From df70cd1da9537e0af3e8f62062a01d1ba9bd7160 Mon Sep 17 00:00:00 2001
From: Dan Goodliffe <dan@randomdan.homeip.net>
Date: Sun, 4 Jul 2021 19:27:32 +0100
Subject: Support bulk upload to PQ

---
 lib/output/pq/pqConn.cpp | 36 ++++++++++++++++++++++++++++++++++++
 lib/output/pq/pqConn.h   |  4 ++++
 2 files changed, 40 insertions(+)

diff --git a/lib/output/pq/pqConn.cpp b/lib/output/pq/pqConn.cpp
index 76a3a75..53fd3db 100644
--- a/lib/output/pq/pqConn.cpp
+++ b/lib/output/pq/pqConn.cpp
@@ -1,6 +1,7 @@
 #include "pqConn.h"
 #include "pqBindings.h"
 #include "pqStmt.h"
+#include <compileTimeFormatter.h>
 #include <dbConn.h>
 #include <helpers.h>
 #include <libpq-fe.h>
@@ -62,6 +63,41 @@ namespace MyGrate::Output::Pq {
 		query("ROLLBACK");
 	}
 
+	FILE *
+	PqConn::beginBulkUpload(const char * schema, const char * table)
+	{
+		ResPtr res {PQexec(conn.get(), scprintf<"COPY %?.%? FROM STDIN">(schema, table).c_str()), &PQclear};
+		verify<PqErr>(PQresultStatus(res.get()) == PGRES_COPY_IN, "begin copy", res.get());
+		return fopencookie(this, "w",
+				{nullptr,
+						[](void * cookie, const char * buf, size_t size) -> ssize_t {
+							auto pq = static_cast<PqConn *>(cookie);
+							int rc;
+							while (!(rc = PQputCopyData(pq->conn.get(), buf, size))) {
+								sleep(1);
+							}
+							verify<PqErr>(rc == 1, "copy data", pq->conn.get());
+							return size;
+						},
+						nullptr,
+						[](void * cookie) -> int {
+							static_cast<PqConn *>(cookie)->endBulkUpload(nullptr);
+							return 0;
+						}});
+	}
+
+	void
+	PqConn::endBulkUpload(const char * errormsg)
+	{
+		int rc;
+		while (!(rc = PQputCopyEnd(this->conn.get(), errormsg))) {
+			sleep(1);
+		}
+		verify<PqErr>(rc == 1, "copy end rc", conn.get());
+		ResPtr res {PQgetResult(conn.get()), &PQclear};
+		verify<PqErr>(PQresultStatus(res.get()) == PGRES_COMMAND_OK, "end copy", res.get());
+	}
+
 	void
 	PqConn::notice_processor(void * p, const char * n)
 	{
diff --git a/lib/output/pq/pqConn.h b/lib/output/pq/pqConn.h
index 3b27f97..6ee6dc0 100644
--- a/lib/output/pq/pqConn.h
+++ b/lib/output/pq/pqConn.h
@@ -2,6 +2,7 @@
 #define MYGRATE_OUTPUT_PQ_PQCONN_H
 
 #include <cstddef>
+#include <cstdio>
 #include <dbConn.h>
 #include <functional>
 #include <initializer_list>
@@ -36,6 +37,9 @@ namespace MyGrate::Output::Pq {
 		void commitTx() override;
 		void rollbackTx() override;
 
+		FILE * beginBulkUpload(const char * schema, const char * table);
+		void endBulkUpload(const char * errormsg);
+
 		const std::string connstr;
 
 	private:
-- 
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