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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) 2001-2020, 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 "access/htup_details.h"
38 #include "access/relation.h"
39 #include "access/reloptions.h"
40 #include "access/table.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 "libpq-fe.h"
52 #include "mb/pg_wchar.h"
53 #include "miscadmin.h"
54 #include "parser/scansup.h"
55 #include "utils/acl.h"
56 #include "utils/builtins.h"
57 #include "utils/fmgroids.h"
58 #include "utils/guc.h"
59 #include "utils/lsyscache.h"
60 #include "utils/memutils.h"
61 #include "utils/rel.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 *indnkeyatts);
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  bool fail, const char *fmt,...) pg_attribute_printf(5, 6);
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, fail,
445  "while opening cursor \"%s\"", curname);
447  }
448 
449  PQclear(res);
451 }
452 
453 /*
454  * closes a cursor
455  */
457 Datum
459 {
460  PGconn *conn;
461  PGresult *res = NULL;
462  char *curname = NULL;
463  char *conname = NULL;
465  remoteConn *rconn = NULL;
466  bool fail = true; /* default to backward compatible behavior */
467 
468  dblink_init();
469  initStringInfo(&buf);
470 
471  if (PG_NARGS() == 1)
472  {
473  /* text */
474  curname = text_to_cstring(PG_GETARG_TEXT_PP(0));
475  rconn = pconn;
476  }
477  else if (PG_NARGS() == 2)
478  {
479  /* might be text,text or text,bool */
480  if (get_fn_expr_argtype(fcinfo->flinfo, 1) == BOOLOID)
481  {
482  curname = text_to_cstring(PG_GETARG_TEXT_PP(0));
483  fail = PG_GETARG_BOOL(1);
484  rconn = pconn;
485  }
486  else
487  {
488  conname = text_to_cstring(PG_GETARG_TEXT_PP(0));
489  curname = text_to_cstring(PG_GETARG_TEXT_PP(1));
490  rconn = getConnectionByName(conname);
491  }
492  }
493  if (PG_NARGS() == 3)
494  {
495  /* text,text,bool */
496  conname = text_to_cstring(PG_GETARG_TEXT_PP(0));
497  curname = text_to_cstring(PG_GETARG_TEXT_PP(1));
498  fail = PG_GETARG_BOOL(2);
499  rconn = getConnectionByName(conname);
500  }
501 
502  if (!rconn || !rconn->conn)
503  dblink_conn_not_avail(conname);
504 
505  conn = rconn->conn;
506 
507  appendStringInfo(&buf, "CLOSE %s", curname);
508 
509  /* close the cursor */
510  res = PQexec(conn, buf.data);
511  if (!res || PQresultStatus(res) != PGRES_COMMAND_OK)
512  {
513  dblink_res_error(conn, conname, res, fail,
514  "while closing cursor \"%s\"", curname);
516  }
517 
518  PQclear(res);
519 
520  /* if we started a transaction, decrement cursor count */
521  if (rconn->newXactForCursor)
522  {
523  (rconn->openCursorCount)--;
524 
525  /* if count is zero, commit the transaction */
526  if (rconn->openCursorCount == 0)
527  {
528  rconn->newXactForCursor = false;
529 
530  res = PQexec(conn, "COMMIT");
531  if (PQresultStatus(res) != PGRES_COMMAND_OK)
532  dblink_res_internalerror(conn, res, "commit error");
533  PQclear(res);
534  }
535  }
536 
538 }
539 
540 /*
541  * Fetch results from an open cursor
542  */
544 Datum
546 {
547  PGresult *res = NULL;
548  char *conname = NULL;
549  remoteConn *rconn = NULL;
550  PGconn *conn = NULL;
552  char *curname = NULL;
553  int howmany = 0;
554  bool fail = true; /* default to backward compatible */
555 
556  prepTuplestoreResult(fcinfo);
557 
558  dblink_init();
559 
560  if (PG_NARGS() == 4)
561  {
562  /* text,text,int,bool */
563  conname = text_to_cstring(PG_GETARG_TEXT_PP(0));
564  curname = text_to_cstring(PG_GETARG_TEXT_PP(1));
565  howmany = PG_GETARG_INT32(2);
566  fail = PG_GETARG_BOOL(3);
567 
568  rconn = getConnectionByName(conname);
569  if (rconn)
570  conn = rconn->conn;
571  }
572  else if (PG_NARGS() == 3)
573  {
574  /* text,text,int or text,int,bool */
575  if (get_fn_expr_argtype(fcinfo->flinfo, 2) == BOOLOID)
576  {
577  curname = text_to_cstring(PG_GETARG_TEXT_PP(0));
578  howmany = PG_GETARG_INT32(1);
579  fail = PG_GETARG_BOOL(2);
580  conn = pconn->conn;
581  }
582  else
583  {
584  conname = text_to_cstring(PG_GETARG_TEXT_PP(0));
585  curname = text_to_cstring(PG_GETARG_TEXT_PP(1));
586  howmany = PG_GETARG_INT32(2);
587 
588  rconn = getConnectionByName(conname);
589  if (rconn)
590  conn = rconn->conn;
591  }
592  }
593  else if (PG_NARGS() == 2)
594  {
595  /* text,int */
596  curname = text_to_cstring(PG_GETARG_TEXT_PP(0));
597  howmany = PG_GETARG_INT32(1);
598  conn = pconn->conn;
599  }
600 
601  if (!conn)
602  dblink_conn_not_avail(conname);
603 
604  initStringInfo(&buf);
605  appendStringInfo(&buf, "FETCH %d FROM %s", howmany, curname);
606 
607  /*
608  * Try to execute the query. Note that since libpq uses malloc, the
609  * PGresult will be long-lived even though we are still in a short-lived
610  * memory context.
611  */
612  res = PQexec(conn, buf.data);
613  if (!res ||
614  (PQresultStatus(res) != PGRES_COMMAND_OK &&
616  {
617  dblink_res_error(conn, conname, res, fail,
618  "while fetching from cursor \"%s\"", curname);
619  return (Datum) 0;
620  }
621  else if (PQresultStatus(res) == PGRES_COMMAND_OK)
622  {
623  /* cursor does not exist - closed already or bad name */
624  PQclear(res);
625  ereport(ERROR,
626  (errcode(ERRCODE_INVALID_CURSOR_NAME),
627  errmsg("cursor \"%s\" does not exist", curname)));
628  }
629 
630  materializeResult(fcinfo, conn, res);
631  return (Datum) 0;
632 }
633 
634 /*
635  * Note: this is the new preferred version of dblink
636  */
638 Datum
640 {
641  return dblink_record_internal(fcinfo, false);
642 }
643 
645 Datum
647 {
648  PGconn *conn;
649  char *sql;
650  int retval;
651 
652  if (PG_NARGS() == 2)
653  {
656  }
657  else
658  /* shouldn't happen */
659  elog(ERROR, "wrong number of arguments");
660 
661  /* async query send */
662  retval = PQsendQuery(conn, sql);
663  if (retval != 1)
664  elog(NOTICE, "could not send query: %s", pchomp(PQerrorMessage(conn)));
665 
666  PG_RETURN_INT32(retval);
667 }
668 
670 Datum
672 {
673  return dblink_record_internal(fcinfo, true);
674 }
675 
676 static Datum
678 {
679  PGconn *volatile conn = NULL;
680  volatile bool freeconn = false;
681 
682  prepTuplestoreResult(fcinfo);
683 
684  dblink_init();
685 
686  PG_TRY();
687  {
688  char *sql = NULL;
689  char *conname = NULL;
690  bool fail = true; /* default to backward compatible */
691 
692  if (!is_async)
693  {
694  if (PG_NARGS() == 3)
695  {
696  /* text,text,bool */
697  conname = text_to_cstring(PG_GETARG_TEXT_PP(0));
699  fail = PG_GETARG_BOOL(2);
700  dblink_get_conn(conname, &conn, &conname, &freeconn);
701  }
702  else if (PG_NARGS() == 2)
703  {
704  /* text,text or text,bool */
705  if (get_fn_expr_argtype(fcinfo->flinfo, 1) == BOOLOID)
706  {
708  fail = PG_GETARG_BOOL(1);
709  conn = pconn->conn;
710  }
711  else
712  {
713  conname = text_to_cstring(PG_GETARG_TEXT_PP(0));
715  dblink_get_conn(conname, &conn, &conname, &freeconn);
716  }
717  }
718  else if (PG_NARGS() == 1)
719  {
720  /* text */
721  conn = pconn->conn;
723  }
724  else
725  /* shouldn't happen */
726  elog(ERROR, "wrong number of arguments");
727  }
728  else /* is_async */
729  {
730  /* get async result */
731  conname = text_to_cstring(PG_GETARG_TEXT_PP(0));
732 
733  if (PG_NARGS() == 2)
734  {
735  /* text,bool */
736  fail = PG_GETARG_BOOL(1);
737  conn = dblink_get_named_conn(conname);
738  }
739  else if (PG_NARGS() == 1)
740  {
741  /* text */
742  conn = dblink_get_named_conn(conname);
743  }
744  else
745  /* shouldn't happen */
746  elog(ERROR, "wrong number of arguments");
747  }
748 
749  if (!conn)
750  dblink_conn_not_avail(conname);
751 
752  if (!is_async)
753  {
754  /* synchronous query, use efficient tuple collection method */
755  materializeQueryResult(fcinfo, conn, conname, sql, fail);
756  }
757  else
758  {
759  /* async result retrieval, do it the old way */
760  PGresult *res = PQgetResult(conn);
761 
762  /* NULL means we're all done with the async results */
763  if (res)
764  {
765  if (PQresultStatus(res) != PGRES_COMMAND_OK &&
767  {
768  dblink_res_error(conn, conname, res, fail,
769  "while executing query");
770  /* if fail isn't set, we'll return an empty query result */
771  }
772  else
773  {
774  materializeResult(fcinfo, conn, res);
775  }
776  }
777  }
778  }
779  PG_FINALLY();
780  {
781  /* if needed, close the connection to the database */
782  if (freeconn)
783  PQfinish(conn);
784  }
785  PG_END_TRY();
786 
787  return (Datum) 0;
788 }
789 
790 /*
791  * Verify function caller can handle a tuplestore result, and set up for that.
792  *
793  * Note: if the caller returns without actually creating a tuplestore, the
794  * executor will treat the function result as an empty set.
