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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 
64 #include "dblink.h"
65 
67 
68 typedef struct remoteConn
69 {
70  PGconn *conn; /* Hold the remote connection */
71  int openCursorCount; /* The number of open cursors */
72  bool newXactForCursor; /* Opened a transaction for a cursor */
73 } remoteConn;
74 
75 typedef struct storeInfo
76 {
81  char **cstrs;
82  /* temp storage for results to avoid leaks on exception */
85 } storeInfo;
86 
87 /*
88  * Internal declarations
89  */
90 static Datum dblink_record_internal(FunctionCallInfo fcinfo, bool is_async);
91 static void prepTuplestoreResult(FunctionCallInfo fcinfo);
92 static void materializeResult(FunctionCallInfo fcinfo, PGconn *conn,
93  PGresult *res);
94 static void materializeQueryResult(FunctionCallInfo fcinfo,
95  PGconn *conn,
96  const char *conname,
97  const char *sql,
98  bool fail);
99 static PGresult *storeQueryResult(volatile storeInfo *sinfo, PGconn *conn, const char *sql);
100 static void storeRow(volatile storeInfo *sinfo, PGresult *res, bool first);
101 static remoteConn *getConnectionByName(const char *name);
102 static HTAB *createConnHash(void);
103 static void createNewConnection(const char *name, remoteConn *rconn);
104 static void deleteConnection(const char *name);
105 static char **get_pkey_attnames(Relation rel, int16 *numatts);
106 static char **get_text_array_contents(ArrayType *array, int *numitems);
107 static char *get_sql_insert(Relation rel, int *pkattnums, int pknumatts, char **src_pkattvals, char **tgt_pkattvals);
108 static char *get_sql_delete(Relation rel, int *pkattnums, int pknumatts, char **tgt_pkattvals);
109 static char *get_sql_update(Relation rel, int *pkattnums, int pknumatts, char **src_pkattvals, char **tgt_pkattvals);
110 static char *quote_ident_cstr(char *rawstr);
111 static int get_attnum_pk_pos(int *pkattnums, int pknumatts, int key);
112 static HeapTuple get_tuple_of_interest(Relation rel, int *pkattnums, int pknumatts, char **src_pkattvals);
113 static Relation get_rel_from_relname(text *relname_text, LOCKMODE lockmode, AclMode aclmode);
114 static char *generate_relation_name(Relation rel);
115 static void dblink_connstr_check(const char *connstr);
116 static void dblink_security_check(PGconn *conn, remoteConn *rconn);
117 static void dblink_res_error(PGconn *conn, const char *conname, PGresult *res,
118  const char *dblink_context_msg, bool fail);
119 static char *get_connect_string(const char *servername);
120 static char *escape_param_str(const char *from);
121 static void validate_pkattnums(Relation rel,
122  int2vector *pkattnums_arg, int32 pknumatts_arg,
123  int **pkattnums, int *pknumatts);
125  const char *option, Oid context);
126 static int applyRemoteGucs(PGconn *conn);
127 static void restoreLocalGucs(int nestlevel);
128 
129 /* Global */
132 
133 /*
134  * Following is list that holds multiple remote connections.
135  * Calling convention of each dblink function changes to accept
136  * connection name as the first parameter. The connection list is
137  * much like ecpg e.g. a mapping between a name and a PGconn object.
138  */
139 
140 typedef struct remoteConnHashEnt
141 {
145 
146 /* initial number of connection hashes */
147 #define NUMCONN 16
148 
149 /* general utility */
150 #define xpfree(var_) \
151  do { \
152  if (var_ != NULL) \
153  { \
154  pfree(var_); \
155  var_ = NULL; \
156  } \
157  } while (0)
158 
159 #define xpstrdup(var_c, var_) \
160  do { \
161  if (var_ != NULL) \
162  var_c = pstrdup(var_); \
163  else \
164  var_c = NULL; \
165  } while (0)
166 
167 #define DBLINK_RES_INTERNALERROR(p2) \
168  do { \
169  msg = pstrdup(PQerrorMessage(conn)); \
170  if (res) \
171  PQclear(res); \
172  elog(ERROR, "%s: %s", p2, msg); \
173  } while (0)
174 
175 #define DBLINK_CONN_NOT_AVAIL \
176  do { \
177  if(conname) \
178  ereport(ERROR, \
179  (errcode(ERRCODE_CONNECTION_DOES_NOT_EXIST), \
180  errmsg("connection \"%s\" not available", conname))); \
181  else \
182  ereport(ERROR, \
183  (errcode(ERRCODE_CONNECTION_DOES_NOT_EXIST), \
184  errmsg("connection not available"))); \
185  } while (0)
186 
187 #define DBLINK_GET_CONN \
188  do { \
189  char *conname_or_str = text_to_cstring(PG_GETARG_TEXT_PP(0)); \
190  rconn = getConnectionByName(conname_or_str); \
191  if (rconn) \
192  { \
193  conn = rconn->conn; \
194  conname = conname_or_str; \
195  } \
196  else \
197  { \
198  connstr = get_connect_string(conname_or_str); \
199  if (connstr == NULL) \
200  { \
201  connstr = conname_or_str; \
202  } \
203  dblink_connstr_check(connstr); \
204  conn = PQconnectdb(connstr); \
205  if (PQstatus(conn) == CONNECTION_BAD) \
206  { \
207  msg = pstrdup(PQerrorMessage(conn)); \
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()) \
216  PQsetClientEncoding(conn, GetDatabaseEncodingName()); \
217  freeconn = true; \
218  } \
219  } while (0)
220 
221 #define DBLINK_GET_NAMED_CONN \
222  do { \
223  conname = text_to_cstring(PG_GETARG_TEXT_PP(0)); \
224  rconn = getConnectionByName(conname); \
225  if (rconn) \
226  conn = rconn->conn; \
227  else \
228  DBLINK_CONN_NOT_AVAIL; \
229  } while (0)
230 
231 #define DBLINK_INIT \
232  do { \
233  if (!pconn) \
234  { \
235  pconn = (remoteConn *) MemoryContextAlloc(TopMemoryContext, sizeof(remoteConn)); \
236  pconn->conn = NULL; \
237  pconn->openCursorCount = 0; \
238  pconn->newXactForCursor = FALSE; \
239  } \
240  } while (0)
241 
242 /*
243  * Create a persistent connection to another database
244  */
246 Datum
248 {
249  char *conname_or_str = NULL;
250  char *connstr = NULL;
251  char *connname = NULL;
252  char *msg;
253  PGconn *conn = NULL;
254  remoteConn *rconn = NULL;
255 
256  DBLINK_INIT;
257 
258  if (PG_NARGS() == 2)
259  {
260  conname_or_str = text_to_cstring(PG_GETARG_TEXT_PP(1));
261  connname = text_to_cstring(PG_GETARG_TEXT_PP(0));
262  }
263  else if (PG_NARGS() == 1)
264  conname_or_str = text_to_cstring(PG_GETARG_TEXT_PP(0));
265 
266  if (connname)
268  sizeof(remoteConn));
269 
270  /* first check for valid foreign data server */
271  connstr = get_connect_string(conname_or_str);
272  if (connstr == NULL)
273  connstr = conname_or_str;
274 
275  /* check password in connection string if not superuser */
276  dblink_connstr_check(connstr);
277  conn = PQconnectdb(connstr);
278 
279  if (PQstatus(conn) == CONNECTION_BAD)
280  {
281  msg = pstrdup(PQerrorMessage(conn));
282  PQfinish(conn);
283  if (rconn)
284  pfree(rconn);
285 
286  ereport(ERROR,
287  (errcode(ERRCODE_SQLCLIENT_UNABLE_TO_ESTABLISH_SQLCONNECTION),
288  errmsg("could not establish connection"),
289  errdetail_internal("%s", msg)));
290  }
291 
292  /* check password actually used if not superuser */
293  dblink_security_check(conn, rconn);
294 
295  /* attempt to set client encoding to match server encoding, if needed */
296  if (PQclientEncoding(conn) != GetDatabaseEncoding())
298 
299  if (connname)
300  {
301  rconn->conn = conn;
302  createNewConnection(connname, rconn);
303  }
304  else
305  pconn->conn = conn;
306 
308 }
309 
310 /*
311  * Clear a persistent connection to another database
312  */
314 Datum
316 {
317  char *conname = NULL;
318  remoteConn *rconn = NULL;
319  PGconn *conn = NULL;
320 
321  DBLINK_INIT;
322 
323  if (PG_NARGS() == 1)
324  {
325  conname = text_to_cstring(PG_GETARG_TEXT_PP(0));
326  rconn = getConnectionByName(conname);
327  if (rconn)
328  conn = rconn->conn;
329  }
330  else
331  conn = pconn->conn;
332 
333  if (!conn)
335 
336  PQfinish(conn);
337  if (rconn)
338  {
339  deleteConnection(conname);
340  pfree(rconn);
341  }
342  else
343  pconn->conn = NULL;
344 
346 }
347 
348 /*
349  * opens a cursor using a persistent connection
350  */
352 Datum
354 {
355  char *msg;
356  PGresult *res = NULL;
357  PGconn *conn = NULL;
358  char *curname = NULL;
359  char *sql = NULL;
360  char *conname = NULL;
362  remoteConn *rconn = NULL;
363  bool fail = true; /* default to backward compatible behavior */
364 
365  DBLINK_INIT;
366  initStringInfo(&buf);
367 
368  if (PG_NARGS() == 2)
369  {
370  /* text,text */
371  curname = text_to_cstring(PG_GETARG_TEXT_PP(0));
373  rconn = pconn;
374  }
375  else if (PG_NARGS() == 3)
376  {
377  /* might be text,text,text or text,text,bool */
378  if (get_fn_expr_argtype(fcinfo->flinfo, 2) == BOOLOID)
379  {
380  curname = text_to_cstring(PG_GETARG_TEXT_PP(0));
382  fail = PG_GETARG_BOOL(2);
383  rconn = pconn;
384  }
385  else
386  {
387  conname = text_to_cstring(PG_GETARG_TEXT_PP(0));
388  curname = text_to_cstring(PG_GETARG_TEXT_PP(1));
390  rconn = getConnectionByName(conname);
391  }
392  }
393  else if (PG_NARGS() == 4)
394  {
395  /* text,text,text,bool */
396  conname = text_to_cstring(PG_GETARG_TEXT_PP(0));
397  curname = text_to_cstring(PG_GETARG_TEXT_PP(1));
399  fail = PG_GETARG_BOOL(3);
400  rconn = getConnectionByName(conname);
401  }
402 
403  if (!rconn || !rconn->conn)
405  else
406  conn = rconn->conn;
407 
408  /* If we are not in a transaction, start one */
409  if (PQtransactionStatus(conn) == PQTRANS_IDLE)
410  {
411  res = PQexec(conn, "BEGIN");
412  if (PQresultStatus(res) != PGRES_COMMAND_OK)
413  DBLINK_RES_INTERNALERROR("begin error");
414  PQclear(res);
415  rconn->newXactForCursor = TRUE;
416 
417  /*
418  * Since transaction state was IDLE, we force cursor count to
419  * initially be 0. This is needed as a previous ABORT might have wiped
420  * out our transaction without maintaining the cursor count for us.
