用堆叠诊断增强异常处理
PostgreSQL 中的事务与错误处理
Jason Myers
Principal Engineer
捕获更多错误信息
DO $$
BEGIN
UPDATE inventory SET cost = 35.0 WHERE name = 'Macaron';
UPDATE inventory SET cost = 3.50 WHERE name = 'Panellets';
EXCEPTION
WHEN others THEN
INSERT INTO errors (msg) VALUES ('Max cost is 10!');
RAISE INFO 'Max cost is 10!';
END;
$$ language 'plpgsql';
使用堆叠诊断
DO $$ DECLARE exc_message text; exc_detail text;BEGIN UPDATE inventory SET cost = 35.0 WHERE name = 'Macaron'; UPDATE inventory SET cost = 3.50 WHERE name = 'Panellets';EXCEPTION WHEN others THEN GET STACKED DIAGNOSTICS exc_message = MESSAGE_TEXT, exc_detail = PG_EXCEPTION_DETAIL; INSERT INTO errors (msg, detail) VALUES (exc_message, exc_detail); RAISE INFO 'Exception Messaage: % | Exception Details: %', exc_message, exc_detail; END$$;
诊断输出示例
INFO: Exception Messaage: new row for relation "inventory" violates check constraint
"cost_check" | Exception Details: Failing row contains (7, 35, Macaron).
DO
postgres=# \x on
Expanded display is on.
postgres=# select msg, detail from errors;
-[ RECORD 1 ]-------------------------------------------------------------------
msg | new row for relation "inventory" violates check constraint "cost_check"
detail | Failing row contains (7, 35, Macaron).
能拿到哪些信息？
| Name | Description |
|---|---|
| RETURNED_SQLSTATE | 异常的 SQLSTATE 错误码 |
| COLUMN_NAME | 与异常相关的列名 |
| CONSTRAINT_NAME | 与异常相关的约束名 |
| MESSAGE_TEXT | 异常主消息文本 |
| PG_EXCEPTION_DETAIL | 异常详细信息文本（如有） |
1 https://www.postgresql.org/docs/12/plpgsql-control-structures.html
更多诊断数据点
| Name | Description |
|---|---|
| PG_DATATYPE_NAME | 与异常相关的数据类型名 |
| TABLE_NAME | 与异常相关的表名 |
| SCHEMA_NAME | 与异常相关的模式名 |
| PG_EXCEPTION_HINT | 异常提示信息（如有） |
| PG_EXCEPTION_CONTEXT | 异常发生时的调用栈文本 |
Passons à la pratique !
PostgreSQL 中的事务与错误处理
