diff options
| -rw-r--r-- | src/backend/access/transam/xlogreader.c | 30 |
1 files changed, 12 insertions, 18 deletions
diff --git a/src/backend/access/transam/xlogreader.c b/src/backend/access/transam/xlogreader.c index 75164f686e5..9499f848b0d 100644 --- a/src/backend/access/transam/xlogreader.c +++ b/src/backend/access/transam/xlogreader.c @@ -164,7 +164,7 @@ allocate_recordbuf(XLogReaderState *state, uint32 reclength) * If RecPtr is not NULL, try to read a record at that position. Otherwise * try to read a record just after the last one previously read. * - * If the page_read callback fails to read the requested data, NULL is + * If the read_page callback fails to read the requested data, NULL is * returned. The callback is expected to have reported the error; errormsg * is set to NULL. * @@ -217,10 +217,16 @@ XLogReadRecord(XLogReaderState *state, XLogRecPtr RecPtr, char **errormsg) } targetPagePtr = RecPtr - (RecPtr % XLOG_BLCKSZ); + targetRecOff = RecPtr % XLOG_BLCKSZ; - /* Read the page containing the record into state->readBuf */ - readOff = ReadPageInternal(state, targetPagePtr, SizeOfXLogRecord); - + /* + * Read the page containing the record into state->readBuf. Request + * enough byte to cover the whole record header, or at least the part of + * it that fits on the same page. + */ + readOff = ReadPageInternal(state, + targetPagePtr, + Min(targetRecOff + SizeOfXLogRecord, XLOG_BLCKSZ)); if (readOff < 0) goto err; @@ -229,7 +235,6 @@ XLogReadRecord(XLogReaderState *state, XLogRecPtr RecPtr, char **errormsg) * examine it now. */ pageHeaderSize = XLogPageHeaderSize((XLogPageHeader) state->readBuf); - targetRecOff = RecPtr % XLOG_BLCKSZ; if (targetRecOff == 0) { /* @@ -257,16 +262,6 @@ XLogReadRecord(XLogReaderState *state, XLogRecPtr RecPtr, char **errormsg) Assert(pageHeaderSize <= readOff); /* - * Ensure the whole record header or at least the part on this page is - * read. - */ - readOff = ReadPageInternal(state, - targetPagePtr, - Min(targetRecOff + SizeOfXLogRecord, XLOG_BLCKSZ)); - if (readOff < 0) - goto err; - - /* * Read the record length. * * NB: Even though we use an XLogRecord pointer here, the whole record @@ -463,7 +458,7 @@ err: } /* - * Read a single xlog page including at least [pagestart, RecPtr] of valid data + * Read a single xlog page including at least [pageptr, reqLen] of valid data * via the read_page() callback. * * 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) * record is. This is so that we can check the additional identification * info that is present in the first page's "long" header. */ - if (targetSegNo != state->readSegNo && - targetPageOff != 0) + if (targetSegNo != state->readSegNo && targetPageOff != 0) { XLogPageHeader hdr; XLogRecPtr targetSegmentPtr = pageptr - targetPageOff; |