795  */
796 static void
798 {
799  ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
800 
801  /* check to see if query supports us returning a tuplestore */
802  if (rsinfo == NULL || !IsA(rsinfo, ReturnSetInfo))
803  ereport(ERROR,
804  (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
805  errmsg("set-valued function called in context that cannot accept a set")));
806  if (!(rsinfo->allowedModes & SFRM_Materialize))
807  ereport(ERROR,
808  (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
809  errmsg("materialize mode required, but it is not allowed in this context")));
810 
811  /* let the executor know we're sending back a tuplestore */
812  rsinfo->returnMode = SFRM_Materialize;
813 
814  /* caller must fill these to return a non-empty result */
815  rsinfo->setResult = NULL;
816  rsinfo->setDesc = NULL;
817 }
818 
819 /*
820  * Copy the contents of the PGresult into a tuplestore to be returned
821  * as the result of the current function.
822  * The PGresult will be released in this function.
823  */
824 static void
826 {
827  ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
828 
829  /* prepTuplestoreResult must have been called previously */
830  Assert(rsinfo->returnMode == SFRM_Materialize);
831 
832  PG_TRY();
833  {
834  TupleDesc tupdesc;
835  bool is_sql_cmd;
836  int ntuples;
837  int nfields;
838 
839  if (PQresultStatus(res) == PGRES_COMMAND_OK)
840  {
841  is_sql_cmd = true;
842 
843  /*
844  * need a tuple descriptor representing one TEXT column to return
845  * the command status string as our result tuple
846  */
847  tupdesc = CreateTemplateTupleDesc(1);
848  TupleDescInitEntry(tupdesc, (AttrNumber) 1, "status",
849  TEXTOID, -1, 0);
850  ntuples = 1;
851  nfields = 1;
852  }
853  else
854  {
856 
857  is_sql_cmd = false;
858 
859  /* get a tuple descriptor for our result type */
860  switch (get_call_result_type(fcinfo, NULL, &tupdesc))
861  {
862  case TYPEFUNC_COMPOSITE:
863  /* success */
864  break;
865  case TYPEFUNC_RECORD:
866  /* failed to determine actual type of RECORD */
867  ereport(ERROR,
868  (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
869  errmsg("function returning record called in context "
870  "that cannot accept type record")));
871  break;
872  default:
873  /* result type isn't composite */
874  elog(ERROR, "return type must be a row type");
875  break;
876  }
877 
878  /* make sure we have a persistent copy of the tupdesc */
879  tupdesc = CreateTupleDescCopy(tupdesc);
880  ntuples = PQntuples(res);
881  nfields = PQnfields(res);
882  }
883 
884  /*
885  * check result and tuple descriptor have the same number of columns
886  */
887  if (nfields != tupdesc->natts)
888  ereport(ERROR,
889  (errcode(ERRCODE_DATATYPE_MISMATCH),
890  errmsg("remote query result rowtype does not match "
891  "the specified FROM clause rowtype")));
892 
893  if (ntuples > 0)
894  {
895  AttInMetadata *attinmeta;
896  int nestlevel = -1;
897  Tuplestorestate *tupstore;
898  MemoryContext oldcontext;
899  int row;
900  char **values;
901 
902  attinmeta = TupleDescGetAttInMetadata(tupdesc);
903 
904  /* Set GUCs to ensure we read GUC-sensitive data types correctly */
905  if (!is_sql_cmd)
906  nestlevel = applyRemoteGucs(conn);
907 
908  oldcontext = MemoryContextSwitchTo(
910  tupstore = tuplestore_begin_heap(true, false, work_mem);
911  rsinfo->setResult = tupstore;
912  rsinfo->setDesc = tupdesc;
913  MemoryContextSwitchTo(oldcontext);
914 
915  values = (char **) palloc(nfields * sizeof(char *));
916 
917  /* put all tuples into the tuplestore */
918  for (row = 0; row < ntuples; row++)
919  {
920  HeapTuple tuple;
921 
922  if (!is_sql_cmd)
923  {
924  int i;
925 
926  for (i = 0; i < nfields; i++)
927  {
928  if (PQgetisnull(res, row, i))
929  values[i] = NULL;
930  else
931  values[i] = PQgetvalue(res, row, i);
932  }
933  }
934  else
935  {
936  values[0] = PQcmdStatus(res);
937  }
938 
939  /* build the tuple and put it into the tuplestore. */
940  tuple = BuildTupleFromCStrings(attinmeta, values);
941  tuplestore_puttuple(tupstore, tuple);
942  }
943 
944  /* clean up GUC settings, if we changed any */
945  restoreLocalGucs(nestlevel);
946 
947  /* clean up and return the tuplestore */
948  tuplestore_donestoring(tupstore);
949  }
950  }
951  PG_FINALLY();
952  {
953  /* be sure to release the libpq result */
954  PQclear(res);
955  }
956  PG_END_TRY();
957 }
958 
959 /*
960  * Execute the given SQL command and store its results into a tuplestore
961  * to be returned as the result of the current function.
962  *
963  * This is equivalent to PQexec followed by materializeResult, but we make
964  * use of libpq's single-row mode to avoid accumulating the whole result
965  * inside libpq before it gets transferred to the tuplestore.
966  */
967 static void
969  PGconn *conn,
970  const char *conname,
971  const char *sql,
972  bool fail)
973 {
974  ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
975  PGresult *volatile res = NULL;
976  volatile storeInfo sinfo = {0};
977 
978  /* prepTuplestoreResult must have been called previously */
979  Assert(rsinfo->returnMode == SFRM_Materialize);
980 
981  sinfo.fcinfo = fcinfo;
982 
983  PG_TRY();
984  {
985  /* Create short-lived memory context for data conversions */
986  sinfo.tmpcontext = AllocSetContextCreate(CurrentMemoryContext,
987  "dblink temporary context",
989 
990  /* execute query, collecting any tuples into the tuplestore */
991  res = storeQueryResult(&sinfo, conn, sql);
992 
993  if (!res ||
994  (PQresultStatus(res) != PGRES_COMMAND_OK &&
996  {
997  /*
998  * dblink_res_error will clear the passed PGresult, so we need
999  * this ugly dance to avoid doing so twice during error exit
1000  */
1001  PGresult *res1 = res;
1002 
1003  res = NULL;
1004  dblink_res_error(conn, conname, res1, fail,
1005  "while executing query");
1006  /* if fail isn't set, we'll return an empty query result */
1007  }
1008  else if (PQresultStatus(res) == PGRES_COMMAND_OK)
1009  {
1010  /*
1011  * storeRow didn't get called, so we need to convert the command
1012  * status string to a tuple manually
1013  */
1014  TupleDesc tupdesc;
1015  AttInMetadata *attinmeta;
1016  Tuplestorestate *tupstore;
1017  HeapTuple tuple;
1018  char *values[1];
1019  MemoryContext oldcontext;
1020 
1021  /*
1022  * need a tuple descriptor representing one TEXT column to return
1023  * the command status string as our result tuple
1024  */
1025  tupdesc = CreateTemplateTupleDesc(1);
1026  TupleDescInitEntry(tupdesc, (AttrNumber) 1, "status",
1027  TEXTOID, -1, 0);
1028  attinmeta = TupleDescGetAttInMetadata(tupdesc);
1029 
1030  oldcontext = MemoryContextSwitchTo(
1031  rsinfo->econtext->ecxt_per_query_memory);
1032  tupstore = tuplestore_begin_heap(true, false, work_mem);
1033  rsinfo->setResult = tupstore;
1034  rsinfo->setDesc = tupdesc;
1035  MemoryContextSwitchTo(oldcontext);
1036 
1037  values[0] = PQcmdStatus(res);
1038 
1039  /* build the tuple and put it into the tuplestore. */
1040  tuple = BuildTupleFromCStrings(attinmeta, values);
1041  tuplestore_puttuple(tupstore, tuple);
1042 
1043  PQclear(res);
1044  res = NULL;
1045  }
1046  else
1047  {
1049  /* storeRow should have created a tuplestore */
1050  Assert(rsinfo->setResult != NULL);
1051 
1052  PQclear(res);
1053  res = NULL;
1054  }
1055 
1056  /* clean up data conversion short-lived memory context */
1057  if (sinfo.tmpcontext != NULL)
1058  MemoryContextDelete(sinfo.tmpcontext);
1059  sinfo.tmpcontext = NULL;
1060 
1061  PQclear(sinfo.last_res);
1062  sinfo.last_res = NULL;
1063  PQclear(sinfo.cur_res);
1064  sinfo.cur_res = NULL;
1065  }
1066  PG_CATCH();
1067  {
1068  /* be sure to release any libpq result we collected */
1069  PQclear(res);
1070  PQclear(sinfo.last_res);
1071  PQclear(sinfo.cur_res);
1072  /* and clear out any pending data in libpq */
1073  while ((res = PQgetResult(conn)) != NULL)
1074  PQclear(res);
1075  PG_RE_THROW();
1076  }
1077  PG_END_TRY();
1078 }
1079 
1080 /*
1081  * Execute query, and send any result rows to sinfo->tuplestore.
1082  */
1083 static PGresult *
1084 storeQueryResult(volatile storeInfo *sinfo, PGconn *conn, const char *sql)
1085 {
1086  bool first = true;
1087  int nestlevel = -1;
1088  PGresult *res;
1089 
1090  if (!PQsendQuery(conn, sql))
1091  elog(ERROR, "could not send query: %s", pchomp(PQerrorMessage(conn)));
1092 
1093  if (!PQsetSingleRowMode(conn)) /* shouldn't fail */
1094  elog(ERROR, "failed to set single-row mode for dblink query");
1095 
1096  for (;;)
1097  {
1099 
1100  sinfo->cur_res = PQgetResult(conn);
1101  if (!sinfo->cur_res)
1102  break;
1103 
1104  if (PQresultStatus(sinfo->cur_res) == PGRES_SINGLE_TUPLE)
1105  {
1106  /* got one row from possibly-bigger resultset */
1107 
1108  /*
1109  * Set GUCs to ensure we read GUC-sensitive data types correctly.
1110  * We shouldn't do this until we have a row in hand, to ensure
1111  * libpq has seen any earlier ParameterStatus protocol messages.
