From 947f6da75e10042b2fd66a4ff523c8a1d5da3aeb Mon Sep 17 00:00:00 2001 From: Christian Schwarz Date: Tue, 25 Jun 2024 17:04:44 +0200 Subject: [PATCH] L0 flush: avoid short-lived allocation when checking key_range empty (#8154) We only use `keys` to check if it's empty so we can bail out early. No need to collect the keys for that. Found this while doing research for https://github.com/neondatabase/neon/issues/7418 --- pageserver/src/tenant/storage_layer/inmemory_layer.rs | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-) diff --git a/pageserver/src/tenant/storage_layer/inmemory_layer.rs b/pageserver/src/tenant/storage_layer/inmemory_layer.rs index 1ecc56ce993f..6624fb7e6ba5 100644 --- a/pageserver/src/tenant/storage_layer/inmemory_layer.rs +++ b/pageserver/src/tenant/storage_layer/inmemory_layer.rs @@ -622,18 +622,16 @@ impl InMemoryLayer { let end_lsn = *self.end_lsn.get().unwrap(); - let keys: Vec<_> = if let Some(key_range) = key_range { + let key_count = if let Some(key_range) = key_range { inner .index .iter() .filter(|(k, _)| key_range.contains(k)) - .map(|(k, m)| (k.to_i128(), m)) - .collect() + .count() } else { - inner.index.iter().map(|(k, m)| (k.to_i128(), m)).collect() + inner.index.len() }; - - if keys.is_empty() { + if key_count == 0 { return Ok(None); }