RDS for PostgreSQL wait events - Amazon Relational Database Service
Services or capabilities described in Amazon Web Services documentation might vary by Region. To see the differences applicable to the China Regions, see Getting Started with Amazon Web Services in China (PDF).

RDS for PostgreSQL wait events

The following table lists the wait events for RDS for PostgreSQL that most commonly indicate performance problems, and summarizes the most common causes and corrective actions..

Wait event Definition

Client:ClientRead

This event occurs when RDS for PostgreSQL is waiting to receive data from the client.

Client:ClientWrite

This event occurs when RDS for PostgreSQL is waiting to write data to the client.

CPU

 This event occurs when a thread is active in CPU or is waiting for CPU.

IO:BufFileRead and IO:BufFileWrite

These events occur when RDS for PostgreSQL creates temporary files.

IO:DataFileRead

This event occurs when a connection waits on a backend process to read a required page from storage because the page isn't available in shared memory.

IO:WALWrite This event occurs when RDS for PostgreSQL is waiting for the write-ahead log (WAL) buffers to be written to a WAL file.

Lock:advisory

This event occurs when a PostgreSQL application uses a lock to coordinate activity across multiple sessions.

Lock:extend

This event occurs when a backend process is waiting to lock a relation to extend it while another process has a lock on that relation for the same purpose.

Lock:Relation

This event occurs when a query is waiting to acquire a lock on a table or view that's currently locked by another transaction.

Lock:transactionid

 This event occurs when a transaction is waiting for a row-level lock.

Lock:tuple

This event occurs when a backend process is waiting to acquire a lock on a tuple.

LWLock:BufferMapping (LWLock:buffer_mapping)

This event occurs when a session is waiting to associate a data block with a buffer in the shared buffer pool.

LWLock:BufferIO (IPC:BufferIO)

This event occurs when RDS for PostgreSQL is waiting for other processes to finish their input/output (I/O) operations when concurrently trying to access a page.

LWLock:buffer_content (BufferContent)

This event occurs when a session is waiting to read or write a data page in memory while another session has that page locked for writing.

LWLock:lock_manager (LWLock:lockmanager)

This event occurs when the RDS for PostgreSQL engine maintains the shared lock's memory area to allocate, check, and deallocate a lock when a fast path lock isn't possible.

Timeout:PgSleep

This event occurs when a server process has called the pg_sleep function and is waiting for the sleep timeout to expire.

Timeout:VacuumDelay

 This event indicates that the vacuum process is sleeping because the estimated cost limit has been reached.