Re: "BEGIN TRANSACTION" and "START TRANSACTION": different error handling

Hi all,

I am using psqlodbc to connect to PostgreSQL8.2.4 server on Linux.
The manual says "BEGIN TRANSACATION" is equlvalent to "START
TRANSACTION", but it turns out that they throw different error message
and have different effect to subsequent queries.

I have a table "CREATE TEMPORARY TABLE ooid (oid_ INTEGER NOT NULL);"
The autocommit is set to on. When inserting into ooid with a NULL
value within a transaction, I expect the transaction is aborted and
rollback is executed automatically. With the transaction started by
"BEGIN TRANSACTION", PostgreSQL runs as expected. The server log shows
error message is "ERROR: null value in column "oid_" violates
not-null constraint", and any following query runs well.
-----
2009-09-24 13:53:13 JST jmdb postgres STATEMENT: BEGIN TRANSACTION;
DELETE FROM pid; INSERT INTO pid VALUES (9765); DELETE FROM jid;
INSERT INTO jid VALUES (644); DELETE FROM did; INSERT INTO did VALUES
(2029); DELETE FROM ooid; INSERT INTO ooid (SELECT COALESCE( (SELECT
Document.oid_ FROM Document, Job WHERE Document.DocNum = (SELECT
DocNum FROM did) AND Job.jobId = (SELECT jobId FROM jid) AND
Document.memberOf_ = Job.oid_ AND Job.assignedTo_ = (SELECT
PrinterObjId FROM pid)), NULL)); update Document set DocName=NULL
where Document.oid_=(SELECT oid_ FROM ooid);update Document set
DocLastModified = CURRENT_TIMESTAMP where Document.oid_=(SELECT oid_
FROM ooid); COMMIT;

2009-09-24 13:53:17 JST jmdb postgres ERROR: null value in column
"oid_" violates not-null constraint
-----

When the transaction is started by "START TRANSACTION", the error
message is different, and all following query failed with the same
error message "ERROR: current transaction is aborted, commands
ignored until end of transaction block".
-----
2009-09-24 13:53:59 JST jmdb postgres STATEMENT: START TRANSACTION;
DELETE FROM pid; INSERT INTO pid VALUES (9765); DELETE FROM jid;
INSERT INTO jid VALUES (779); DELETE FROM did; INSERT INTO did VALUES
(2530); DELETE FROM ooid; INSERT INTO ooid (SELECT COALESCE( (SELECT
Document.oid_ FROM Document, Job WHERE Document.DocNum = (SELECT
DocNum FROM did) AND Job.jobId = (SELECT jobId FROM jid) AND
Document.memberOf_ = Job.oid_ AND Job.assignedTo_ = (SELECT
PrinterObjId FROM pid)), NULL)); update Document set DocName=NULL
where Document.oid_=(SELECT oid_ FROM ooid);update Document set
DocLastModified = CURRENT_TIMESTAMP where Document.oid_=(SELECT oid_
FROM ooid); COMMIT;

2009-09-24 13:53:59 JST jmdb postgres ERROR: current transaction is
aborted, commands ignored until end of transaction block
2009-09-24 13:53:59 JST jmdb postgres STATEMENT: SELECT oid_,DocName
FROM DocView WHERE DocNum=2530 and DocJobId=779 and pid_=0 FOR READ
ONLY
2009-09-24 13:53:59 JST jmdb postgres ERROR: current transaction is
aborted, commands ignored until end of transaction block
2009-09-24 13:53:59 JST jmdb postgres STATEMENT: DELETE FROM Printer
WHERE PrinterObjId=0;
2009-09-24 13:53:59 JST jmdb postgres ERROR: current transaction is
aborted, commands ignored until end of transaction block
-----

I searched archives, but no related comment is found.
Should I do some setting on server to make the "START TRANSACTION" act
as "BEGIN TRANSACTION"?

Thank you.

Greetings,
Ning Xie

On Thu, 2009-09-24 at 17:51 +0900, ning wrote:
> Hi all,
>
> I am using psqlodbc to connect to PostgreSQL8.2.4 server on Linux.
> The manual says "BEGIN TRANSACATION" is equlvalent to "START
> TRANSACTION", but it turns out that they throw different error message
> and have different effect to subsequent queries.
>
> I have a table "CREATE TEMPORARY TABLE ooid (oid_ INTEGER NOT NULL);"
> The autocommit is set to on. When inserting into ooid with a NULL
> value within a transaction, I expect the transaction is aborted and
> rollback is executed automatically. With the transaction started by
> "BEGIN TRANSACTION", PostgreSQL runs as expected. The server log shows
> error message is "ERROR: null value in column "oid_" violates
> not-null constraint", and any following query runs well.

