|
让数据库变成只读模式，目前PostgreSQL没有严格意义上的只读模式（如临时表在只读事务中还是可以使用的）。通过调整参数或设置事务模式可以将后续登录的SESSION或者当前事务设置为只读模式。
在只读模式下,PostgreSQL不允许如下SQL:
When a transaction is read-only,the following SQL commands are disallowed: INSERT,UPDATE,DELETE,and COPY FROM if the table they would write to is not a temporary table; all CREATE,ALTER,and DROP commands; COMMENT,GRANT,REVOKE,TRUNCATE ; and EXPLAIN ANALYZE and EXECUTE if the command they would execute is among those listed. This is a high-level notion of read-only that does not prevent all writes to disk. 在SQL模式下进入只读事务的方法： digoal=> begin; BEGIN digoal=> set transaction read only; SET 参数配置 : default_transaction_read_only = on 配置完后pg_ctl reload -D $PGDATA 配置完参数后，不影响已经连接的SESSION，仅仅对后续连接上来的SESSION生效。新建的SESSION进来后事务就是read only模式。 digoal=> show default_transaction_read_only digoal-> ; default_transaction_read_only ------------------------------- on digoal=> delete from tbl_test; ERROR: cannot execute DELETE in a read-only transaction # 可以设置事务级WRITE覆盖这个默认值 digoal=> begin; BEGIN digoal=> set transaction read write; SET digoal=> delete from tbl_test; DELETE 1008 # 或者设置SESSION级参数，覆盖之 digoal=> set session default_transaction_read_only=off; SET digoal=> delete from tbl_test; DELETE 1008 （编辑：李大同）
【声明】本站内容均来自网络，其相关言论仅代表作者个人观点，不代表本站立场。若无意侵犯到您的权利，请及时与联系站长删除相关内容!
|
