diff options
| -rw-r--r-- | src/backend/access/transam/xlog.c | 24 |
1 files changed, 6 insertions, 18 deletions
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c index 4e14c242b15..50c347a6795 100644 --- a/src/backend/access/transam/xlog.c +++ b/src/backend/access/transam/xlog.c @@ -1710,12 +1710,13 @@ GetXLogBuffer(XLogRecPtr ptr, TimeLineID tli) * of bytes read successfully. * * Fewer than 'count' bytes may be read if some of the requested WAL data has - * already been evicted from the WAL buffers, or if the caller requests data - * that is not yet available. + * already been evicted. * * No locks are taken. * - * The 'tli' argument is only used as a convenient safety check so that + * Caller should ensure that it reads no further than LogwrtResult.Write + * (which should have been updated by the caller when determining how far to + * read). The 'tli' argument is only used as a convenient safety check so that * callers do not read from WAL buffers on a historical timeline. */ Size @@ -1724,26 +1725,13 @@ WALReadFromBuffers(char *dstbuf, XLogRecPtr startptr, Size count, { char *pdst = dstbuf; XLogRecPtr recptr = startptr; - XLogRecPtr upto; - Size nbytes; + Size nbytes = count; if (RecoveryInProgress() || tli != GetWALInsertionTimeLine()) return 0; Assert(!XLogRecPtrIsInvalid(startptr)); - - /* - * Don't read past the available WAL data. - * - * Check using local copy of LogwrtResult. Ordinarily it's been updated by - * the caller when determining how far to read; but if not, it just means - * we'll read less data. - * - * XXX: the available WAL could be extended to the WAL insert pointer by - * calling WaitXLogInsertionsToFinish(). - */ - upto = Min(startptr + count, LogwrtResult.Write); - nbytes = upto - startptr; + Assert(startptr + count <= LogwrtResult.Write); /* * Loop through the buffers without a lock. For each buffer, atomically |