"I expect the transaction is aborted and rollback is executed
automatically." - this is not how postgreSQL behaves. PostgreSQL needs
an explicit end of transaction from client, either COMMIT; or ROLLBACK;

when run from psql, they both act the same, except the string returned

hannu=# begin transaction;
BEGIN
hannu=# select 1/0;
ERROR: division by zero
hannu=# select 1/0;
ERROR: current transaction is aborted, commands ignored until end of
transaction block
hannu=# abort;
ROLLBACK
hannu=# start transaction;
START TRANSACTION
hannu=# select 1/0;
ERROR: division by zero
hannu=# select 1/0;
ERROR: current transaction is aborted, commands ignored until end of
transaction block
hannu=# abort;
ROLLBACK

I suspect, that psqlodbc is the one doing the automatic rollback and it
seems to rely on reply "BEGIN" to establish an in-transaction state.

so when "start transaction;" returns "START TRANSACTION" instead of
"BEGIN", psqlodbc does not realise that it is in transaction and does
not initiate the automatic rollback.

> -----
> 2009-09-24 13:53:13 JST jmdb postgres STATEMENT: BEGIN TRANSACTION;
> DELETE FROM pid; INSERT INTO pid VALUES (9765); DELETE FROM jid;
> INSERT INTO jid VALUES (644); DELETE FROM did; INSERT INTO did VALUES
> (2029); DELETE FROM ooid; INSERT INTO ooid (SELECT COALESCE( (SELECT
> Document.oid_ FROM Document, Job WHERE Document.DocNum = (SELECT
> DocNum FROM did) AND Job.jobId = (SELECT jobId FROM jid) AND
> Document.memberOf_ = Job.oid_ AND Job.assignedTo_ = (SELECT
> PrinterObjId FROM pid)), NULL)); update Document set DocName=NULL
> where Document.oid_=(SELECT oid_ FROM ooid);update Document set
> DocLastModified = CURRENT_TIMESTAMP where Document.oid_=(SELECT oid_
> FROM ooid); COMMIT;
>
> 2009-09-24 13:53:17 JST jmdb postgres ERROR: null value in column
> "oid_" violates not-null constraint
> -----
>
> When the transaction is started by "START TRANSACTION", the error
> message is different, and all following query failed with the same
> error message "ERROR: current transaction is aborted, commands
> ignored until end of transaction block".
> -----
> 2009-09-24 13:53:59 JST jmdb postgres STATEMENT: START TRANSACTION;
> DELETE FROM pid; INSERT INTO pid VALUES (9765); DELETE FROM jid;
> INSERT INTO jid VALUES (779); DELETE FROM did; INSERT INTO did VALUES
> (2530); DELETE FROM ooid; INSERT INTO ooid (SELECT COALESCE( (SELECT
> Document.oid_ FROM Document, Job WHERE Document.DocNum = (SELECT
> DocNum FROM did) AND Job.jobId = (SELECT jobId FROM jid) AND
> Document.memberOf_ = Job.oid_ AND Job.assignedTo_ = (SELECT
> PrinterObjId FROM pid)), NULL)); update Document set DocName=NULL
> where Document.oid_=(SELECT oid_ FROM ooid);update Document set
> DocLastModified = CURRENT_TIMESTAMP where Document.oid_=(SELECT oid_
> FROM ooid); COMMIT;
>
> 2009-09-24 13:53:59 JST jmdb postgres ERROR: current transaction is
> aborted, commands ignored until end of transaction block
> 2009-09-24 13:53:59 JST jmdb postgres STATEMENT: SELECT oid_,DocName
> FROM DocView WHERE DocNum=2530 and DocJobId=779 and pid_=0 FOR READ
> ONLY
> 2009-09-24 13:53:59 JST jmdb postgres ERROR: current transaction is
> aborted, commands ignored until end of transaction block
> 2009-09-24 13:53:59 JST jmdb postgres STATEMENT: DELETE FROM Printer
> WHERE PrinterObjId=0;
> 2009-09-24 13:53:59 JST jmdb postgres ERROR: current transaction is
> aborted, commands ignored until end of transaction block
> -----
>
> I searched archives, but no related comment is found.
> Should I do some setting on server to make the "START TRANSACTION" act
> as "BEGIN TRANSACTION"?
>
> Thank you.
>
> Greetings,
> Ning Xie
>