421  */
422  rconn->openCursorCount = 0;
423  }
424 
425  /* if we started a transaction, increment cursor count */
426  if (rconn->newXactForCursor)
427  (rconn->openCursorCount)++;
428 
429  appendStringInfo(&buf, "DECLARE %s CURSOR FOR %s", curname, sql);
430  res = PQexec(conn, buf.data);
431  if (!res || PQresultStatus(res) != PGRES_COMMAND_OK)
432  {
433  dblink_res_error(conn, conname, res, "could not open cursor", fail);
435  }
436 
437  PQclear(res);
439 }
440 
441 /*
442  * closes a cursor
443  */
445 Datum
447 {
448  PGconn *conn = NULL;
449  PGresult *res = NULL;
450  char *curname = NULL;
451  char *conname = NULL;
453  char *msg;
454  remoteConn *rconn = NULL;
455  bool fail = true; /* default to backward compatible behavior */
456 
457  DBLINK_INIT;
458  initStringInfo(&buf);
459 
460  if (PG_NARGS() == 1)
461  {
462  /* text */
463  curname = text_to_cstring(PG_GETARG_TEXT_PP(0));
464  rconn = pconn;
465  }
466  else if (PG_NARGS() == 2)
467  {
468  /* might be text,text or text,bool */
469  if (get_fn_expr_argtype(fcinfo->flinfo, 1) == BOOLOID)
470  {
471  curname = text_to_cstring(PG_GETARG_TEXT_PP(0));
472  fail = PG_GETARG_BOOL(1);
473  rconn = pconn;
474  }
475  else
476  {
477  conname = text_to_cstring(PG_GETARG_TEXT_PP(0));
478  curname = text_to_cstring(PG_GETARG_TEXT_PP(1));
479  rconn = getConnectionByName(conname);
480  }
481  }
482  if (PG_NARGS() == 3)
483  {
484  /* text,text,bool */
485  conname = text_to_cstring(PG_GETARG_TEXT_PP(0));
486  curname = text_to_cstring(PG_GETARG_TEXT_PP(1));
487  fail = PG_GETARG_BOOL(2);
488  rconn = getConnectionByName(conname);
489  }
490 
491  if (!rconn || !rconn->conn)
493  else
494  conn = rconn->conn;
495 
496  appendStringInfo(&buf, "CLOSE %s", curname);
497 
498  /* close the cursor */
499  res = PQexec(conn, buf.data);
500  if (!res || PQresultStatus(res) != PGRES_COMMAND_OK)
501  {
502  dblink_res_error(conn, conname, res, "could not close cursor", fail);
504  }
505 
506  PQclear(res);
507 
508  /* if we started a transaction, decrement cursor count */
509  if (rconn->newXactForCursor)
510  {
511  (rconn->openCursorCount)--;
512 
513  /* if count is zero, commit the transaction */
514  if (rconn->openCursorCount == 0)
515  {
516  rconn->newXactForCursor = FALSE;
517 
518  res = PQexec(conn, "COMMIT");
519  if (PQresultStatus(res) != PGRES_COMMAND_OK)
520  DBLINK_RES_INTERNALERROR("commit error");
521  PQclear(res);
522  }
523  }
524 
526 }
527 
528 /*
529  * Fetch results from an open cursor
530  */
532 Datum
534 {
535  PGresult *res = NULL;
536  char *conname = NULL;
537  remoteConn *rconn = NULL;
538  PGconn *conn = NULL;
540  char *curname = NULL;
541  int howmany = 0;
542  bool fail = true; /* default to backward compatible */
543 
544  prepTuplestoreResult(fcinfo);
545 
546  DBLINK_INIT;
547 
548  if (PG_NARGS() == 4)
549  {
550  /* text,text,int,bool */
551  conname = text_to_cstring(PG_GETARG_TEXT_PP(0));
552  curname = text_to_cstring(PG_GETARG_TEXT_PP(1));
553  howmany = PG_GETARG_INT32(2);
554  fail = PG_GETARG_BOOL(3);
555 
556  rconn = getConnectionByName(conname);
557  if (rconn)
558  conn = rconn->conn;
559  }
560  else if (PG_NARGS() == 3)
561  {
562  /* text,text,int or text,int,bool */
563  if (get_fn_expr_argtype(fcinfo->flinfo, 2) == BOOLOID)
564  {
565  curname = text_to_cstring(PG_GETARG_TEXT_PP(0));
566  howmany = PG_GETARG_INT32(1);
567  fail = PG_GETARG_BOOL(2);
568  conn = pconn->conn;
569  }
570  else
571  {
572  conname = text_to_cstring(PG_GETARG_TEXT_PP(0));
573  curname = text_to_cstring(PG_GETARG_TEXT_PP(1));
574  howmany = PG_GETARG_INT32(2);
575 
576  rconn = getConnectionByName(conname);
577  if (rconn)
578  conn = rconn->conn;
579  }
580  }
581  else if (PG_NARGS() == 2)
582  {
583  /* text,int */
584  curname = text_to_cstring(PG_GETARG_TEXT_PP(0));
585  howmany = PG_GETARG_INT32(1);
586  conn = pconn->conn;
587  }
588 
589  if (!conn)
591 
592  initStringInfo(&buf);
593  appendStringInfo(&buf, "FETCH %d FROM %s", howmany, curname);
594 
595  /*
596  * Try to execute the query. Note that since libpq uses malloc, the
597  * PGresult will be long-lived even though we are still in a short-lived
598  * memory context.
599  */
600  res = PQexec(conn, buf.data);
601  if (!res ||
602  (PQresultStatus(res) != PGRES_COMMAND_OK &&
604  {
605  dblink_res_error(conn, conname, res,
606  "could not fetch from cursor", fail);
607  return (Datum) 0;
608  }
609  else if (PQresultStatus(res) == PGRES_COMMAND_OK)
610  {
611  /* cursor does not exist - closed already or bad name */
612  PQclear(res);
613  ereport(ERROR,
614  (errcode(ERRCODE_INVALID_CURSOR_NAME),
615  errmsg("cursor \"%s\" does not exist", curname)));
616  }
617 
618  materializeResult(fcinfo, conn, res);
619  return (Datum) 0;
620 }
621 
622 /*
623  * Note: this is the new preferred version of dblink
624  */
626 Datum
628 {
629  return dblink_record_internal(fcinfo, false);
630 }
631 
633 Datum
635 {
636  char *conname = NULL;
637  PGconn *conn = NULL;
638  char *sql = NULL;
639  remoteConn *rconn = NULL;
640  int retval;
641 
642  if (PG_NARGS() == 2)
643  {
646  }
647  else
648  /* shouldn't happen */
649  elog(ERROR, "wrong number of arguments");
650 
651  /* async query send */
652  retval = PQsendQuery(conn, sql);
653  if (retval != 1)
654  elog(NOTICE, "could not send query: %s", PQerrorMessage(conn));
655 
656  PG_RETURN_INT32(retval);
657 }
658 
660 Datum
662 {
663  return dblink_record_internal(fcinfo, true);
664 }
665 
666 static Datum
668 {
669  PGconn *volatile conn = NULL;
670  volatile bool freeconn = false;
671 
672  prepTuplestoreResult(fcinfo);
673 
674  DBLINK_INIT;
675 
676  PG_TRY();
677  {
678  char *msg;
679  char *connstr = NULL;
680  char *sql = NULL;
681  char *conname = NULL;
682  remoteConn *rconn = NULL;
683  bool fail = true; /* default to backward compatible */
684 
685  if (!is_async)
686  {
687  if (PG_NARGS() == 3)
688  {
689  /* text,text,bool */
692  fail = PG_GETARG_BOOL(2);
693  }
694  else if (PG_NARGS() == 2)
695  {
696  /* text,text or text,bool */
697  if (get_fn_expr_argtype(fcinfo->flinfo, 1) == BOOLOID)
698  {
699  conn = pconn->conn;
701  fail = PG_GETARG_BOOL(1);
702  }
703  else
704  {
707  }
708  }
709  else if (PG_NARGS() == 1)
710  {
711  /* text */
712  conn = pconn->conn;
714  }
715  else
716  /* shouldn't happen */
717  elog(ERROR, "wrong number of arguments");
718  }
719  else /* is_async */
720  {
721  /* get async result */
722  if (PG_NARGS() == 2)
723  {
724  /* text,bool */
726  fail = PG_GETARG_BOOL(1);
727  }
728  else if (PG_NARGS() == 1)
729  {
730  /* text */
732  }
733  else
734  /* shouldn't happen */
735  elog(ERROR, "wrong number of arguments");
736  }
737 
738  if (!conn)
740 
741  if (!is_async)
742  {
743  /* synchronous query, use efficient tuple collection method */
744  materializeQueryResult(fcinfo, conn, conname, sql, fail);
745  }
746  else
747  {
748  /* async result retrieval, do it the old way */
749  PGresult *res = PQgetResult(conn);
750 
751  /* NULL means we're all done with the async results */
752  if (res)
753  {
754  if (PQresultStatus(res) != PGRES_COMMAND_OK &&
756  {
757  dblink_res_error(conn, conname, res,
758  "could not execute query", fail);
759  /* if fail isn't set, we'll return an empty query result */
760  }
761  else
762  {
763  materializeResult(fcinfo, conn, res);
764  }
765  }
766  }
767  }
768  PG_CATCH();
769  {
770  /* if needed, close the connection to the database */
771  if (freeconn)
772  PQfinish(conn);
773  PG_RE_THROW();
774  }
775  PG_END_TRY();
776 
777  /* if needed, close the connection to the database */
778  if (freeconn)
779  PQfinish(conn);
780 
781  return (Datum) 0;
782 }
783 
784 /*
785  * Verify function caller can handle a tuplestore result, and set up for that.
786  *
787  * Note: if the caller returns without actually creating a tuplestore, the
788  * executor will treat the function result as an empty set.
