The PGresult represents a
- synchronization point in pipeline mode, requested by
- .
+ synchronization point in pipeline mode, requested by either
+ or
+ .
This status occurs only when pipeline mode has been selected.
,
,
,
- , or
+ ,
+ , or
call, and returns it.
A null pointer is returned when the command is complete and there
client sends them. The server will begin executing the commands in the
pipeline immediately, not waiting for the end of the pipeline.
Note that results are buffered on the server side; the server flushes
- that buffer when a synchronization point is established with
- PQpipelineSync, or when
+ that buffer when a synchronization point is established with either
+ PQpipelineSync or
+ PQsendPipelineSync, or when
PQsendFlushRequest is called.
If any statement encounters an error, the server aborts the current
transaction and does not execute any subsequent command in the queue
PGresult types PGRES_PIPELINE_SYNC
and PGRES_PIPELINE_ABORTED.
PGRES_PIPELINE_SYNC is reported exactly once for each
- PQpipelineSync at the corresponding point
+ PQpipelineSync or
+ PQsendPipelineSync at the corresponding point
in the pipeline.
PGRES_PIPELINE_ABORTED is emitted in place of a normal
query result for the first error and all subsequent results
PQresultStatus will report a
PGRES_PIPELINE_ABORTED result for each remaining queued
operation in an aborted pipeline. The result for
- PQpipelineSync is reported as
+ PQpipelineSync or
+ PQsendPipelineSync is reported as
PGRES_PIPELINE_SYNC to signal the end of the aborted pipeline
and resumption of normal result processing.
+
+
PQsendPipelineSyncPQsendPipelineSync+
+
+ Marks a synchronization point in a pipeline by sending a
+ sync message
+ without flushing the send buffer. This serves as
+ the delimiter of an implicit transaction and an error recovery
+ point; see .
+
+
+int PQsendPipelineSync(PGconn *conn);
+
+
+ Returns 1 for success. Returns 0 if the connection is not in
+ pipeline mode or sending a
+ sync message
+ failed.
+ Note that the message is not itself flushed to the server automatically;
+ use PQflush if necessary.
+
+
+
+
PQsendFlushRequestPQsendFlushRequest
PQsendClosePrepared 190
PQsendClosePortal 191
PQchangePassword 192
+PQsendPipelineSync 193
const char *target);
static int check_field_number(const PGresult *res, int field_num);
static void pqPipelineProcessQueue(PGconn *conn);
+static int pqPipelineSyncInternal(PGconn *conn, bool immediate_flush);
static int pqPipelineFlush(PGconn *conn);
/*
* PQpipelineSync
* Send a Sync message as part of a pipeline, and flush to server
+ */
+int
+PQpipelineSync(PGconn *conn)
+{
+ return pqPipelineSyncInternal(conn, true);
+}
+
+/*
+ * PQsendPipelineSync
+ * Send a Sync message as part of a pipeline, without flushing to server
+ */
+int
+PQsendPipelineSync(PGconn *conn)
+{
+ return pqPipelineSyncInternal(conn, false);
+}
+
+/*
+ * Workhorse function for PQpipelineSync and PQsendPipelineSync.
*
* It's legal to start submitting more commands in the pipeline immediately,
* without waiting for the results of the current pipeline. There's no need to
* end pipeline mode and start it again.
*
- * If a command in a pipeline fails, every subsequent command up to and including
- * the result to the Sync message sent by PQpipelineSync gets set to
- * PGRES_PIPELINE_ABORTED state. If the whole pipeline is processed without
- * error, a PGresult with PGRES_PIPELINE_SYNC is produced.
+ * If a command in a pipeline fails, every subsequent command up to and
+ * including the result to the Sync message sent by pqPipelineSyncInternal
+ * gets set to PGRES_PIPELINE_ABORTED state. If the whole pipeline is
+ * processed without error, a PGresult with PGRES_PIPELINE_SYNC is produced.
*
- * Queries can already have been sent before PQpipelineSync is called, but
- * PQpipelineSync needs to be called before retrieving command results.
+ * Queries can already have been sent before pqPipelineSyncInternal is called,
+ * but pqPipelineSyncInternal needs to be called before retrieving command
+ * results.
*
* The connection will remain in pipeline mode and unavailable for new
* synchronous command execution functions until all results from the pipeline
* are processed by the client.
+ *
+ * immediate_flush controls if the flush happens immediately after sending the
+ * Sync message or not.
*/
-int
-PQpipelineSync(PGconn *conn)
+static int
+pqPipelineSyncInternal(PGconn *conn, bool immediate_flush)
{
PGcmdQueueEntry *entry;
/*
* Give the data a push. In nonblock mode, don't complain if we're unable
* to send it all; PQgetResult() will do any additional flushing needed.
