Re: [GENERAL] How to get transaction started always in WRITE mode.

[rob stone]

On Tue, 2017-07-25 at 11:32 +0200, Adam Šlachta wrote:
> Hello,
>  
> In short: Is there any way how to setup PostgreSql 9.6 to always
> start a transaction in WRITE mode?
>  
> Our related configuration:
> "default_transaction_isolation" --> "read committed"
> "default_transaction_read_only" --> "off"
>  
>  
> Longer description (for those who are interested, since it is not
> only PostgreSQL related):
>  
> We are facing problems with "cannot execute  in
> a read-only transaction" exception
> (org.postgresql.util.PSQLException).
> It is very likely the problem is caused by our code, however at the
> moment the fastest solution before we solve the things properly would
> be to setup WRITE mode for all started transactions on a database-
> setup-level.
>  
> SW we use:
> -> Java 8
> -> Hibernate 5.1.2
> -> spring-data-jpa 1.10.4.RELEASE
> -> spring-beans, spring-core, other spring stuff of version
> 4.2.8.RELEASE
>  
> Related configuration (I don't want to spam here with long list of
> configuration files so I pick-up what I consider important):
> Hibernate -> first & second level cache switched OFF
> SessionFactory ->
> org.springframework.orm.hibernate5.LocalSessionFactoryBean
> transactionManager ->
> org.springframework.orm.jpa.JpaTransactionManager
> Spring @Transactional(read-only) hint -> where we could we set it to
> "false"
> Our typical @Repository extends
> org.springframework.data.jpa.repository.JpaRepository, which uses
> implementation from
> org.springframework.data.jpa.repository.support.SimpleJpaRepository.
>  
> Thank you very much for any hints.
> Adam Slachta
> 
> 

Hello Adam,

There is a Hibernate parameter that overrides the database's default
isolation level:-

hibernate.connection.isolation

Are you certain that second level caching is off?
You can make a class in a cache immutable by:-



Don't know if that helps but your problem seems to be a configuration
issue in Hibernate.

Cheers,
Rob


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Re: [GENERAL] How to get transaction started always in WRITE mode.

[Jerry Sievers]

Adam Šlachta  writes:

> Hello Scott and other potential readers/writers,
>
>  
>
>> Login to the database with psql as the same user that your java app
> connects with try: 
>
>> 
>
>> show default_transaction_read_only;
>
>>  This can be set per-user, it's possible you're getting tripped up
> there.
>
>  
>
> show default_transaction_read_only;
>
> OFF -> this was run under the same user as our application while the
> application was running;
>
>  
>
>> Also, what happens if you run: 
>
>>  
>
>> select pg_is_in_recovery();
>
>> This can happen if you connect to a postgres slave instead of a
> master.  Make sure you're always connecting to a master node for
> executing writes.  
>
>  
>
> select pg_is_in_recovery() returns “F”, however we have not
> configured master/slave (I guess this is mostly used for replication
> right?).
>
>  
>
>> Is it possible that your code / connect layer is setting
> default_transaction_read_only to TRUE when the app connects?
>
>  
>
> Well, this might be hard to tell, since we would have to be sure all
> those layers (hibernate/spring) does not “somehow” set read-only to
> true. We have tried to set it up correctly, but most probably that’s
> where the problem root cause is.
>
> Do you know how to find it out eg. in PostgreSQL logs how the
> read-only flag is setup for current transaction? We have tried to
> enable full logging (postgresql.conf) however reading it is quite
> tough and we did not get any closer to the solution.

Also make sure there's no DB or role specific override.  psql \drds may
reveal something.

Full statement logging via log_statement=all or
log_min_duration_statement=0 should certainly have shown you something
if it's being set explicitly by client and/or pooler.

>
>  
>
> Thank you for your help so far,
>
> Adam
>
>  
>
>  
>
>  
>
>  
>
>  
>
>
>
>
> ---
> This e-mail message including any attachments is for the sole use of
> the intended recipient(s) and may contain privileged or confidential
> information. Any unauthorized review, use, disclosure or distribution
> is prohibited. If you are not the intended recipient, please
> immediately contact the sender by reply e-mail and delete the
> original message and destroy all copies thereof.
>
> Tato zpráva včetně veškerých příloh je důvěrná a mohou ji využít
> pouze osoby, jimž je adresována. Nejste-li adresátem zprávy, obsah i
> s přílohami a kopiemi bezodkladně odstraňte ze svého systému a dále
> ji nijak nevyužívejte. Upozorňujeme Vás, že využívání zpráv, které
> Vám nejsou určeny, je zakázáno, včetně jejich přímého či nepřímého
> zveřejňování, kopírování, tištění, rozšiřování anebo jakéhokoli
> právního jednání učiněného při spoléhání se na jejich obsah. Pokud
> jste zprávu obdrželi omylem, postupujte stejně a neprodleně
> informujte odesílatele.
>
> Der Inhalt dieser E-Mail ist vertraulich und ausschließlich für den
> bezeichneten Adressaten bestimmt. Wenn Sie nicht der vorgesehene
> Adressat dieser E-Mail oder dessen Vertreter sein sollten, so
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>
>
>
>

-- 
Jerry Sievers
Postgres DBA/Development Consulting
e: postgres.consult...@comcast.net
p: 312.241.7800


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Re: [GENERAL] How to get transaction started always in WRITE mode.

