3 files changed, 31 insertions, 6 deletions
diff --git a/src/backend/access/transam/xlogreader.c b/src/backend/access/transam/xlogreader.c
index cf5db23cb86..02d4414bac7 100644
--- a/src/backend/access/transam/xlogreader.c
+++ b/src/backend/access/transam/xlogreader.c
@@ -987,6 +987,13 @@ ReadPageInternal(XLogReaderState *state, XLogRecPtr pageptr, int reqLen)
 		return state->readLen;
 
 	/*
+	 * Invalidate contents of internal buffer before read attempt.  Just set
+	 * the length to 0, rather than a full XLogReaderInvalReadState(), so we
+	 * don't forget the segment we last successfully read.
+	 */
+	state->readLen = 0;
+
+	/*
 	 * Data is not in our buffer.
 	 *
 	 * Every time we actually read the segment, even if we looked at parts of
@@ -1066,11 +1073,8 @@ ReadPageInternal(XLogReaderState *state, XLogRecPtr pageptr, int reqLen)
 	return readLen;
 
 err:
-	if (state->errormsg_buf[0] != '\0')
-	{
-		state->errormsg_deferred = true;
-		XLogReaderInvalReadState(state);
-	}
+	XLogReaderInvalReadState(state);
+
 	return XLREAD_FAIL;
 }
 
@@ -1323,6 +1327,16 @@ XLogReaderValidatePageHeader(XLogReaderState *state, XLogRecPtr recptr,
 }
 
 /*
+ * Forget about an error produced by XLogReaderValidatePageHeader().
+ */
+void
+XLogReaderResetError(XLogReaderState *state)
+{
+	state->errormsg_buf[0] = '\0';
+	state->errormsg_deferred = false;
+}
+
+/*
  * Find the first record with an lsn >= RecPtr.
  *
  * This is different from XLogBeginRead() in that RecPtr doesn't need to point
diff --git a/src/backend/access/transam/xlogrecovery.c b/src/backend/access/transam/xlogrecovery.c
index f6f894b36d1..f4aeda771c0 100644
--- a/src/backend/access/transam/xlogrecovery.c
+++ b/src/backend/access/transam/xlogrecovery.c
@@ -3339,13 +3339,21 @@ retry:
 					(errmsg_internal("%s", xlogreader->errormsg_buf)));
 
 		/* reset any error XLogReaderValidatePageHeader() might have set */
-		xlogreader->errormsg_buf[0] = '\0';
+		XLogReaderResetError(xlogreader);
 		goto next_record_is_invalid;
 	}
 
 	return readLen;
 
 next_record_is_invalid:
+
+	/*
+	 * If we're reading ahead, give up fast.  Retries and error reporting will
+	 * be handled by a later read when recovery catches up to this point.
+	 */
+	if (xlogreader->nonblocking)
+		return XLREAD_WOULDBLOCK;
+
 	lastSourceFailed = true;
 
 	if (readFile >= 0)
diff --git a/src/include/access/xlogreader.h b/src/include/access/xlogreader.h
index e73ea4a8408..6b851693b16 100644
--- a/src/include/access/xlogreader.h
+++ b/src/include/access/xlogreader.h
@@ -373,6 +373,9 @@ extern DecodedXLogRecord *XLogReadAhead(XLogReaderState *state,
 extern bool XLogReaderValidatePageHeader(XLogReaderState *state,
 										 XLogRecPtr recptr, char *phdr);
 
+/* Forget error produced by XLogReaderValidatePageHeader(). */
+extern void XLogReaderResetError(XLogReaderState *state);
+
 /*
  * Error information from WALRead that both backend and frontend caller can
  * process.  Currently only errors from pg_pread can be reported.