On 2021-Jun-23, Boris Kolpackov wrote: > If, however, I execute it by checking for results before sending the > next INSERT, I get the following call sequence: > > PQsendQueryPrepared() # INSERT #1 > PQflush() > PQsendQueryPrepared() # INSERT #2 > PQflush() > ... > PQsendQueryPrepared() # INSERT #~400 > PQflush() > PQconsumeInput() # At this point select() indicates we can read. > PQgetResult() # NULL (???) > PQgetResult() # INSERT #1 > PQgetResult() # NULL > PQgetResult() # INSERT #2 > PQgetResult() # NULL
IIUC the problem is that PQgetResult is indeed not prepared to deal with a result the first time until after the queue has been "prepared", and this happens on calling PQpipelineSync. But I think the formulation in the attached patch works too, and the resulting code is less surprising. I wrote a test case that works as you describe, and indeed with the original code it gets a NULL initially; that disappears with the attached patch. Can you give it a try? Thanks -- Álvaro Herrera Valdivia, Chile "Escucha y olvidarás; ve y recordarás; haz y entenderás" (Confucio)
>From 4073abc0ef8b4404915b949b3058ba47b7c51ba9 Mon Sep 17 00:00:00 2001 From: Alvaro Herrera <alvhe...@alvh.no-ip.org> Date: Thu, 24 Jun 2021 18:24:04 -0400 Subject: [PATCH] Fix libpq state machine --- src/interfaces/libpq/fe-exec.c | 19 +++++-------------- 1 file changed, 5 insertions(+), 14 deletions(-) diff --git a/src/interfaces/libpq/fe-exec.c b/src/interfaces/libpq/fe-exec.c index 7bd5b3a7b9..8403a9bbca 100644 --- a/src/interfaces/libpq/fe-exec.c +++ b/src/interfaces/libpq/fe-exec.c @@ -1375,8 +1375,7 @@ PQsendQueryInternal(PGconn *conn, const char *query, bool newQuery) /* OK, it's launched! */ pqAppendCmdQueueEntry(conn, entry); - if (conn->pipelineStatus == PQ_PIPELINE_OFF) - conn->asyncStatus = PGASYNC_BUSY; + conn->asyncStatus = PGASYNC_BUSY; return 1; sendFailed: @@ -1513,8 +1512,7 @@ PQsendPrepare(PGconn *conn, pqAppendCmdQueueEntry(conn, entry); - if (conn->pipelineStatus == PQ_PIPELINE_OFF) - conn->asyncStatus = PGASYNC_BUSY; + conn->asyncStatus = PGASYNC_BUSY; /* * Give the data a push (in pipeline mode, only if we're past the size @@ -1817,8 +1815,7 @@ PQsendQueryGuts(PGconn *conn, /* OK, it's launched! */ pqAppendCmdQueueEntry(conn, entry); - if (conn->pipelineStatus == PQ_PIPELINE_OFF) - conn->asyncStatus = PGASYNC_BUSY; + conn->asyncStatus = PGASYNC_BUSY; return 1; sendFailed: @@ -2448,8 +2445,7 @@ PQsendDescribe(PGconn *conn, char desc_type, const char *desc_target) /* OK, it's launched! */ pqAppendCmdQueueEntry(conn, entry); - if (conn->pipelineStatus == PQ_PIPELINE_OFF) - conn->asyncStatus = PGASYNC_BUSY; + conn->asyncStatus = PGASYNC_BUSY; return 1; sendFailed: @@ -3084,12 +3080,7 @@ PQpipelineSync(PGconn *conn) */ if (PQflush(conn) < 0) goto sendFailed; - - /* - * Call pqPipelineProcessQueue so the user can call start calling - * PQgetResult. - */ - pqPipelineProcessQueue(conn); + conn->asyncStatus = PGASYNC_BUSY; return 1; -- 2.30.2