789  */
790 static void
792 {
793  ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
794 
795  /* check to see if query supports us returning a tuplestore */
796  if (rsinfo == NULL || !IsA(rsinfo, ReturnSetInfo))
797  ereport(ERROR,
798  (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
799  errmsg("set-valued function called in context that cannot accept a set")));
800  if (!(rsinfo->allowedModes & SFRM_Materialize))
801  ereport(ERROR,
802  (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
803  errmsg("materialize mode required, but it is not allowed in this context")));
804 
805  /* let the executor know we're sending back a tuplestore */
806  rsinfo->returnMode = SFRM_Materialize;
807 
808  /* caller must fill these to return a non-empty result */
809  rsinfo->setResult = NULL;
810  rsinfo->setDesc = NULL;
811 }
812 
813 /*
814  * Copy the contents of the PGresult into a tuplestore to be returned
815  * as the result of the current function.
816  * The PGresult will be released in this function.
817  */
818 static void
820 {
821  ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
822 
823  /* prepTuplestoreResult must have been called previously */
824  Assert(rsinfo->returnMode == SFRM_Materialize);
825 
826  PG_TRY();
827  {
828  TupleDesc tupdesc;
829  bool is_sql_cmd;
830  int ntuples;
831  int nfields;
832 
833  if (PQresultStatus(res) == PGRES_COMMAND_OK)
834  {
835  is_sql_cmd = true;
836 
837  /*
838  * need a tuple descriptor representing one TEXT column to return
839  * the command status string as our result tuple
840  */
841  tupdesc = CreateTemplateTupleDesc(1, false);
842  TupleDescInitEntry(tupdesc, (AttrNumber) 1, "status",
843  TEXTOID, -1, 0);
844  ntuples = 1;
845  nfields = 1;
846  }
847  else
848  {
850 
851  is_sql_cmd = false;
852 
853  /* get a tuple descriptor for our result type */
854  switch (get_call_result_type(fcinfo, NULL, &tupdesc))
855  {
856  case TYPEFUNC_COMPOSITE:
857  /* success */
858  break;
859  case TYPEFUNC_RECORD:
860  /* failed to determine actual type of RECORD */
861  ereport(ERROR,
862  (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
863  errmsg("function returning record called in context "
864  "that cannot accept type record")));
865  break;
866  default:
867  /* result type isn't composite */
868  elog(ERROR, "return type must be a row type");
869  break;
870  }
871 
872  /* make sure we have a persistent copy of the tupdesc */
873  tupdesc = CreateTupleDescCopy(tupdesc);
874  ntuples = PQntuples(res);
875  nfields = PQnfields(res);
876  }
877 
878  /*
879  * check result and tuple descriptor have the same number of columns
880  */
881  if (nfields != tupdesc->natts)
882  ereport(ERROR,
883  (errcode(ERRCODE_DATATYPE_MISMATCH),
884  errmsg("remote query result rowtype does not match "
885  "the specified FROM clause rowtype")));
886 
887  if (ntuples > 0)
888  {
889  AttInMetadata *attinmeta;
890  int nestlevel = -1;
891  Tuplestorestate *tupstore;
892  MemoryContext oldcontext;
893  int row;
894  char **values;
895 
896  attinmeta = TupleDescGetAttInMetadata(tupdesc);
897 
898  /* Set GUCs to ensure we read GUC-sensitive data types correctly */
899  if (!is_sql_cmd)
900  nestlevel = applyRemoteGucs(conn);
901 
902  oldcontext = MemoryContextSwitchTo(
904  tupstore = tuplestore_begin_heap(true, false, work_mem);
905  rsinfo->setResult = tupstore;
906  rsinfo->setDesc = tupdesc;
907  MemoryContextSwitchTo(oldcontext);
908 
909  values = (char **) palloc(nfields * sizeof(char *));
910 
911  /* put all tuples into the tuplestore */
912  for (row = 0; row < ntuples; row++)
913  {
914  HeapTuple tuple;
915 
916  if (!is_sql_cmd)
917  {
918  int i;
919 
920  for (i = 0; i < nfields; i++)
921  {
922  if (PQgetisnull(res, row, i))
923  values[i] = NULL;
924  else
925  values[i] = PQgetvalue(res, row, i);
926  }
927  }
928  else
929  {
930  values[0] = PQcmdStatus(res);
931  }
932 
933  /* build the tuple and put it into the tuplestore. */
934  tuple = BuildTupleFromCStrings(attinmeta, values);
935  tuplestore_puttuple(tupstore, tuple);
936  }
937 
938  /* clean up GUC settings, if we changed any */
939  restoreLocalGucs(nestlevel);
940 
941  /* clean up and return the tuplestore */
942  tuplestore_donestoring(tupstore);
943  }
944 
945  PQclear(res);
946  }
947  PG_CATCH();
948  {
949  /* be sure to release the libpq result */
950  PQclear(res);
951  PG_RE_THROW();
952  }
953  PG_END_TRY();
954 }
955 
956 /*
957  * Execute the given SQL command and store its results into a tuplestore
958  * to be returned as the result of the current function.
959  *
960  * This is equivalent to PQexec followed by materializeResult, but we make
961  * use of libpq's single-row mode to avoid accumulating the whole result
962  * inside libpq before it gets transferred to the tuplestore.
963  */
964 static void
966  PGconn *conn,
967  const char *conname,
968  const char *sql,
969  bool fail)
970 {
971  ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
972  PGresult *volatile res = NULL;
973  volatile storeInfo sinfo;
974 
975  /* prepTuplestoreResult must have been called previously */
976  Assert(rsinfo->returnMode == SFRM_Materialize);
977 
978  /* initialize storeInfo to empty */
979  memset((void *) &sinfo, 0, sizeof(sinfo));
980  sinfo.fcinfo = fcinfo;
981 
982  PG_TRY();
983  {
984  /* Create short-lived memory context for data conversions */
985  sinfo.tmpcontext = AllocSetContextCreate(CurrentMemoryContext,
986  "dblink temporary context",
988 
989  /* execute query, collecting any tuples into the tuplestore */
990  res = storeQueryResult(&sinfo, conn, sql);
991 
992  if (!res ||
993  (PQresultStatus(res) != PGRES_COMMAND_OK &&
995  {
996  /*
997  * dblink_res_error will clear the passed PGresult, so we need
998  * this ugly dance to avoid doing so twice during error exit
999  */
1000  PGresult *res1 = res;
1001 
1002  res = NULL;
1003  dblink_res_error(conn, conname, res1,
1004  "could not execute query", fail);
1005  /* if fail isn't set, we'll return an empty query result */
1006  }
1007  else if (PQresultStatus(res) == PGRES_COMMAND_OK)
1008  {
1009  /*
1010  * storeRow didn't get called, so we need to convert the command
1011  * status string to a tuple manually
1012  */
1013  TupleDesc tupdesc;
1014  AttInMetadata *attinmeta;
1015  Tuplestorestate *tupstore;
1016  HeapTuple tuple;
1017  char *values[1];
1018  MemoryContext oldcontext;
1019 
1020  /*
1021  * need a tuple descriptor representing one TEXT column to return
1022  * the command status string as our result tuple
1023  */
1024  tupdesc = CreateTemplateTupleDesc(1, false);
1025  TupleDescInitEntry(tupdesc, (AttrNumber) 1, "status",
1026  TEXTOID, -1, 0);
1027  attinmeta = TupleDescGetAttInMetadata(tupdesc);
1028 
1029  oldcontext = MemoryContextSwitchTo(
1030  rsinfo->econtext->ecxt_per_query_memory);
1031  tupstore = tuplestore_begin_heap(true, false, work_mem);
1032  rsinfo->setResult = tupstore;
1033  rsinfo->setDesc = tupdesc;
1034  MemoryContextSwitchTo(oldcontext);
1035 
1036  values[0] = PQcmdStatus(res);
1037 
1038  /* build the tuple and put it into the tuplestore. */
1039  tuple = BuildTupleFromCStrings(attinmeta, values);
1040  tuplestore_puttuple(tupstore, tuple);
1041 
1042  PQclear(res);
1043  res = NULL;
1044  }
1045  else
1046  {
1048  /* storeRow should have created a tuplestore */
1049  Assert(rsinfo->setResult != NULL);
1050 
1051  PQclear(res);
1052  res = NULL;
1053  }
1054 
1055  /* clean up data conversion short-lived memory context */
1056  if (sinfo.tmpcontext != NULL)
1057  MemoryContextDelete(sinfo.tmpcontext);
1058  sinfo.tmpcontext = NULL;
1059 
1060  PQclear(sinfo.last_res);
1061  sinfo.last_res = NULL;
1062  PQclear(sinfo.cur_res);
1063  sinfo.cur_res = NULL;
1064  }
1065  PG_CATCH();
1066  {
1067  /* be sure to release any libpq result we collected */
1068  PQclear(res);
1069  PQclear(sinfo.last_res);
1070  PQclear(sinfo.cur_res);
1071  /* and clear out any pending data in libpq */
1072  while ((res = PQgetResult(conn)) != NULL)
1073  PQclear(res);
1074  PG_RE_THROW();
1075  }
1076  PG_END_TRY();
1077 }
1078 
1079 /*
1080  * Execute query, and send any result rows to sinfo->tuplestore.
1081  */
1082 static PGresult *
1083 storeQueryResult(volatile storeInfo *sinfo, PGconn *conn, const char *sql)
1084 {
1085  bool first = true;
1086  int nestlevel = -1;
1087  PGresult *res;
1088 
1089  if (!PQsendQuery(conn, sql))
1090  elog(ERROR, "could not send query: %s", PQerrorMessage(conn));
1091 
1092  if (!PQsetSingleRowMode(conn)) /* shouldn't fail */
1093  elog(ERROR, "failed to set single-row mode for dblink query");
1094 
1095  for (;;)
1096  {
1098 
1099  sinfo->cur_res = PQgetResult(conn);
1100  if (!sinfo->cur_res)
1101  break;
1102 
1103  if (PQresultStatus(sinfo->cur_res) == PGRES_SINGLE_TUPLE)
1104  {
1105  /* got one row from possibly-bigger resultset */
1106 
1107  /*
1108  * Set GUCs to ensure we read GUC-sensitive data types correctly.
1109  * We shouldn't do this until we have a row in hand, to ensure
1110  * libpq has seen any earlier ParameterStatus protocol messages.
