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Type: Improvement
Resolution: Duplicate
Priority: Major - P3
Fix Version/s: None
Affects Version/s: None
Component/s: Replication, Storage
Labels:
None

Case:
Confidence Status:
None
Work Order:
3

Aha! Reference:
None
Tracking Level:
None
Risk Status:
None
Exec Notes:
None
Goal Name:
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Goal Link:
None

Currently replication applies batches of oplog entries holding a lock to ensure that no reads can consume data which is not in the same causal order as the primary.

Instead of locking and blocking readers we can instead use a snapshot for reads from the last consistent replication state and essentially hide all writes until we reach a new consistent state. In addition to detaching replication writes from affecting readers (both users and other replicas) this also allows storage engines to optimize writing of replicated data to improve performance and reduce IO, since all replicated data is transient and disposable until committed.

duplicates

SERVER-34192 Secondary reads during batch applications

Closed

is duplicated by

SERVER-21858 A high throughput update workload in a replica set can cause starvation of secondary reads

Closed

SERVER-24661 Secondary block reader a very long time when replay oplog

Closed

is related to

SERVER-25168 Foreground index build blocks all R/W on ALL database on a sharded cluster with secondaryPreferred read preference

Closed

SERVER-5729 Special-case concurrency model for oplog, make reads not block as much

Closed

SERVER-6883 index creation on secondaries need not block readers

Closed

SERVER-29123 Why is ParallelBatchWriterMode used when Applying Oplogs

Closed

SERVER-31359 when large inserts into mongo, lots of global lock occur

Closed

related to

WT-2649 Some way to indicate valid points in the WT log

Closed

SERVER-21862 Use record store directly to read from oplog for replication

Closed

(3 is related to, 2 related to)

Assignee:: Louis Williams
Reporter:: Scott Hernandez (Inactive)
Participants:: deyukong, Eric Milkie, Louis Williams, Scott Hernandez, Zhang Youdong
Votes:: 22 Vote for this issue
Watchers:: 36 Start watching this issue

Created:: Sep 09 2015 03:01:41 PM UTC
Updated:: Nov 15 2021 03:11:42 PM UTC
Resolved:: Apr 13 2018 04:11:35 PM UTC

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