
#define IndexIndrelidIndexId
Definition: indexing.h:162
uint64 max_calls
Definition: funcapi.h:74
#define PG_DIAG_CONTEXT
Definition: postgres_ext.h:64
PGconn * PQconnectdb(const char *conninfo)
Definition: fe-connect.c:585
#define SRF_RETURN_DONE(_funcctx)
Definition: funcapi.h:309
static char * connstr
Definition: pg_dumpall.c:64
#define SRF_FIRSTCALL_INIT()
Definition: funcapi.h:287