1111  */
1112  if (first && nestlevel < 0)
1113  nestlevel = applyRemoteGucs(conn);
1114 
1115  storeRow(sinfo, sinfo->cur_res, first);
1116 
1117  PQclear(sinfo->cur_res);
1118  sinfo->cur_res = NULL;
1119  first = false;
1120  }
1121  else
1122  {
1123  /* if empty resultset, fill tuplestore header */
1124  if (first && PQresultStatus(sinfo->cur_res) == PGRES_TUPLES_OK)
1125  storeRow(sinfo, sinfo->cur_res, first);
1126 
1127  /* store completed result at last_res */
1128  PQclear(sinfo->last_res);
1129  sinfo->last_res = sinfo->cur_res;
1130  sinfo->cur_res = NULL;
1131  first = true;
1132  }
1133  }
1134 
1135  /* clean up GUC settings, if we changed any */
1136  restoreLocalGucs(nestlevel);
1137 
1138  /* return last_res */
1139  res = sinfo->last_res;
1140  sinfo->last_res = NULL;
1141  return res;
1142 }
1143 
1144 /*
1145  * Send single row to sinfo->tuplestore.
1146  *
1147  * If "first" is true, create the tuplestore using PGresult's metadata
1148  * (in this case the PGresult might contain either zero or one row).
1149  */
1150 static void
1151 storeRow(volatile storeInfo *sinfo, PGresult *res, bool first)
1152 {
1153  int nfields = PQnfields(res);
1154  HeapTuple tuple;
1155  int i;
1156  MemoryContext oldcontext;
1157 
1158  if (first)
1159  {
1160  /* Prepare for new result set */
1161  ReturnSetInfo *rsinfo = (ReturnSetInfo *) sinfo->fcinfo->resultinfo;
1162  TupleDesc tupdesc;
1163 
1164  /*
1165  * It's possible to get more than one result set if the query string
1166  * contained multiple SQL commands. In that case, we follow PQexec's
1167  * traditional behavior of throwing away all but the last result.
1168  */
1169  if (sinfo->tuplestore)
1170  tuplestore_end(sinfo->tuplestore);
1171  sinfo->tuplestore = NULL;
1172 
1173  /* get a tuple descriptor for our result type */
1174  switch (get_call_result_type(sinfo->fcinfo, NULL, &tupdesc))
1175  {
1176  case TYPEFUNC_COMPOSITE:
1177  /* success */
1178  break;
1179  case TYPEFUNC_RECORD:
1180  /* failed to determine actual type of RECORD */
1181  ereport(ERROR,
1182  (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
1183  errmsg("function returning record called in context "
1184  "that cannot accept type record")));
1185  break;
1186  default:
1187  /* result type isn't composite */
1188  elog(ERROR, "return type must be a row type");
1189  break;
1190  }
1191 
1192  /* make sure we have a persistent copy of the tupdesc */
1193  tupdesc = CreateTupleDescCopy(tupdesc);
1194 
1195  /* check result and tuple descriptor have the same number of columns */
1196  if (nfields != tupdesc->natts)
1197  ereport(ERROR,
1198  (errcode(ERRCODE_DATATYPE_MISMATCH),
1199  errmsg("remote query result rowtype does not match "
1200  "the specified FROM clause rowtype")));
1201 
1202  /* Prepare attinmeta for later data conversions */
1203  sinfo->attinmeta = TupleDescGetAttInMetadata(tupdesc);
1204 
1205  /* Create a new, empty tuplestore */
1206  oldcontext = MemoryContextSwitchTo(rsinfo->econtext->ecxt_per_query_memory);
1207  sinfo->tuplestore = tuplestore_begin_heap(true, false, work_mem);
1208  rsinfo->setResult = sinfo->tuplestore;
1209  rsinfo->setDesc = tupdesc;
1210  MemoryContextSwitchTo(oldcontext);
1211 
1212  /* Done if empty resultset */
1213  if (PQntuples(res) == 0)
1214  return;
1215 
1216  /*
1217  * Set up sufficiently-wide string pointers array; this won't change
1218  * in size so it's easy to preallocate.
1219  */
1220  if (sinfo->cstrs)
1221  pfree(sinfo->cstrs);
1222  sinfo->cstrs = (char **) palloc(nfields * sizeof(char *));
1223  }
1224 
1225  /* Should have a single-row result if we get here */
1226  Assert(PQntuples(res) == 1);
1227 
1228  /*
1229  * Do the following work in a temp context that we reset after each tuple.
1230  * This cleans up not only the data we have direct access to, but any
1231  * cruft the I/O functions might leak.
1232  */
1233  oldcontext = MemoryContextSwitchTo(sinfo->tmpcontext);
1234 
1235  /*
1236  * Fill cstrs with null-terminated strings of column values.
1237  */
1238  for (i = 0; i < nfields; i++)
1239  {
1240  if (PQgetisnull(res, 0, i))
1241  sinfo->cstrs[i] = NULL;
1242  else
1243  sinfo->cstrs[i] = PQgetvalue(res, 0, i);
1244  }
1245 
1246  /* Convert row to a tuple, and add it to the tuplestore */
1247  tuple = BuildTupleFromCStrings(sinfo->attinmeta, sinfo->cstrs);
1248 
1249  tuplestore_puttuple(sinfo->tuplestore, tuple);
1250 
1251  /* Clean up */
1252  MemoryContextSwitchTo(oldcontext);
1254 }
1255 
1256 /*
1257  * List all open dblink connections by name.
1258  * Returns an array of all connection names.
1259  * Takes no params
1260  */
1262 Datum
1264 {
1266  remoteConnHashEnt *hentry;
1267  ArrayBuildState *astate = NULL;
1268 
1269  if (remoteConnHash)
1270  {
1271  hash_seq_init(&status, remoteConnHash);
1272  while ((hentry = (remoteConnHashEnt *) hash_seq_search(&status)) != NULL)
1273  {
1274  /* stash away current value */
1275  astate = accumArrayResult(astate,
1276  CStringGetTextDatum(hentry->name),
1277  false, TEXTOID, CurrentMemoryContext);
1278  }
1279  }
1280 
1281  if (astate)
1284  else
1285  PG_RETURN_NULL();
1286 }
1287 
1288 /*
1289  * Checks if a given remote connection is busy
1290  *
1291  * Returns 1 if the connection is busy, 0 otherwise
1292  * Params:
1293  * text connection_name - name of the connection to check
1294  *
1295  */
1297 Datum
1299 {
1300  char *conname = NULL;
1301  PGconn *conn = NULL;
1302  remoteConn *rconn = NULL;
1303 
1304  DBLINK_INIT;
1306 
1307  PQconsumeInput(conn);
1308  PG_RETURN_INT32(PQisBusy(conn));
1309 }
1310 
1311 /*
1312  * Cancels a running request on a connection
1313  *
1314  * Returns text:
1315  * "OK" if the cancel request has been sent correctly,
1316  * an error message otherwise
1317  *
1318  * Params:
1319  * text connection_name - name of the connection to check
1320  *
1321  */
1323 Datum
1325 {
1326  int res = 0;
1327  char *conname = NULL;
1328  PGconn *conn = NULL;
1329  remoteConn *rconn = NULL;
1330  PGcancel *cancel;
1331  char errbuf[256];
1332 
1333  DBLINK_INIT;
1335  cancel = PQgetCancel(conn);
1336 
1337  res = PQcancel(cancel, errbuf, 256);
1338  PQfreeCancel(cancel);
1339 
1340  if (res == 1)
1342  else
1344 }
1345 
1346 
1347 /*
1348  * Get error message from a connection
1349  *
1350  * Returns text:
1351  * "OK" if no error, an error message otherwise
1352  *
1353  * Params:
1354  * text connection_name - name of the connection to check
1355  *
1356  */
1358 Datum
1360 {
1361  char *msg;
1362  char *conname = NULL;
1363  PGconn *conn = NULL;
1364  remoteConn *rconn = NULL;
1365 
1366  DBLINK_INIT;
1368 
1369  msg = PQerrorMessage(conn);
1370  if (msg == NULL || msg[0] == '\0')
1372  else
1374 }
1375 
1376 /*
1377  * Execute an SQL non-SELECT command
1378  */
1380 Datum
1382 {
1383  text *volatile sql_cmd_status = NULL;
1384  PGconn *volatile conn = NULL;
1385  volatile bool freeconn = false;
1386 
1387  DBLINK_INIT;
1388 
1389  PG_TRY();
1390  {
1391  char *msg;
1392  PGresult *res = NULL;
1393  char *connstr = NULL;
1394  char *sql = NULL;
1395  char *conname = NULL;
1396  remoteConn *rconn = NULL;
1397  bool fail = true; /* default to backward compatible behavior */
1398 
1399  if (PG_NARGS() == 3)
1400  {
1401  /* must be text,text,bool */
1404  fail = PG_GETARG_BOOL(2);
1405  }
1406  else if (PG_NARGS() == 2)
1407  {
1408  /* might be text,text or text,bool */
1409  if (get_fn_expr_argtype(fcinfo->flinfo, 1) == BOOLOID)
1410  {
1411  conn = pconn->conn;
1413  fail = PG_GETARG_BOOL(1);
1414  }
1415  else
1416  {
1419  }
1420  }
1421  else if (PG_NARGS() == 1)
1422  {
1423  /* must be single text argument */
1424  conn = pconn->conn;
1426  }
1427  else
1428  /* shouldn't happen */
1429  elog(ERROR, "wrong number of arguments");
1430 
1431  if (!conn)
1433 
1434  res = PQexec(conn, sql);
1435  if (!res ||
1436  (PQresultStatus(res) != PGRES_COMMAND_OK &&
1438  {
1439  dblink_res_error(conn, conname, res,
1440  "could not execute command", fail);
1441 
1442  /*
1443  * and save a copy of the command status string to return as our
1444  * result tuple
1445  */
1446  sql_cmd_status = cstring_to_text("ERROR");
1447  }
1448  else if (PQresultStatus(res) == PGRES_COMMAND_OK)
1449  {
1450  /*
1451  * and save a copy of the command status string to return as our
1452  * result tuple
1453  */
1454  sql_cmd_status = cstring_to_text(PQcmdStatus(res));
1455  PQclear(res);
1456  }
1457  else
1458  {
1459  PQclear(res);
1460  ereport(ERROR,
1461  (errcode(ERRCODE_S_R_E_PROHIBITED_SQL_STATEMENT_ATTEMPTED),
1462  errmsg("statement returning results not allowed")));
1463  }
1464  }
1465  PG_CATCH();
1466  {
1467  /* if needed, close the connection to the database */
1468  if (freeconn)
1469  PQfinish(conn);
1470  PG_RE_THROW();
1471  }
1472  PG_END_TRY();
1473 
1474  /* if needed, close the connection to the database */
1475  if (freeconn)
1476  PQfinish(conn);
1477 
1478  PG_RETURN_TEXT_P(sql_cmd_status);
1479 }
1480 
1481 
1482 /*
1483  * dblink_get_pkey
1484  *
1485  * Return list of primary key fields for the supplied relation,
1486  * or NULL if none exists.
