diff --git a/contrib/dblink/dblink.c b/contrib/dblink/dblink.c
index 1e62d8091a9d2bdf60af6745d5a01ee14ee5cf5a..a67a836eba1fc5e3ea14701284b831269fbc3357 100644
--- a/contrib/dblink/dblink.c
+++ b/contrib/dblink/dblink.c
@@ -70,6 +70,9 @@ typedef struct storeInfo
AttInMetadata *attinmeta;
MemoryContext tmpcontext;
char **cstrs;
+ /* temp storage for results to avoid leaks on exception */
+ PGresult *last_res;
+ PGresult *cur_res;
} storeInfo;
/*
@@ -83,8 +86,8 @@ static void materializeQueryResult(FunctionCallInfo fcinfo,
const char *conname,
const char *sql,
bool fail);
-static int storeHandler(PGresult *res, const PGdataValue *columns,
- const char **errmsgp, void *param);
+static PGresult *storeQueryResult(storeInfo *sinfo, PGconn *conn, const char *sql);
+static void storeRow(storeInfo *sinfo, PGresult *res, bool first);
static remoteConn *getConnectionByName(const char *name);
static HTAB *createConnHash(void);
static void createNewConnection(const char *name, remoteConn *rconn);
@@ -630,7 +633,7 @@ dblink_send_query(PG_FUNCTION_ARGS)
/* async query send */
retval = PQsendQuery(conn, sql);
if (retval != 1)
- elog(NOTICE, "%s", PQerrorMessage(conn));
+ elog(NOTICE, "could not send query: %s", PQerrorMessage(conn));
PG_RETURN_INT32(retval);
}
@@ -927,8 +930,10 @@ materializeResult(FunctionCallInfo fcinfo, PGresult *res)
/*
* Execute the given SQL command and store its results into a tuplestore
* to be returned as the result of the current function.
+ *
* This is equivalent to PQexec followed by materializeResult, but we make
- * use of libpq's "row processor" API to reduce per-row overhead.
+ * use of libpq's single-row mode to avoid accumulating the whole result
+ * inside libpq before it gets transferred to the tuplestore.
*/
static void
materializeQueryResult(FunctionCallInfo fcinfo,
@@ -944,19 +949,14 @@ materializeQueryResult(FunctionCallInfo fcinfo,
/* prepTuplestoreResult must have been called previously */
Assert(rsinfo->returnMode == SFRM_Materialize);
+ /* initialize storeInfo to empty */
+ memset(&sinfo, 0, sizeof(sinfo));
+ sinfo.fcinfo = fcinfo;
+
PG_TRY();
{
- /* initialize storeInfo to empty */
- memset(&sinfo, 0, sizeof(sinfo));
- sinfo.fcinfo = fcinfo;
-
- /* We'll collect tuples using storeHandler */
- PQsetRowProcessor(conn, storeHandler, &sinfo);
-
- res = PQexec(conn, sql);
-
- /* We don't keep the custom row processor installed permanently */
- PQsetRowProcessor(conn, NULL, NULL);
+ /* execute query, collecting any tuples into the tuplestore */
+ res = storeQueryResult(&sinfo, conn, sql);
if (!res ||
(PQresultStatus(res) != PGRES_COMMAND_OK &&
@@ -975,8 +975,8 @@ materializeQueryResult(FunctionCallInfo fcinfo,
else if (PQresultStatus(res) == PGRES_COMMAND_OK)
{
/*
- * storeHandler didn't get called, so we need to convert the
- * command status string to a tuple manually
+ * storeRow didn't get called, so we need to convert the command
+ * status string to a tuple manually
*/
TupleDesc tupdesc;
AttInMetadata *attinmeta;
@@ -1008,25 +1008,30 @@ materializeQueryResult(FunctionCallInfo fcinfo,
tuplestore_puttuple(tupstore, tuple);
PQclear(res);
+ res = NULL;
}
else
{
Assert(PQresultStatus(res) == PGRES_TUPLES_OK);
- /* storeHandler should have created a tuplestore */
+ /* storeRow should have created a tuplestore */
Assert(rsinfo->setResult != NULL);
PQclear(res);
+ res = NULL;
}
+ PQclear(sinfo.last_res);
+ sinfo.last_res = NULL;
+ PQclear(sinfo.cur_res);
+ sinfo.cur_res = NULL;
}
PG_CATCH();
{
- /* be sure to unset the custom row processor */
- PQsetRowProcessor(conn, NULL, NULL);
/* be sure to release any libpq result we collected */
- if (res)
- PQclear(res);
+ PQclear(res);
+ PQclear(sinfo.last_res);
+ PQclear(sinfo.cur_res);
/* and clear out any pending data in libpq */
- while ((res = PQskipResult(conn)) != NULL)
+ while ((res = PQgetResult(conn)) != NULL)
PQclear(res);
PG_RE_THROW();
}
@@ -1034,23 +1039,72 @@ materializeQueryResult(FunctionCallInfo fcinfo,
}
/*
- * Custom row processor for materializeQueryResult.
- * Prototype of this function must match PQrowProcessor.
+ * Execute query, and send any result rows to sinfo->tuplestore.
*/
-static int
-storeHandler(PGresult *res, const PGdataValue *columns,
- const char **errmsgp, void *param)
+static PGresult *
+storeQueryResult(storeInfo *sinfo, PGconn *conn, const char *sql)
+{
+ bool first = true;
+ PGresult *res;
+
+ if (!PQsendQuery(conn, sql))
+ elog(ERROR, "could not send query: %s", PQerrorMessage(conn));
+
+ if (!PQsetSingleRowMode(conn)) /* shouldn't fail */
+ elog(ERROR, "failed to set single-row mode for dblink query");
+
+ for (;;)
+ {
+ CHECK_FOR_INTERRUPTS();
+
+ sinfo->cur_res = PQgetResult(conn);
+ if (!sinfo->cur_res)
+ break;
+
+ if (PQresultStatus(sinfo->cur_res) == PGRES_SINGLE_TUPLE)
+ {
+ /* got one row from possibly-bigger resultset */
+ storeRow(sinfo, sinfo->cur_res, first);
+
+ PQclear(sinfo->cur_res);
+ sinfo->cur_res = NULL;
+ first = false;
+ }
+ else
+ {
+ /* if empty resultset, fill tuplestore header */
+ if (first && PQresultStatus(sinfo->cur_res) == PGRES_TUPLES_OK)
+ storeRow(sinfo, sinfo->cur_res, first);
+
+ /* store completed result at last_res */
+ PQclear(sinfo->last_res);
+ sinfo->last_res = sinfo->cur_res;
+ sinfo->cur_res = NULL;
+ first = true;
+ }
+ }
+
+ /* return last_res */
+ res = sinfo->last_res;
+ sinfo->last_res = NULL;
+ return res;
+}
+
+/*
+ * Send single row to sinfo->tuplestore.
+ *
+ * If "first" is true, create the tuplestore using PGresult's metadata
+ * (in this case the PGresult might contain either zero or one row).
+ */
+static void
+storeRow(storeInfo *sinfo, PGresult *res, bool first)
{
- storeInfo *sinfo = (storeInfo *) param;
int nfields = PQnfields(res);
- char **cstrs = sinfo->cstrs;
HeapTuple tuple;
- char *pbuf;
- int pbuflen;
int i;
MemoryContext oldcontext;
- if (columns == NULL)
+ if (first)
{
/* Prepare for new result set */
ReturnSetInfo *rsinfo = (ReturnSetInfo *) sinfo->fcinfo->resultinfo;
@@ -1098,13 +1152,16 @@ storeHandler(PGresult *res, const PGdataValue *columns,
sinfo->attinmeta = TupleDescGetAttInMetadata(tupdesc);
/* Create a new, empty tuplestore */
- oldcontext = MemoryContextSwitchTo(
- rsinfo->econtext->ecxt_per_query_memory);
+ oldcontext = MemoryContextSwitchTo(rsinfo->econtext->ecxt_per_query_memory);
sinfo->tuplestore = tuplestore_begin_heap(true, false, work_mem);
rsinfo->setResult = sinfo->tuplestore;
rsinfo->setDesc = tupdesc;
MemoryContextSwitchTo(oldcontext);
+ /* Done if empty resultset */
+ if (PQntuples(res) == 0)
+ return;
+
/*
* Set up sufficiently-wide string pointers array; this won't change
* in size so it's easy to preallocate.
