synchronize_seqscans
This allows sequential scans of large tables to synchronize with each other, so that concurrent scans read the same block at about the same time and hence share the I/O workload. When this is enabled, a scan might start in the middle of the table and then “wrap around” the end to cover all rows, so as to synchronize with the activity of scans already in progress. This can result in unpredictable changes in the row ordering returned by queries that have no ORDER BY clause. Setting this parameter to off ensures the pre-8.3 behavior in which a sequential scan always starts from the beginning of the table. The default is on.
英文手册覆盖始于 PostgreSQL 7.4. 来源历史与运行验证各自保留独立版本边界。
当前阅读 PG 18·选择有来源记录的版本
此版本暂无所选语言的定义，以下显示原始英文内容。
- boot val
- on
- category
- Version and Platform Compatibility / Previous PostgreSQL Versions
- context
- user
- documented
- true
- enumvals
- 未知
- extra desc
- 未知
- lang
- en
- max val
- 未知
- metadata version
- 18
- min val
- 未知
- name
- synchronize_seqscans
- short desc
- Enables synchronized sequential scans.
- source
- pg-settings-source-snapshot
- unit
- 未知
- vartype
- bool
版本定义 PG 18
This allows sequential scans of large tables to synchronize with each other, so that concurrent scans read the same block at about the same time and hence share the I/O workload. When this is enabled, a scan might start in the middle of the table and then “wrap around” the end to cover all rows, so as to synchronize with the activity of scans already in progress. This can result in unpredictable changes in the row ordering returned by queries that have no ORDER BY clause. Setting this parameter to off ensures the pre-8.3 behavior in which a sequential scan always starts from the beginning of the table. The default is on.
比较版本
来源引用
定义来源
center · PostgreSQL 18 · english-manuals:88ba0373c4f0bacb733c6039eaea01b7e794b6bafe7aaa72761def999ebd2e84
正文语言: en · english-manuals:88ba0373c4f0bacb733c6039eaea01b7e794b6bafe7aaa72761def999ebd2e84