What is WAL in postgresql?

Where is Postgres WAL?

WAL logs are stored in the directory pg_wal under the data directory, as a set of segment files, normally each 16 MB in size (but the size can be changed by altering the --wal-segsize initdb option).

What is WAL buffer in PostgreSQL?

WAL Buffers The write ahead log (WAL) buffers are also called "transaction log buffers", which is an amount of memory allocation for storing WAL data. This WAL data is the metadata information about changes to the actual data, and is sufficient to reconstruct actual data during database recovery operations.

What is WAL writer in PostgreSQL?

In PostgreSQL, the history data are known as XLOG record(s) or WAL data. XLOG records are written into the in-memory WAL buffer by change operations such as insertion, deletion, or commit action. They are immediately written into a WAL segment file on the storage when a transaction commits/aborts.

What is the use of WAL?

In computer science, write-ahead logging (WAL) is a family of techniques for providing atomicity and durability (two of the ACID properties) in database systems. The changes are first recorded in the log, which must be written to stable storage, before the changes are written to the database.