@@ -1121,11 +1178,10 @@ storeHandler(PGresult *res, const PGdataValue *columns,
ALLOCSET_DEFAULT_MINSIZE,
ALLOCSET_DEFAULT_INITSIZE,
ALLOCSET_DEFAULT_MAXSIZE);
-
- return 1;
}
- CHECK_FOR_INTERRUPTS();
+ /* Should have a single-row result if we get here */
+ Assert(PQntuples(res) == 1);
/*
* Do the following work in a temp context that we reset after each tuple.
@@ -1135,46 +1191,24 @@ storeHandler(PGresult *res, const PGdataValue *columns,
oldcontext = MemoryContextSwitchTo(sinfo->tmpcontext);
/*
- * The strings passed to us are not null-terminated, but the datatype
- * input functions we're about to call require null termination. Copy the
- * strings and add null termination. As a micro-optimization, allocate
- * all the strings with one palloc.
+ * Fill cstrs with null-terminated strings of column values.
*/
- pbuflen = nfields; /* count the null terminators themselves */
for (i = 0; i < nfields; i++)
{
- int len = columns[i].len;
-
- if (len > 0)
- pbuflen += len;
- }
- pbuf = (char *) palloc(pbuflen);
-
- for (i = 0; i < nfields; i++)
- {
- int len = columns[i].len;
-
- if (len < 0)
- cstrs[i] = NULL;
+ if (PQgetisnull(res, 0, i))
+ sinfo->cstrs[i] = NULL;
else
- {
- cstrs[i] = pbuf;
- memcpy(pbuf, columns[i].value, len);
- pbuf += len;
- *pbuf++ = '\0';
- }
+ sinfo->cstrs[i] = PQgetvalue(res, 0, i);
}
/* Convert row to a tuple, and add it to the tuplestore */
- tuple = BuildTupleFromCStrings(sinfo->attinmeta, cstrs);
+ tuple = BuildTupleFromCStrings(sinfo->attinmeta, sinfo->cstrs);
tuplestore_puttuple(sinfo->tuplestore, tuple);
/* Clean up */
MemoryContextSwitchTo(oldcontext);
MemoryContextReset(sinfo->tmpcontext);
-
- return 1;
}
/*
diff --git a/doc/src/sgml/libpq.sgml b/doc/src/sgml/libpq.sgml
index 5c5dd68db30a717c59deff93a9a12d895d734677..255c5c1abb84127abfa8f7df9bc9a76a9c11fb19 100644
--- a/doc/src/sgml/libpq.sgml
+++ b/doc/src/sgml/libpq.sgml
@@ -2418,14 +2418,28 @@ ExecStatusType PQresultStatus(const PGresult *res);
<term><literal>PGRES_COPY_BOTH</literal></term>
<listitem>
<para>
- Copy In/Out (to and from server) data transfer started. This is
- currently used only for streaming replication.
+ Copy In/Out (to and from server) data transfer started. This
+ feature is currently used only for streaming replication,
+ so this status should not occur in ordinary applications.
+ </para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry id="libpq-pgres-single-tuple">
+ <term><literal>PGRES_SINGLE_TUPLE</literal></term>
+ <listitem>
+ <para>
+ The <structname>PGresult</> contains a single result tuple
+ from the current command. This status occurs only when
+ single-row mode has been selected for the query
+ (see <xref linkend="libpq-single-row-mode">).
</para>
</listitem>
</varlistentry>
</variablelist>
- If the result status is <literal>PGRES_TUPLES_OK</literal>, then
+ If the result status is <literal>PGRES_TUPLES_OK</literal> or
+ <literal>PGRES_SINGLE_TUPLE</literal>, then
the functions described below can be used to retrieve the rows
returned by the query. Note that a <command>SELECT</command>
command that happens to retrieve zero rows still shows
@@ -2726,7 +2740,8 @@ void PQclear(PGresult *res);
These functions are used to extract information from a
<structname>PGresult</structname> object that represents a successful
query result (that is, one that has status
- <literal>PGRES_TUPLES_OK</literal>). They can also be used to extract
+ <literal>PGRES_TUPLES_OK</literal> or <literal>PGRES_SINGLE_TUPLE</>).
+ They can also be used to extract
information from a successful Describe operation: a Describe's result
has all the same column information that actual execution of the query
would provide, but it has zero rows. For objects with other status values,
@@ -3738,7 +3753,7 @@ unsigned char *PQunescapeBytea(const unsigned char *from, size_t *to_length);
<para>
The <function>PQexec</function> function is adequate for submitting
- commands in normal, synchronous applications. It has a couple of
+ commands in normal, synchronous applications. It has a few
deficiencies, however, that can be of importance to some users:
<itemizedlist>
@@ -3769,6 +3784,15 @@ unsigned char *PQunescapeBytea(const unsigned char *from, size_t *to_length);
<function>PQexec</function>.
</para>
</listitem>
+
+ <listitem>
+ <para>
+ <function>PQexec</function> always collects the command's entire result,
+ buffering it in a single <structname>PGresult</structname>. While
+ this simplifies error-handling logic for the application, it can be
+ impractical for results containing many rows.
+ </para>
+ </listitem>
</itemizedlist>
</para>
@@ -3984,8 +4008,11 @@ int PQsendDescribePortal(PGconn *conn, const char *portalName);
Waits for the next result from a prior
<function>PQsendQuery</function>,
<function>PQsendQueryParams</function>,
- <function>PQsendPrepare</function>, or
- <function>PQsendQueryPrepared</function> call, and returns it.
+ <function>PQsendPrepare</function>,
+ <function>PQsendQueryPrepared</function>,
+ <function>PQsendDescribePrepared</function>, or
+ <function>PQsendDescribePortal</function>
+ call, and returns it.
A null pointer is returned when the command is complete and there
will be no more results.
<synopsis>
@@ -4012,7 +4039,7 @@ PGresult *PQgetResult(PGconn *conn);
<para>
Even when <function>PQresultStatus</function> indicates a fatal
error, <function>PQgetResult</function> should be called until it
- returns a null pointer to allow <application>libpq</> to
+ returns a null pointer, to allow <application>libpq</> to
process the error information completely.
</para>
</note>
@@ -4029,7 +4056,18 @@ PGresult *PQgetResult(PGconn *conn);
can be obtained individually. (This allows a simple form of overlapped
processing, by the way: the client can be handling the results of one
command while the server is still working on later queries in the same
- command string.) However, calling <function>PQgetResult</function>
+ command string.)
+ </para>
+
+ <para>
+ Another frequently-desired feature that can be obtained with
+ <function>PQsendQuery</function> and <function>PQgetResult</function>
+ is retrieving large query results a row at a time. This is discussed
+ in <xref linkend="libpq-single-row-mode">.
