rust/neon
1
0
Fork 0
mirror of https://github.com/neondatabase/neon.git synced 2026-01-15 17:32:56 +00:00
Code Issues Packages Projects Releases Wiki Activity

Refactor generation of ClearVisibilityMapFlags records.

Browse Source 
With fewer mutable variables, for sake of clarity.
This commit is contained in:
Heikki Linnakangas
2024-01-04 18:23:59 +02:00
parent aa95a07d27
commit b1d701dc06
1 changed files with 75 additions and 55 deletions
Download Patch File Download Diff File Expand all files Collapse all files

130
pageserver/src/walingest.rs
View File

@@ -718,75 +718,95 @@ impl WalIngest {
relnode: decoded.blocks[0].rnode_relnode,
};
let mut new_vm_blk = new_heap_blkno.map(pg_constants::HEAPBLK_TO_MAPBLOCK);
let mut old_vm_blk = old_heap_blkno.map(pg_constants::HEAPBLK_TO_MAPBLOCK);
self.clear_visibility_map_bits(
modification,
vm_rel,
new_heap_blkno,
old_heap_blkno,
flags,
ctx).await?;
}
Ok(())
}
// Sometimes, Postgres seems to create heap WAL records with the
// ALL_VISIBLE_CLEARED flag set, even though the bit in the VM page is
// not set. In fact, it's possible that the VM page does not exist at all.
// In that case, we don't want to store a record to clear the VM bit;
// replaying it would fail to find the previous image of the page, because
// it doesn't exist. So check if the VM page(s) exist, and skip the WAL
// record if it doesn't.
let vm_size = get_relsize(modification, vm_rel, ctx).await?;
if let Some(blknum) = new_vm_blk {
if blknum >= vm_size {
new_vm_blk = None;
}
}
if let Some(blknum) = old_vm_blk {
if blknum >= vm_size {
old_vm_blk = None;
}
/// Write NeonWalRecord::ClearVisibilityMapFlags records for clearing the VM bits
/// corresponding to new_heap_blkno and old_heap_blkno.
async fn clear_visibility_map_bits(
&mut self,
modification: &mut DatadirModification<'_>,
vm_rel: RelTag,
new_heap_blkno: Option<u32>,
old_heap_blkno: Option<u32>,
flags: u8,
ctx: &RequestContext,
) -> anyhow::Result<()> {
// Determine the VM pages containing the old and the new heap block.
//
// Sometimes, Postgres seems to create heap WAL records with the
// ALL_VISIBLE_CLEARED flag set, even though the bit in the VM page is
// not set. In fact, it's possible that the VM page does not exist at all.
// In that case, we don't want to store a record to clear the VM bit;
// replaying it would fail to find the previous image of the page, because
// it doesn't exist. So check if the VM page(s) exist, and skip the WAL
// record if it doesn't.
let vm_size = get_relsize(modification, vm_rel, ctx).await?;
let heap_to_vm_blk = |heap_blkno| {
let vm_blk = pg_constants::HEAPBLK_TO_MAPBLOCK(heap_blkno);
if vm_blk >= vm_size {
None
} else {
Some(vm_blk)
}
};
let new_vm_blk = new_heap_blkno.map(heap_to_vm_blk).flatten();
let old_vm_blk = old_heap_blkno.map(heap_to_vm_blk).flatten();
if new_vm_blk.is_some() || old_vm_blk.is_some() {
if new_vm_blk == old_vm_blk {
// An UPDATE record that needs to clear the bits for both old and the
// new page, both of which reside on the same VM page.
if new_vm_blk.is_some() || old_vm_blk.is_some() {
if new_vm_blk == old_vm_blk {
// An UPDATE record that needs to clear the bits for both old and the
// new page, both of which reside on the same VM page.
self.put_rel_wal_record(
modification,
vm_rel,
new_vm_blk.unwrap(),
NeonWalRecord::ClearVisibilityMapFlags {
new_heap_blkno,
old_heap_blkno,
flags,
},
ctx,
)
.await?;
} else {
// Clear VM bits for one heap page, or for two pages that reside on
// different VM pages.
if let Some(new_vm_blk) = new_vm_blk {
self.put_rel_wal_record(
modification,
vm_rel,
new_vm_blk.unwrap(),
new_vm_blk,
NeonWalRecord::ClearVisibilityMapFlags {
new_heap_blkno,
old_heap_blkno: None,
flags,
},
ctx,
)
.await?;
}
if let Some(old_vm_blk) = old_vm_blk {
self.put_rel_wal_record(
modification,
vm_rel,
old_vm_blk,
NeonWalRecord::ClearVisibilityMapFlags {
new_heap_blkno: None,
old_heap_blkno,
flags,
},
ctx,
)
.await?;
} else {
// Clear VM bits for one heap page, or for two pages that reside on
// different VM pages.
if let Some(new_vm_blk) = new_vm_blk {
self.put_rel_wal_record(
modification,
vm_rel,
new_vm_blk,
NeonWalRecord::ClearVisibilityMapFlags {
new_heap_blkno,
old_heap_blkno: None,
flags,
},
ctx,
)
.await?;
}
if let Some(old_vm_blk) = old_vm_blk {
self.put_rel_wal_record(
modification,
vm_rel,
old_vm_blk,
NeonWalRecord::ClearVisibilityMapFlags {
new_heap_blkno: None,
old_heap_blkno,
flags,
},
ctx,
)
.await?;
}
}
}
}