1487  */
1489 Datum
1491 {
1492  int16 numatts;
1493  char **results;
1494  FuncCallContext *funcctx;
1495  int32 call_cntr;
1496  int32 max_calls;
1497  AttInMetadata *attinmeta;
1498  MemoryContext oldcontext;
1499 
1500  /* stuff done only on the first call of the function */
1501  if (SRF_IS_FIRSTCALL())
1502  {
1503  Relation rel;
1504  TupleDesc tupdesc;
1505 
1506  /* create a function context for cross-call persistence */
1507  funcctx = SRF_FIRSTCALL_INIT();
1508 
1509  /*
1510  * switch to memory context appropriate for multiple function calls
1511  */
1512  oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
1513 
1514  /* open target relation */
1516 
1517  /* get the array of attnums */
1518  results = get_pkey_attnames(rel, &numatts);
1519 
1521 
1522  /*
1523  * need a tuple descriptor representing one INT and one TEXT column
1524  */
1525  tupdesc = CreateTemplateTupleDesc(2, false);
1526  TupleDescInitEntry(tupdesc, (AttrNumber) 1, "position",
1527  INT4OID, -1, 0);
1528  TupleDescInitEntry(tupdesc, (AttrNumber) 2, "colname",
1529  TEXTOID, -1, 0);
1530 
1531  /*
1532  * Generate attribute metadata needed later to produce tuples from raw
1533  * C strings
1534  */
1535  attinmeta = TupleDescGetAttInMetadata(tupdesc);
1536  funcctx->attinmeta = attinmeta;
1537 
1538  if ((results != NULL) && (numatts > 0))
1539  {
1540  funcctx->max_calls = numatts;
1541 
1542  /* got results, keep track of them */
1543  funcctx->user_fctx = results;
1544  }
1545  else
1546  {
1547  /* fast track when no results */
1548  MemoryContextSwitchTo(oldcontext);
1549  SRF_RETURN_DONE(funcctx);
1550  }
1551 
1552  MemoryContextSwitchTo(oldcontext);
1553  }
1554 
1555  /* stuff done on every call of the function */
1556  funcctx = SRF_PERCALL_SETUP();
1557 
1558  /*
1559  * initialize per-call variables
1560  */
1561  call_cntr = funcctx->call_cntr;
1562  max_calls = funcctx->max_calls;
1563 
1564  results = (char **) funcctx->user_fctx;
1565  attinmeta = funcctx->attinmeta;
1566 
1567  if (call_cntr < max_calls) /* do when there is more left to send */
1568  {
1569  char **values;
1570  HeapTuple tuple;
1571  Datum result;
1572 
1573  values = (char **) palloc(2 * sizeof(char *));
1574  values[0] = psprintf("%d", call_cntr + 1);
1575  values[1] = results[call_cntr];
1576 
1577  /* build the tuple */
1578  tuple = BuildTupleFromCStrings(attinmeta, values);
1579 
1580  /* make the tuple into a datum */
1581  result = HeapTupleGetDatum(tuple);
1582 
1583  SRF_RETURN_NEXT(funcctx, result);
1584  }
1585  else
1586  {
1587  /* do when there is no more left */
1588  SRF_RETURN_DONE(funcctx);
1589  }
1590 }
1591 
1592 
1593 /*
1594  * dblink_build_sql_insert
1595  *
1596  * Used to generate an SQL insert statement
1597  * based on an existing tuple in a local relation.
1598  * This is useful for selectively replicating data
1599  * to another server via dblink.
1600  *
1601  * API:
1602  * <relname> - name of local table of interest
1603  * <pkattnums> - an int2vector of attnums which will be used
1604  * to identify the local tuple of interest
1605  * <pknumatts> - number of attnums in pkattnums
1606  * <src_pkattvals_arry> - text array of key values which will be used
1607  * to identify the local tuple of interest
1608  * <tgt_pkattvals_arry> - text array of key values which will be used
1609  * to build the string for execution remotely. These are substituted
1610  * for their counterparts in src_pkattvals_arry
1611  */
1613 Datum
1615 {
1616  text *relname_text = PG_GETARG_TEXT_P(0);
1617  int2vector *pkattnums_arg = (int2vector *) PG_GETARG_POINTER(1);
1618  int32 pknumatts_arg = PG_GETARG_INT32(2);
1619  ArrayType *src_pkattvals_arry = PG_GETARG_ARRAYTYPE_P(3);
1620  ArrayType *tgt_pkattvals_arry = PG_GETARG_ARRAYTYPE_P(4);
1621  Relation rel;
1622  int *pkattnums;
1623  int pknumatts;
1624  char **src_pkattvals;
1625  char **tgt_pkattvals;
1626  int src_nitems;
1627  int tgt_nitems;
1628  char *sql;
1629 
1630  /*
1631  * Open target relation.
1632  */
1633  rel = get_rel_from_relname(relname_text, AccessShareLock, ACL_SELECT);
1634 
1635  /*
1636  * Process pkattnums argument.
1637  */
1638  validate_pkattnums(rel, pkattnums_arg, pknumatts_arg,
1639  &pkattnums, &pknumatts);
1640 
1641  /*
1642  * Source array is made up of key values that will be used to locate the
1643  * tuple of interest from the local system.
1644  */
1645  src_pkattvals = get_text_array_contents(src_pkattvals_arry, &src_nitems);
1646 
1647  /*
1648  * There should be one source array key value for each key attnum
1649  */
1650  if (src_nitems != pknumatts)
1651  ereport(ERROR,
1652  (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
1653  errmsg("source key array length must match number of key " \
1654  "attributes")));
1655 
1656  /*
1657  * Target array is made up of key values that will be used to build the
1658  * SQL string for use on the remote system.
1659  */
1660  tgt_pkattvals = get_text_array_contents(tgt_pkattvals_arry, &tgt_nitems);
1661 
1662  /*
1663  * There should be one target array key value for each key attnum
1664  */
1665  if (tgt_nitems != pknumatts)
1666  ereport(ERROR,
1667  (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
1668  errmsg("target key array length must match number of key " \
1669  "attributes")));
1670 
1671  /*
1672  * Prep work is finally done. Go get the SQL string.
1673  */
1674  sql = get_sql_insert(rel, pkattnums, pknumatts, src_pkattvals, tgt_pkattvals);
1675 
1676  /*
1677  * Now we can close the relation.
1678  */
1680 
1681  /*
1682  * And send it
1683  */
1685 }
1686 
1687 
1688 /*
1689  * dblink_build_sql_delete
1690  *
1691  * Used to generate an SQL delete statement.
1692  * This is useful for selectively replicating a
1693  * delete to another server via dblink.
1694  *
1695  * API:
1696  * <relname> - name of remote table of interest
1697  * <pkattnums> - an int2vector of attnums which will be used
1698  * to identify the remote tuple of interest
1699  * <pknumatts> - number of attnums in pkattnums
1700  * <tgt_pkattvals_arry> - text array of key values which will be used
1701  * to build the string for execution remotely.
1702  */
1704 Datum
1706 {
1707  text *relname_text = PG_GETARG_TEXT_P(0);
1708  int2vector *pkattnums_arg = (int2vector *) PG_GETARG_POINTER(1);
1709  int32 pknumatts_arg = PG_GETARG_INT32(2);
1710  ArrayType *tgt_pkattvals_arry = PG_GETARG_ARRAYTYPE_P(3);
1711  Relation rel;
1712  int *pkattnums;
1713  int pknumatts;
1714  char **tgt_pkattvals;
1715  int tgt_nitems;
1716  char *sql;
1717 
1718  /*
1719  * Open target relation.
1720  */
1721  rel = get_rel_from_relname(relname_text, AccessShareLock, ACL_SELECT);
1722 
1723  /*
1724  * Process pkattnums argument.
1725  */
1726  validate_pkattnums(rel, pkattnums_arg, pknumatts_arg,
1727  &pkattnums, &pknumatts);
1728 
1729  /*
1730  * Target array is made up of key values that will be used to build the
1731  * SQL string for use on the remote system.
1732  */
1733  tgt_pkattvals = get_text_array_contents(tgt_pkattvals_arry, &tgt_nitems);
1734 
1735  /*
1736  * There should be one target array key value for each key attnum
1737  */
1738  if (tgt_nitems != pknumatts)
1739  ereport(ERROR,
1740  (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
1741  errmsg("target key array length must match number of key " \
1742  "attributes")));
1743 
1744  /*
1745  * Prep work is finally done. Go get the SQL string.
1746  */
1747  sql = get_sql_delete(rel, pkattnums, pknumatts, tgt_pkattvals);
1748 
1749  /*
1750  * Now we can close the relation.
1751  */
1753 
1754  /*
1755  * And send it
1756  */
1758 }
1759 
1760 
1761 /*
1762  * dblink_build_sql_update
1763  *
1764  * Used to generate an SQL update statement
1765  * based on an existing tuple in a local relation.
1766  * This is useful for selectively replicating data
1767  * to another server via dblink.
1768  *
1769  * API:
1770  * <relname> - name of local table of interest
1771  * <pkattnums> - an int2vector of attnums which will be used
1772  * to identify the local tuple of interest
1773  * <pknumatts> - number of attnums in pkattnums
1774  * <src_pkattvals_arry> - text array of key values which will be used
1775  * to identify the local tuple of interest
1776  * <tgt_pkattvals_arry> - text array of key values which will be used
1777  * to build the string for execution remotely. These are substituted
1778  * for their counterparts in src_pkattvals_arry
1779  */
1781 Datum
1783 {
1784  text *relname_text = PG_GETARG_TEXT_P(0);
1785  int2vector *pkattnums_arg = (int2vector *) PG_GETARG_POINTER(1);
1786  int32 pknumatts_arg = PG_GETARG_INT32(2);
1787  ArrayType *src_pkattvals_arry = PG_GETARG_ARRAYTYPE_P(3);
1788  ArrayType *tgt_pkattvals_arry = PG_GETARG_ARRAYTYPE_P(4);
1789  Relation rel;
1790  int *pkattnums;
1791  int pknumatts;
1792  char **src_pkattvals;
1793  char **tgt_pkattvals;
1794  int src_nitems;
1795  int tgt_nitems;
1796  char *sql;
1797 
1798  /*
1799  * Open target relation.
1800  */
1801  rel = get_rel_from_relname(relname_text, AccessShareLock, ACL_SELECT);
1802 
1803  /*
1804  * Process pkattnums argument.