+ </para>
+
+ <para>
+ By itself, calling <function>PQgetResult</function>
will still cause the client to block until the server completes the
next <acronym>SQL</acronym> command. This can be avoided by proper
use of two more functions:
@@ -4238,6 +4276,98 @@ int PQflush(PGconn *conn);
</sect1>
+ <sect1 id="libpq-single-row-mode">
+ <title>Retrieving Query Results Row-By-Row</title>
+
+ <indexterm zone="libpq-single-row-mode">
+ <primary>libpq</primary>
+ <secondary>single-row mode</secondary>
+ </indexterm>
+
+ <para>
+ Ordinarily, <application>libpq</> collects a SQL command's
+ entire result and returns it to the application as a single
+ <structname>PGresult</structname>. This can be unworkable for commands
+ that return a large number of rows. For such cases, applications can use
+ <function>PQsendQuery</function> and <function>PQgetResult</function> in
+ <firstterm>single-row mode</>. In this mode, the result row(s) are
+ returned to the application one at a time, as they are received from the
+ server.
+ </para>
+
+ <para>
+ To enter single-row mode, call <function>PQsetSingleRowMode</function>
+ immediately after a successful call of <function>PQsendQuery</function>
+ (or a sibling function). This mode selection is effective only for the
+ currently executing query. Then call <function>PQgetResult</function>
+ repeatedly, until it returns null, as documented in <xref
+ linkend="libpq-async">. If the query returns any rows, they are returned
+ as individual <structname>PGresult</structname> objects, which look like
+ normal query results except for having status code
+ <literal>PGRES_SINGLE_TUPLE</literal> instead of
+ <literal>PGRES_TUPLES_OK</literal>. After the last row, or immediately if
+ the query returns zero rows, a zero-row object with status
+ <literal>PGRES_TUPLES_OK</literal> is returned; this is the signal that no
+ more rows will arrive. (But note that it is still necessary to continue
+ calling <function>PQgetResult</function> until it returns null.) All of
+ these <structname>PGresult</structname> objects will contain the same row
+ description data (column names, types, etc) that an ordinary
+ <structname>PGresult</structname> object for the query would have.
+ Each object should be freed with <function>PQclear</function> as usual.
+ </para>
+
+ <para>
+ <variablelist>
+ <varlistentry id="libpq-pqsetsinglerowmode">
+ <term>
+ <function>PQsetSingleRowMode</function>
+ <indexterm>
+ <primary>PQsetSingleRowMode</primary>
+ </indexterm>
+ </term>
+
+ <listitem>
+ <para>
+ Select single-row mode for the currently-executing query.
+
+<synopsis>
+int PQsetSingleRowMode(PGconn *conn);
+</synopsis>
+ </para>
+
+ <para>
+ This function can only be called immediately after
+ <function>PQsendQuery</function> or one of its sibling functions,
+ before any other operation on the connection such as
+ <function>PQconsumeInput</function> or
+ <function>PQgetResult</function>. If called at the correct time,
+ the function activates single-row mode for the current query and
+ returns 1. Otherwise the mode stays unchanged and the function
+ returns 0. In any case, the mode reverts to normal after
+ completion of the current query.
+ </para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </para>
+
+ <caution>
+ <para>
+ While processing a query, the server may return some rows and then
+ encounter an error, causing the query to be aborted. Ordinarily,
+ <application>libpq</> discards any such rows and reports only the
+ error. But in single-row mode, those rows will have already been
+ returned to the application. Hence, the application will see some
+ <literal>PGRES_SINGLE_TUPLE</literal> <structname>PGresult</structname>
+ objects followed by a <literal>PGRES_FATAL_ERROR</literal> object. For
+ proper transactional behavior, the application must be designed to
+ discard or undo whatever has been done with the previously-processed
+ rows, if the query ultimately fails.
+ </para>
+ </caution>
+
+ </sect1>
+
<sect1 id="libpq-cancel">
<title>Canceling Queries in Progress</title>
@@ -5700,274 +5830,6 @@ defaultNoticeProcessor(void *arg, const char *message)
</sect1>
- <sect1 id="libpq-row-processor">
- <title>Custom Row Processing</title>
-
- <indexterm zone="libpq-row-processor">
- <primary>PQrowProcessor</primary>
- </indexterm>
-
- <indexterm zone="libpq-row-processor">
- <primary>row processor</primary>
- <secondary>in libpq</secondary>
- </indexterm>
-
- <para>
- Ordinarily, when receiving a query result from the server,
- <application>libpq</> adds each row value to the current
- <type>PGresult</type> until the entire result set is received; then
- the <type>PGresult</type> is returned to the application as a unit.
- This approach is simple to work with, but becomes inefficient for large
- result sets. To improve performance, an application can register a
- custom <firstterm>row processor</> function that processes each row
- as the data is received from the network. The custom row processor could
- process the data fully, or store it into some application-specific data
- structure for later processing.
- </para>
-
- <caution>
- <para>
- The row processor function sees the rows before it is known whether the
- query will succeed overall, since the server might return some rows before
- encountering an error. For proper transactional behavior, it must be
- possible to discard or undo whatever the row processor has done, if the
- query ultimately fails.
- </para>
- </caution>
-
- <para>
- When using a custom row processor, row data is not accumulated into the
- <type>PGresult</type>, so the <type>PGresult</type> ultimately delivered to
- the application will contain no rows (<function>PQntuples</> =
- <literal>0</>). However, it still has <function>PQresultStatus</> =
- <literal>PGRES_TUPLES_OK</>, and it contains correct information about the
- set of columns in the query result. On the other hand, if the query fails
- partway through, the returned <type>PGresult</type> has
- <function>PQresultStatus</> = <literal>PGRES_FATAL_ERROR</>. The
- application must be prepared to undo any actions of the row processor
- whenever it gets a <literal>PGRES_FATAL_ERROR</> result.
- </para>
-
- <para>
- A custom row processor is registered for a particular connection by
- calling <function>PQsetRowProcessor</function>, described below.
- This row processor will be used for all subsequent query results on that
- connection until changed again. A row processor function must have a
- signature matching
-
-<synopsis>
-typedef int (*PQrowProcessor) (PGresult *res, const PGdataValue *columns,
- const char **errmsgp, void *param);
-</synopsis>
- where <type>PGdataValue</> is described by
-<synopsis>
-typedef struct pgDataValue
-{
- int len; /* data length in bytes, or <0 if NULL */
- const char *value; /* data value, without zero-termination */
-} PGdataValue;
-</synopsis>
- </para>
-
- <para>
- The <parameter>res</> parameter is the <literal>PGRES_TUPLES_OK</>
- <type>PGresult</type> that will eventually be delivered to the calling
- application (if no error intervenes). It contains information about
- the set of columns in the query result, but no row data. In particular the
- row processor must fetch <literal>PQnfields(res)</> to know the number of
- data columns.
- </para>
-
- <para>
- Immediately after <application>libpq</> has determined the result set's
- column information, it will make a call to the row processor with
- <parameter>columns</parameter> set to NULL, but the other parameters as
- usual. The row processor can use this call to initialize for a new result
- set; if it has nothing to do, it can just return <literal>1</>. In
- subsequent calls, one per received row, <parameter>columns</parameter>
- is non-NULL and points to an array of <type>PGdataValue</> structs, one per
- data column.
- </para>
-
- <para>
- <parameter>errmsgp</parameter> is an output parameter used only for error
- reporting. If the row processor needs to report an error, it can set
- <literal>*</><parameter>errmsgp</parameter> to point to a suitable message
- string (and then return <literal>-1</>). As a special case, returning
- <literal>-1</> without changing <literal>*</><parameter>errmsgp</parameter>
- from its initial value of NULL is taken to mean <quote>out of memory</>.
- </para>
-
- <para>
- The last parameter, <parameter>param</parameter>, is just a void pointer
- passed through from <function>PQsetRowProcessor</function>. This can be
- used for communication between the row processor function and the
- surrounding application.
- </para>
-
- <para>
- In the <type>PGdataValue</> array passed to a row processor, data values
- cannot be assumed to be zero-terminated, whether the data format is text
- or binary. A SQL NULL value is indicated by a negative length field.