1112  */
1113  if (first && nestlevel < 0)
1114  nestlevel = applyRemoteGucs(conn);
1115 
1116  storeRow(sinfo, sinfo->cur_res, first);
1117 
1118  PQclear(sinfo->cur_res);
1119  sinfo->cur_res = NULL;
1120  first = false;
1121  }
1122  else
1123  {
1124  /* if empty resultset, fill tuplestore header */
1125  if (first && PQresultStatus(sinfo->cur_res) == PGRES_TUPLES_OK)
1126  storeRow(sinfo, sinfo->cur_res, first);
1127 
1128  /* store completed result at last_res */
1129  PQclear(sinfo->last_res);
1130  sinfo->last_res = sinfo->cur_res;
1131  sinfo->cur_res = NULL;
1132  first = true;
1133  }
1134  }
1135 
1136  /* clean up GUC settings, if we changed any */
1137  restoreLocalGucs(nestlevel);
1138 
1139  /* return last_res */
1140  res = sinfo->last_res;
1141  sinfo->last_res = NULL;
1142  return res;
1143 }
1144 
1145 /*
1146  * Send single row to sinfo->tuplestore.
1147  *
1148  * If "first" is true, create the tuplestore using PGresult's metadata
1149  * (in this case the PGresult might contain either zero or one row).
1150  */
1151 static void
1152 storeRow(volatile storeInfo *sinfo, PGresult *res, bool first)
1153 {
1154  int nfields = PQnfields(res);
1155  HeapTuple tuple;
1156  int i;
1157  MemoryContext oldcontext;
1158 
1159  if (first)
1160  {
1161  /* Prepare for new result set */
1162  ReturnSetInfo *rsinfo = (ReturnSetInfo *) sinfo->fcinfo->resultinfo;
1163  TupleDesc tupdesc;
1164 
1165  /*
1166  * It's possible to get more than one result set if the query string
1167  * contained multiple SQL commands. In that case, we follow PQexec's
1168  * traditional behavior of throwing away all but the last result.
1169  */
1170  if (sinfo->tuplestore)
1171  tuplestore_end(sinfo->tuplestore);
1172  sinfo->tuplestore = NULL;
1173 
1174  /* get a tuple descriptor for our result type */
1175  switch (get_call_result_type(sinfo->fcinfo, NULL, &tupdesc))
1176  {
1177  case TYPEFUNC_COMPOSITE:
1178  /* success */
1179  break;
1180  case TYPEFUNC_RECORD:
1181  /* failed to determine actual type of RECORD */
1182  ereport(ERROR,
1183  (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
1184  errmsg("function returning record called in context "
1185  "that cannot accept type record")));
1186  break;
1187  default:
1188  /* result type isn't composite */
1189  elog(ERROR, "return type must be a row type");
1190  break;
1191  }
1192 
1193  /* make sure we have a persistent copy of the tupdesc */
1194  tupdesc = CreateTupleDescCopy(tupdesc);
1195 
1196  /* check result and tuple descriptor have the same number of columns */
1197  if (nfields != tupdesc->natts)
1198  ereport(ERROR,
1199  (errcode(ERRCODE_DATATYPE_MISMATCH),
1200  errmsg("remote query result rowtype does not match "
1201  "the specified FROM clause rowtype")));
1202 
1203  /* Prepare attinmeta for later data conversions */
1204  sinfo->attinmeta = TupleDescGetAttInMetadata(tupdesc);
1205 
1206  /* Create a new, empty tuplestore */
1207  oldcontext = MemoryContextSwitchTo(rsinfo->econtext->ecxt_per_query_memory);
1208  sinfo->tuplestore = tuplestore_begin_heap(true, false, work_mem);
1209  rsinfo->setResult = sinfo->tuplestore;
1210  rsinfo->setDesc = tupdesc;
1211  MemoryContextSwitchTo(oldcontext);
1212 
1213  /* Done if empty resultset */
1214  if (PQntuples(res) == 0)
1215  return;
1216 
1217  /*
1218  * Set up sufficiently-wide string pointers array; this won't change
1219  * in size so it's easy to preallocate.
1220  */
1221  if (sinfo->cstrs)
1222  pfree(sinfo->cstrs);
1223  sinfo->cstrs = (char **) palloc(nfields * sizeof(char *));
1224  }
1225 
1226  /* Should have a single-row result if we get here */
1227  Assert(PQntuples(res) == 1);
1228 
1229  /*
1230  * Do the following work in a temp context that we reset after each tuple.
1231  * This cleans up not only the data we have direct access to, but any
1232  * cruft the I/O functions might leak.
1233  */
1234  oldcontext = MemoryContextSwitchTo(sinfo->tmpcontext);
1235 
1236  /*
1237  * Fill cstrs with null-terminated strings of column values.
1238  */
1239  for (i = 0; i < nfields; i++)
1240  {
1241  if (PQgetisnull(res, 0, i))
1242  sinfo->cstrs[i] = NULL;
1243  else
1244  sinfo->cstrs[i] = PQgetvalue(res, 0, i);
1245  }
1246 
1247  /* Convert row to a tuple, and add it to the tuplestore */
1248  tuple = BuildTupleFromCStrings(sinfo->attinmeta, sinfo->cstrs);
1249 
1250  tuplestore_puttuple(sinfo->tuplestore, tuple);
1251 
1252  /* Clean up */
1253  MemoryContextSwitchTo(oldcontext);
1255 }
1256 
1257 /*
1258  * List all open dblink connections by name.
1259  * Returns an array of all connection names.
1260  * Takes no params
1261  */
1263 Datum
1265 {
1267  remoteConnHashEnt *hentry;
1268  ArrayBuildState *astate = NULL;
1269 
1270  if (remoteConnHash)
1271  {
1272  hash_seq_init(&status, remoteConnHash);
1273  while ((hentry = (remoteConnHashEnt *) hash_seq_search(&status)) != NULL)
1274  {
1275  /* stash away current value */
1276  astate = accumArrayResult(astate,
1277  CStringGetTextDatum(hentry->name),
1278  false, TEXTOID, CurrentMemoryContext);
1279  }
1280  }
1281 
1282  if (astate)
1285  else
1286  PG_RETURN_NULL();
1287 }
1288 
1289 /*
1290  * Checks if a given remote connection is busy
1291  *
1292  * Returns 1 if the connection is busy, 0 otherwise
1293  * Params:
1294  * text connection_name - name of the connection to check
1295  *
1296  */
1298 Datum
1300 {
1301  PGconn *conn;
1302 
1303  dblink_init();
1305 
1306  PQconsumeInput(conn);
1307  PG_RETURN_INT32(PQisBusy(conn));
1308 }
1309 
1310 /*
1311  * Cancels a running request on a connection
1312  *
1313  * Returns text:
1314  * "OK" if the cancel request has been sent correctly,
1315  * an error message otherwise
1316  *
1317  * Params:
1318  * text connection_name - name of the connection to check
1319  *
1320  */
1322 Datum
1324 {
1325  int res;
1326  PGconn *conn;
1327  PGcancel *cancel;
1328  char errbuf[256];
1329 
1330  dblink_init();
1332  cancel = PQgetCancel(conn);
1333 
1334  res = PQcancel(cancel, errbuf, 256);
1335  PQfreeCancel(cancel);
1336 
1337  if (res == 1)
1339  else
1341 }
1342 
1343 
1344 /*
1345  * Get error message from a connection
1346  *
1347  * Returns text:
1348  * "OK" if no error, an error message otherwise
1349  *
1350  * Params:
1351  * text connection_name - name of the connection to check
1352  *
1353  */
1355 Datum
1357 {
1358  char *msg;
1359  PGconn *conn;
1360 
1361  dblink_init();
1363 
1364  msg = PQerrorMessage(conn);
1365  if (msg == NULL || msg[0] == '\0')
1367  else
1369 }
1370 
1371 /*
1372  * Execute an SQL non-SELECT command
1373  */
1375 Datum
1377 {
1378  text *volatile sql_cmd_status = NULL;
1379  PGconn *volatile conn = NULL;
1380  volatile bool freeconn = false;
1381 
1382  dblink_init();
1383 
1384  PG_TRY();
1385  {
1386  PGresult *res = NULL;
1387  char *sql = NULL;
1388  char *conname = NULL;
1389  bool fail = true; /* default to backward compatible behavior */
1390 
1391  if (PG_NARGS() == 3)
1392  {
1393  /* must be text,text,bool */
1394  conname = text_to_cstring(PG_GETARG_TEXT_PP(0));
1396  fail = PG_GETARG_BOOL(2);
1397  dblink_get_conn(conname, &conn, &conname, &freeconn);
1398  }
1399  else if (PG_NARGS() == 2)
1400  {
1401  /* might be text,text or text,bool */
1402  if (get_fn_expr_argtype(fcinfo->flinfo, 1) == BOOLOID)
1403  {
1405  fail = PG_GETARG_BOOL(1);
1406  conn = pconn->conn;
1407  }
1408  else
1409  {
1410  conname = text_to_cstring(PG_GETARG_TEXT_PP(0));
1412  dblink_get_conn(conname, &conn, &conname, &freeconn);
1413  }
1414  }
1415  else if (PG_NARGS() == 1)
1416  {
1417  /* must be single text argument */
1418  conn = pconn->conn;
1420  }
1421  else
1422  /* shouldn't happen */
1423  elog(ERROR, "wrong number of arguments");
1424 
1425  if (!conn)
1426  dblink_conn_not_avail(conname);
1427 
1428  res = PQexec(conn, sql);
1429  if (!res ||
1430  (PQresultStatus(res) != PGRES_COMMAND_OK &&
1432  {
1433  dblink_res_error(conn, conname, res, fail,
1434  "while executing command");
1435 
1436  /*
1437  * and save a copy of the command status string to return as our
1438  * result tuple
1439  */
1440  sql_cmd_status = cstring_to_text("ERROR");
1441  }
1442  else if (PQresultStatus(res) == PGRES_COMMAND_OK)
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(PQcmdStatus(res));
1449  PQclear(res);
1450  }
1451  else
1452  {
1453  PQclear(res);
1454  ereport(ERROR,
1455  (errcode(ERRCODE_S_R_E_PROHIBITED_SQL_STATEMENT_ATTEMPTED),
1456  errmsg("statement returning results not allowed")));
1457  }
1458  }
1459  PG_FINALLY();
1460  {
1461  /* if needed, close the connection to the database */
1462  if (freeconn)
1463  PQfinish(conn);
1464  }
1465  PG_END_TRY();
1466 
1467  PG_RETURN_TEXT_P(sql_cmd_status);
1468 }
1469 
1470 
1471 /*
1472  * dblink_get_pkey
1473  *
1474  * Return list of primary key fields for the supplied relation,
1475  * or NULL if none exists.