1805  */
1806  validate_pkattnums(rel, pkattnums_arg, pknumatts_arg,
1807  &pkattnums, &pknumatts);
1808 
1809  /*
1810  * Source array is made up of key values that will be used to locate the
1811  * tuple of interest from the local system.
1812  */
1813  src_pkattvals = get_text_array_contents(src_pkattvals_arry, &src_nitems);
1814 
1815  /*
1816  * There should be one source array key value for each key attnum
1817  */
1818  if (src_nitems != pknumatts)
1819  ereport(ERROR,
1820  (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
1821  errmsg("source key array length must match number of key " \
1822  "attributes")));
1823 
1824  /*
1825  * Target array is made up of key values that will be used to build the
1826  * SQL string for use on the remote system.
1827  */
1828  tgt_pkattvals = get_text_array_contents(tgt_pkattvals_arry, &tgt_nitems);
1829 
1830  /*
1831  * There should be one target array key value for each key attnum
1832  */
1833  if (tgt_nitems != pknumatts)
1834  ereport(ERROR,
1835  (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
1836  errmsg("target key array length must match number of key " \
1837  "attributes")));
1838 
1839  /*
1840  * Prep work is finally done. Go get the SQL string.
1841  */
1842  sql = get_sql_update(rel, pkattnums, pknumatts, src_pkattvals, tgt_pkattvals);
1843 
1844  /*
1845  * Now we can close the relation.
1846  */
1848 
1849  /*
1850  * And send it
1851  */
1853 }
1854 
1855 /*
1856  * dblink_current_query
1857  * return the current query string
1858  * to allow its use in (among other things)
1859  * rewrite rules
1860  */
1862 Datum
1864 {
1865  /* This is now just an alias for the built-in function current_query() */
1866  PG_RETURN_DATUM(current_query(fcinfo));
1867 }
1868 
1869 /*
1870  * Retrieve async notifications for a connection.
1871  *
1872  * Returns a setof record of notifications, or an empty set if none received.
1873  * Can optionally take a named connection as parameter, but uses the unnamed
1874  * connection per default.
1875  *
1876  */
1877 #define DBLINK_NOTIFY_COLS 3
1878 
1880 Datum
1882 {
1883  char *conname = NULL;
1884  PGconn *conn = NULL;
1885  remoteConn *rconn = NULL;
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  if (tupdesc->attrs[i]->attisdropped)
2176  continue;
2177 
2178  if (needComma)
2179  appendStringInfoChar(&buf, ',');
2180 
2182  quote_ident_cstr(NameStr(tupdesc->attrs[i]->attname)));
2183  needComma = true;
2184  }
2185 
2186  appendStringInfoString(&buf, ") VALUES(");
2187 
2188  /*
2189  * Note: i is physical column number (counting from 0).
2190  */
2191  needComma = false;
2192  for (i = 0; i < natts; i++)
2193  {
2194  if (tupdesc->attrs[i]->attisdropped)
2195  continue;
2196 
2197  if (needComma)
2198  appendStringInfoChar(&buf, ',');
2199 
2200  key = get_attnum_pk_pos(pkattnums, pknumatts, i);
2201 
2202  if (key >= 0)
2203  val = tgt_pkattvals[key] ? pstrdup(tgt_pkattvals[key]) : NULL;
2204  else
2205  val = SPI_getvalue(tuple, tupdesc, i + 1);
2206 
2207  if (val != NULL)
2208  {
2210  pfree(val);
2211  }
2212  else
2213  appendStringInfoString(&buf, "NULL");
2214  needComma = true;
2215  }
2216  appendStringInfoChar(&buf, ')');
2217 
2218  return (buf.data);
2219 }
2220 
2221 static char *
2222 get_sql_delete(Relation rel, int *pkattnums, int pknumatts, char **tgt_pkattvals)
2223 {
2224  char *relname;
2225  TupleDesc tupdesc;
2227  int i;
2228 
2229  initStringInfo(&buf);
2230 
2231  /* get relation name including any needed schema prefix and quoting */
2232  relname = generate_relation_name(rel);
2233 
2234  tupdesc = rel->rd_att;
2235 
2236  appendStringInfo(&buf, "DELETE FROM %s WHERE ", relname);
2237  for (i = 0; i < pknumatts; i++)
2238  {
2239  int pkattnum = pkattnums[i];
2240 
2241  if (i > 0)
2242  appendStringInfoString(&buf, " AND ");
2243 
2245  quote_ident_cstr(NameStr(tupdesc->attrs[pkattnum]->attname)));
2246 
2247  if (tgt_pkattvals[i] != NULL)
2248  appendStringInfo(&buf, " = %s",
2249  quote_literal_cstr(tgt_pkattvals[i]));
2250  else
2251  appendStringInfoString(&buf, " IS NULL");
2252  }
2253 
2254  return (buf.data);
2255 }
2256 
2257 static char *
2258 get_sql_update(Relation rel, int *pkattnums, int pknumatts, char **src_pkattvals, char **tgt_pkattvals)
2259 {
2260  char *relname;
2261  HeapTuple tuple;
2262  TupleDesc tupdesc;
2263  int natts;
2265  char *val;
2266  int key;
2267  int i;
2268  bool needComma;
2269 
2270  initStringInfo(&buf);
2271 
2272  /* get relation name including any needed schema prefix and quoting */
2273  relname = generate_relation_name(rel);
2274 
2275  tupdesc = rel->rd_att;
2276  natts = tupdesc->natts;
2277 
2278  tuple = get_tuple_of_interest(rel, pkattnums, pknumatts, src_pkattvals);
2279  if (!tuple)
2280  ereport(ERROR,
2281  (errcode(ERRCODE_CARDINALITY_VIOLATION),
2282  errmsg("source row not found")));
2283 
2284  appendStringInfo(&buf, "UPDATE %s SET ", relname);
2285 
2286  /*
2287  * Note: i is physical column number (counting from 0).
2288  */
2289  needComma = false;
2290  for (i = 0; i < natts; i++)
2291  {
2292  if (tupdesc->attrs[i]->attisdropped)
2293  continue;
2294 
2295  if (needComma)
2296  appendStringInfoString(&buf, ", ");
2297 
2298  appendStringInfo(&buf, "%s = ",
2299  quote_ident_cstr(NameStr(tupdesc->attrs[i]->attname)));
2300 
2301  key = get_attnum_pk_pos(pkattnums, pknumatts, i);
2302 
2303  if (key >= 0)
2304  val = tgt_pkattvals[key] ? pstrdup(tgt_pkattvals[key]) : NULL;
2305  else
2306  val = SPI_getvalue(tuple, tupdesc, i + 1);
2307 
2308  if (val != NULL)
2309  {
2311  pfree(val);
2312  }
2313  else
2314  appendStringInfoString(&buf, "NULL");
2315  needComma = true;
2316  }
2317 
2318  appendStringInfoString(&buf, " WHERE ");
2319 
2320  for (i = 0; i < pknumatts; i++)
2321  {
2322  int pkattnum = pkattnums[i];
2323 
2324  if (i > 0)
2325  appendStringInfoString(&buf, " AND ");
2326 
2328  quote_ident_cstr(NameStr(tupdesc->attrs[pkattnum]->attname)));
2329 
2330  val = tgt_pkattvals[i];
2331 
2332  if (val != NULL)
2333  appendStringInfo(&buf, " = %s", quote_literal_cstr(val));
2334  else
2335  appendStringInfoString(&buf, " IS NULL");
2336  }
2337 
2338  return (buf.data);
2339 }
2340 
2341 /*
2342  * Return a properly quoted identifier.
2343  * Uses quote_ident in quote.c
2344  */
2345 static char *
2346 quote_ident_cstr(char *rawstr)
2347 {
2348  text *rawstr_text;
2349  text *result_text;
2350  char *result;
2351 
2352  rawstr_text = cstring_to_text(rawstr);
2354  PointerGetDatum(rawstr_text)));
2355  result = text_to_cstring(result_text);
2356 
2357  return result;
2358 }
2359 
2360 static int
2361 get_attnum_pk_pos(int *pkattnums, int pknumatts, int key)
2362 {
2363  int i;
2364 
2365  /*
2366  * Not likely a long list anyway, so just scan for the value
2367  */
2368  for (i = 0; i < pknumatts; i++)
2369  if (key == pkattnums[i])
2370  return i;
2371 
2372  return -1;
2373 }
2374 
2375 static HeapTuple
2376 get_tuple_of_interest(Relation rel, int *pkattnums, int pknumatts, char **src_pkattvals)
2377 {
2378  char *relname;
2379  TupleDesc tupdesc;
2380  int natts;
2382  int ret;
2383  HeapTuple tuple;
2384  int i;
2385 
2386  /*
2387  * Connect to SPI manager
2388  */
2389  if ((ret = SPI_connect()) < 0)
2390  /* internal error */
2391  elog(ERROR, "SPI connect failure - returned %d", ret);
2392 
2393  initStringInfo(&buf);
2394 
2395  /* get relation name including any needed schema prefix and quoting */
2396  relname = generate_relation_name(rel);
2397 
2398  tupdesc = rel->rd_att;
2399  natts = tupdesc->natts;
2400 
2401  /*
2402  * Build sql statement to look up tuple of interest, ie, the one matching
2403  * src_pkattvals. We used to use "SELECT *" here, but it's simpler to
2404  * generate a result tuple that matches the table's physical structure,
2405  * with NULLs for any dropped columns. Otherwise we have to deal with two
2406  * different tupdescs and everything's very confusing.