- </para>
-
- <para>
- The row processor <emphasis>must</> process the row data values
- immediately, or else copy them into application-controlled storage.
- The value pointers passed to the row processor point into
- <application>libpq</>'s internal data input buffer, which will be
- overwritten by the next packet fetch.
- </para>
-
- <para>
- The row processor function must return either <literal>1</> or
- <literal>-1</>.
- <literal>1</> is the normal, successful result value; <application>libpq</>
- will continue with receiving row values from the server and passing them to
- the row processor. <literal>-1</> indicates that the row processor has
- encountered an error. In that case,
- <application>libpq</> will discard all remaining rows in the result set
- and then return a <literal>PGRES_FATAL_ERROR</> <type>PGresult</type> to
- the application (containing the specified error message, or <quote>out of
- memory for query result</> if <literal>*</><parameter>errmsgp</parameter>
- was left as NULL).
- </para>
-
- <para>
- Another option for exiting a row processor is to throw an exception using
- C's <function>longjmp()</> or C++'s <literal>throw</>. If this is done,
- processing of the incoming data can be resumed later by calling
- <function>PQgetResult</>; the row processor will be invoked as normal for
- any remaining rows in the current result.
- As with any usage of <function>PQgetResult</>, the application
- should continue calling <function>PQgetResult</> until it gets a NULL
- result before issuing any new query.
- </para>
-
- <para>
- In some cases, an exception may mean that the remainder of the
- query result is not interesting. In such cases the application can discard
- the remaining rows with <function>PQskipResult</>, described below.
- Another possible recovery option is to close the connection altogether with
- <function>PQfinish</>.
- </para>
-
- <para>
- <variablelist>
- <varlistentry id="libpq-pqsetrowprocessor">
- <term>
- <function>PQsetRowProcessor</function>
- <indexterm>
- <primary>PQsetRowProcessor</primary>
- </indexterm>
- </term>
-
- <listitem>
- <para>
- Sets a callback function to process each row.
-
-<synopsis>
-void PQsetRowProcessor(PGconn *conn, PQrowProcessor func, void *param);
-</synopsis>
- </para>
-
- <para>
- The specified row processor function <parameter>func</> is installed as
- the active row processor for the given connection <parameter>conn</>.
- Also, <parameter>param</> is installed as the passthrough pointer to
- pass to it. Alternatively, if <parameter>func</> is NULL, the standard
- row processor is reinstalled on the given connection (and
- <parameter>param</> is ignored).
- </para>
-
- <para>
- Although the row processor can be changed at any time in the life of a
- connection, it's generally unwise to do so while a query is active.
- In particular, when using asynchronous mode, be aware that both
- <function>PQisBusy</> and <function>PQgetResult</> can call the current
- row processor.
- </para>
- </listitem>
- </varlistentry>
-
- <varlistentry id="libpq-pqgetrowprocessor">
- <term>
- <function>PQgetRowProcessor</function>
- <indexterm>
- <primary>PQgetRowProcessor</primary>
- </indexterm>
- </term>
-
- <listitem>
- <para>
- Fetches the current row processor for the specified connection.
-
-<synopsis>
-PQrowProcessor PQgetRowProcessor(const PGconn *conn, void **param);
-</synopsis>
- </para>
-
- <para>
- In addition to returning the row processor function pointer, the
- current passthrough pointer will be returned at
- <literal>*</><parameter>param</>, if <parameter>param</> is not NULL.
- </para>
- </listitem>
- </varlistentry>
-
- <varlistentry id="libpq-pqskipresult">
- <term>
- <function>PQskipResult</function>
- <indexterm>
- <primary>PQskipResult</primary>
- </indexterm>
- </term>
-
- <listitem>
- <para>
- Discard all the remaining rows in the incoming result set.
-
-<synopsis>
-PGresult *PQskipResult(PGconn *conn);
-</synopsis>
- </para>
-
- <para>
- This is a simple convenience function to discard incoming data after a
- row processor has failed or it's determined that the rest of the result
- set is not interesting. <function>PQskipResult</> is exactly
- equivalent to <function>PQgetResult</> except that it transiently
- installs a dummy row processor function that just discards data.
- The returned <type>PGresult</> can be discarded without further ado
- if it has status <literal>PGRES_TUPLES_OK</>; but other status values
- should be handled normally. (In particular,
- <literal>PGRES_FATAL_ERROR</> indicates a server-reported error that
- will still need to be dealt with.)
- As when using <function>PQgetResult</>, one should usually repeat the
- call until NULL is returned to ensure the connection has reached an
- idle state. Another possible usage is to call
- <function>PQskipResult</> just once, and then resume using
- <function>PQgetResult</> to process subsequent result sets normally.
- </para>
-
- <para>
- Because <function>PQskipResult</> will wait for server input, it is not
- very useful in asynchronous applications. In particular you should not
- code a loop of <function>PQisBusy</> and <function>PQskipResult</>,
- because that will result in the installed row processor being called
- within <function>PQisBusy</>. To get the proper behavior in an
- asynchronous application, you'll need to install a dummy row processor
- (or set a flag to make your normal row processor do nothing) and leave
- it that way until you have discarded all incoming data via your normal
- <function>PQisBusy</> and <function>PQgetResult</> loop.
- </para>
- </listitem>
- </varlistentry>
- </variablelist>
- </para>
-
- </sect1>
-
<sect1 id="libpq-events">
<title>Event System</title>
diff --git a/src/interfaces/libpq/exports.txt b/src/interfaces/libpq/exports.txt
index 1251455f1f6d92c74e206b5a9b8dcdeb36ac9b98..9d95e262be3fbf26731c0926013db56dbc4e00ab 100644
--- a/src/interfaces/libpq/exports.txt
+++ b/src/interfaces/libpq/exports.txt
@@ -160,6 +160,4 @@ PQconnectStartParams 157
PQping 158
PQpingParams 159
PQlibVersion 160
-PQsetRowProcessor 161
-PQgetRowProcessor 162
-PQskipResult 163
+PQsetSingleRowMode 161
diff --git a/src/interfaces/libpq/fe-connect.c b/src/interfaces/libpq/fe-connect.c
index a32258a8cbab5e655484d0471c031864fa5084de..adaab7aaade60a980b7eaf5b6e9734444c72b930 100644
--- a/src/interfaces/libpq/fe-connect.c
+++ b/src/interfaces/libpq/fe-connect.c
@@ -2709,8 +2709,7 @@ makeEmptyPGconn(void)
/* Zero all pointers and booleans */
MemSet(conn, 0, sizeof(PGconn));
- /* install default row processor and notice hooks */
- PQsetRowProcessor(conn, NULL, NULL);
+ /* install default notice hooks */
conn->noticeHooks.noticeRec = defaultNoticeReceiver;
conn->noticeHooks.noticeProc = defaultNoticeProcessor;
@@ -4658,7 +4657,7 @@ conninfo_uri_parse_options(PQconninfoOption *options, const char *uri,
if (p == host)
{