1476  */
1478 Datum
1480 {
1481  int16 indnkeyatts;
1482  char **results;
1483  FuncCallContext *funcctx;
1484  int32 call_cntr;
1485  int32 max_calls;
1486  AttInMetadata *attinmeta;
1487  MemoryContext oldcontext;
1488 
1489  /* stuff done only on the first call of the function */
1490  if (SRF_IS_FIRSTCALL())
1491  {
1492  Relation rel;
1493  TupleDesc tupdesc;
1494 
1495  /* create a function context for cross-call persistence */
1496  funcctx = SRF_FIRSTCALL_INIT();
1497 
1498  /*
1499  * switch to memory context appropriate for multiple function calls
1500  */
1501  oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
1502 
1503  /* open target relation */
1505 
1506  /* get the array of attnums */
1507  results = get_pkey_attnames(rel, &indnkeyatts);
1508 
1510 
1511  /*
1512  * need a tuple descriptor representing one INT and one TEXT column
1513  */
1514  tupdesc = CreateTemplateTupleDesc(2);
1515  TupleDescInitEntry(tupdesc, (AttrNumber) 1, "position",
1516  INT4OID, -1, 0);
1517  TupleDescInitEntry(tupdesc, (AttrNumber) 2, "colname",
1518  TEXTOID, -1, 0);
1519 
1520  /*
1521  * Generate attribute metadata needed later to produce tuples from raw
1522  * C strings
1523  */
1524  attinmeta = TupleDescGetAttInMetadata(tupdesc);
1525  funcctx->attinmeta = attinmeta;
1526 
1527  if ((results != NULL) && (indnkeyatts > 0))
1528  {
1529  funcctx->max_calls = indnkeyatts;
1530 
1531  /* got results, keep track of them */
1532  funcctx->user_fctx = results;
1533  }
1534  else
1535  {
1536  /* fast track when no results */
1537  MemoryContextSwitchTo(oldcontext);
1538  SRF_RETURN_DONE(funcctx);
1539  }
1540 
1541  MemoryContextSwitchTo(oldcontext);
1542  }
1543 
1544  /* stuff done on every call of the function */
1545  funcctx = SRF_PERCALL_SETUP();
1546 
1547  /*
1548  * initialize per-call variables
1549  */
1550  call_cntr = funcctx->call_cntr;
1551  max_calls = funcctx->max_calls;
1552 
1553  results = (char **) funcctx->user_fctx;
1554  attinmeta = funcctx->attinmeta;
1555 
1556  if (call_cntr < max_calls) /* do when there is more left to send */
1557  {
1558  char **values;
1559  HeapTuple tuple;
1560  Datum result;
1561 
1562  values = (char **) palloc(2 * sizeof(char *));
1563  values[0] = psprintf("%d", call_cntr + 1);
1564  values[1] = results[call_cntr];
1565 
1566  /* build the tuple */
1567  tuple = BuildTupleFromCStrings(attinmeta, values);
1568 
1569  /* make the tuple into a datum */
1570  result = HeapTupleGetDatum(tuple);
1571 
1572  SRF_RETURN_NEXT(funcctx, result);
1573  }
1574  else
1575  {
1576  /* do when there is no more left */
1577  SRF_RETURN_DONE(funcctx);
1578  }
1579 }
1580 
1581 
1582 /*
1583  * dblink_build_sql_insert
1584  *
1585  * Used to generate an SQL insert statement
1586  * based on an existing tuple in a local relation.
1587  * This is useful for selectively replicating data
1588  * to another server via dblink.
1589  *
1590  * API:
1591  * <relname> - name of local table of interest
1592  * <pkattnums> - an int2vector of attnums which will be used
1593  * to identify the local tuple of interest
1594  * <pknumatts> - number of attnums in pkattnums
1595  * <src_pkattvals_arry> - text array of key values which will be used
1596  * to identify the local tuple of interest
1597  * <tgt_pkattvals_arry> - text array of key values which will be used
1598  * to build the string for execution remotely. These are substituted
1599  * for their counterparts in src_pkattvals_arry
1600  */
1602 Datum
1604 {
1605  text *relname_text = PG_GETARG_TEXT_PP(0);
1606  int2vector *pkattnums_arg = (int2vector *) PG_GETARG_POINTER(1);
1607  int32 pknumatts_arg = PG_GETARG_INT32(2);
1608  ArrayType *src_pkattvals_arry = PG_GETARG_ARRAYTYPE_P(3);
1609  ArrayType *tgt_pkattvals_arry = PG_GETARG_ARRAYTYPE_P(4);
1610  Relation rel;
1611  int *pkattnums;
1612  int pknumatts;
1613  char **src_pkattvals;
1614  char **tgt_pkattvals;
1615  int src_nitems;
1616  int tgt_nitems;
1617  char *sql;
1618 
1619  /*
1620  * Open target relation.
1621  */
1622  rel = get_rel_from_relname(relname_text, AccessShareLock, ACL_SELECT);
1623 
1624  /*
1625  * Process pkattnums argument.
1626  */
1627  validate_pkattnums(rel, pkattnums_arg, pknumatts_arg,
1628  &pkattnums, &pknumatts);
1629 
1630  /*
1631  * Source array is made up of key values that will be used to locate the
1632  * tuple of interest from the local system.
1633  */
1634  src_pkattvals = get_text_array_contents(src_pkattvals_arry, &src_nitems);
1635 
1636  /*
1637  * There should be one source array key value for each key attnum
1638  */
1639  if (src_nitems != pknumatts)
1640  ereport(ERROR,
1641  (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
1642  errmsg("source key array length must match number of key attributes")));
1643 
1644  /*
1645  * Target array is made up of key values that will be used to build the
1646  * SQL string for use on the remote system.
1647  */
1648  tgt_pkattvals = get_text_array_contents(tgt_pkattvals_arry, &tgt_nitems);
1649 
1650  /*
1651  * There should be one target array key value for each key attnum
1652  */
1653  if (tgt_nitems != pknumatts)
1654  ereport(ERROR,
1655  (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
1656  errmsg("target key array length must match number of key attributes")));
1657 
1658  /*
1659  * Prep work is finally done. Go get the SQL string.
1660  */
1661  sql = get_sql_insert(rel, pkattnums, pknumatts, src_pkattvals, tgt_pkattvals);
1662 
1663  /*
1664  * Now we can close the relation.
1665  */
1667 
1668  /*
1669  * And send it
1670  */
1672 }
1673 
1674 
1675 /*
1676  * dblink_build_sql_delete
1677  *
1678  * Used to generate an SQL delete statement.
1679  * This is useful for selectively replicating a
1680  * delete to another server via dblink.
1681  *
1682  * API:
1683  * <relname> - name of remote table of interest
1684  * <pkattnums> - an int2vector of attnums which will be used
1685  * to identify the remote tuple of interest
1686  * <pknumatts> - number of attnums in pkattnums
1687  * <tgt_pkattvals_arry> - text array of key values which will be used
1688  * to build the string for execution remotely.
1689  */
1691 Datum
1693 {
1694  text *relname_text = PG_GETARG_TEXT_PP(0);
1695  int2vector *pkattnums_arg = (int2vector *) PG_GETARG_POINTER(1);
1696  int32 pknumatts_arg = PG_GETARG_INT32(2);
1697  ArrayType *tgt_pkattvals_arry = PG_GETARG_ARRAYTYPE_P(3);
1698  Relation rel;
1699  int *pkattnums;
1700  int pknumatts;
1701  char **tgt_pkattvals;
1702  int tgt_nitems;
1703  char *sql;
1704 
1705  /*
1706  * Open target relation.
1707  */
1708  rel = get_rel_from_relname(relname_text, AccessShareLock, ACL_SELECT);
1709 
1710  /*
1711  * Process pkattnums argument.
1712  */
1713  validate_pkattnums(rel, pkattnums_arg, pknumatts_arg,
1714  &pkattnums, &pknumatts);
1715 
1716  /*
1717  * Target array is made up of key values that will be used to build the
1718  * SQL string for use on the remote system.
1719  */
1720  tgt_pkattvals = get_text_array_contents(tgt_pkattvals_arry, &tgt_nitems);
1721 
1722  /*
1723  * There should be one target array key value for each key attnum
1724  */
1725  if (tgt_nitems != pknumatts)
1726  ereport(ERROR,
1727  (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
1728  errmsg("target key array length must match number of key attributes")));
1729 
1730  /*
1731  * Prep work is finally done. Go get the SQL string.
1732  */
1733  sql = get_sql_delete(rel, pkattnums, pknumatts, tgt_pkattvals);
1734 
1735  /*
1736  * Now we can close the relation.
1737  */
1739 
1740  /*
1741  * And send it
1742  */
1744 }
1745 
1746 
1747 /*
1748  * dblink_build_sql_update
1749  *
1750  * Used to generate an SQL update statement
1751  * based on an existing tuple in a local relation.
1752  * This is useful for selectively replicating data
1753  * to another server via dblink.
1754  *
1755  * API:
1756  * <relname> - name of local table of interest
1757  * <pkattnums> - an int2vector of attnums which will be used
1758  * to identify the local tuple of interest
1759  * <pknumatts> - number of attnums in pkattnums
1760  * <src_pkattvals_arry> - text array of key values which will be used
1761  * to identify the local tuple of interest
1762  * <tgt_pkattvals_arry> - text array of key values which will be used
1763  * to build the string for execution remotely. These are substituted
1764  * for their counterparts in src_pkattvals_arry
1765  */
1767 Datum
1769 {
1770  text *relname_text = PG_GETARG_TEXT_PP(0);
1771  int2vector *pkattnums_arg = (int2vector *) PG_GETARG_POINTER(1);
1772  int32 pknumatts_arg = PG_GETARG_INT32(2);
1773  ArrayType *src_pkattvals_arry = PG_GETARG_ARRAYTYPE_P(3);
1774  ArrayType *tgt_pkattvals_arry = PG_GETARG_ARRAYTYPE_P(4);
1775  Relation rel;
1776  int *pkattnums;
1777  int pknumatts;
1778  char **src_pkattvals;
1779  char **tgt_pkattvals;
1780  int src_nitems;
1781  int tgt_nitems;
1782  char *sql;
1783 
1784  /*
1785  * Open target relation.
1786  */
1787  rel = get_rel_from_relname(relname_text, AccessShareLock, ACL_SELECT);
1788 
1789  /*
1790  * Process pkattnums argument.
