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Have SELECT and CREATE TABLE AS queries return a row count. While this
is invisible in psql, other interfaces, like libpq, make this value visible. Boszormenyi Zoltan
1 parent 346a721 commit aa7e7ae

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4 files changed

+43
-37
lines changed

4 files changed

+43
-37
lines changed

‎doc/src/sgml/libpq.sgml

Lines changed: 10 additions & 11 deletions
Original file line numberDiff line numberDiff line change
@@ -1,4 +1,4 @@
1-
<!-- $PostgreSQL: pgsql/doc/src/sgml/libpq.sgml,v 1.297 2010/02/05 03:09:04 joe Exp $ -->
1+
<!-- $PostgreSQL: pgsql/doc/src/sgml/libpq.sgml,v 1.298 2010/02/16 20:58:13 momjian Exp $ -->
22

33
<chapter id="libpq">
44
<title><application>libpq</application> - C Library</title>
@@ -2869,12 +2869,11 @@ typedef struct {
28692869
</sect2>
28702870

28712871
<sect2 id="libpq-exec-nonselect">
2872-
<title>Retrieving Result Information for Other Commands</title>
2872+
<title>Retrieving Other Result Information</title>
28732873

28742874
<para>
2875-
These functions are used to extract information from
2876-
<structname>PGresult</structname> objects that are not
2877-
<command>SELECT</> results.
2875+
These functions are used to extract other information from
2876+
<structname>PGresult</structname> objects.
28782877
</para>
28792878

28802879
<variablelist>
@@ -2925,12 +2924,12 @@ typedef struct {
29252924
This function returns a string containing the number of rows
29262925
affected by the <acronym>SQL</> statement that generated the
29272926
<structname>PGresult</>. This function can only be used following
2928-
the execution of an <command>INSERT</>, <command>UPDATE</>,
2929-
<command>DELETE</>, <command>MOVE</>, <command>FETCH</>, or
2930-
<command>COPY</> statement, or an <command>EXECUTE</> of a
2931-
prepared query that contains an <command>INSERT</>,
2932-
<command>UPDATE</>, or <command>DELETE</> statement. If the
2933-
command that generated the <structname>PGresult</> was anything
2927+
the execution of a <command>SELECT</>, <command>CREATE TABLE AS</>,
2928+
<command>INSERT</>, <command>UPDATE</>, <command>DELETE</>,
2929+
<command>MOVE</>, <command>FETCH</>, or <command>COPY</> statement,
2930+
or an <command>EXECUTE</> of a prepared query that contains an
2931+
<command>INSERT</>, <command>UPDATE</>, or <command>DELETE</> statement.
2932+
If the command that generated the <structname>PGresult</> was anything
29342933
else, <function>PQcmdTuples</> returns an empty string. The caller
29352934
should not free the return value directly. It will be freed when
29362935
the associated <structname>PGresult</> handle is passed to

‎doc/src/sgml/protocol.sgml

Lines changed: 7 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -1,4 +1,4 @@
1-
<!-- $PostgreSQL: pgsql/doc/src/sgml/protocol.sgml,v 1.79 2010/02/16 20:15:14 momjian Exp $ -->
1+
<!-- $PostgreSQL: pgsql/doc/src/sgml/protocol.sgml,v 1.80 2010/02/16 20:58:14 momjian Exp $ -->
22

33
<chapter id="protocol">
44
<title>Frontend/Backend Protocol</title>
@@ -2221,6 +2221,12 @@ CommandComplete (B)
22212221
<replaceable>rows</replaceable> is the number of rows updated.
22222222
</para>
22232223

2224+
<para>
2225+
For a <command>SELECT</command> or <command>CREATE TABLE AS</command>
2226+
command, the tag is <literal>SELECT <replaceable>rows</replaceable></literal>
2227+
where <replaceable>rows</replaceable> is the number of rows retrieved.
2228+
</para>
2229+
22242230
<para>
22252231
For a <command>MOVE</command> command, the tag is
22262232
<literal>MOVE <replaceable>rows</replaceable></literal> where

