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Do not overwrite an existing image layer.

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See github issues #1594 and #1690

Co-authored-by: Konstantin Knizhnik <knizhnik@neon.tech>
This commit is contained in:
Heikki Linnakangas
2022-07-05 11:27:51 +03:00
committed by Heikki Linnakangas
parent 05f6a1394d
commit bb69e0920c
2 changed files with 25 additions and 9 deletions
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29
pageserver/src/layered_repository.rs
View File

@@ -1923,15 +1923,28 @@ impl LayeredTimeline {
} else {
Lsn(0)
};
// Let's consider an example:
//
// delta layer with LSN range 71-81
// delta layer with LSN range 81-91
// delta layer with LSN range 91-101
// image layer at LSN 100
//
// If 'lsn' is still 100, i.e. no new WAL has been processed since the last image layer,
// there's no need to create a new one. We check this case explicitly, to avoid passing
// a bogus range to count_deltas below, with start > end. It's even possible that there
// are some delta layers *later* than current 'lsn', if more WAL was processed and flushed
// after we read last_record_lsn, which is passed here in the 'lsn' argument.
if img_lsn < lsn {
let num_deltas = layers.count_deltas(&img_range, &(img_lsn..lsn))?;
let num_deltas = layers.count_deltas(&img_range, &(img_lsn..lsn))?;
debug!(
"range {}-{}, has {} deltas on this timeline",
img_range.start, img_range.end, num_deltas
);
if num_deltas >= self.get_image_creation_threshold() {
return Ok(true);
debug!(
"key range {}-{}, has {} deltas on this timeline in LSN range {}..{}",
img_range.start, img_range.end, num_deltas, img_lsn, lsn
);
if num_deltas >= self.get_image_creation_threshold() {
return Ok(true);
}
}
}
}

5
pageserver/src/layered_repository/image_layer.rs
View File

@@ -445,7 +445,10 @@ impl ImageLayerWriter {
},
);
info!("new image layer {}", path.display());
let mut file = VirtualFile::create(&path)?;
let mut file = VirtualFile::open_with_options(
&path,
std::fs::OpenOptions::new().write(true).create_new(true),
)?;
// make room for the header block
file.seek(SeekFrom::Start(PAGE_SZ as u64))?;
let blob_writer = WriteBlobWriter::new(file, PAGE_SZ as u64);