+ * If immediate_flush is disabled, the data is pushed if we are past the
+ * size threshold.
*/
- if (PQflush(conn) < 0)
- goto sendFailed;
+ if (immediate_flush)
+ {
+ if (pqFlush(conn) < 0)
+ goto sendFailed;
+ }
+ else
+ {
+ if (pqPipelineFlush(conn) < 0)
+ goto sendFailed;
+ }
/* OK, it's launched! */
pqAppendCmdQueueEntry(conn, entry);
extern int PQexitPipelineMode(PGconn *conn);
extern int PQpipelineSync(PGconn *conn);
extern int PQsendFlushRequest(PGconn *conn);
+extern int PQsendPipelineSync(PGconn *conn);
/* LISTEN/NOTIFY support */
extern PGnotify *PQnotifies(PGconn *conn);
if (PQenterPipelineMode(conn) != 1)
pg_fatal("failed to enter pipeline mode: %s", PQerrorMessage(conn));
+ /* first pipeline */
if (PQsendQueryParams(conn, "SELECT $1", 1, dummy_param_oids,
dummy_params, NULL, NULL, 0) != 1)
pg_fatal("dispatching first SELECT failed: %s", PQerrorMessage(conn));
if (PQpipelineSync(conn) != 1)
pg_fatal("Pipeline sync failed: %s", PQerrorMessage(conn));
+ /* second pipeline */
if (PQsendQueryParams(conn, "SELECT $1", 1, dummy_param_oids,
dummy_params, NULL, NULL, 0) != 1)
pg_fatal("dispatching second SELECT failed: %s", PQerrorMessage(conn));
+ /* Skip flushing once. */
+ if (PQsendPipelineSync(conn) != 1)
+ pg_fatal("Pipeline sync failed: %s", PQerrorMessage(conn));
+
+ /* third pipeline */
+ if (PQsendQueryParams(conn, "SELECT $1", 1, dummy_param_oids,
+ dummy_params, NULL, NULL, 0) != 1)
+ pg_fatal("dispatching third SELECT failed: %s", PQerrorMessage(conn));
+
if (PQpipelineSync(conn) != 1)
pg_fatal("pipeline sync failed: %s", PQerrorMessage(conn));
/* OK, start processing the results */
+
+ /* first pipeline */
+
res = PQgetResult(conn);
if (res == NULL)
pg_fatal("PQgetResult returned null when there's a pipeline item: %s",
if (PQresultStatus(res) != PGRES_TUPLES_OK)
pg_fatal("Unexpected result code %s from second pipeline item",
PQresStatus(PQresultStatus(res)));
+ PQclear(res);
+ res = NULL;
+
+ if (PQgetResult(conn) != NULL)
+ pg_fatal("PQgetResult returned something extra after first result");
+
+ if (PQexitPipelineMode(conn) != 0)
+ pg_fatal("exiting pipeline mode after query but before sync succeeded incorrectly");
+
+ res = PQgetResult(conn);
+ if (res == NULL)
+ pg_fatal("PQgetResult returned null when sync result expected: %s",
+ PQerrorMessage(conn));
+
+ if (PQresultStatus(res) != PGRES_PIPELINE_SYNC)
+ pg_fatal("Unexpected result code %s instead of sync result, error: %s",
+ PQresStatus(PQresultStatus(res)), PQerrorMessage(conn));
+ PQclear(res);
+
+ /* third pipeline */
+
+ res = PQgetResult(conn);
+ if (res == NULL)
+ pg_fatal("PQgetResult returned null when there's a pipeline item: %s",
+ PQerrorMessage(conn));
+
+ if (PQresultStatus(res) != PGRES_TUPLES_OK)
+ pg_fatal("Unexpected result code %s from third pipeline item",
+ PQresStatus(PQresultStatus(res)));
res = PQgetResult(conn);
if (res != NULL)
F 6 Describe P ""
F 9 Execute "" 0
F 4 Sync
+F 21 Parse "" "SELECT $1" 1 NNNN
+F 19 Bind "" "" 0 1 1 '1' 1 0
+F 6 Describe P ""
+F 9 Execute "" 0
+F 4 Sync
+B 4 ParseComplete
+B 4 BindComplete
+B 33 RowDescription 1 "?column?" NNNN 0 NNNN 4 -1 0
+B 11 DataRow 1 1 '1'
+B 13 CommandComplete "SELECT 1"
+B 5 ReadyForQuery I
B 4 ParseComplete
B 4 BindComplete
B 33 RowDescription 1 "?column?" NNNN 0 NNNN 4 -1 0
projects / postgresql.git / commitdiff