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jconwayjconway
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When a cursor is opened using dblink_open, only start a transaction
if there isn't one already open. Upon dblink_close, only commit the open transaction if it was started by dblink_open, and only then when all cursors opened by dblink_open are closed. The transaction accounting is done individually for all named connections, plus the persistent unnamed connection.
1 parent c62b29a commit 056eb14

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3 files changed

+193
-39
lines changed

3 files changed

+193
-39
lines changed

‎contrib/dblink/dblink.c

Lines changed: 75 additions & 39 deletions
Original file line numberDiff line numberDiff line change
@@ -60,9 +60,9 @@
6060

6161
typedef struct remoteConn
6262
{
63-
PGconn *conn; /* Hold the remote connection */
64-
int autoXactCursors;/* Indicates the number of open cursors,
65-
* non-zero means we opened the xact ourselves */
63+
PGconn *conn; /* Hold the remote connection */
64+
int openCursorCount; /* The number of open cursors */
65+
bool newXactForCursor; /* Opened a transaction for a cursor */
6666
} remoteConn;
6767

6868
/*
@@ -84,10 +84,8 @@ static Oid get_relid_from_relname(text *relname_text);
8484
static char *generate_relation_name(Oid relid);
8585

8686
/* Global */
87-
List *res_id = NIL;
88-
int res_id_index = 0;
89-
PGconn *persistent_conn = NULL;
90-
static HTAB *remoteConnHash = NULL;
87+
static remoteConn *pconn = NULL;
88+
static HTAB *remoteConnHash = NULL;
9189

9290
/*
9391
* Following is list that holds multiple remote connections.
@@ -184,6 +182,16 @@ typedef struct remoteConnHashEnt
184182
} \
185183
} while (0)
186184

185+
#define DBLINK_INIT \
186+
do { \
187+
if (!pconn) \
188+
{ \
189+
pconn = (remoteConn *) MemoryContextAlloc(TopMemoryContext, sizeof(remoteConn)); \
190+
pconn->conn = NULL; \
191+
pconn->openCursorCount = 0; \
192+
pconn->newXactForCursor = FALSE; \
193+
} \
194+
} while (0)
187195

188196
/*
189197
* Create a persistent connection to another database
@@ -199,6 +207,8 @@ dblink_connect(PG_FUNCTION_ARGS)
199207
PGconn *conn = NULL;
200208
remoteConn *rconn = NULL;
201209

210+
DBLINK_INIT;
211+
202212
if (PG_NARGS() == 2)
203213
{
204214
connstr = GET_STR(PG_GETARG_TEXT_P(1));
@@ -234,7 +244,7 @@ dblink_connect(PG_FUNCTION_ARGS)
234244
createNewConnection(connname, rconn);
235245
}
236246
else
237-
persistent_conn = conn;
247+
pconn->conn = conn;
238248

239249
PG_RETURN_TEXT_P(GET_TEXT("OK"));
240250
}
@@ -250,6 +260,8 @@ dblink_disconnect(PG_FUNCTION_ARGS)
250260
remoteConn *rconn = NULL;
251261
PGconn *conn = NULL;
252262

263+
DBLINK_INIT;
264+
253265
if (PG_NARGS() == 1)
254266
{
255267
conname = GET_STR(PG_GETARG_TEXT_P(0));
@@ -258,7 +270,7 @@ dblink_disconnect(PG_FUNCTION_ARGS)
258270
conn = rconn->conn;
259271
}
260272
else
261-
conn = persistent_conn;
273+
conn = pconn->conn;
262274

263275
if (!conn)
264276
DBLINK_CONN_NOT_AVAIL;
@@ -270,7 +282,7 @@ dblink_disconnect(PG_FUNCTION_ARGS)
270282
pfree(rconn);
271283
}
272284
else
273-
persistent_conn = NULL;
285+
pconn->conn = NULL;
274286

275287
PG_RETURN_TEXT_P(GET_TEXT("OK"));
276288
}
@@ -292,12 +304,14 @@ dblink_open(PG_FUNCTION_ARGS)
292304
remoteConn *rconn = NULL;
293305
bool fail = true; /* default to backward compatible behavior */
294306

