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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.

mydb=# begin;

BEGIN

mydb=#  set transaction read only;

SET

–插入数据失败

mydb=# insert into t values(generate_series(1,10000),’rudy’);

ERROR:  cannot execute INSERT in a read-only transaction