Wiki / Statistics & Metrics / pg_stat_io
pg_stat_io.evictions
Number of times a block has been written out from a shared or local buffer in order to make it available for another use. In context normal, this counts the number of times a block was evicted from a buffer and replaced with another block. In conte…
Reading PostgreSQL 18.6.
Description
Number of times a block has been written out from a shared or local buffer in order to make it available for another use. In context normal, this counts the number of times a block was evicted from a buffer and replaced with another block. In contexts bulkwrite, bulkread, and vacuum, this counts the number of times a block was evicted from shared buffers in order to add the shared buffer to a separate, size-limited ring buffer for use in a bulk I/O operation.
- View
- pg_stat_io
- Field
- evictions
- SQL type
- bigint
- Units named in the field definition
- Not specified
- Reset observation
- Time at which these statistics were last reset.
Usage
SELECT evictions FROM pg_catalog.pg_stat_io;View semantics
The pg_stat_io view will contain one row for each combination of backend type, target I/O object, and I/O context, showing cluster-wide I/O statistics. Combinations which do not make sense are omitted. Currently, I/O on relations (e.g. tables, indexes) and WAL activity are tracked. However, relation I/O which bypasses shared buffers (e.g. when moving a table from one tablespace to another) is currently not tracked.
Collection and reset context
Read the same-version statistics collection and view documentation below for reset scope and visibility. No per-field reset rule is inferred from the field name.
Inspect this field
Example query; no execution result or measured value is asserted.
SELECT evictions FROM pg_catalog.pg_stat_io;Related entries
Documentation and source
Source build
- Version
- 18.6
- Build
- https://ftp.postgresql.org/pub/source/v18.6/postgresql-18.6.tar.bz2
- Source fingerprint
555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f
Compare versions
PostgreSQL 15 → 16: added.
--- PostgreSQL 15
+++ PostgreSQL 16
@@ -1 +1,6 @@
-Not recorded in this version
+{
+ "field": "evictions",
+ "sql_type": "bigint",
+ "units_mentioned": [],
+ "view": "pg_stat_io"
+}Compares recorded interfaces and attributes. Source fingerprints and build metadata are excluded; an absent sample is not proof of the introduction or removal release.
Related entries
Export JSON · Back to Statistics & Metrics · Recorded in PostgreSQL 16 through 20; the first sample is not necessarily its introduction.