On Thu, Sep 24, 2009 at 12:16:43PM +0300, Hannu Krosing wrote:
> "I expect the transaction is aborted and rollback is executed
> automatically." - this is not how postgreSQL behaves. PostgreSQL needs
> an explicit end of transaction from client, either COMMIT; or ROLLBACK;
>
> when run from psql, they both act the same, except the string returned
>
> hannu=# begin transaction;
> BEGIN
> hannu=# select 1/0;
> ERROR: division by zero
> hannu=# select 1/0;
> ERROR: current transaction is aborted, commands ignored until end of
> transaction block
> hannu=# abort;
> ROLLBACK
> hannu=# start transaction;
> START TRANSACTION
> hannu=# select 1/0;
> ERROR: division by zero
> hannu=# select 1/0;
> ERROR: current transaction is aborted, commands ignored until end of
> transaction block
> hannu=# abort;
> ROLLBACK
>
> I suspect, that psqlodbc is the one doing the automatic rollback and it
> seems to rely on reply "BEGIN" to establish an in-transaction state.
>
> so when "start transaction;" returns "START TRANSACTION" instead of
> "BEGIN", psqlodbc does not realise that it is in transaction and does
> not initiate the automatic rollback.

Well. I'd always thought BEGIN and START were syntactic Aspartame and had
the same underlying implementation. So this is a surprise. Why do they
return a different status?

-dg
`
--
David Gould daveg(at)sonic(dot)net 510 536 1443 510 282 0869
If simplicity worked, the world would be overrun with insects.