‎src/backend/tcop/pquery.c

Lines changed: 23 additions & 23 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $PostgreSQL: pgsql/src/backend/tcop/pquery.c,v 1.135 2010/02/13 22:45:41 momjian Exp $
11+
* $PostgreSQL: pgsql/src/backend/tcop/pquery.c,v 1.136 2010/02/16 20:58:14 momjian Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -205,7 +205,8 @@ ProcessQuery(PlannedStmt *plan,
205205
switch (queryDesc->operation)
206206
{
207207
case CMD_SELECT:
208-
strcpy(completionTag, "SELECT");
208+
snprintf(completionTag, COMPLETION_TAG_BUFSIZE,
209+
"SELECT %u", queryDesc->estate->es_processed);
209210
break;
210211
case CMD_INSERT:
211212
if (queryDesc->estate->es_processed == 1)
@@ -714,6 +715,7 @@ PortalRun(Portal portal, long count, bool isTopLevel,
714715
char *completionTag)
715716
{
716717
bool result;
718+
uint32 nprocessed;
717719
ResourceOwner saveTopTransactionResourceOwner;
718720
MemoryContext saveTopTransactionContext;
719721
Portal saveActivePortal;
@@ -776,39 +778,35 @@ PortalRun(Portal portal, long count, bool isTopLevel,
776778
switch (portal->strategy)
777779
{
778780
case PORTAL_ONE_SELECT:
779-
(void) PortalRunSelect(portal, true, count, dest);
780-
781-
/* we know the query is supposed to set the tag */
782-
if (completionTag && portal->commandTag)
783-
strcpy(completionTag, portal->commandTag);
784-
785-
/* Mark portal not active */
786-
portal->status = PORTAL_READY;
787-
788-
/*
789-
* Since it's a forward fetch, say DONE iff atEnd is now true.
790-
*/
791-
result = portal->atEnd;
792-
break;
793-
794781
case PORTAL_ONE_RETURNING:
795782
case PORTAL_UTIL_SELECT:
796783

797784
/*
798785
* If we have not yet run the command, do so, storing its
799-
* results in the portal's tuplestore.
786+
* results in the portal's tuplestore. Do this only for the
787+
* PORTAL_ONE_RETURNING and PORTAL_UTIL_SELECT cases.
800788
*/
801-
if (!portal->holdStore)
789+
if (portal->strategy != PORTAL_ONE_SELECT && !portal->holdStore)
802790
FillPortalStore(portal, isTopLevel);
803791

804792
/*
805793
* Now fetch desired portion of results.
806794
*/
807-
(void) PortalRunSelect(portal, true, count, dest);
795+
nprocessed = PortalRunSelect(portal, true, count, dest);
808796

809-
/* we know the query is supposed to set the tag */
797+
/*
798+
* If the portal result contains a command tag and the caller
799+
* gave us a pointer to store it, copy it. Patch the "SELECT"
800+
* tag to also provide the rowcount.
801+
*/
810802
if (completionTag && portal->commandTag)
811-
strcpy(completionTag, portal->commandTag);
803+
{
804+
if (strcmp(portal->commandTag, "SELECT") == 0)
805+
snprintf(completionTag, COMPLETION_TAG_BUFSIZE,
806+
"SELECT %u", nprocessed);
807+
else
808+
strcpy(completionTag, portal->commandTag);
809+
}
812810

813811
/* Mark portal not active */
814812
portal->status = PORTAL_READY;
@@ -1331,7 +1329,9 @@ PortalRunMulti(Portal portal, bool isTopLevel,
13311329
{
13321330
if (portal->commandTag)
13331331
strcpy(completionTag, portal->commandTag);
1334-
if (strcmp(completionTag, "INSERT") == 0)
1332+
if (strcmp(completionTag, "SELECT") == 0)
1333+
sprintf(completionTag, "SELECT 0 0");
1334+
else if (strcmp(completionTag, "INSERT") == 0)
13351335
strcpy(completionTag, "INSERT 0 0");
13361336
else if (strcmp(completionTag, "UPDATE") == 0)
13371337
strcpy(completionTag, "UPDATE 0");

‎src/interfaces/libpq/fe-exec.c

Lines changed: 3 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $PostgreSQL: pgsql/src/interfaces/libpq/fe-exec.c,v 1.208 2010/01/21 18:43:25 rhaas Exp $
11+
* $PostgreSQL: pgsql/src/interfaces/libpq/fe-exec.c,v 1.209 2010/02/16 20:58:14 momjian Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -2752,7 +2752,8 @@ PQcmdTuples(PGresult *res)
27522752
goto interpret_error; /* no space? */
27532753
p++;
27542754
}
2755-
else if (strncmp(res->cmdStatus, "DELETE ", 7) == 0 ||
2755+
else if (strncmp(res->cmdStatus, "SELECT ", 7) == 0 ||
2756+
strncmp(res->cmdStatus, "DELETE ", 7) == 0 ||
27562757
strncmp(res->cmdStatus, "UPDATE ", 7) == 0)
27572758
p = res->cmdStatus + 7;
27582759
else if (strncmp(res->cmdStatus, "FETCH ", 6) == 0)

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