On Thu, Dec 16, 2010 at 17:13, Tom Lane <[email protected]> wrote:
> Magnus Hagander <[email protected]> writes:
>> On Thu, Dec 16, 2010 at 17:07, Tom Lane <[email protected]> wrote:
>>> because if you're trying to link against an older libpq, the link will
>>> fail before you ever get to execute. So let's have a less implausible
>>> use-case please.
>
>> Look back at the very start of the thread.
>
> OK, but let's document those examples instead.
Something like this better?
--
Magnus Hagander
Me: http://www.hagander.net/
Work: http://www.redpill-linpro.com/
diff --git a/doc/src/sgml/libpq.sgml b/doc/src/sgml/libpq.sgml
index c502439..a776df4 100644
--- a/doc/src/sgml/libpq.sgml
+++ b/doc/src/sgml/libpq.sgml
@@ -5359,6 +5359,50 @@ void *PQresultAlloc(PGresult *res, size_t nBytes);
</listitem>
</varlistentry>
+ <varlistentry id="libpq-pqlibversion">
+ <term>
+ <function>PQlibVersion</function>
+ <indexterm>
+ <primary>PQlibVersion</primary>
+ <seealso>PQserverVersion</seealso>
+ </indexterm>
+ </term>
+
+ <listitem>
+ <para>
+ Return the version of <productname>libpq</> that is being used.
+<synopsis>
+int PQlibVersion(void);
+</synopsis>
+ </para>
+
+ <para>
+ The result value of this function can be used to determine, at
+ runtime, if a specific functionality is available in the currently
+ loaded version of libpq. Examples of this include whether specific
+ connection options are available for <function>PQconnectdb</> and
+ the new <type>bytea</> encoding in PostgreSQL 9.0 that requires
+ libpq version 9.0 or later to work.
+ </para>
+
+ <para>
+ The number is formed by converting the major, minor, and revision
+ numbers into two-decimal-digit numbers and appending them together.
+ For example, version 9.1 will be returned as 90100, and version
+ 9.1.2 will be returned as 90102 (leading zeroes are not shown).
+ </para>
+
+ <note>
+ <para>
+ This function appeared in <productname>PostgreSQL</> version 9.1, so
+ it cannot be used to detect required functionality in earlier
+ versions, since linking to it will create a load time dependency
+ on version 9.1.
+ </para>
+ </note>
+ </listitem>
+ </varlistentry>
+
</variablelist>
</sect1>
diff --git a/src/interfaces/libpq/exports.txt b/src/interfaces/libpq/exports.txt
index a6c73af..1af8df6 100644
--- a/src/interfaces/libpq/exports.txt
+++ b/src/interfaces/libpq/exports.txt
@@ -159,3 +159,4 @@ PQconnectdbParams 156
PQconnectStartParams 157
PQping 158
PQpingParams 159
+PQlibVersion 160
diff --git a/src/interfaces/libpq/fe-misc.c b/src/interfaces/libpq/fe-misc.c
index 24ab7cf..999f60b 100644
--- a/src/interfaces/libpq/fe-misc.c
+++ b/src/interfaces/libpq/fe-misc.c
@@ -66,6 +66,14 @@ static int pqSocketCheck(PGconn *conn, int forRead, int forWrite,
time_t end_time);
static int pqSocketPoll(int sock, int forRead, int forWrite, time_t end_time);
+/*
+ * PQlibVersion: return the libpq version number
+ */
+int
+PQlibVersion(void)
+{
+ return PG_VERSION_NUM;
+}
/*
* fputnbytes: print exactly N bytes to a file
diff --git a/src/interfaces/libpq/libpq-fe.h b/src/interfaces/libpq/libpq-fe.h
index 271afed..6075ea8 100644
--- a/src/interfaces/libpq/libpq-fe.h
+++ b/src/interfaces/libpq/libpq-fe.h
@@ -547,6 +547,9 @@ extern int lo_export(PGconn *conn, Oid lobjId, const char *filename);
/* === in fe-misc.c === */
+/* Get the version of the libpq library in use */
+extern int PQlibVersion(void);
+
/* Determine length of multibyte encoded char at *s */
extern int PQmblen(const char *s, int encoding);
--
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