1791  */
1792  validate_pkattnums(rel, pkattnums_arg, pknumatts_arg,
1793  &pkattnums, &pknumatts);
1794 
1795  /*
1796  * Source array is made up of key values that will be used to locate the
1797  * tuple of interest from the local system.
1798  */
1799  src_pkattvals = get_text_array_contents(src_pkattvals_arry, &src_nitems);
1800 
1801  /*
1802  * There should be one source array key value for each key attnum
1803  */
1804  if (src_nitems != pknumatts)
1805  ereport(ERROR,
1806  (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
1807  errmsg("source key array length must match number of key attributes")));
1808 
1809  /*
1810  * Target array is made up of key values that will be used to build the
1811  * SQL string for use on the remote system.
1812  */
1813  tgt_pkattvals = get_text_array_contents(tgt_pkattvals_arry, &tgt_nitems);
1814 
1815  /*
1816  * There should be one target array key value for each key attnum
1817  */
1818  if (tgt_nitems != pknumatts)
1819  ereport(ERROR,
1820  (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
1821  errmsg("target key array length must match number of key attributes")));
1822 
1823  /*
1824  * Prep work is finally done. Go get the SQL string.
1825  */
1826  sql = get_sql_update(rel, pkattnums, pknumatts, src_pkattvals, tgt_pkattvals);
1827 
1828  /*
1829  * Now we can close the relation.
1830  */
1832 
1833  /*
1834  * And send it
1835  */
1837 }
1838 
1839 /*
1840  * dblink_current_query
1841  * return the current query string
1842  * to allow its use in (among other things)
1843  * rewrite rules
1844  */
1846 Datum
1848 {
1849  /* This is now just an alias for the built-in function current_query() */
1850  PG_RETURN_DATUM(current_query(fcinfo));
1851 }
1852 
1853 /*
1854  * Retrieve async notifications for a connection.
1855  *
1856  * Returns a setof record of notifications, or an empty set if none received.
1857  * Can optionally take a named connection as parameter, but uses the unnamed
1858  * connection per default.
1859  *
1860  */
1861 #define DBLINK_NOTIFY_COLS 3
1862 
1864 Datum
1866 {
1867  PGconn *conn;
1868  PGnotify *notify;
1869  ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
1870  TupleDesc tupdesc;
1871  Tuplestorestate *tupstore;
1872  MemoryContext per_query_ctx;
1873  MemoryContext oldcontext;
1874 
1875  prepTuplestoreResult(fcinfo);
1876 
1877  dblink_init();
1878  if (PG_NARGS() == 1)
1880  else
1881  conn = pconn->conn;
1882 
1883  /* create the tuplestore in per-query memory */
1884  per_query_ctx = rsinfo->econtext->ecxt_per_query_memory;
1885  oldcontext = MemoryContextSwitchTo(per_query_ctx);
1886 
1888  TupleDescInitEntry(tupdesc, (AttrNumber) 1, "notify_name",
1889  TEXTOID, -1, 0);
1890  TupleDescInitEntry(tupdesc, (AttrNumber) 2, "be_pid",
1891  INT4OID, -1, 0);
1892  TupleDescInitEntry(tupdesc, (AttrNumber) 3, "extra",
1893  TEXTOID, -1, 0);
1894 
1895  tupstore = tuplestore_begin_heap(true, false, work_mem);
1896  rsinfo->setResult = tupstore;
1897  rsinfo->setDesc = tupdesc;
1898 
1899  MemoryContextSwitchTo(oldcontext);
1900 
1901  PQconsumeInput(conn);
1902  while ((notify = PQnotifies(conn)) != NULL)
1903  {
1904  Datum values[DBLINK_NOTIFY_COLS];
1905  bool nulls[DBLINK_NOTIFY_COLS];
1906 
1907  memset(values, 0, sizeof(values));
1908  memset(nulls, 0, sizeof(nulls));
1909 
1910  if (notify->relname != NULL)
1911  values[0] = CStringGetTextDatum(notify->relname);
1912  else
1913  nulls[0] = true;
1914 
1915  values[1] = Int32GetDatum(notify->be_pid);
1916 
1917  if (notify->extra != NULL)
1918  values[2] = CStringGetTextDatum(notify->extra);
1919  else
1920  nulls[2] = true;
1921 
1922  tuplestore_putvalues(tupstore, tupdesc, values, nulls);
1923 
1924  PQfreemem(notify);
1925  PQconsumeInput(conn);
1926  }
1927 
1928  /* clean up and return the tuplestore */
1929  tuplestore_donestoring(tupstore);
1930 
1931  return (Datum) 0;
1932 }
1933 
1934 /*
1935  * Validate the options given to a dblink foreign server or user mapping.
1936  * Raise an error if any option is invalid.
1937  *
1938  * We just check the names of options here, so semantic errors in options,
1939  * such as invalid numeric format, will be detected at the attempt to connect.
1940  */
1942 Datum
1944 {
1945  List *options_list = untransformRelOptions(PG_GETARG_DATUM(0));
1946  Oid context = PG_GETARG_OID(1);
1947  ListCell *cell;
1948 
1949  static const PQconninfoOption *options = NULL;
1950 
1951  /*
1952  * Get list of valid libpq options.
1953  *
1954  * To avoid unnecessary work, we get the list once and use it throughout
1955  * the lifetime of this backend process. We don't need to care about
1956  * memory context issues, because PQconndefaults allocates with malloc.
1957  */
1958  if (!options)
1959  {
1960  options = PQconndefaults();
1961  if (!options) /* assume reason for failure is OOM */
1962  ereport(ERROR,
1963  (errcode(ERRCODE_FDW_OUT_OF_MEMORY),
1964  errmsg("out of memory"),
1965  errdetail("Could not get libpq's default connection options.")));
1966  }
1967 
1968  /* Validate each supplied option. */
1969  foreach(cell, options_list)
1970  {
1971  DefElem *def = (DefElem *) lfirst(cell);
1972 
1973  if (!is_valid_dblink_option(options, def->defname, context))
1974  {
1975  /*
1976  * Unknown option, or invalid option for the context specified, so
1977  * complain about it. Provide a hint with list of valid options
1978  * for the context.
1979  */
1981  const PQconninfoOption *opt;
1982 
1983  initStringInfo(&buf);
1984  for (opt = options; opt->keyword; opt++)
1985  {
1986  if (is_valid_dblink_option(options, opt->keyword, context))
1987  appendStringInfo(&buf, "%s%s",
1988  (buf.len > 0) ? ", " : "",
1989  opt->keyword);
1990  }
1991  ereport(ERROR,
1992  (errcode(ERRCODE_FDW_OPTION_NAME_NOT_FOUND),
1993  errmsg("invalid option \"%s\"", def->defname),
1994  errhint("Valid options in this context are: %s",
1995  buf.data)));
1996  }
1997  }
1998 
1999  PG_RETURN_VOID();
2000 }
2001 
2002 
2003 /*************************************************************
2004  * internal functions
2005  */
2006 
2007 
2008 /*
2009  * get_pkey_attnames
2010  *
2011  * Get the primary key attnames for the given relation.
2012  * Return NULL, and set indnkeyatts = 0, if no primary key exists.
2013  */
2014 static char **
2016 {
2017  Relation indexRelation;
2018  ScanKeyData skey;
2019  SysScanDesc scan;
2020  HeapTuple indexTuple;
2021  int i;
2022  char **result = NULL;
2023  TupleDesc tupdesc;
2024 
2025  /* initialize indnkeyatts to 0 in case no primary key exists */
2026  *indnkeyatts = 0;
2027 
2028  tupdesc = rel->rd_att;
2029 
2030  /* Prepare to scan pg_index for entries having indrelid = this rel. */
2031  indexRelation = table_open(IndexRelationId, AccessShareLock);
2032  ScanKeyInit(&skey,
2033  Anum_pg_index_indrelid,
2034  BTEqualStrategyNumber, F_OIDEQ,
2036 
2037  scan = systable_beginscan(indexRelation, IndexIndrelidIndexId, true,
2038  NULL, 1, &skey);
2039 
2040  while (HeapTupleIsValid(indexTuple = systable_getnext(scan)))
2041  {
2042  Form_pg_index index = (Form_pg_index) GETSTRUCT(indexTuple);
2043 
2044  /* we're only interested if it is the primary key */
2045  if (index->indisprimary)
2046  {
2047  *indnkeyatts = index->indnkeyatts;
2048  if (*indnkeyatts > 0)
2049  {
2050  result = (char **) palloc(*indnkeyatts * sizeof(char *));
2051 
2052  for (i = 0; i < *indnkeyatts; i++)
2053  result[i] = SPI_fname(tupdesc, index->indkey.values[i]);
2054  }
2055  break;
2056  }
2057  }
2058 
2059  systable_endscan(scan);
2060  table_close(indexRelation, AccessShareLock);
2061 
2062  return result;
2063 }
2064 
2065 /*
2066  * Deconstruct a text[] into C-strings (note any NULL elements will be
2067  * returned as NULL pointers)
2068  */
2069 static char **
2070 get_text_array_contents(ArrayType *array, int *numitems)
2071 {
2072  int ndim = ARR_NDIM(array);
2073  int *dims = ARR_DIMS(array);
2074  int nitems;
2075  int16 typlen;
2076  bool typbyval;
2077  char typalign;
2078  char **values;
2079  char *ptr;
2080  bits8 *bitmap;
2081  int bitmask;
2082  int i;
2083 
2084  Assert(ARR_ELEMTYPE(array) == TEXTOID);
2085 
2086  *numitems = nitems = ArrayGetNItems(ndim, dims);
2087 
2089  &typlen, &typbyval, &typalign);
2090 
2091  values = (char **) palloc(nitems * sizeof(char *));
2092 
2093  ptr = ARR_DATA_PTR(array);
2094  bitmap = ARR_NULLBITMAP(array);
2095  bitmask = 1;
2096 
2097  for (i = 0; i < nitems; i++)
2098  {
2099  if (bitmap && (*bitmap & bitmask) == 0)
2100  {
2101  values[i] = NULL;
2102  }
2103  else
2104  {
2105  values[i] = TextDatumGetCString(PointerGetDatum(ptr));
2106  ptr = att_addlength_pointer(ptr, typlen, ptr);
2107  ptr = (char *) att_align_nominal(ptr, typalign);
2108  }
2109 
2110  /* advance bitmap pointer if any */
2111  if (bitmap)
2112  {
2113  bitmask <<= 1;
2114  if (bitmask == 0x100)
2115  {
2116  bitmap++;
2117  bitmask = 1;
2118  }
2119  }
2120  }
2121 
2122  return values;
2123 }
2124 
2125 static char *
2126 get_sql_insert(Relation rel, int *pkattnums, int pknumatts, char **src_pkattvals, char **tgt_pkattvals)
2127 {
2128  char *relname;
2129  HeapTuple tuple;
2130  TupleDesc tupdesc;
2131  int natts;
2133  char *val;
2134  int key;
2135  int i;
2136  bool needComma;
2137 
2138  initStringInfo(&buf);
2139 
2140  /* get relation name including any needed schema prefix and quoting */
2141  relname = generate_relation_name(rel);
2142 
2143  tupdesc = rel->rd_att;
2144  natts = tupdesc->natts;
2145 
2146  tuple = get_tuple_of_interest(rel, pkattnums, pknumatts, src_pkattvals);
2147  if (!tuple)
2148  ereport(ERROR,
2149  (errcode(ERRCODE_CARDINALITY_VIOLATION),
2150  errmsg("source row not found")));
2151 
2152  appendStringInfo(&buf, "INSERT INTO %s(", relname);
2153 
2154  needComma = false;
2155  for (i = 0; i < natts; i++)
2156  {
2157  Form_pg_attribute att = TupleDescAttr(tupdesc, i);
2158 
2159  if (att->attisdropped)
2160  continue;
2161 
2162  if (needComma)
2163  appendStringInfoChar(&buf, ',');
2164 
2166  quote_ident_cstr(NameStr(att->attname)));
2167  needComma = true;
2168  }
2169 
2170  appendStringInfoString(&buf, ") VALUES(");
2171 
2172  /*
2173  * Note: i is physical column number (counting from 0).