printfPQExpBuffer(errorMessage,
- libpq_gettext("IPv6 host address may not be empty in URI: \"%s\"\n"),
+ libpq_gettext("IPv6 host address may not be empty in URI: \"%s\"\n"),
uri);
goto cleanup;
}
@@ -4878,7 +4877,7 @@ conninfo_uri_parse_params(char *params,
printfPQExpBuffer(errorMessage,
libpq_gettext(
- "invalid URI query parameter: \"%s\"\n"),
+ "invalid URI query parameter: \"%s\"\n"),
keyword);
return false;
}
@@ -4943,7 +4942,7 @@ conninfo_uri_decode(const char *str, PQExpBuffer errorMessage)
if (!(get_hexdigit(*q++, &hi) && get_hexdigit(*q++, &lo)))
{
printfPQExpBuffer(errorMessage,
- libpq_gettext("invalid percent-encoded token: \"%s\"\n"),
+ libpq_gettext("invalid percent-encoded token: \"%s\"\n"),
str);
free(buf);
return NULL;
@@ -5594,8 +5593,8 @@ static void
dot_pg_pass_warning(PGconn *conn)
{
/* If it was 'invalid authorization', add .pgpass mention */
- if (conn->dot_pgpass_used && conn->password_needed && conn->result &&
/* only works with >= 9.0 servers */
+ if (conn->dot_pgpass_used && conn->password_needed && conn->result &&
strcmp(PQresultErrorField(conn->result, PG_DIAG_SQLSTATE),
ERRCODE_INVALID_PASSWORD) == 0)
{
diff --git a/src/interfaces/libpq/fe-exec.c b/src/interfaces/libpq/fe-exec.c
index badc0b32a8e8f3e33e42729a8f8899475a0de31b..53516db723492f11fc9f4bdc6d4d351693c4c22f 100644
--- a/src/interfaces/libpq/fe-exec.c
+++ b/src/interfaces/libpq/fe-exec.c
@@ -38,7 +38,8 @@ char *const pgresStatus[] = {
"PGRES_BAD_RESPONSE",
"PGRES_NONFATAL_ERROR",
"PGRES_FATAL_ERROR",
- "PGRES_COPY_BOTH"
+ "PGRES_COPY_BOTH",
+ "PGRES_SINGLE_TUPLE"
};
/*
@@ -51,8 +52,6 @@ static bool static_std_strings = false;
static PGEvent *dupEvents(PGEvent *events, int count);
static bool pqAddTuple(PGresult *res, PGresAttValue *tup);
-static int pqStdRowProcessor(PGresult *res, const PGdataValue *columns,
- const char **errmsgp, void *param);
static bool PQsendQueryStart(PGconn *conn);
static int PQsendQueryGuts(PGconn *conn,
const char *command,
@@ -64,8 +63,6 @@ static int PQsendQueryGuts(PGconn *conn,
const int *paramFormats,
int resultFormat);
static void parseInput(PGconn *conn);
-static int dummyRowProcessor(PGresult *res, const PGdataValue *columns,
- const char **errmsgp, void *param);
static bool PQexecStart(PGconn *conn);
static PGresult *PQexecFinish(PGconn *conn);
static int PQsendDescribe(PGconn *conn, char desc_type,
@@ -181,6 +178,7 @@ PQmakeEmptyPGresult(PGconn *conn, ExecStatusType status)
case PGRES_COPY_OUT:
case PGRES_COPY_IN:
case PGRES_COPY_BOTH:
+ case PGRES_SINGLE_TUPLE:
/* non-error cases */
break;
default:
@@ -698,6 +696,8 @@ PQclear(PGresult *res)
/*
* Handy subroutine to deallocate any partially constructed async result.
+ *
+ * Any "next" result gets cleared too.
*/
void
pqClearAsyncResult(PGconn *conn)
@@ -705,6 +705,9 @@ pqClearAsyncResult(PGconn *conn)
if (conn->result)
PQclear(conn->result);
conn->result = NULL;
+ if (conn->next_result)
+ PQclear(conn->next_result);
+ conn->next_result = NULL;
}
/*
@@ -758,7 +761,6 @@ pqPrepareAsyncResult(PGconn *conn)
* conn->errorMessage.
*/
res = conn->result;
- conn->result = NULL; /* handing over ownership to caller */
if (!res)
res = PQmakeEmptyPGresult(conn, PGRES_FATAL_ERROR);
else
@@ -771,6 +773,16 @@ pqPrepareAsyncResult(PGconn *conn)
appendPQExpBufferStr(&conn->errorMessage,
PQresultErrorMessage(res));
}
+
+ /*
+ * Replace conn->result with next_result, if any. In the normal case
+ * there isn't a next result and we're just dropping ownership of the
+ * current result. In single-row mode this restores the situation to what
+ * it was before we created the current single-row result.
+ */
+ conn->result = conn->next_result;
+ conn->next_result = NULL;
+
return res;
}
@@ -981,85 +993,55 @@ pqSaveParameterStatus(PGconn *conn, const char *name, const char *value)
/*
- * PQsetRowProcessor
- * Set function that copies row data out from the network buffer,
- * along with a passthrough parameter for it.
- */
-void
-PQsetRowProcessor(PGconn *conn, PQrowProcessor func, void *param)
-{
- if (!conn)
- return;
-
- if (func)
- {
- /* set custom row processor */
- conn->rowProcessor = func;
- conn->rowProcessorParam = param;
- }
- else
- {
- /* set default row processor */
- conn->rowProcessor = pqStdRowProcessor;
- conn->rowProcessorParam = conn;
- }
-}
-
-/*
- * PQgetRowProcessor
- * Get current row processor of PGconn.
- * If param is not NULL, also store the passthrough parameter at *param.
- */
-PQrowProcessor
-PQgetRowProcessor(const PGconn *conn, void **param)
-{
- if (!conn)
- {
- if (param)
- *param = NULL;
- return NULL;
- }
-
- if (param)
- *param = conn->rowProcessorParam;
- return conn->rowProcessor;
-}
-
-/*
- * pqStdRowProcessor
- * Add the received row to the PGresult structure
- * Returns 1 if OK, -1 if error occurred.
+ * pqRowProcessor
+ * Add the received row to the current async result (conn->result).
+ * Returns 1 if OK, 0 if error occurred.
+ *
+ * On error, *errmsgp can be set to an error string to be returned.
+ * If it is left NULL, the error is presumed to be "out of memory".
*
- * Note: "param" should point to the PGconn, but we don't actually need that
- * as of the current coding.
+ * In single-row mode, we create a new result holding just the current row,
+ * stashing the previous result in conn->next_result so that it becomes
+ * active again after pqPrepareAsyncResult(). This allows the result metadata
+ * (column descriptions) to be carried forward to each result row.
*/
-static int
-pqStdRowProcessor(PGresult *res, const PGdataValue *columns,
- const char **errmsgp, void *param)
+int
+pqRowProcessor(PGconn *conn, const char **errmsgp)
{
+ PGresult *res = conn->result;
int nfields = res->numAttributes;
+ const PGdataValue *columns = conn->rowBuf;
PGresAttValue *tup;
int i;
- if (columns == NULL)
+ /*
+ * In single-row mode, make a new PGresult that will hold just this one
+ * row; the original conn->result is left unchanged so that it can be used
+ * again as the template for future rows.
+ */
+ if (conn->singleRowMode)
{
- /* New result set ... we have nothing to do in this function. */
- return 1;
+ /* Copy everything that should be in the result at this point */
+ res = PQcopyResult(res,
+ PG_COPYRES_ATTRS | PG_COPYRES_EVENTS |
+ PG_COPYRES_NOTICEHOOKS);
+ if (!res)
+ return 0;
}
/*
* Basically we just allocate space in the PGresult for each field and
* copy the data over.
*
- * Note: on malloc failure, we return -1 leaving *errmsgp still NULL,
- * which caller will take to mean "out of memory". This is preferable to
- * trying to set up such a message here, because evidently there's not
- * enough memory for gettext() to do anything.
+ * Note: on malloc failure, we return 0 leaving *errmsgp still NULL, which
+ * caller will take to mean "out of memory". This is preferable to trying
+ * to set up such a message here, because evidently there's not enough
+ * memory for gettext() to do anything.
