Parameter · Resource Usage / Memory
serializable_buffers
Sets the size of the dedicated buffer pool used for the serializable transaction cache.
- Default:
256kB - Type: integer (8kB)
- Range: 128kB … 1GB
- Applies: Restart required
In plain words
The SERIALIZABLE isolation level remembers information about committed transactions that may still conflict with running ones. When that does not fit in memory it is pushed out to pg_serial; this setting is how many 8 kB pages of it are cached.
For DBAs and operators
Configurable since PostgreSQL 17 (default 32, multiple of 16). Only relevant if you use SERIALIZABLE. The summarised old-transaction data goes to pg_serial when the predicate-lock structures (sized by max_pred_locks_per_transaction) overflow, typically with long-running serializable transactions alongside many short ones. Watch pg_stat_slru name = 'serializable' and SerialSLRU / SerialBuffer wait events. Many ERROR: could not serialize access due to read/write dependencies among transactions are a workload issue, not a buffer one.
How to change it
Change in postgresql.conf or ALTER SYSTEM, then restart the server.
See it in context
Related parameters
max_pred_locks_per_transaction default_transaction_isolation