2174  */
2175  needComma = false;
2176  for (i = 0; i < natts; i++)
2177  {
2178  if (TupleDescAttr(tupdesc, i)->attisdropped)
2179  continue;
2180 
2181  if (needComma)
2182  appendStringInfoChar(&buf, ',');
2183 
2184  key = get_attnum_pk_pos(pkattnums, pknumatts, i);
2185 
2186  if (key >= 0)
2187  val = tgt_pkattvals[key] ? pstrdup(tgt_pkattvals[key]) : NULL;
2188  else
2189  val = SPI_getvalue(tuple, tupdesc, i + 1);
2190 
2191  if (val != NULL)
2192  {
2194  pfree(val);
2195  }
2196  else
2197  appendStringInfoString(&buf, "NULL");
2198  needComma = true;
2199  }
2200  appendStringInfoChar(&buf, ')');
2201 
2202  return buf.data;
2203 }
2204 
2205 static char *
2206 get_sql_delete(Relation rel, int *pkattnums, int pknumatts, char **tgt_pkattvals)
2207 {
2208  char *relname;
2209  TupleDesc tupdesc;
2211  int i;
2212 
2213  initStringInfo(&buf);
2214 
2215  /* get relation name including any needed schema prefix and quoting */
2216  relname = generate_relation_name(rel);
2217 
2218  tupdesc = rel->rd_att;
2219 
2220  appendStringInfo(&buf, "DELETE FROM %s WHERE ", relname);
2221  for (i = 0; i < pknumatts; i++)
2222  {
2223  int pkattnum = pkattnums[i];
2224  Form_pg_attribute attr = TupleDescAttr(tupdesc, pkattnum);
2225 
2226  if (i > 0)
2227  appendStringInfoString(&buf, " AND ");
2228 
2230  quote_ident_cstr(NameStr(attr->attname)));
2231 
2232  if (tgt_pkattvals[i] != NULL)
2233  appendStringInfo(&buf, " = %s",
2234  quote_literal_cstr(tgt_pkattvals[i]));
2235  else
2236  appendStringInfoString(&buf, " IS NULL");
2237  }
2238 
2239  return buf.data;
2240 }
2241 
2242 static char *
2243 get_sql_update(Relation rel, int *pkattnums, int pknumatts, char **src_pkattvals, char **tgt_pkattvals)
2244 {
2245  char *relname;
2246  HeapTuple tuple;
2247  TupleDesc tupdesc;
2248  int natts;
2250  char *val;
2251  int key;
2252  int i;
2253  bool needComma;
2254 
2255  initStringInfo(&buf);
2256 
2257  /* get relation name including any needed schema prefix and quoting */
2258  relname = generate_relation_name(rel);
2259 
2260  tupdesc = rel->rd_att;
2261  natts = tupdesc->natts;
2262 
2263  tuple = get_tuple_of_interest(rel, pkattnums, pknumatts, src_pkattvals);
2264  if (!tuple)
2265  ereport(ERROR,
2266  (errcode(ERRCODE_CARDINALITY_VIOLATION),
2267  errmsg("source row not found")));
2268 
2269  appendStringInfo(&buf, "UPDATE %s SET ", relname);
2270 
2271  /*
2272  * Note: i is physical column number (counting from 0).
2273  */
2274  needComma = false;
2275  for (i = 0; i < natts; i++)
2276  {
2277  Form_pg_attribute attr = TupleDescAttr(tupdesc, i);
2278 
2279  if (attr->attisdropped)
2280  continue;
2281 
2282  if (needComma)
2283  appendStringInfoString(&buf, ", ");
2284 
2285  appendStringInfo(&buf, "%s = ",
2286  quote_ident_cstr(NameStr(attr->attname)));
2287 
2288  key = get_attnum_pk_pos(pkattnums, pknumatts, i);
2289 
2290  if (key >= 0)
2291  val = tgt_pkattvals[key] ? pstrdup(tgt_pkattvals[key]) : NULL;
2292  else
2293  val = SPI_getvalue(tuple, tupdesc, i + 1);
2294 
2295  if (val != NULL)
2296  {
2298  pfree(val);
2299  }
2300  else
2301  appendStringInfoString(&buf, "NULL");
2302  needComma = true;
2303  }
2304 
2305  appendStringInfoString(&buf, " WHERE ");
2306 
2307  for (i = 0; i < pknumatts; i++)
2308  {
2309  int pkattnum = pkattnums[i];
2310  Form_pg_attribute attr = TupleDescAttr(tupdesc, pkattnum);
2311 
2312  if (i > 0)
2313  appendStringInfoString(&buf, " AND ");
2314 
2316  quote_ident_cstr(NameStr(attr->attname)));
2317 
2318  val = tgt_pkattvals[i];
2319 
2320  if (val != NULL)
2321  appendStringInfo(&buf, " = %s", quote_literal_cstr(val));
2322  else
2323  appendStringInfoString(&buf, " IS NULL");
2324  }
2325 
2326  return buf.data;
2327 }
2328 
2329 /*
2330  * Return a properly quoted identifier.
2331  * Uses quote_ident in quote.c
2332  */
2333 static char *
2334 quote_ident_cstr(char *rawstr)
2335 {
2336  text *rawstr_text;
2337  text *result_text;
2338  char *result;
2339 
2340  rawstr_text = cstring_to_text(rawstr);
2342  PointerGetDatum(rawstr_text)));
2343  result = text_to_cstring(result_text);
2344 
2345  return result;
2346 }
2347 
2348 static int
2349 get_attnum_pk_pos(int *pkattnums, int pknumatts, int key)
2350 {
2351  int i;
2352 
2353  /*
2354  * Not likely a long list anyway, so just scan for the value
2355  */
2356  for (i = 0; i < pknumatts; i++)
2357  if (key == pkattnums[i])
2358  return i;
2359 
2360  return -1;
2361 }
2362 
2363 static HeapTuple
2364 get_tuple_of_interest(Relation rel, int *pkattnums, int pknumatts, char **src_pkattvals)
2365 {
2366  char *relname;
2367  TupleDesc tupdesc;
2368  int natts;
2370  int ret;
2371  HeapTuple tuple;
2372  int i;
2373 
2374  /*
2375  * Connect to SPI manager
2376  */
2377  if ((ret = SPI_connect()) < 0)
2378  /* internal error */
2379  elog(ERROR, "SPI connect failure - returned %d", ret);
2380 
2381  initStringInfo(&buf);
2382 
2383  /* get relation name including any needed schema prefix and quoting */
2384  relname = generate_relation_name(rel);
2385 
2386  tupdesc = rel->rd_att;
2387  natts = tupdesc->natts;
2388 
2389  /*
2390  * Build sql statement to look up tuple of interest, ie, the one matching
2391  * src_pkattvals. We used to use "SELECT *" here, but it's simpler to
2392  * generate a result tuple that matches the table's physical structure,
2393  * with NULLs for any dropped columns. Otherwise we have to deal with two
2394  * different tupdescs and everything's very confusing.
2395  */
2396  appendStringInfoString(&buf, "SELECT ");
2397 
2398  for (i = 0; i < natts; i++)
2399  {
2400  Form_pg_attribute attr = TupleDescAttr(tupdesc, i);
2401 
2402  if (i > 0)
2403  appendStringInfoString(&buf, ", ");
2404 
2405  if (attr->attisdropped)
2406  appendStringInfoString(&buf, "NULL");
2407  else
2409  quote_ident_cstr(NameStr(attr->attname)));
2410  }
2411 
2412  appendStringInfo(&buf, " FROM %s WHERE ", relname);
2413 
2414  for (i = 0; i < pknumatts; i++)
2415  {
2416  int pkattnum = pkattnums[i];
2417  Form_pg_attribute attr = TupleDescAttr(tupdesc, pkattnum);
2418 
2419  if (i > 0)
2420  appendStringInfoString(&buf, " AND ");
2421 
2423  quote_ident_cstr(NameStr(attr->attname)));
2424 
2425  if (src_pkattvals[i] != NULL)
2426  appendStringInfo(&buf, " = %s",
2427  quote_literal_cstr(src_pkattvals[i]));
2428  else
2429  appendStringInfoString(&buf, " IS NULL");
2430  }
2431 
2432  /*
2433  * Retrieve the desired tuple
2434  */
2435  ret = SPI_exec(buf.data, 0);
2436  pfree(buf.data);
2437 
2438  /*
2439  * Only allow one qualifying tuple
2440  */
2441  if ((ret == SPI_OK_SELECT) && (SPI_processed > 1))
2442  ereport(ERROR,
2443  (errcode(ERRCODE_CARDINALITY_VIOLATION),
2444  errmsg("source criteria matched more than one record")));
2445 
2446  else if (ret == SPI_OK_SELECT && SPI_processed == 1)
2447  {
2448  SPITupleTable *tuptable = SPI_tuptable;
2449 
2450  tuple = SPI_copytuple(tuptable->vals[0]);
2451  SPI_finish();
2452 
2453  return tuple;
2454  }
2455  else
2456  {
2457  /*
2458  * no qualifying tuples
2459  */
2460  SPI_finish();
2461 
2462  return NULL;
2463  }
2464 
2465  /*
2466  * never reached, but keep compiler quiet
2467  */
2468  return NULL;
2469 }
2470 
2471 /*
2472  * Open the relation named by relname_text, acquire specified type of lock,
2473  * verify we have specified permissions.