*/
tup = (PGresAttValue *)
pqResultAlloc(res, nfields * sizeof(PGresAttValue), TRUE);
if (tup == NULL)
- return -1;
+ goto fail;
for (i = 0; i < nfields; i++)
{
@@ -1078,7 +1060,7 @@ pqStdRowProcessor(PGresult *res, const PGdataValue *columns,
val = (char *) pqResultAlloc(res, clen + 1, isbinary);
if (val == NULL)
- return -1;
+ goto fail;
/* copy and zero-terminate the data (even if it's binary) */
memcpy(val, columns[i].value, clen);
@@ -1091,10 +1073,30 @@ pqStdRowProcessor(PGresult *res, const PGdataValue *columns,
/* And add the tuple to the PGresult's tuple array */
if (!pqAddTuple(res, tup))
- return -1;
+ goto fail;
+
+ /*
+ * Success. In single-row mode, make the result available to the client
+ * immediately.
+ */
+ if (conn->singleRowMode)
+ {
+ /* Change result status to special single-row value */
+ res->resultStatus = PGRES_SINGLE_TUPLE;
+ /* Stash old result for re-use later */
+ conn->next_result = conn->result;
+ conn->result = res;
+ /* And mark the result ready to return */
+ conn->asyncStatus = PGASYNC_READY;
+ }
- /* Success */
return 1;
+
+fail:
+ /* release locally allocated PGresult, if we made one */
+ if (res != conn->result)
+ PQclear(res);
+ return 0;
}
@@ -1343,6 +1345,10 @@ PQsendQueryStart(PGconn *conn)
/* initialize async result-accumulation state */
conn->result = NULL;
+ conn->next_result = NULL;
+
+ /* reset single-row processing mode */
+ conn->singleRowMode = false;
/* ready to send command message */
return true;
@@ -1547,6 +1553,31 @@ pqHandleSendFailure(PGconn *conn)
parseInput(conn);
}
+/*
+ * Select row-by-row processing mode
+ */
+int
+PQsetSingleRowMode(PGconn *conn)
+{
+ /*
+ * Only allow setting the flag when we have launched a query and not yet
+ * received any results.
+ */
+ if (!conn)
+ return 0;
+ if (conn->asyncStatus != PGASYNC_BUSY)
+ return 0;
+ if (conn->queryclass != PGQUERY_SIMPLE &&
+ conn->queryclass != PGQUERY_EXTENDED)
+ return 0;
+ if (conn->result)
+ return 0;
+
+ /* OK, set flag */
+ conn->singleRowMode = true;
+ return 1;
+}
+
/*
* Consume any available input from the backend
* 0 return: some kind of trouble
@@ -1587,9 +1618,6 @@ PQconsumeInput(PGconn *conn)
* parseInput: if appropriate, parse input data from backend
* until input is exhausted or a stopping state is reached.
* Note that this function will NOT attempt to read more data from the backend.
- *
- * Note: callers of parseInput must be prepared for a longjmp exit when we are
- * in PGASYNC_BUSY state, since an external row processor might do that.
*/
static void
parseInput(PGconn *conn)
@@ -1737,49 +1765,6 @@ PQgetResult(PGconn *conn)
return res;
}
-/*
- * PQskipResult
- * Get the next PGresult produced by a query, but discard any data rows.
- *
- * This is mainly useful for cleaning up after a longjmp out of a row
- * processor, when resuming processing of the current query result isn't
- * wanted. Note that this is of little value in an async-style application,
- * since any preceding calls to PQisBusy would have already called the regular
- * row processor.
- */
-PGresult *
-PQskipResult(PGconn *conn)
-{
- PGresult *res;
- PQrowProcessor savedRowProcessor;
-
- if (!conn)
- return NULL;
-
- /* temporarily install dummy row processor */
- savedRowProcessor = conn->rowProcessor;
- conn->rowProcessor = dummyRowProcessor;
- /* no need to save/change rowProcessorParam */
-
- /* fetch the next result */
- res = PQgetResult(conn);
-
- /* restore previous row processor */
- conn->rowProcessor = savedRowProcessor;
-
- return res;
-}
-
-/*
- * Do-nothing row processor for PQskipResult
- */
-static int
-dummyRowProcessor(PGresult *res, const PGdataValue *columns,
- const char **errmsgp, void *param)
-{
- return 1;
-}
-
/*
* PQexec
@@ -1886,7 +1871,7 @@ PQexecStart(PGconn *conn)
* Silently discard any prior query result that application didn't eat.
* This is probably poor design, but it's here for backward compatibility.
*/
- while ((result = PQskipResult(conn)) != NULL)
+ while ((result = PQgetResult(conn)) != NULL)
{
ExecStatusType resultStatus = result->resultStatus;
diff --git a/src/interfaces/libpq/fe-lobj.c b/src/interfaces/libpq/fe-lobj.c
index 13fd98c2f913d3818758e75bac96822306981b52..f3a6d0341c13ce644a7f1b2f15919385b85d6a6e 100644
--- a/src/interfaces/libpq/fe-lobj.c
+++ b/src/interfaces/libpq/fe-lobj.c
@@ -682,8 +682,6 @@ lo_initialize(PGconn *conn)
int n;
const char *query;
const char *fname;
- PQrowProcessor savedRowProcessor;
- void *savedRowProcessorParam;
Oid foid;
if (!conn)
@@ -732,16 +730,7 @@ lo_initialize(PGconn *conn)
"or proname = 'loread' "
"or proname = 'lowrite'";
- /* Ensure the standard row processor is used to collect the result */
- savedRowProcessor = conn->rowProcessor;
- savedRowProcessorParam = conn->rowProcessorParam;
- PQsetRowProcessor(conn, NULL, NULL);
-
res = PQexec(conn, query);
-
- conn->rowProcessor = savedRowProcessor;
- conn->rowProcessorParam = savedRowProcessorParam;
-
if (res == NULL)
{
free(lobjfuncs);
diff --git a/src/interfaces/libpq/fe-protocol2.c b/src/interfaces/libpq/fe-protocol2.c
index 8dbd6b6982395850fc167eb20cb8d5590d33122f..1ba5885cd3b419a97f4fc5ea897eac209f364897 100644
--- a/src/interfaces/libpq/fe-protocol2.c
+++ b/src/interfaces/libpq/fe-protocol2.c
@@ -49,19 +49,11 @@ static int getNotify(PGconn *conn);
PostgresPollingStatusType
pqSetenvPoll(PGconn *conn)
{
- PostgresPollingStatusType result;
PGresult *res;
- PQrowProcessor savedRowProcessor;
- void *savedRowProcessorParam;
if (conn == NULL || conn->status == CONNECTION_BAD)
return PGRES_POLLING_FAILED;
- /* Ensure the standard row processor is used to collect any results */
- savedRowProcessor = conn->rowProcessor;
- savedRowProcessorParam = conn->rowProcessorParam;
- PQsetRowProcessor(conn, NULL, NULL);
-
/* Check whether there are any data for us */
switch (conn->setenv_state)
{
@@ -77,10 +69,7 @@ pqSetenvPoll(PGconn *conn)
if (n < 0)
goto error_return;
if (n == 0)
- {
- result = PGRES_POLLING_READING;
- goto normal_return;
- }
+ return PGRES_POLLING_READING;
break;
}
@@ -94,8 +83,7 @@ pqSetenvPoll(PGconn *conn)
/* Should we raise an error if called when not active? */
case SETENV_STATE_IDLE:
- result = PGRES_POLLING_OK;
- goto normal_return;
+ return PGRES_POLLING_OK;
default:
printfPQExpBuffer(&conn->errorMessage,
@@ -192,10 +180,7 @@ pqSetenvPoll(PGconn *conn)
case SETENV_STATE_CLIENT_ENCODING_WAIT:
{
if (PQisBusy(conn))
- {
- result = PGRES_POLLING_READING;
- goto normal_return;
- }
+ return PGRES_POLLING_READING;
res = PQgetResult(conn);
@@ -220,10 +205,7 @@ pqSetenvPoll(PGconn *conn)
case SETENV_STATE_OPTION_WAIT:
{
if (PQisBusy(conn))
- {
- result = PGRES_POLLING_READING;
- goto normal_return;
- }
+ return PGRES_POLLING_READING;
res = PQgetResult(conn);
@@ -262,17 +244,13 @@ pqSetenvPoll(PGconn *conn)
goto error_return;
conn->setenv_state = SETENV_STATE_QUERY1_WAIT;
- result = PGRES_POLLING_READING;
- goto normal_return;
+ return PGRES_POLLING_READING;
}
case SETENV_STATE_QUERY1_WAIT:
{
if (PQisBusy(conn))
- {
- result = PGRES_POLLING_READING;
- goto normal_return;
- }
+ return PGRES_POLLING_READING;
res = PQgetResult(conn);
@@ -349,17 +327,13 @@ pqSetenvPoll(PGconn *conn)
goto error_return;
conn->setenv_state = SETENV_STATE_QUERY2_WAIT;
- result = PGRES_POLLING_READING;
- goto normal_return;
+ return PGRES_POLLING_READING;
}
case SETENV_STATE_QUERY2_WAIT:
{
if (PQisBusy(conn))
- {
- result = PGRES_POLLING_READING;
- goto normal_return;
- }
+ return PGRES_POLLING_READING;
res = PQgetResult(conn);
@@ -406,8 +380,7 @@ pqSetenvPoll(PGconn *conn)
{
/* Query finished, so we're done */
conn->setenv_state = SETENV_STATE_IDLE;
- result = PGRES_POLLING_OK;
- goto normal_return;
+ return PGRES_POLLING_OK;
}
break;
}
@@ -425,12 +398,7 @@ pqSetenvPoll(PGconn *conn)
error_return:
conn->setenv_state = SETENV_STATE_IDLE;
- result = PGRES_POLLING_FAILED;
-
-normal_return:
- conn->rowProcessor = savedRowProcessor;
- conn->rowProcessorParam = savedRowProcessorParam;
- return result;
+ return PGRES_POLLING_FAILED;
}
@@ -438,9 +406,6 @@ normal_return:
* parseInput: if appropriate, parse input data from backend
* until input is exhausted or a stopping state is reached.
