@@ -164,7 +164,7 @@ allocate_recordbuf(XLogReaderState *state, uint32 reclength)
164164 * If RecPtr is not NULL, try to read a record at that position. Otherwise
165165 * try to read a record just after the last one previously read.
166166 *
167- * If thepage_read callback fails to read the requested data, NULL is
167+ * If theread_page callback fails to read the requested data, NULL is
168168 * returned. The callback is expected to have reported the error; errormsg
169169 * is set to NULL.
170170 *
@@ -217,10 +217,16 @@ XLogReadRecord(XLogReaderState *state, XLogRecPtr RecPtr, char **errormsg)
217217}
218218
219219targetPagePtr = RecPtr - (RecPtr %XLOG_BLCKSZ );
220+ targetRecOff = RecPtr %XLOG_BLCKSZ ;
220221
221- /* Read the page containing the record into state->readBuf */
222- readOff = ReadPageInternal (state ,targetPagePtr ,SizeOfXLogRecord );
223-
222+ /*
223+ * Read the page containing the record into state->readBuf. Request
224+ * enough byte to cover the whole record header, or at least the part of
225+ * it that fits on the same page.
226+ */
227+ readOff = ReadPageInternal (state ,
228+ targetPagePtr ,
229+ Min (targetRecOff + SizeOfXLogRecord ,XLOG_BLCKSZ ));
224230if (readOff < 0 )
225231gotoerr ;
226232
@@ -229,7 +235,6 @@ XLogReadRecord(XLogReaderState *state, XLogRecPtr RecPtr, char **errormsg)
229235 * examine it now.
230236 */
231237pageHeaderSize = XLogPageHeaderSize ((XLogPageHeader )state -> readBuf );
232- targetRecOff = RecPtr %XLOG_BLCKSZ ;
233238if (targetRecOff == 0 )
234239{
235240/*
@@ -256,16 +261,6 @@ XLogReadRecord(XLogReaderState *state, XLogRecPtr RecPtr, char **errormsg)
256261/* ReadPageInternal has verified the page header */
257262Assert (pageHeaderSize <=readOff );
258263
259- /*
260- * Ensure the whole record header or at least the part on this page is
261- * read.
262- */
263- readOff = ReadPageInternal (state ,
264- targetPagePtr ,
265- Min (targetRecOff + SizeOfXLogRecord ,XLOG_BLCKSZ ));
266- if (readOff < 0 )
267- gotoerr ;
268-
269264/*
270265 * Read the record length.
271266 *
@@ -463,7 +458,7 @@ XLogReadRecord(XLogReaderState *state, XLogRecPtr RecPtr, char **errormsg)
463458}
464459
465460/*
466- * Read a single xlog page including at least [pagestart, RecPtr ] of valid data
461+ * Read a single xlog page including at least [pageptr, reqLen ] of valid data
467462 * via the read_page() callback.
468463 *
469464 * Returns -1 if the required page cannot be read for some reason; errormsg_buf
@@ -502,8 +497,7 @@ ReadPageInternal(XLogReaderState *state, XLogRecPtr pageptr, int reqLen)
502497 * record is. This is so that we can check the additional identification
503498 * info that is present in the first page's "long" header.
504499 */
505- if (targetSegNo != state -> readSegNo &&
506- targetPageOff != 0 )
500+ if (targetSegNo != state -> readSegNo && targetPageOff != 0 )
507501{
508502XLogPageHeader hdr ;
509503XLogRecPtr targetSegmentPtr = pageptr - targetPageOff ;