On Thu, Sep 24, 2009 at 6:16 PM, Hannu Krosing <hannu(at)krosing(dot)net> wrote:
> On Thu, 2009-09-24 at 17:51 +0900, ning wrote:
>> Hi all,
>>
>> I am using psqlodbc to connect to PostgreSQL8.2.4 server on Linux.
>> The manual says "BEGIN TRANSACATION" is equlvalent to "START
>> TRANSACTION", but it turns out that they throw different error message
>> and have different effect to subsequent queries.
>>
>> I have a table "CREATE TEMPORARY TABLE ooid (oid_ INTEGER NOT NULL);"
>> The autocommit is set to on. When inserting into ooid with a NULL
>> value within a transaction, I expect the transaction is aborted and
>> rollback is executed automatically. With the transaction started by
>> "BEGIN TRANSACTION", PostgreSQL runs as expected. The server log shows
>> error message is "ERROR:  null value in column "oid_" violates
>> not-null constraint", and any following query runs well.
>
> "I expect the transaction is aborted and rollback is executed
> automatically." - this is not how postgreSQL behaves. PostgreSQL needs
> an explicit end of transaction from client, either COMMIT; or ROLLBACK;
>
> when run from psql, they both act the same, except the string returned
>
> hannu=# begin transaction;
> BEGIN
> hannu=# select 1/0;
> ERROR:  division by zero
> hannu=# select 1/0;
> ERROR:  current transaction is aborted, commands ignored until end of
> transaction block
> hannu=# abort;
> ROLLBACK
> hannu=# start transaction;
> START TRANSACTION
> hannu=# select 1/0;
> ERROR:  division by zero
> hannu=# select 1/0;
> ERROR:  current transaction is aborted, commands ignored until end of
> transaction block
> hannu=# abort;
> ROLLBACK
>
> I suspect, that psqlodbc is the one doing the automatic rollback and it
> seems to rely on reply "BEGIN" to establish an in-transaction state.
>
> so when "start transaction;" returns "START TRANSACTION" instead of
> "BEGIN", psqlodbc does not realise that it is in transaction and does
> not initiate the automatic rollback.
>
>> -----
>> 2009-09-24 13:53:13 JST jmdb postgres STATEMENT:  BEGIN TRANSACTION;
>> DELETE FROM pid; INSERT INTO pid VALUES (9765); DELETE FROM jid;
>> INSERT INTO jid VALUES (644); DELETE FROM did; INSERT INTO did VALUES
>> (2029); DELETE FROM ooid; INSERT INTO ooid (SELECT COALESCE(  (SELECT
>> Document.oid_    FROM Document, Job    WHERE Document.DocNum = (SELECT
>> DocNum FROM did)    AND Job.jobId = (SELECT jobId FROM jid)    AND
>> Document.memberOf_ = Job.oid_    AND Job.assignedTo_ = (SELECT
>> PrinterObjId FROM pid)),   NULL)); update Document set DocName=NULL
>> where Document.oid_=(SELECT oid_ FROM ooid);update Document set
>> DocLastModified = CURRENT_TIMESTAMP where Document.oid_=(SELECT oid_
>> FROM ooid); COMMIT;
>>
>> 2009-09-24 13:53:17 JST jmdb postgres ERROR:  null value in column
>> "oid_" violates not-null constraint
>> -----
>>
>> When the transaction is started by "START TRANSACTION", the error
>> message is different, and all following query failed with the same
>> error message "ERROR:  current transaction is aborted, commands
>> ignored until end of transaction block".
>> -----
>> 2009-09-24 13:53:59 JST jmdb postgres STATEMENT:  START TRANSACTION;
>> DELETE FROM pid; INSERT INTO pid VALUES (9765); DELETE FROM jid;
>> INSERT INTO jid VALUES (779); DELETE FROM did; INSERT INTO did VALUES
>> (2530); DELETE FROM ooid; INSERT INTO ooid (SELECT COALESCE(  (SELECT
>> Document.oid_    FROM Document, Job    WHERE Document.DocNum = (SELECT
>> DocNum FROM did)    AND Job.jobId = (SELECT jobId FROM jid)    AND
>> Document.memberOf_ = Job.oid_    AND Job.assignedTo_ = (SELECT
>> PrinterObjId FROM pid)),   NULL)); update Document set DocName=NULL
>> where Document.oid_=(SELECT oid_ FROM ooid);update Document set
>> DocLastModified = CURRENT_TIMESTAMP where Document.oid_=(SELECT oid_
>> FROM ooid); COMMIT;
>>
>> 2009-09-24 13:53:59 JST jmdb postgres ERROR:  current transaction is
>> aborted, commands ignored until end of transaction block
>> 2009-09-24 13:53:59 JST jmdb postgres STATEMENT:  SELECT oid_,DocName
>> FROM DocView WHERE DocNum=2530 and DocJobId=779 and pid_=0 FOR READ
>> ONLY
>> 2009-09-24 13:53:59 JST jmdb postgres ERROR:  current transaction is
>> aborted, commands ignored until end of transaction block
>> 2009-09-24 13:53:59 JST jmdb postgres STATEMENT:  DELETE FROM Printer
>> WHERE PrinterObjId=0;
>> 2009-09-24 13:53:59 JST jmdb postgres ERROR:  current transaction is
>> aborted, commands ignored until end of transaction block
>> -----
>>
>> I searched archives, but no related comment is found.
>> Should I do some setting on server to make the "START TRANSACTION" act
>> as "BEGIN TRANSACTION"?
>>
>> Thank you.
>>
>> Greetings,
>> Ning Xie
>>
>
>

hank you Hannu.

"PostgreSQL needs an explicit end of transaction from client, either
COMMIT; or ROLLBACK;"

In psql, after error occurred in transaction an explicit COMMIT leads
to ROLLBACK, either for "begin transaction" or "start transaction".
Doesn't this imply the PostgreSQL server react a "ROLLBACK" when
receiving a "COMMIT" according to the server-side state? Or do you
mean that it's psql that sends a "ROLLBACK" to server when receiving a
"COMMIT" according to the client-side state(which is based on the
reply of the server)? I am a little confused.

postgres=# begin transaction;
BEGIN
postgres=# select 1/0;
ERROR: division by zero
postgres=# select 1/0;
ERROR: current transaction is aborted, commands ignored until end of
transaction block
postgres=# commit;
ROLLBACK
postgres=# start transaction;
START TRANSACTION
postgres=# select 1/0;
ERROR: division by zero
postgres=# select 1/0;
ERROR: current transaction is aborted, commands ignored until end of
transaction block
postgres=# commit;
ROLLBACK
postgres=#

Thank you.
Ning Xie