307+
DBLINK_INIT;
308+
295309
if (PG_NARGS() == 2)
296310
{
297311
/* text,text */
298312
curname = GET_STR(PG_GETARG_TEXT_P(0));
299313
sql = GET_STR(PG_GETARG_TEXT_P(1));
300-
conn = persistent_conn;
314+
rconn = pconn;
301315
}
302316
else if (PG_NARGS() == 3)
303317
{
@@ -307,16 +321,14 @@ dblink_open(PG_FUNCTION_ARGS)
307321
curname = GET_STR(PG_GETARG_TEXT_P(0));
308322
sql = GET_STR(PG_GETARG_TEXT_P(1));
309323
fail = PG_GETARG_BOOL(2);
310-
conn = persistent_conn;
324+
rconn = pconn;
311325
}
312326
else
313327
{
314328
conname = GET_STR(PG_GETARG_TEXT_P(0));
315329
curname = GET_STR(PG_GETARG_TEXT_P(1));
316330
sql = GET_STR(PG_GETARG_TEXT_P(2));
317331
rconn = getConnectionByName(conname);
318-
if (rconn)
319-
conn = rconn->conn;
320332
}
321333
}
322334
else if (PG_NARGS() == 4)
@@ -327,18 +339,26 @@ dblink_open(PG_FUNCTION_ARGS)
327339
sql = GET_STR(PG_GETARG_TEXT_P(2));
328340
fail = PG_GETARG_BOOL(3);
329341
rconn = getConnectionByName(conname);
330-
if (rconn)
331-
conn = rconn->conn;
332342
}
333343

334-
if (!conn)
344+
if (!rconn || !rconn->conn)
335345
DBLINK_CONN_NOT_AVAIL;
346+
else
347+
conn = rconn->conn;
336348

337-
res = PQexec(conn, "BEGIN");
338-
if (PQresultStatus(res) != PGRES_COMMAND_OK)
339-
DBLINK_RES_INTERNALERROR("begin error");
349+
/* If we are not in a transaction, start one */
350+
if (PQtransactionStatus(conn) == PQTRANS_IDLE)
351+
{
352+
res = PQexec(conn, "BEGIN");
353+
if (PQresultStatus(res) != PGRES_COMMAND_OK)
354+
DBLINK_RES_INTERNALERROR("begin error");
355+
PQclear(res);
356+
rconn->newXactForCursor = TRUE;
357+
}
340358

341-
PQclear(res);
359+
/* if we started a transaction, increment cursor count */
360+
if (rconn->newXactForCursor)
361+
(rconn->openCursorCount)++;
342362

343363
appendStringInfo(str, "DECLARE %s CURSOR FOR %s", curname, sql);
344364
res = PQexec(conn, str->data);
@@ -373,11 +393,13 @@ dblink_close(PG_FUNCTION_ARGS)
373393
remoteConn *rconn = NULL;
374394
bool fail = true; /* default to backward compatible behavior */
375395

396+
DBLINK_INIT;
397+
376398
if (PG_NARGS() == 1)
377399
{
378400
/* text */
379401
curname = GET_STR(PG_GETARG_TEXT_P(0));
380-
conn = persistent_conn;
402+
rconn = pconn;
381403
}
382404
else if (PG_NARGS() == 2)
383405
{
@@ -386,15 +408,13 @@ dblink_close(PG_FUNCTION_ARGS)
386408
{
387409
curname = GET_STR(PG_GETARG_TEXT_P(0));
388410
fail = PG_GETARG_BOOL(1);
389-
conn = persistent_conn;
411+
rconn = pconn;
390412
}
391413
else
392414
{
393415
conname = GET_STR(PG_GETARG_TEXT_P(0));
394416
curname = GET_STR(PG_GETARG_TEXT_P(1));
395417
rconn = getConnectionByName(conname);
396-
if (rconn)
397-
conn = rconn->conn;
398418
}
399419
}
400420
if (PG_NARGS() == 3)
@@ -404,12 +424,12 @@ dblink_close(PG_FUNCTION_ARGS)
404424
curname = GET_STR(PG_GETARG_TEXT_P(1));
405425
fail = PG_GETARG_BOOL(2);
406426
rconn = getConnectionByName(conname);
407-
if (rconn)
408-
conn = rconn->conn;
409427
}
410428

411-
if (!conn)
429+
if (!rconn || !rconn->conn)
412430
DBLINK_CONN_NOT_AVAIL;
431+
else
432+
conn = rconn->conn;
413433