* Note that this function will NOT attempt to read more data from the backend.
- *
- * Note: callers of parseInput must be prepared for a longjmp exit when we are
- * in PGASYNC_BUSY state, since an external row processor might do that.
*/
void
pqParseInput2(PGconn *conn)
@@ -746,31 +711,16 @@ getRowDescriptions(PGconn *conn)
/* Success! */
conn->result = result;
- /*
- * Advance inStart to show that the "T" message has been processed. We
- * must do this before calling the row processor, in case it longjmps.
- */
+ /* Advance inStart to show that the "T" message has been processed. */
conn->inStart = conn->inCursor;
- /* Give the row processor a chance to initialize for new result set */
- errmsg = NULL;
- switch ((*conn->rowProcessor) (result, NULL, &errmsg,
- conn->rowProcessorParam))
- {
- case 1:
- /* everything is good */
- return 0;
-
- case -1:
- /* error, report the errmsg below */
- break;
+ /*
+ * We could perform additional setup for the new result set here, but for
+ * now there's nothing else to do.
+ */
- default:
- /* unrecognized return code */
- errmsg = libpq_gettext("unrecognized return value from row processor");
- break;
- }
- goto set_error_result;
+ /* And we're done. */
+ return 0;
advance_and_error:
@@ -781,8 +731,6 @@ advance_and_error:
*/
conn->inStart = conn->inEnd;
-set_error_result:
-
/*
* Replace partially constructed result with an error result. First
* discard the old result to try to win back some memory.
@@ -790,7 +738,7 @@ set_error_result:
pqClearAsyncResult(conn);
/*
- * If row processor didn't provide an error message, assume "out of
+ * If preceding code didn't provide an error message, assume "out of
* memory" was meant. The advantage of having this special case is that
* freeing the old result first greatly improves the odds that gettext()
* will succeed in providing a translation.
@@ -937,31 +885,15 @@ getAnotherTuple(PGconn *conn, bool binary)
free(bitmap);
bitmap = NULL;
- /*
- * Advance inStart to show that the "D" message has been processed. We
- * must do this before calling the row processor, in case it longjmps.
- */
+ /* Advance inStart to show that the "D" message has been processed. */
conn->inStart = conn->inCursor;
- /* Pass the completed row values to rowProcessor */
+ /* Process the collected row */
errmsg = NULL;
- switch ((*conn->rowProcessor) (result, rowbuf, &errmsg,
- conn->rowProcessorParam))
- {
- case 1:
- /* everything is good */
- return 0;
+ if (pqRowProcessor(conn, &errmsg))
+ return 0; /* normal, successful exit */
- case -1:
- /* error, report the errmsg below */
- break;
-
- default:
- /* unrecognized return code */
- errmsg = libpq_gettext("unrecognized return value from row processor");
- break;
- }
- goto set_error_result;
+ goto set_error_result; /* pqRowProcessor failed, report it */
advance_and_error:
@@ -981,7 +913,7 @@ set_error_result:
pqClearAsyncResult(conn);
/*
- * If row processor didn't provide an error message, assume "out of
+ * If preceding code didn't provide an error message, assume "out of
* memory" was meant. The advantage of having this special case is that
* freeing the old result first greatly improves the odds that gettext()
* will succeed in providing a translation.
diff --git a/src/interfaces/libpq/fe-protocol3.c b/src/interfaces/libpq/fe-protocol3.c
index 173af2e0a79ef3b443de515cda851e277deaed2d..d289f82285fea00d5de20542e43ea103493f9e58 100644
--- a/src/interfaces/libpq/fe-protocol3.c
+++ b/src/interfaces/libpq/fe-protocol3.c
@@ -61,9 +61,6 @@ static int build_startup_packet(const PGconn *conn, char *packet,
* parseInput: if appropriate, parse input data from backend
* until input is exhausted or a stopping state is reached.
* Note that this function will NOT attempt to read more data from the backend.
- *
- * Note: callers of parseInput must be prepared for a longjmp exit when we are
- * in PGASYNC_BUSY state, since an external row processor might do that.
*/
void
pqParseInput3(PGconn *conn)
@@ -446,10 +443,6 @@ handleSyncLoss(PGconn *conn, char id, int msgLength)
* Returns: 0 if processed message successfully, EOF to suspend parsing
* (the latter case is not actually used currently).
* In either case, conn->inStart has been advanced past the message.
- *
- * Note: the row processor could also choose to longjmp out of libpq,
- * in which case the library's state must allow for resumption at the
- * next message.
*/
static int
getRowDescriptions(PGconn *conn, int msgLength)
@@ -564,10 +557,7 @@ getRowDescriptions(PGconn *conn, int msgLength)
/* Success! */
conn->result = result;
- /*
- * Advance inStart to show that the "T" message has been processed. We
- * must do this before calling the row processor, in case it longjmps.
- */
+ /* Advance inStart to show that the "T" message has been processed. */
conn->inStart = conn->inCursor;
/*
@@ -580,25 +570,13 @@ getRowDescriptions(PGconn *conn, int msgLength)
return 0;
}
- /* Give the row processor a chance to initialize for new result set */
- errmsg = NULL;
- switch ((*conn->rowProcessor) (result, NULL, &errmsg,
- conn->rowProcessorParam))
- {
- case 1:
- /* everything is good */
- return 0;
-
- case -1:
- /* error, report the errmsg below */
- break;
+ /*
+ * We could perform additional setup for the new result set here, but for
+ * now there's nothing else to do.
+ */
- default:
- /* unrecognized return code */
- errmsg = libpq_gettext("unrecognized return value from row processor");
- break;
- }
- goto set_error_result;
+ /* And we're done. */
+ return 0;
advance_and_error:
/* Discard unsaved result, if any */
@@ -608,8 +586,6 @@ advance_and_error:
/* Discard the failed message by pretending we read it */
conn->inStart += 5 + msgLength;
-set_error_result:
-
/*
* Replace partially constructed result with an error result. First
* discard the old result to try to win back some memory.
