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Add a PQfireResultCreateEvents function to allow applications to mimic the
sequence of operations that libpq goes through while creating a PGresult. Also, remove ill-considered "const" decoration on parameters passed to event procedures.
This commit is contained in:
Tom Lane
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4e57668da4
commit
3290e6180f
@ -1,4 +1,4 @@
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<!-- $PostgreSQL: pgsql/doc/src/sgml/libpq.sgml,v 1.262 2008/09/19 16:40:40 tgl Exp $ -->
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<!-- $PostgreSQL: pgsql/doc/src/sgml/libpq.sgml,v 1.263 2008/09/19 20:06:13 tgl Exp $ -->
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<chapter id="libpq">
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<title><application>libpq</application> - C Library</title>
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@ -4592,10 +4592,11 @@ char *pg_encoding_to_char(int <replaceable>encoding_id</replaceable>);
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<parameter>conn</parameter> is not null and <parameter>status</>
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indicates an error, the current error message of the specified
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connection is copied into the <structname>PGresult</structname>.
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Also, if <parameter>conn</parameter> is not null, any event handlers
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Also, if <parameter>conn</parameter> is not null, any event procedures
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registered in the connection are copied into the
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<structname>PGresult</structname> (but they don't get
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<literal>PGEVT_RESULTCREATE</> calls).
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<structname>PGresult</structname>. (They do not get
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<literal>PGEVT_RESULTCREATE</> calls, but see
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<function>PQfireResultCreateEvents</function>.)
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Note that <function>PQclear</function> should eventually be called
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on the object, just as with a <structname>PGresult</structname>
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returned by <application>libpq</application> itself.
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@ -4603,6 +4604,46 @@ char *pg_encoding_to_char(int <replaceable>encoding_id</replaceable>);
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>
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<function>PQfireResultCreateEvents</function>
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<indexterm>
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<primary>PQfireResultCreateEvents</primary>
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</indexterm>
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</term>
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<listitem>
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<para>
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Fires a <literal>PGEVT_RESULTCREATE</literal> event (see <xref
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linkend="libpq-events">) for each event procedure registered in the
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<structname>PGresult</structname> object. Returns non-zero for success,
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zero if any event procedure fails.
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<synopsis>
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int PQfireResultCreateEvents(PGconn *conn, PGresult *res);
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</synopsis>
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</para>
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<para>
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The <literal>conn</> argument is passed through to event procedures
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but not used directly. It can be <literal>NULL</> if the event
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procedures won't use it.
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</para>
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<para>
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Event procedures that have already received a
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<literal>PGEVT_RESULTCREATE</> or <literal>PGEVT_RESULTCOPY</> event
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for this object are not fired again.
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</para>
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<para>
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The main reason that this function is separate from
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<function>PQmakeEmptyPGResult</function> is that it is often appropriate
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to create a <structname>PGresult</structname> and fill it with data
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before invoking the event procedures.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>
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<function>PQcopyResult</function>
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@ -4904,7 +4945,7 @@ defaultNoticeProcessor(void *arg, const char *message)
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<synopsis>
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typedef struct
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{
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const PGconn *conn;
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PGconn *conn;
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} PGEventRegister;
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</synopsis>
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@ -4937,7 +4978,7 @@ typedef struct
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<synopsis>
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typedef struct
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{
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const PGconn *conn;
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PGconn *conn;
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} PGEventConnReset;
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</synopsis>
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@ -4967,7 +5008,7 @@ typedef struct
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<synopsis>
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typedef struct
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{
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const PGconn *conn;
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PGconn *conn;
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} PGEventConnDestroy;
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</synopsis>
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@ -4995,7 +5036,7 @@ typedef struct
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<synopsis>
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typedef struct
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{
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const PGconn *conn;
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PGconn *conn;
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PGresult *result;
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} PGEventResultCreate;
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</synopsis>
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@ -5063,7 +5104,7 @@ typedef struct
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<synopsis>
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typedef struct
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{
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const PGresult *result;
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PGresult *result;
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} PGEventResultDestroy;
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</synopsis>
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@ -1,4 +1,4 @@
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# $PostgreSQL: pgsql/src/interfaces/libpq/exports.txt,v 1.20 2008/09/17 04:31:08 tgl Exp $
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# $PostgreSQL: pgsql/src/interfaces/libpq/exports.txt,v 1.21 2008/09/19 20:06:13 tgl Exp $
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# Functions to be exported by libpq DLLs
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PQconnectdb 1
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PQsetdbLogin 2
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@ -150,3 +150,4 @@ PQinstanceData 147
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PQsetInstanceData 148
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PQresultInstanceData 149
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PQresultSetInstanceData 150
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PQfireResultCreateEvents 151
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@ -8,7 +8,7 @@
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*
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/interfaces/libpq/libpq-events.c,v 1.2 2008/09/19 16:40:40 tgl Exp $
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* $PostgreSQL: pgsql/src/interfaces/libpq/libpq-events.c,v 1.3 2008/09/19 20:06:13 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -175,3 +175,35 @@ PQresultInstanceData(const PGresult *result, PGEventProc proc)
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return NULL;
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}
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/*
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* Fire RESULTCREATE events for an application-created PGresult.
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*
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* The conn argument can be NULL if event procedures won't use it.
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*/
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int
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PQfireResultCreateEvents(PGconn *conn, PGresult *res)
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{
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int i;
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if (!res)
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return FALSE;
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for (i = 0; i < res->nEvents; i++)
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{
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if (!res->events[i].resultInitialized)
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{
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PGEventResultCreate evt;
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evt.conn = conn;
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evt.result = res;
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if (!res->events[i].proc(PGEVT_RESULTCREATE, &evt,
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res->events[i].passThrough))
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return FALSE;
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res->events[i].resultInitialized = TRUE;
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}
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}
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return TRUE;
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}
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@ -8,7 +8,7 @@
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* Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* $PostgreSQL: pgsql/src/interfaces/libpq/libpq-events.h,v 1.1 2008/09/17 04:31:08 tgl Exp $
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* $PostgreSQL: pgsql/src/interfaces/libpq/libpq-events.h,v 1.2 2008/09/19 20:06:13 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -36,22 +36,22 @@ typedef enum
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typedef struct
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{
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const PGconn *conn;
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PGconn *conn;
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} PGEventRegister;
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typedef struct
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{
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const PGconn *conn;
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PGconn *conn;
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} PGEventConnReset;
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typedef struct
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{
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const PGconn *conn;
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PGconn *conn;
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} PGEventConnDestroy;
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typedef struct
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{
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const PGconn *conn;
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PGconn *conn;
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PGresult *result;
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} PGEventResultCreate;
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@ -63,7 +63,7 @@ typedef struct
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typedef struct
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{
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const PGresult *result;
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PGresult *result;
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} PGEventResultDestroy;
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typedef int (*PGEventProc) (PGEventId evtId, void *evtInfo, void *passThrough);
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@ -84,6 +84,9 @@ extern int PQresultSetInstanceData(PGresult *result, PGEventProc proc, void *dat
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/* Gets the PGresult instance data for the provided proc. */
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extern void *PQresultInstanceData(const PGresult *result, PGEventProc proc);
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/* Fires RESULTCREATE events for an application-created PGresult. */
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extern int PQfireResultCreateEvents(PGconn *conn, PGresult *res);
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#ifdef __cplusplus
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}
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#endif
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