[Adam Šlachta]

Hello Scott and other potential readers/writers,
 
> Login to the database with psql as the same user that your java app connects 
> with try: 
> 
> show default_transaction_read_only;
>  This can be set per-user, it's possible you're getting tripped up there.
 
show default_transaction_read_only;
OFF -> this was run under the same user as our application while the 
application was running;
 
> Also, what happens if you run: 
>  
> select pg_is_in_recovery();
> This can happen if you connect to a postgres slave instead of a master.  Make 
> sure you're always connecting to a master node for executing writes.  
 
select pg_is_in_recovery() returns “F”, however we have not configured 
master/slave (I guess this is mostly used for replication right?).
 
> Is it possible that your code / connect layer is setting 
> default_transaction_read_only to TRUE when the app connects?
 
Well, this might be hard to tell, since we would have to be sure all those 
layers (hibernate/spring) does not “somehow” set read-only to true. We have 
tried to set it up correctly, but most probably that’s where the problem root 
cause is.
Do you know how to find it out eg. in PostgreSQL logs how the read-only flag is 
setup for current transaction? We have tried to enable full logging 
(postgresql.conf) however reading it is quite tough and we did not get any 
closer to the solution.
 
Thank you for your help so far,
Adam


---
This e-mail message including any attachments is for the sole use of the 
intended recipient(s) and may contain privileged or confidential information. 
Any unauthorized review, use, disclosure or distribution is prohibited. If you 
are not the intended recipient, please immediately contact the sender by reply 
e-mail and delete the original message and destroy all copies thereof. 

Tato zpráva včetně veškerých příloh je důvěrná a mohou ji využít pouze osoby, 
jimž je adresována. Nejste-li adresátem zprávy, obsah i s přílohami a kopiemi 
bezodkladně odstraňte ze svého systému a dále ji nijak nevyužívejte. 
Upozorňujeme Vás, že využívání zpráv, které Vám nejsou určeny, je zakázáno, 
včetně jejich přímého či nepřímého zveřejňování, kopírování, tištění, 
rozšiřování anebo jakéhokoli právního jednání učiněného při spoléhání se na 
jejich obsah. Pokud jste zprávu obdrželi omylem, postupujte stejně a neprodleně 
informujte odesílatele. 

Der Inhalt dieser E-Mail ist vertraulich und ausschließlich für den 
bezeichneten Adressaten bestimmt. Wenn Sie nicht der vorgesehene Adressat 
dieser E-Mail oder dessen Vertreter sein sollten, so beachten Sie bitte, dass 
jede Form der Kenntnisnahme, Veröffentlichung, Vervielfältigung oder Weitergabe 
des Inhalts dieser E-Mail unzulässig ist. Wir bitten Sie, sich in diesem Fall 
mit dem Absender der E-Mail in Verbindung zu setzen.

Re: [GENERAL] How to get transaction started always in WRITE mode.

[Scott Mead]

On Tue, Jul 25, 2017 at 5:32 AM, Adam Šlachta 
wrote:

> Hello,
>
>
>
> In short: Is there any way how to setup PostgreSql 9.6 to always start a
> transaction in WRITE mode?
>
>
>
> Our related configuration:
>
> "default_transaction_isolation" --> "read committed"
>
> "default_transaction_read_only" --> "off"
>

Login to the database with psql as the same user that your java app
connects with try:

show default_transaction_read_only;

This can be set per-user, it's possible you're getting tripped up there.
Also, what happens if you run:

select pg_is_in_recovery();


This can happen if you connect to a postgres slave instead of a master.
Make sure you're always connecting to a master node for executing writes.


>
>
>
> Longer description (for those who are interested, since it is not only
> PostgreSQL related):
>
>
>
> We are facing problems with "cannot execute  in a
> read-only transaction" exception (org.postgresql.util.PSQLException).
>
> It is very likely the problem is caused by our code, however at the moment
> the fastest solution before we solve the things properly would be to setup
> WRITE mode for all started transactions on a database-setup-level.
>
>
>
> SW we use:
>
> -> Java 8
>
> -> Hibernate 5.1.2
>
> -> spring-data-jpa 1.10.4.RELEASE
>
> -> spring-beans, spring-core, other spring stuff of version 4.2.8.RELEASE
>
>
>
> Related configuration (I don't want to spam here with long list of
> configuration files so I pick-up what I consider important):
>
> Hibernate -> first & second level cache switched OFF
>
> SessionFactory -> org.springframework.orm.hibernate5.
> LocalSessionFactoryBean
>
> transactionManager -> org.springframework.orm.jpa.JpaTransactionManager
>
> Spring @Transactional(read-only) hint -> where we could we set it to
> "false"
>
> Our typical @Repository extends 
> org.springframework.data.jpa.repository.JpaRepository,
> which uses implementation from org.springframework.data.jpa.
> repository.support.SimpleJpaRepository.
>

Is it possible that your code / connect layer is setting
default_transaction_read_only to TRUE when the app connects?