414434
appendStringInfo(str, "CLOSE %s", curname);
415435

@@ -428,12 +448,22 @@ dblink_close(PG_FUNCTION_ARGS)
428448

429449
PQclear(res);
430450

431-
/* commit the transaction */
432-
res = PQexec(conn, "COMMIT");
433-
if (PQresultStatus(res) != PGRES_COMMAND_OK)
434-
DBLINK_RES_INTERNALERROR("commit error");
451+
/* if we started a transaction, decrement cursor count */
452+
if (rconn->newXactForCursor)
453+
{
454+
(rconn->openCursorCount)--;
435455

436-
PQclear(res);
456+
/* if count is zero, commit the transaction */
457+
if (rconn->openCursorCount == 0)
458+
{
459+
rconn->newXactForCursor = FALSE;
460+
461+
res = PQexec(conn, "COMMIT");
462+
if (PQresultStatus(res) != PGRES_COMMAND_OK)
463+
DBLINK_RES_INTERNALERROR("commit error");
464+
PQclear(res);
465+
}
466+
}
437467

438468
PG_RETURN_TEXT_P(GET_TEXT("OK"));
439469
}
@@ -456,6 +486,8 @@ dblink_fetch(PG_FUNCTION_ARGS)
456486
char *conname = NULL;
457487
remoteConn *rconn = NULL;
458488

489+
DBLINK_INIT;
490+
459491
/* stuff done only on the first call of the function */
460492
if (SRF_IS_FIRSTCALL())
461493
{
@@ -485,7 +517,7 @@ dblink_fetch(PG_FUNCTION_ARGS)
485517
curname = GET_STR(PG_GETARG_TEXT_P(0));
486518
howmany = PG_GETARG_INT32(1);
487519
fail = PG_GETARG_BOOL(2);
488-
conn = persistent_conn;
520+
conn = pconn->conn;
489521
}
490522
else
491523
{
@@ -503,7 +535,7 @@ dblink_fetch(PG_FUNCTION_ARGS)
503535
/* text,int */
504536
curname = GET_STR(PG_GETARG_TEXT_P(0));
505537
howmany = PG_GETARG_INT32(1);
506-
conn = persistent_conn;
538+
conn = pconn->conn;
507539
}
508540

509541
if (!conn)
@@ -648,6 +680,8 @@ dblink_record(PG_FUNCTION_ARGS)
648680
MemoryContext oldcontext;
649681
bool freeconn = false;
650682

683+
DBLINK_INIT;
684+
651685
/* stuff done only on the first call of the function */
652686
if (SRF_IS_FIRSTCALL())
653687
{
@@ -678,7 +712,7 @@ dblink_record(PG_FUNCTION_ARGS)
678712
/* text,text or text,bool */
679713
if (get_fn_expr_argtype(fcinfo->flinfo, 1) == BOOLOID)
680714
{
681-
conn = persistent_conn;
715+
conn = pconn->conn;
682716
sql = GET_STR(PG_GETARG_TEXT_P(0));
683717
fail = PG_GETARG_BOOL(1);
684718
}
@@ -691,7 +725,7 @@ dblink_record(PG_FUNCTION_ARGS)
691725
else if (PG_NARGS() == 1)
692726
{
693727
/* text */
694-
conn = persistent_conn;
728+
conn = pconn->conn;
695729
sql = GET_STR(PG_GETARG_TEXT_P(0));
696730
}
697731
else
@@ -857,6 +891,8 @@ dblink_exec(PG_FUNCTION_ARGS)
857891
bool freeconn = false;
858892
bool fail = true; /* default to backward compatible behavior */
859893

894+
DBLINK_INIT;
895+
860896
if (PG_NARGS() == 3)
861897
{
862898
/* must be text,text,bool */
@@ -869,7 +905,7 @@ dblink_exec(PG_FUNCTION_ARGS)
869905
/* might be text,text or text,bool */
870906
if (get_fn_expr_argtype(fcinfo->flinfo, 1) == BOOLOID)
871907
{
872-
conn = persistent_conn;
908+
conn = pconn->conn;
873909
sql = GET_STR(PG_GETARG_TEXT_P(0));
874910
fail = PG_GETARG_BOOL(1);
875911
}
@@ -882,7 +918,7 @@ dblink_exec(PG_FUNCTION_ARGS)
882918
else if (PG_NARGS() == 1)
883919
{
884920
/* must be single text argument */
885-
conn = persistent_conn;
921+
conn = pconn->conn;
886922
sql = GET_STR(PG_GETARG_TEXT_P(0));
887923
}
888924
else

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