2407  */
2408  appendStringInfoString(&buf, "SELECT ");
2409 
2410  for (i = 0; i < natts; i++)
2411  {
2412  if (i > 0)
2413  appendStringInfoString(&buf, ", ");
2414 
2415  if (tupdesc->attrs[i]->attisdropped)
2416  appendStringInfoString(&buf, "NULL");
2417  else
2419  quote_ident_cstr(NameStr(tupdesc->attrs[i]->attname)));
2420  }
2421 
2422  appendStringInfo(&buf, " FROM %s WHERE ", relname);
2423 
2424  for (i = 0; i < pknumatts; i++)
2425  {
2426  int pkattnum = pkattnums[i];
2427 
2428  if (i > 0)
2429  appendStringInfoString(&buf, " AND ");
2430 
2432  quote_ident_cstr(NameStr(tupdesc->attrs[pkattnum]->attname)));
2433 
2434  if (src_pkattvals[i] != NULL)
2435  appendStringInfo(&buf, " = %s",
2436  quote_literal_cstr(src_pkattvals[i]));
2437  else
2438  appendStringInfoString(&buf, " IS NULL");
2439  }
2440 
2441  /*
2442  * Retrieve the desired tuple
2443  */
2444  ret = SPI_exec(buf.data, 0);
2445  pfree(buf.data);
2446 
2447  /*
2448  * Only allow one qualifying tuple
2449  */
2450  if ((ret == SPI_OK_SELECT) && (SPI_processed > 1))
2451  ereport(ERROR,
2452  (errcode(ERRCODE_CARDINALITY_VIOLATION),
2453  errmsg("source criteria matched more than one record")));
2454 
2455  else if (ret == SPI_OK_SELECT && SPI_processed == 1)
2456  {
2457  SPITupleTable *tuptable = SPI_tuptable;
2458 
2459  tuple = SPI_copytuple(tuptable->vals[0]);
2460  SPI_finish();
2461 
2462  return tuple;
2463  }
2464  else
2465  {
2466  /*
2467  * no qualifying tuples
2468  */
2469  SPI_finish();
2470 
2471  return NULL;
2472  }
2473 
2474  /*
2475  * never reached, but keep compiler quiet
2476  */
2477  return NULL;
2478 }
2479 
2480 /*
2481  * Open the relation named by relname_text, acquire specified type of lock,
2482  * verify we have specified permissions.
2483  * Caller must close rel when done with it.
2484  */
2485 static Relation
2486 get_rel_from_relname(text *relname_text, LOCKMODE lockmode, AclMode aclmode)
2487 {
2488  RangeVar *relvar;
2489  Relation rel;
2490  AclResult aclresult;
2491 
2492  relvar = makeRangeVarFromNameList(textToQualifiedNameList(relname_text));
2493  rel = heap_openrv(relvar, lockmode);
2494 
2495  aclresult = pg_class_aclcheck(RelationGetRelid(rel), GetUserId(),
2496  aclmode);
2497  if (aclresult != ACLCHECK_OK)
2498  aclcheck_error(aclresult, ACL_KIND_CLASS,
2500 
2501  return rel;
2502 }
2503 
2504 /*
2505  * generate_relation_name - copied from ruleutils.c
2506  * Compute the name to display for a relation
2507  *
2508  * The result includes all necessary quoting and schema-prefixing.
2509  */
2510 static char *
2512 {
2513  char *nspname;
2514  char *result;
2515 
2516  /* Qualify the name if not visible in search path */
2518  nspname = NULL;
2519  else
2520  nspname = get_namespace_name(rel->rd_rel->relnamespace);
2521 
2522  result = quote_qualified_identifier(nspname, RelationGetRelationName(rel));
2523 
2524  return result;
2525 }
2526 
2527 
2528 static remoteConn *
2530 {
2531  remoteConnHashEnt *hentry;
2532  char *key;
2533 
2534  if (!remoteConnHash)
2535  remoteConnHash = createConnHash();
2536 
2537  key = pstrdup(name);
2538  truncate_identifier(key, strlen(key), false);
2539  hentry = (remoteConnHashEnt *) hash_search(remoteConnHash,
2540  key, HASH_FIND, NULL);
2541 
2542  if (hentry)
2543  return (hentry->rconn);
2544 
2545  return (NULL);
2546 }
2547 
2548 static HTAB *
2550 {
2551  HASHCTL ctl;
2552 
2553  ctl.keysize = NAMEDATALEN;
2554  ctl.entrysize = sizeof(remoteConnHashEnt);
2555 
2556  return hash_create("Remote Con hash", NUMCONN, &ctl, HASH_ELEM);
2557 }
2558 
2559 static void
2561 {
2562  remoteConnHashEnt *hentry;
2563  bool found;
2564  char *key;
2565 
2566  if (!remoteConnHash)
2567  remoteConnHash = createConnHash();
2568 
2569  key = pstrdup(name);
2570  truncate_identifier(key, strlen(key), true);
2571  hentry = (remoteConnHashEnt *) hash_search(remoteConnHash, key,
2572  HASH_ENTER, &found);
2573 
2574  if (found)
2575  {
2576  PQfinish(rconn->conn);
2577  pfree(rconn);
2578 
2579  ereport(ERROR,
2581  errmsg("duplicate connection name")));
2582  }
2583 
2584  hentry->rconn = rconn;
2585  strlcpy(hentry->name, name, sizeof(hentry->name));
2586 }
2587 
2588 static void
2590 {
2591  remoteConnHashEnt *hentry;
2592  bool found;
2593  char *key;
2594 
2595  if (!remoteConnHash)
2596  remoteConnHash = createConnHash();
2597 
2598  key = pstrdup(name);
2599  truncate_identifier(key, strlen(key), false);
2600  hentry = (remoteConnHashEnt *) hash_search(remoteConnHash,
2601  key, HASH_REMOVE, &found);
2602 
2603  if (!hentry)
2604  ereport(ERROR,
2605  (errcode(ERRCODE_UNDEFINED_OBJECT),
2606  errmsg("undefined connection name")));
2607 
2608 }
2609 
2610 static void
2612 {
2613  if (!superuser())
2614  {
2615  if (!PQconnectionUsedPassword(conn))
2616  {
2617  PQfinish(conn);
2618  if (rconn)
2619  pfree(rconn);
2620 
2621  ereport(ERROR,
2622  (errcode(ERRCODE_S_R_E_PROHIBITED_SQL_STATEMENT_ATTEMPTED),
2623  errmsg("password is required"),
2624  errdetail("Non-superuser cannot connect if the server does not request a password."),
2625  errhint("Target server's authentication method must be changed.")));
2626  }
2627  }
2628 }
2629 
2630 /*
2631  * For non-superusers, insist that the connstr specify a password. This
2632  * prevents a password from being picked up from .pgpass, a service file,
2633  * the environment, etc. We don't want the postgres user's passwords
2634  * to be accessible to non-superusers.
2635  */
2636 static void
2638 {
2639  if (!superuser())
2640  {
2643  bool connstr_gives_password = false;
2644 
2645  options = PQconninfoParse(connstr, NULL);
2646  if (options)
2647  {
2648  for (option = options; option->keyword != NULL; option++)
2649  {
2650  if (strcmp(option->keyword, "password") == 0)
2651  {
2652  if (option->val != NULL && option->val[0] != '\0')
2653  {
2654  connstr_gives_password = true;
2655  break;
2656  }
2657  }
2658  }
2659  PQconninfoFree(options);
2660  }
2661 
2662  if (!connstr_gives_password)
2663  ereport(ERROR,
2664  (errcode(ERRCODE_S_R_E_PROHIBITED_SQL_STATEMENT_ATTEMPTED),
2665  errmsg("password is required"),
2666  errdetail("Non-superusers must provide a password in the connection string.")));
2667  }
2668 }
2669 
2670 static void
2671 dblink_res_error(PGconn *conn, const char *conname, PGresult *res,
2672  const char *dblink_context_msg, bool fail)
2673 {
2674  int level;
2675  char *pg_diag_sqlstate = PQresultErrorField(res, PG_DIAG_SQLSTATE);
2676  char *pg_diag_message_primary = PQresultErrorField(res, PG_DIAG_MESSAGE_PRIMARY);
2677  char *pg_diag_message_detail = PQresultErrorField(res, PG_DIAG_MESSAGE_DETAIL);
2678  char *pg_diag_message_hint = PQresultErrorField(res, PG_DIAG_MESSAGE_HINT);
2679  char *pg_diag_context = PQresultErrorField(res, PG_DIAG_CONTEXT);
2680  int sqlstate;
2681  char *message_primary;
2682  char *message_detail;
2683  char *message_hint;
2684  char *message_context;
2685  const char *dblink_context_conname = "unnamed";
2686 
2687  if (fail)
2688  level = ERROR;
2689  else
2690  level = NOTICE;
2691 
2692  if (pg_diag_sqlstate)
2693  sqlstate = MAKE_SQLSTATE(pg_diag_sqlstate[0],
2694  pg_diag_sqlstate[1],
2695  pg_diag_sqlstate[2],
2696  pg_diag_sqlstate[3],
2697  pg_diag_sqlstate[4]);
2698  else
2699  sqlstate = ERRCODE_CONNECTION_FAILURE;
2700 
2701  xpstrdup(message_primary, pg_diag_message_primary);
2702  xpstrdup(message_detail, pg_diag_message_detail);
2703  xpstrdup(message_hint, pg_diag_message_hint);
2704  xpstrdup(message_context, pg_diag_context);
2705 
2706  /*
2707  * If we don't get a message from the PGresult, try the PGconn. This
2708  * is needed because for connection-level failures, PQexec may just
2709  * return NULL, not a PGresult at all.
2710  */
2711  if (message_primary == NULL)
2712  message_primary = PQerrorMessage(conn);
2713 
2714  if (res)
2715  PQclear(res);
2716 
2717  if (conname)
2718  dblink_context_conname = conname;
2719 
2720  ereport(level,
2721  (errcode(sqlstate),
2722  message_primary ? errmsg_internal("%s", message_primary) :
2723  errmsg("could not obtain message string for remote error"),
2724  message_detail ? errdetail_internal("%s", message_detail) : 0,
2725  message_hint ? errhint("%s", message_hint) : 0,
2726  message_context ? errcontext("%s", message_context) : 0,
2727  errcontext("Error occurred on dblink connection named \"%s\": %s.",
2728  dblink_context_conname, dblink_context_msg)));
2729 }
2730 
2731 /*
2732  * Obtain connection string for a foreign server
2733  */
2734 static char *
2735 get_connect_string(const char *servername)
2736 {
2737  ForeignServer *foreign_server = NULL;
2738  UserMapping *user_mapping;
2739  ListCell *cell;
2741  ForeignDataWrapper *fdw;
2742  AclResult aclresult;
2743  char *srvname;
2744 
2745  static const PQconninfoOption *options = NULL;
2746 
2747  /*
2748  * Get list of valid libpq options.
2749  *
2750  * To avoid unnecessary work, we get the list once and use it throughout
2751  * the lifetime of this backend process. We don't need to care about
2752  * memory context issues, because PQconndefaults allocates with malloc.