>
>
> Thank you very much for any hints.
>
> Adam Slachta
>
>
>
> ---
> This e-mail message including any attachments is for the sole use of the
> intended recipient(s) and may contain privileged or confidential
> information. Any unauthorized review, use, disclosure or distribution is
> prohibited. If you are not the intended recipient, please immediately
> contact the sender by reply e-mail and delete the original message and
> destroy all copies thereof.
>
> Tato zpráva včetně veškerých příloh je důvěrná a mohou ji využít pouze
> osoby, jimž je adresována. Nejste-li adresátem zprávy, obsah i s přílohami
> a kopiemi bezodkladně odstraňte ze svého systému a dále ji nijak
> nevyužívejte. Upozorňujeme Vás, že využívání zpráv, které Vám nejsou
> určeny, je zakázáno, včetně jejich přímého či nepřímého zveřejňování,
> kopírování, tištění, rozšiřování anebo jakéhokoli právního jednání
> učiněného při spoléhání se na jejich obsah. Pokud jste zprávu obdrželi
> omylem, postupujte stejně a neprodleně informujte odesílatele.
>
> Der Inhalt dieser E-Mail ist vertraulich und ausschließlich für den
> bezeichneten Adressaten bestimmt. Wenn Sie nicht der vorgesehene Adressat
> dieser E-Mail oder dessen Vertreter sein sollten, so beachten Sie bitte,
> dass jede Form der Kenntnisnahme, Veröffentlichung, Vervielfältigung oder
> Weitergabe des Inhalts dieser E-Mail unzulässig ist. Wir bitten Sie, sich
> in diesem Fall mit dem Absender der E-Mail in Verbindung zu setzen.
>
>


-- 
--
Scott Mead
Sr. Architect
*OpenSCG *
http://openscg.com

[GENERAL] How to get transaction started always in WRITE mode.

[Adam Šlachta]

Hello,
 
In short: Is there any way how to setup PostgreSql 9.6 to always start a 
transaction in WRITE mode?
 
Our related configuration:
"default_transaction_isolation" --> "read committed"
"default_transaction_read_only" --> "off"
 
 
Longer description (for those who are interested, since it is not only 
PostgreSQL related):
 
We are facing problems with "cannot execute  in a 
read-only transaction" exception (org.postgresql.util.PSQLException).
It is very likely the problem is caused by our code, however at the moment the 
fastest solution before we solve the things properly would be to setup WRITE 
mode for all started transactions on a database-setup-level.
 
SW we use:
-> Java 8
-> Hibernate 5.1.2
-> spring-data-jpa 1.10.4.RELEASE
-> spring-beans, spring-core, other spring stuff of version 4.2.8.RELEASE
 
Related configuration (I don't want to spam here with long list of 
configuration files so I pick-up what I consider important):
Hibernate -> first & second level cache switched OFF
SessionFactory -> org.springframework.orm.hibernate5.LocalSessionFactoryBean
transactionManager -> org.springframework.orm.jpa.JpaTransactionManager
Spring @Transactional(read-only) hint -> where we could we set it to "false"
Our typical @Repository extends 
org.springframework.data.jpa.repository.JpaRepository, which uses 
implementation from 
org.springframework.data.jpa.repository.support.SimpleJpaRepository.
 
Thank you very much for any hints.
Adam Slachta



---
This e-mail message including any attachments is for the sole use of the 
intended recipient(s) and may contain privileged or confidential information. 
Any unauthorized review, use, disclosure or distribution is prohibited. If you 
are not the intended recipient, please immediately contact the sender by reply 
e-mail and delete the original message and destroy all copies thereof. 

Tato zpráva včetně veškerých příloh je důvěrná a mohou ji využít pouze osoby, 
jimž je adresována. Nejste-li adresátem zprávy, obsah i s přílohami a kopiemi 
bezodkladně odstraňte ze svého systému a dále ji nijak nevyužívejte. 
Upozorňujeme Vás, že využívání zpráv, které Vám nejsou určeny, je zakázáno, 
včetně jejich přímého či nepřímého zveřejňování, kopírování, tištění, 
rozšiřování anebo jakéhokoli právního jednání učiněného při spoléhání se na 
jejich obsah. Pokud jste zprávu obdrželi omylem, postupujte stejně a neprodleně 
informujte odesílatele. 

Der Inhalt dieser E-Mail ist vertraulich und ausschließlich für den 
bezeichneten Adressaten bestimmt. Wenn Sie nicht der vorgesehene Adressat 
dieser E-Mail oder dessen Vertreter sein sollten, so beachten Sie bitte, dass 
jede Form der Kenntnisnahme, Veröffentlichung, Vervielfältigung oder Weitergabe 
des Inhalts dieser E-Mail unzulässig ist. Wir bitten Sie, sich in diesem Fall 
mit dem Absender der E-Mail in Verbindung zu setzen.