2474  * Caller must close rel when done with it.
2475  */
2476 static Relation
2477 get_rel_from_relname(text *relname_text, LOCKMODE lockmode, AclMode aclmode)
2478 {
2479  RangeVar *relvar;
2480  Relation rel;
2481  AclResult aclresult;
2482 
2483  relvar = makeRangeVarFromNameList(textToQualifiedNameList(relname_text));
2484  rel = table_openrv(relvar, lockmode);
2485 
2486  aclresult = pg_class_aclcheck(RelationGetRelid(rel), GetUserId(),
2487  aclmode);
2488  if (aclresult != ACLCHECK_OK)
2489  aclcheck_error(aclresult, get_relkind_objtype(rel->rd_rel->relkind),
2491 
2492  return rel;
2493 }
2494 
2495 /*
2496  * generate_relation_name - copied from ruleutils.c
2497  * Compute the name to display for a relation
2498  *
2499  * The result includes all necessary quoting and schema-prefixing.
2500  */
2501 static char *
2503 {
2504  char *nspname;
2505  char *result;
2506 
2507  /* Qualify the name if not visible in search path */
2509  nspname = NULL;
2510  else
2511  nspname = get_namespace_name(rel->rd_rel->relnamespace);
2512 
2513  result = quote_qualified_identifier(nspname, RelationGetRelationName(rel));
2514 
2515  return result;
2516 }
2517 
2518 
2519 static remoteConn *
2521 {
2522  remoteConnHashEnt *hentry;
2523  char *key;
2524 
2525  if (!remoteConnHash)
2527 
2528  key = pstrdup(name);
2529  truncate_identifier(key, strlen(key), false);
2531  key, HASH_FIND, NULL);
2532 
2533  if (hentry)
2534  return hentry->rconn;
2535 
2536  return NULL;
2537 }
2538 
2539 static HTAB *
2541 {
2542  HASHCTL ctl;
2543 
2544  ctl.keysize = NAMEDATALEN;
2545  ctl.entrysize = sizeof(remoteConnHashEnt);
2546 
2547  return hash_create("Remote Con hash", NUMCONN, &ctl, HASH_ELEM);
2548 }
2549 
2550 static void
2552 {
2553  remoteConnHashEnt *hentry;
2554  bool found;
2555  char *key;
2556 
2557  if (!remoteConnHash)
2559 
2560  key = pstrdup(name);
2561  truncate_identifier(key, strlen(key), true);
2562  hentry = (remoteConnHashEnt *) hash_search(remoteConnHash, key,
2563  HASH_ENTER, &found);
2564 
2565  if (found)
2566  {
2567  PQfinish(rconn->conn);
2568  pfree(rconn);
2569 
2570  ereport(ERROR,
2572  errmsg("duplicate connection name")));
2573  }
2574 
2575  hentry->rconn = rconn;
2576  strlcpy(hentry->name, name, sizeof(hentry->name));
2577 }
2578 
2579 static void
2581 {
2582  remoteConnHashEnt *hentry;
2583  bool found;
2584  char *key;
2585 
2586  if (!remoteConnHash)
2588 
2589  key = pstrdup(name);
2590  truncate_identifier(key, strlen(key), false);
2592  key, HASH_REMOVE, &found);
2593 
2594  if (!hentry)
2595  ereport(ERROR,
2596  (errcode(ERRCODE_UNDEFINED_OBJECT),
2597  errmsg("undefined connection name")));
2598 
2599 }
2600 
2601 static void
2603 {
2604  if (!superuser())
2605  {
2606  if (!PQconnectionUsedPassword(conn))
2607  {
2608  PQfinish(conn);
2609  if (rconn)
2610  pfree(rconn);
2611 
2612  ereport(ERROR,
2613  (errcode(ERRCODE_S_R_E_PROHIBITED_SQL_STATEMENT_ATTEMPTED),
2614  errmsg("password is required"),
2615  errdetail("Non-superuser cannot connect if the server does not request a password."),
2616  errhint("Target server's authentication method must be changed.")));
2617  }
2618  }
2619 }
2620 
2621 /*
2622  * For non-superusers, insist that the connstr specify a password. This
2623  * prevents a password from being picked up from .pgpass, a service file,
2624  * the environment, etc. We don't want the postgres user's passwords
2625  * to be accessible to non-superusers.
2626  */
2627 static void
2629 {
2630  if (!superuser())
2631  {
2634  bool connstr_gives_password = false;
2635 
2636  options = PQconninfoParse(connstr, NULL);
2637  if (options)
2638  {
2639  for (option = options; option->keyword != NULL; option++)
2640  {
2641  if (strcmp(option->keyword, "password") == 0)
2642  {
2643  if (option->val != NULL && option->val[0] != '\0')
2644  {
2645  connstr_gives_password = true;
2646  break;
2647  }
2648  }
2649  }
2650  PQconninfoFree(options);
2651  }
2652 
2653  if (!connstr_gives_password)
2654  ereport(ERROR,
2655  (errcode(ERRCODE_S_R_E_PROHIBITED_SQL_STATEMENT_ATTEMPTED),
2656  errmsg("password is required"),
2657  errdetail("Non-superusers must provide a password in the connection string.")));
2658  }
2659 }
2660 
2661 /*
2662  * Report an error received from the remote server
2663  *
2664  * res: the received error result (will be freed)
2665  * fail: true for ERROR ereport, false for NOTICE
2666  * fmt and following args: sprintf-style format and values for errcontext;
2667  * the resulting string should be worded like "while <some action>"
2668  */
2669 static void
2670 dblink_res_error(PGconn *conn, const char *conname, PGresult *res,
2671  bool fail, const char *fmt,...)
2672 {
2673  int level;
2674  char *pg_diag_sqlstate = PQresultErrorField(res, PG_DIAG_SQLSTATE);
2675  char *pg_diag_message_primary = PQresultErrorField(res, PG_DIAG_MESSAGE_PRIMARY);
2676  char *pg_diag_message_detail = PQresultErrorField(res, PG_DIAG_MESSAGE_DETAIL);
2677  char *pg_diag_message_hint = PQresultErrorField(res, PG_DIAG_MESSAGE_HINT);
2678  char *pg_diag_context = PQresultErrorField(res, PG_DIAG_CONTEXT);
2679  int sqlstate;
2680  char *message_primary;
2681  char *message_detail;
2682  char *message_hint;
2683  char *message_context;
2684  va_list ap;
2685  char dblink_context_msg[512];
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  message_primary = xpstrdup(pg_diag_message_primary);
2702  message_detail = xpstrdup(pg_diag_message_detail);
2703  message_hint = xpstrdup(pg_diag_message_hint);
2704  message_context = xpstrdup(pg_diag_context);
2705 
2706  /*
2707  * If we don't get a message from the PGresult, try the PGconn. This is
2708  * needed because for connection-level failures, PQexec may just return
2709  * NULL, not a PGresult at all.
2710  */
2711  if (message_primary == NULL)
2712  message_primary = pchomp(PQerrorMessage(conn));
2713 
2714  /*
2715  * Now that we've copied all the data we need out of the PGresult, it's
2716  * safe to free it. We must do this to avoid PGresult leakage. We're
2717  * leaking all the strings too, but those are in palloc'd memory that will
2718  * get cleaned up eventually.
2719  */
2720  if (res)
2721  PQclear(res);
2722 
2723  /*
2724  * Format the basic errcontext string. Below, we'll add on something
2725  * about the connection name. That's a violation of the translatability
2726  * guidelines about constructing error messages out of parts, but since
2727  * there's no translation support for dblink, there's no need to worry
2728  * about that (yet).
2729  */
2730  va_start(ap, fmt);
2731  vsnprintf(dblink_context_msg, sizeof(dblink_context_msg), fmt, ap);
2732  va_end(ap);
2733 
2734  ereport(level,
2735  (errcode(sqlstate),
2736  message_primary ? errmsg_internal("%s", message_primary) :
2737  errmsg("could not obtain message string for remote error"),
2738  message_detail ? errdetail_internal("%s", message_detail) : 0,
2739  message_hint ? errhint("%s", message_hint) : 0,
2740  message_context ? (errcontext("%s", message_context)) : 0,
2741  conname ?
2742  (errcontext("%s on dblink connection named \"%s\"",
2743  dblink_context_msg, conname)) :
2744  (errcontext("%s on unnamed dblink connection",
2745  dblink_context_msg))));
2746 }
2747 
2748 /*
2749  * Obtain connection string for a foreign server
2750  */
2751 static char *
2752 get_connect_string(const char *servername)
2753 {
2754  ForeignServer *foreign_server = NULL;
2755  UserMapping *user_mapping;
2756  ListCell *cell;
2758  ForeignDataWrapper *fdw;
2759  AclResult aclresult;
2760  char *srvname;
2761 
2762  static const PQconninfoOption *options = NULL;
2763 
2764  initStringInfo(&buf);
2765 
2766  /*
2767  * Get list of valid libpq options.
2768  *
2769  * To avoid unnecessary work, we get the list once and use it throughout
2770  * the lifetime of this backend process. We don't need to care about
2771  * memory context issues, because PQconndefaults allocates with malloc.