2753  */
2754  if (!options)
2755  {
2756  options = PQconndefaults();
2757  if (!options) /* assume reason for failure is OOM */
2758  ereport(ERROR,
2759  (errcode(ERRCODE_FDW_OUT_OF_MEMORY),
2760  errmsg("out of memory"),
2761  errdetail("could not get libpq's default connection options")));
2762  }
2763 
2764  /* first gather the server connstr options */
2765  srvname = pstrdup(servername);
2766  truncate_identifier(srvname, strlen(srvname), false);
2767  foreign_server = GetForeignServerByName(srvname, true);
2768 
2769  if (foreign_server)
2770  {
2771  Oid serverid = foreign_server->serverid;
2772  Oid fdwid = foreign_server->fdwid;
2773  Oid userid = GetUserId();
2774 
2775  user_mapping = GetUserMapping(userid, serverid);
2776  fdw = GetForeignDataWrapper(fdwid);
2777 
2778  /* Check permissions, user must have usage on the server. */
2779  aclresult = pg_foreign_server_aclcheck(serverid, userid, ACL_USAGE);
2780  if (aclresult != ACLCHECK_OK)
2781  aclcheck_error(aclresult, ACL_KIND_FOREIGN_SERVER, foreign_server->servername);
2782 
2783  foreach(cell, fdw->options)
2784  {
2785  DefElem *def = lfirst(cell);
2786 
2788  appendStringInfo(buf, "%s='%s' ", def->defname,
2789  escape_param_str(strVal(def->arg)));
2790  }
2791 
2792  foreach(cell, foreign_server->options)
2793  {
2794  DefElem *def = lfirst(cell);
2795 
2797  appendStringInfo(buf, "%s='%s' ", def->defname,
2798  escape_param_str(strVal(def->arg)));
2799  }
2800 
2801  foreach(cell, user_mapping->options)
2802  {
2803 
2804  DefElem *def = lfirst(cell);
2805 
2807  appendStringInfo(buf, "%s='%s' ", def->defname,
2808  escape_param_str(strVal(def->arg)));
2809  }
2810 
2811  return buf->data;
2812  }
2813  else
2814  return NULL;
2815 }
2816 
2817 /*
2818  * Escaping libpq connect parameter strings.
2819  *
2820  * Replaces "'" with "\'" and "\" with "\\".
2821  */
2822 static char *
2823 escape_param_str(const char *str)
2824 {
2825  const char *cp;
2827 
2828  for (cp = str; *cp; cp++)
2829  {
2830  if (*cp == '\\' || *cp == '\'')
2831  appendStringInfoChar(buf, '\\');
2832  appendStringInfoChar(buf, *cp);
2833  }
2834 
2835  return buf->data;
2836 }
2837 
2838 /*
2839  * Validate the PK-attnums argument for dblink_build_sql_insert() and related
2840  * functions, and translate to the internal representation.
2841  *
2842  * The user supplies an int2vector of 1-based logical attnums, plus a count
2843  * argument (the need for the separate count argument is historical, but we
2844  * still check it). We check that each attnum corresponds to a valid,
2845  * non-dropped attribute of the rel. We do *not* prevent attnums from being
2846  * listed twice, though the actual use-case for such things is dubious.
2847  * Note that before Postgres 9.0, the user's attnums were interpreted as
2848  * physical not logical column numbers; this was changed for future-proofing.
2849  *
2850  * The internal representation is a palloc'd int array of 0-based physical
2851  * attnums.
2852  */
2853 static void
2855  int2vector *pkattnums_arg, int32 pknumatts_arg,
2856  int **pkattnums, int *pknumatts)
2857 {
2858  TupleDesc tupdesc = rel->rd_att;
2859  int natts = tupdesc->natts;
2860  int i;
2861 
2862  /* Don't take more array elements than there are */
2863  pknumatts_arg = Min(pknumatts_arg, pkattnums_arg->dim1);
2864 
2865  /* Must have at least one pk attnum selected */
2866  if (pknumatts_arg <= 0)
2867  ereport(ERROR,
2868  (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
2869  errmsg("number of key attributes must be > 0")));
2870 
2871  /* Allocate output array */
2872  *pkattnums = (int *) palloc(pknumatts_arg * sizeof(int));
2873  *pknumatts = pknumatts_arg;
2874 
2875  /* Validate attnums and convert to internal form */
2876  for (i = 0; i < pknumatts_arg; i++)
2877  {
2878  int pkattnum = pkattnums_arg->values[i];
2879  int lnum;
2880  int j;
2881 
2882  /* Can throw error immediately if out of range */
2883  if (pkattnum <= 0 || pkattnum > natts)
2884  ereport(ERROR,
2885  (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
2886  errmsg("invalid attribute number %d", pkattnum)));
2887 
2888  /* Identify which physical column has this logical number */
2889  lnum = 0;
2890  for (j = 0; j < natts; j++)
2891  {
2892  /* dropped columns don't count */
2893  if (tupdesc->attrs[j]->attisdropped)
2894  continue;
2895 
2896  if (++lnum == pkattnum)
2897  break;
2898  }
2899 
2900  if (j < natts)
2901  (*pkattnums)[i] = j;
2902  else
2903  ereport(ERROR,
2904  (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
2905  errmsg("invalid attribute number %d", pkattnum)));
2906  }
2907 }
2908 
2909 /*
2910  * Check if the specified connection option is valid.
2911  *
2912  * We basically allow whatever libpq thinks is an option, with these
2913  * restrictions:
2914  * debug options: disallowed
2915  * "client_encoding": disallowed
2916  * "user": valid only in USER MAPPING options
2917  * secure options (eg password): valid only in USER MAPPING options
2918  * others: valid only in FOREIGN SERVER options
2919  *
2920  * We disallow client_encoding because it would be overridden anyway via
2921  * PQclientEncoding; allowing it to be specified would merely promote
2922  * confusion.
2923  */
2924 static bool
2926  Oid context)
2927 {
2928  const PQconninfoOption *opt;
2929 
2930  /* Look up the option in libpq result */
2931  for (opt = options; opt->keyword; opt++)
2932  {
2933  if (strcmp(opt->keyword, option) == 0)
2934  break;
2935  }
2936  if (opt->keyword == NULL)
2937  return false;
2938 
2939  /* Disallow debug options (particularly "replication") */
2940  if (strchr(opt->dispchar, 'D'))
2941  return false;
2942 
2943  /* Disallow "client_encoding" */
2944  if (strcmp(opt->keyword, "client_encoding") == 0)
2945  return false;
2946 
2947  /*
2948  * If the option is "user" or marked secure, it should be specified only
2949  * in USER MAPPING. Others should be specified only in SERVER.
2950  */
2951  if (strcmp(opt->keyword, "user") == 0 || strchr(opt->dispchar, '*'))
2952  {
2953  if (context != UserMappingRelationId)
2954  return false;
2955  }
2956  else
2957  {
2958  if (context != ForeignServerRelationId)
2959  return false;
2960  }
2961 
2962  return true;
2963 }
2964 
2965 /*
2966  * Copy the remote session's values of GUCs that affect datatype I/O
2967  * and apply them locally in a new GUC nesting level. Returns the new
2968  * nestlevel (which is needed by restoreLocalGucs to undo the settings),
2969  * or -1 if no new nestlevel was needed.
2970  *
2971  * We use the equivalent of a function SET option to allow the settings to
2972  * persist only until the caller calls restoreLocalGucs. If an error is
2973  * thrown in between, guc.c will take care of undoing the settings.
2974  */
2975 static int
2977 {
2978  static const char *const GUCsAffectingIO[] = {
2979  "DateStyle",
2980  "IntervalStyle"
2981  };
2982 
2983  int nestlevel = -1;
2984  int i;
2985 
2986  for (i = 0; i < lengthof(GUCsAffectingIO); i++)
2987  {
2988  const char *gucName = GUCsAffectingIO[i];
2989  const char *remoteVal = PQparameterStatus(conn, gucName);
2990  const char *localVal;
2991 
2992  /*
2993  * If the remote server is pre-8.4, it won't have IntervalStyle, but
2994  * that's okay because its output format won't be ambiguous. So just
2995  * skip the GUC if we don't get a value for it. (We might eventually
2996  * need more complicated logic with remote-version checks here.)
2997  */
2998  if (remoteVal == NULL)
2999  continue;
3000 
3001  /*
3002  * Avoid GUC-setting overhead if the remote and local GUCs already
3003  * have the same value.
3004  */
3005  localVal = GetConfigOption(gucName, false, false);
3006  Assert(localVal != NULL);
3007 
3008  if (strcmp(remoteVal, localVal) == 0)
3009  continue;
3010 
3011  /* Create new GUC nest level if we didn't already */
3012  if (nestlevel < 0)
3013  nestlevel = NewGUCNestLevel();
3014 
3015  /* Apply the option (this will throw error on failure) */
3016  (void) set_config_option(gucName, remoteVal,
3018  GUC_ACTION_SAVE, true, 0, false);
3019  }
3020 
3021  return nestlevel;
3022 }
3023 
3024 /*
3025  * Restore local GUCs after they have been overlaid with remote settings.
3026  */
3027 static void
3028 restoreLocalGucs(int nestlevel)
3029 {
3030  /* Do nothing if no new nestlevel was created */
3031  if (nestlevel > 0)
3032  AtEOXact_GUC(true, nestlevel);
3033 }
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Definition: pg_type.h:288
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Definition: tupdesc.c:41
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Definition: encode.c:521
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Definition: fmgr.h:248
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Definition: aclchk.c:4397
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Definition: execnodes.h:204
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Definition: bootstrap.c:162
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Definition: execnodes.h:197
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Definition: fe-connect.c:3793
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Definition: postgres.h:487
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Definition: guc.c:5022
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Definition: funcapi.h:90
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Definition: execnodes.h:205
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Definition: mcxt.c:891
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Definition: elog.c:797
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Definition: namespace.c:681
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Definition: scankey.c:76
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Definition: foreign.c:166
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Definition: builtins.h:90
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Definition: fe-exec.c:1846
Definition: c.h:435
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Definition: fmgr.h:150
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Definition: parsenodes.h:675
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Definition: miscadmin.h:97
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Definition: elog.h:219
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Definition: pg_regress.c:222
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Definition: fe-exec.c:3092
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Definition: fe-connect.c:5907
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Definition: elog.h:284
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Definition: guc.c:5865
Definition: pg_list.h:45
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Definition: foreign.h:53
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Definition: array.h:273
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Definition: attnum.h:21
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Definition: fe-exec.c:3200
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Definition: rel.h:413
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Definition: array.h:281
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Definition: informix.c:689
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Definition: fe-exec.c:1702
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Definition: foreign.h:47
#define PG_RETURN_NULL()
Definition: fmgr.h:289
#define PG_END_TRY()
Definition: elog.h:300
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Definition: stratnum.h:31
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Definition: indexing.h:162
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Definition: funcapi.h:74
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Definition: postgres_ext.h:60
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Definition: fe-connect.c:527
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Definition: funcapi.h:309
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Definition: pg_dumpall.c:67
#define SRF_FIRSTCALL_INIT()
Definition: funcapi.h:287