@@ -617,8 +593,10 @@ set_error_result:
pqClearAsyncResult(conn);
/*
- * If row processor didn't provide an error message, assume "out of
- * memory" was meant.
+ * If preceding code didn't provide an error message, assume "out of
+ * memory" was meant. The advantage of having this special case is that
+ * freeing the old result first greatly improves the odds that gettext()
+ * will succeed in providing a translation.
*/
if (!errmsg)
errmsg = libpq_gettext("out of memory for query result");
@@ -695,10 +673,6 @@ failure:
* Returns: 0 if processed message successfully, EOF to suspend parsing
* (the latter case is not actually used currently).
* In either case, conn->inStart has been advanced past the message.
- *
- * Note: the row processor could also choose to longjmp out of libpq,
- * in which case the library's state must allow for resumption at the
- * next message.
*/
static int
getAnotherTuple(PGconn *conn, int msgLength)
@@ -778,31 +752,15 @@ getAnotherTuple(PGconn *conn, int msgLength)
goto advance_and_error;
}
- /*
- * Advance inStart to show that the "D" message has been processed. We
- * must do this before calling the row processor, in case it longjmps.
- */
+ /* Advance inStart to show that the "D" message has been processed. */
conn->inStart = conn->inCursor;
- /* Pass the completed row values to rowProcessor */
+ /* Process the collected row */
errmsg = NULL;
- switch ((*conn->rowProcessor) (result, rowbuf, &errmsg,
- conn->rowProcessorParam))
- {
- case 1:
- /* everything is good */
- return 0;
-
- case -1:
- /* error, report the errmsg below */
- break;
+ if (pqRowProcessor(conn, &errmsg))
+ return 0; /* normal, successful exit */
- default:
- /* unrecognized return code */
- errmsg = libpq_gettext("unrecognized return value from row processor");
- break;
- }
- goto set_error_result;
+ goto set_error_result; /* pqRowProcessor failed, report it */
advance_and_error:
/* Discard the failed message by pretending we read it */
@@ -817,7 +775,7 @@ set_error_result:
pqClearAsyncResult(conn);
/*
- * If row processor didn't provide an error message, assume "out of
+ * If preceding code didn't provide an error message, assume "out of
* memory" was meant. The advantage of having this special case is that
* freeing the old result first greatly improves the odds that gettext()
* will succeed in providing a translation.
diff --git a/src/interfaces/libpq/libpq-fe.h b/src/interfaces/libpq/libpq-fe.h
index 67db6119bbaa35ae31fb58bb902a455b093ea23f..9d05dd20605a84ab4c4ec9d61ef8697fb2f3b77e 100644
--- a/src/interfaces/libpq/libpq-fe.h
+++ b/src/interfaces/libpq/libpq-fe.h
@@ -90,7 +90,8 @@ typedef enum
* backend */
PGRES_NONFATAL_ERROR, /* notice or warning message */
PGRES_FATAL_ERROR, /* query failed */
- PGRES_COPY_BOTH /* Copy In/Out data transfer in progress */
+ PGRES_COPY_BOTH, /* Copy In/Out data transfer in progress */
+ PGRES_SINGLE_TUPLE /* single tuple from larger resultset */
} ExecStatusType;
typedef enum
@@ -129,17 +130,6 @@ typedef struct pg_conn PGconn;
*/
typedef struct pg_result PGresult;
-/* PGdataValue represents a data field value being passed to a row processor.
- * It could be either text or binary data; text data is not zero-terminated.
- * A SQL NULL is represented by len < 0; then value is still valid but there
- * are no data bytes there.
- */
-typedef struct pgDataValue
-{
- int len; /* data length in bytes, or <0 if NULL */
- const char *value; /* data value, without zero-termination */
-} PGdataValue;
-
/* PGcancel encapsulates the information needed to cancel a running
* query on an existing connection.
* The contents of this struct are not supposed to be known to applications.
@@ -161,10 +151,6 @@ typedef struct pgNotify
struct pgNotify *next; /* list link */
} PGnotify;
-/* Function type for row-processor callback */
-typedef int (*PQrowProcessor) (PGresult *res, const PGdataValue *columns,
- const char **errmsgp, void *param);
-
/* Function types for notice-handling callbacks */
typedef void (*PQnoticeReceiver) (void *arg, const PGresult *res);
typedef void (*PQnoticeProcessor) (void *arg, const char *message);
@@ -403,17 +389,13 @@ extern int PQsendQueryPrepared(PGconn *conn,
const int *paramLengths,
const int *paramFormats,
int resultFormat);
+extern int PQsetSingleRowMode(PGconn *conn);
extern PGresult *PQgetResult(PGconn *conn);
-extern PGresult *PQskipResult(PGconn *conn);
/* Routines for managing an asynchronous query */
extern int PQisBusy(PGconn *conn);
extern int PQconsumeInput(PGconn *conn);
-/* Override default per-row processing */
-extern void PQsetRowProcessor(PGconn *conn, PQrowProcessor func, void *param);
-extern PQrowProcessor PQgetRowProcessor(const PGconn *conn, void **param);
-
/* LISTEN/NOTIFY support */
extern PGnotify *PQnotifies(PGconn *conn);
diff --git a/src/interfaces/libpq/libpq-int.h b/src/interfaces/libpq/libpq-int.h
index 4bc89269fababe5e4d8ecbf6e80ca1a8625d4bd5..2bac59c3d879ecabce42ceab3b5133df03a0886a 100644
--- a/src/interfaces/libpq/libpq-int.h
+++ b/src/interfaces/libpq/libpq-int.h
@@ -277,6 +277,17 @@ typedef struct pgLobjfuncs
Oid fn_lo_write; /* OID of backend function LOwrite */
} PGlobjfuncs;
+/* PGdataValue represents a data field value being passed to a row processor.
+ * It could be either text or binary data; text data is not zero-terminated.
+ * A SQL NULL is represented by len < 0; then value is still valid but there
+ * are no data bytes there.
+ */
+typedef struct pgDataValue
+{
+ int len; /* data length in bytes, or <0 if NULL */
+ const char *value; /* data value, without zero-termination */
+} PGdataValue;
+
/*
* PGconn stores all the state data associated with a single connection
* to a backend.
@@ -324,10 +335,6 @@ struct pg_conn
/* Optional file to write trace info to */
FILE *Pfdebug;
- /* Callback procedure for per-row processing */
- PQrowProcessor rowProcessor; /* function pointer */
- void *rowProcessorParam; /* passthrough argument */
-
/* Callback procedures for notice message processing */
PGNoticeHooks noticeHooks;
@@ -346,6 +353,7 @@ struct pg_conn
bool options_valid; /* true if OK to attempt connection */
bool nonblocking; /* whether this connection is using nonblock
* sending semantics */
+ bool singleRowMode; /* return current query result row-by-row? */
char copy_is_binary; /* 1 = copy binary, 0 = copy text */
int copy_already_done; /* # bytes already returned in COPY
* OUT */
@@ -406,6 +414,7 @@ struct pg_conn
/* Status for asynchronous result construction */
PGresult *result; /* result being constructed */
+ PGresult *next_result; /* next result (used in single-row mode) */
/* Assorted state for SSL, GSS, etc */
@@ -517,6 +526,7 @@ extern void pqSaveMessageField(PGresult *res, char code,
const char *value);
extern void pqSaveParameterStatus(PGconn *conn, const char *name,
const char *value);
+extern int pqRowProcessor(PGconn *conn, const char **errmsgp);
extern void pqHandleSendFailure(PGconn *conn);
/* === in fe-protocol2.c === */