2772  */
2773  if (!options)
2774  {
2775  options = PQconndefaults();
2776  if (!options) /* assume reason for failure is OOM */
2777  ereport(ERROR,
2778  (errcode(ERRCODE_FDW_OUT_OF_MEMORY),
2779  errmsg("out of memory"),
2780  errdetail("Could not get libpq's default connection options.")));
2781  }
2782 
2783  /* first gather the server connstr options */
2784  srvname = pstrdup(servername);
2785  truncate_identifier(srvname, strlen(srvname), false);
2786  foreign_server = GetForeignServerByName(srvname, true);
2787 
2788  if (foreign_server)
2789  {
2790  Oid serverid = foreign_server->serverid;
2791  Oid fdwid = foreign_server->fdwid;
2792  Oid userid = GetUserId();
2793 
2794  user_mapping = GetUserMapping(userid, serverid);
2795  fdw = GetForeignDataWrapper(fdwid);
2796 
2797  /* Check permissions, user must have usage on the server. */
2798  aclresult = pg_foreign_server_aclcheck(serverid, userid, ACL_USAGE);
2799  if (aclresult != ACLCHECK_OK)
2800  aclcheck_error(aclresult, OBJECT_FOREIGN_SERVER, foreign_server->servername);
2801 
2802  foreach(cell, fdw->options)
2803  {
2804  DefElem *def = lfirst(cell);
2805 
2806  if (is_valid_dblink_option(options, def->defname, ForeignDataWrapperRelationId))
2807  appendStringInfo(&buf, "%s='%s' ", def->defname,
2808  escape_param_str(strVal(def->arg)));
2809  }
2810 
2811  foreach(cell, foreign_server->options)
2812  {
2813  DefElem *def = lfirst(cell);
2814 
2815  if (is_valid_dblink_option(options, def->defname, ForeignServerRelationId))
2816  appendStringInfo(&buf, "%s='%s' ", def->defname,
2817  escape_param_str(strVal(def->arg)));
2818  }
2819 
2820  foreach(cell, user_mapping->options)
2821  {
2822 
2823  DefElem *def = lfirst(cell);
2824 
2825  if (is_valid_dblink_option(options, def->defname, UserMappingRelationId))
2826  appendStringInfo(&buf, "%s='%s' ", def->defname,
2827  escape_param_str(strVal(def->arg)));
2828  }
2829 
2830  return buf.data;
2831  }
2832  else
2833  return NULL;
2834 }
2835 
2836 /*
2837  * Escaping libpq connect parameter strings.
2838  *
2839  * Replaces "'" with "\'" and "\" with "\\".
2840  */
2841 static char *
2842 escape_param_str(const char *str)
2843 {
2844  const char *cp;
2846 
2847  initStringInfo(&buf);
2848 
2849  for (cp = str; *cp; cp++)
2850  {
2851  if (*cp == '\\' || *cp == '\'')
2852  appendStringInfoChar(&buf, '\\');
2853  appendStringInfoChar(&buf, *cp);
2854  }
2855 
2856  return buf.data;
2857 }
2858 
2859 /*
2860  * Validate the PK-attnums argument for dblink_build_sql_insert() and related
2861  * functions, and translate to the internal representation.
2862  *
2863  * The user supplies an int2vector of 1-based logical attnums, plus a count
2864  * argument (the need for the separate count argument is historical, but we
2865  * still check it). We check that each attnum corresponds to a valid,
2866  * non-dropped attribute of the rel. We do *not* prevent attnums from being
2867  * listed twice, though the actual use-case for such things is dubious.
2868  * Note that before Postgres 9.0, the user's attnums were interpreted as
2869  * physical not logical column numbers; this was changed for future-proofing.
2870  *
2871  * The internal representation is a palloc'd int array of 0-based physical
2872  * attnums.
2873  */
2874 static void
2876  int2vector *pkattnums_arg, int32 pknumatts_arg,
2877  int **pkattnums, int *pknumatts)
2878 {
2879  TupleDesc tupdesc = rel->rd_att;
2880  int natts = tupdesc->natts;
2881  int i;
2882 
2883  /* Don't take more array elements than there are */
2884  pknumatts_arg = Min(pknumatts_arg, pkattnums_arg->dim1);
2885 
2886  /* Must have at least one pk attnum selected */
2887  if (pknumatts_arg <= 0)
2888  ereport(ERROR,
2889  (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
2890  errmsg("number of key attributes must be > 0")));
2891 
2892  /* Allocate output array */
2893  *pkattnums = (int *) palloc(pknumatts_arg * sizeof(int));
2894  *pknumatts = pknumatts_arg;
2895 
2896  /* Validate attnums and convert to internal form */
2897  for (i = 0; i < pknumatts_arg; i++)
2898  {
2899  int pkattnum = pkattnums_arg->values[i];
2900  int lnum;
2901  int j;
2902 
2903  /* Can throw error immediately if out of range */
2904  if (pkattnum <= 0 || pkattnum > natts)
2905  ereport(ERROR,
2906  (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
2907  errmsg("invalid attribute number %d", pkattnum)));
2908 
2909  /* Identify which physical column has this logical number */
2910  lnum = 0;
2911  for (j = 0; j < natts; j++)
2912  {
2913  /* dropped columns don't count */
2914  if (TupleDescAttr(tupdesc, j)->attisdropped)
2915  continue;
2916 
2917  if (++lnum == pkattnum)
2918  break;
2919  }
2920 
2921  if (j < natts)
2922  (*pkattnums)[i] = j;
2923  else
2924  ereport(ERROR,
2925  (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
2926  errmsg("invalid attribute number %d", pkattnum)));
2927  }
2928 }
2929 
2930 /*
2931  * Check if the specified connection option is valid.
2932  *
2933  * We basically allow whatever libpq thinks is an option, with these
2934  * restrictions:
2935  * debug options: disallowed
2936  * "client_encoding": disallowed
2937  * "user": valid only in USER MAPPING options
2938  * secure options (eg password): valid only in USER MAPPING options
2939  * others: valid only in FOREIGN SERVER options
2940  *
2941  * We disallow client_encoding because it would be overridden anyway via
2942  * PQclientEncoding; allowing it to be specified would merely promote
2943  * confusion.
2944  */
2945 static bool
2947  Oid context)
2948 {
2949  const PQconninfoOption *opt;
2950 
2951  /* Look up the option in libpq result */
2952  for (opt = options; opt->keyword; opt++)
2953  {
2954  if (strcmp(opt->keyword, option) == 0)
2955  break;
2956  }
2957  if (opt->keyword == NULL)
2958  return false;
2959 
2960  /* Disallow debug options (particularly "replication") */
2961  if (strchr(opt->dispchar, 'D'))
2962  return false;
2963 
2964  /* Disallow "client_encoding" */
2965  if (strcmp(opt->keyword, "client_encoding") == 0)
2966  return false;
2967 
2968  /*
2969  * If the option is "user" or marked secure, it should be specified only
2970  * in USER MAPPING. Others should be specified only in SERVER.
2971  */
2972  if (strcmp(opt->keyword, "user") == 0 || strchr(opt->dispchar, '*'))
2973  {
2974  if (context != UserMappingRelationId)
2975  return false;
2976  }
2977  else
2978  {
2979  if (context != ForeignServerRelationId)
2980  return false;
2981  }
2982 
2983  return true;
2984 }
2985 
2986 /*
2987  * Copy the remote session's values of GUCs that affect datatype I/O
2988  * and apply them locally in a new GUC nesting level. Returns the new
2989  * nestlevel (which is needed by restoreLocalGucs to undo the settings),
2990  * or -1 if no new nestlevel was needed.
2991  *
2992  * We use the equivalent of a function SET option to allow the settings to
2993  * persist only until the caller calls restoreLocalGucs. If an error is
2994  * thrown in between, guc.c will take care of undoing the settings.
2995  */
2996 static int
2998 {
2999  static const char *const GUCsAffectingIO[] = {
3000  "DateStyle",
3001  "IntervalStyle"
3002  };
3003 
3004  int nestlevel = -1;
3005  int i;
3006 
3007  for (i = 0; i < lengthof(GUCsAffectingIO); i++)
3008  {
3009  const char *gucName = GUCsAffectingIO[i];
3010  const char *remoteVal = PQparameterStatus(conn, gucName);
3011  const char *localVal;
3012 
3013  /*
3014  * If the remote server is pre-8.4, it won't have IntervalStyle, but
3015  * that's okay because its output format won't be ambiguous. So just
3016  * skip the GUC if we don't get a value for it. (We might eventually
3017  * need more complicated logic with remote-version checks here.)
3018  */
3019  if (remoteVal == NULL)
3020  continue;
3021 
3022  /*
3023  * Avoid GUC-setting overhead if the remote and local GUCs already
3024  * have the same value.
3025  */
3026  localVal = GetConfigOption(gucName, false, false);
3027  Assert(localVal != NULL);
3028 
3029  if (strcmp(remoteVal, localVal) == 0)
3030  continue;
3031 
3032  /* Create new GUC nest level if we didn't already */
3033  if (nestlevel < 0)
3034  nestlevel = NewGUCNestLevel();
3035 
3036  /* Apply the option (this will throw error on failure) */
3037  (void) set_config_option(gucName, remoteVal,
3039  GUC_ACTION_SAVE, true, 0, false);
3040  }
3041 
3042  return nestlevel;
3043 }
3044 
3045 /*
3046  * Restore local GUCs after they have been overlaid with remote settings.
3047  */
3048 static void
3049 restoreLocalGucs(int nestlevel)
3050 {
3051  /* Do nothing if no new nestlevel was created */
3052  if (nestlevel > 0)
3053  AtEOXact_GUC(true, nestlevel);
3054 }
void tuplestore_putvalues(Tuplestorestate *state, TupleDesc tdesc, Datum *values, bool *isnull)
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uint64 call_cntr
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Size entrysize
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Definition: execnodes.h:300
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Definition: mcxt.c:949
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Definition: elog.h:228
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Definition: fe-exec.c:1939
Definition: c.h:556
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Definition: fmgr.h:188
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ConnStatusType PQstatus(const PGconn *conn)
Definition: fe-connect.c:6578
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Definition: elog.h:322
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Definition: guc.c:6794
Definition: pg_list.h:50
List * options
Definition: foreign.h:42
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Definition: array.h:280
int16 AttrNumber
Definition: attnum.h:21
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Definition: fe-exec.c:3296
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Definition: rel.h:428
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Definition: array.h:288
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Definition: informix.c:664
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Definition: fe-exec.c:1778
Oid serverid
Definition: foreign.h:36
#define PG_RETURN_NULL()
Definition: fmgr.h:335
#define PG_END_TRY()
Definition: elog.h:347
#define BTEqualStrategyNumber
Definition: stratnum.h:31
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Definition: indexing.h:166
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:686
#define SRF_RETURN_DONE(_funcctx)
Definition: funcapi.h:306
static char * connstr
Definition: pg_dumpall.c:61
#define SRF_FIRSTCALL_INIT()
Definition: funcapi.h:284