I opened up my postgresql.conf file in the postgres data folder and changed the value of max_prepared_connections to a non-zero value.
However, every time I try using a "PREPARE TRANSACTION 'foo';"command, I get an error saying that max_prepared_connections is set to zero.
Am I doing anything wrong? I just want to be able to use the prepare transaction command.
You must restart the PosgreSQL server after changing this parameter.
go to place where postgresql is installed... in windows , go to
C:\Program Files\PostgreSQL\9.5\data\postgresql.conf
open and then search for "max_prepared_transactions" and uncomment it.
and then set max_prepared_transactions = 1
zero disables the feature
(change requires restart)
Note: Increasing max_prepared_transactions costs ~600 bytes of shared memory
per transaction slot, plus lock space (see max_locks_per_transaction).
It is not advisable to set max_prepared_transactions nonzero unless you
actively intend to use prepared transactions.
after that type services in start menu and search for postgresql and stop the service from left top corner. then restart this service.
then restart the jboss server .
I would like to add that there can be a file C:\Program Files\PostgreSQL\10\share\postgresql.conf.sample which has the same structure as Files\PostgreSQL\9.5\data\postgresql.conf. So, you should also change max_prepared_transactions in that file.
Run following Query e.g. ALTER SYSTEM SET max_prepared_transactions = 100;
Restart Service
Validate by running following Query :- SHOW max_prepared_transactions;
Related
I have a problem. I am learning PostgreSQL and I work with pgAdmin 4v4. At this point, I am trying to set PostgreSQL to use as buffers more RAM than my computer has. I am thinking of using something like SET shared_buffers TO '256MB' but I am not sure if it is correct. Do you have any ideas?
SET shared_buffers TO '256MB'
This will not work because shared_buffers must be set at server start and cannot be changed later, and this is a command you would run after the server is already running. You would have to put the setting in postgresql.conf, or specify it with the -B option to the "postgres" command.
You could also set it through 'alter system' command, and it would take effect at the next restart. However, you could easily make it a setting that will cause your system to fail to start again (indeed, that appears to be your goal...), at which point you can't use 'alter system' to fix it, and will have to dig into the .conf files.
I have nearly 600+ files to load in DB2 database version 10.5.9. Each file size is nearly 200 MB. I have a batch script to upload each files in a loop.
My Disk "/mnt/blumeta0/db2/copy"size is 16 GB
If i run this upload with nonrecoverable mode it works. But i cant do that in my prod database.
I tried to db3 connect refresh and db3 terminate after each file uploaded but does not worked.
Manually cleaned up disk /mnt/blumeta0/db2/copy but total size of all files is more than 16 GB so got same error.
I cannot clean folder in script as clean up can be done with super user.
db2 "LOAD FROM $i OF DEL INSERT INTO <table_name>"
SQL3706N A disk full error was encountered on "/mnt/blumeta0/db2/copy".
How DB2 server cleans copy folder? Is there any other alternative i can try?
You suggested that the Load succeeds when using NONRECOVERABLE mode, however fails otherwise with error "SQL3706N A disk full error was encountered on "/mnt/blumeta0/db2/copy".
I'm guessing that the Load is being performed using the COPY YES option. Since the Load command that you pasted does not show the COPY YES option, I'm guessing that you have a special configuration setting enabled that forces Load operations to use COPY YES in order to prevent the table from becoming inaccessible in a rollforward recovery event or HADR standby takeover event. The name of this configuration setting (registry variable) is "DB2_LOAD_COPY_NO_OVERRIDE".
When the Load is performed with COPY YES, a copy of the table pages/extents that were generated during the Load operation is written into a copy image file.
I suspect that you have the registry variable "DB2_LOAD_COPY_NO_OVERRIDE=COPY YES /mnt/blumeta0/db2/copy" configured (you can use db2set -all on the database server to display all configured registry variables). If so, the copy image files are being stored in this path, which at 16GB appears to be too small to contain them all.
You can consider changing the location of this path to somewhere with more disk space, however the path should always be accessible in the event of a database rollforward recovery or hadr standby takeover, otherwise the table will not be accessible after such an event.
I am trying to change some parameteres in postgresql.conf file. I changed the parameters to following values
Shared_buffers: 8000MB
work_mem: 3200MB
maintenance_work_mem: 1600MB
I have postgresql installed on 128GB RAM server. After making these changes I restarted postgresql server. After that when I use psql to check these parameters using show (parameter_name) I get the following values.
Shared_buffers: 8000MB
work_mem: 4MB
maintenance_work_mem: 2047MB
Why did the changes reflect correctly only in the shared_buffer parameter but not in the other two?
I changed the max_wal_size to 4GB and min_wal_size to 1000MB but these parameters did not change too and the values shown are 1GB and 80MB. So in conclustion, of all the changes that I made only the changes to shared_buffers parameter got reflected while others did not change.
Some possibilities what might be the problem:
You edited the wrong postgresql.conf.
You restarted the wrong server.
The value was configured with ALTER SYSTEM.
The value was configured with ALTER USER or ALTER DATABASE.
Use the psql command \drds to see such settings.
To figure out from where PostgreSQL takes the setting, use
SELECT * FROM pg_settings WHERE name = 'work_mem';
We have a hosted PostgreSQL, with no access to the system or *.conf files.
I do have a admin access and can connect to it using Oracle SQL developer.
Can I run any command to increase the max_connections. All other parameters seems to be ok shared mem and buffers can hold more connections so there is not problem there.
Changing max_connection parameter needs a Postgres restart
Commands
Check max_connection just to keep current value in mind
SHOW max_connections;
Change max_connection value
ALTER SYSTEM SET max_connections TO '500';
Restart PostgreSQL server
Apparently, the hosted Postgres we are using does not provide this option. (compose.io)
So the work around is to use a pgbouncer to manage you connections better.
I want to make a script that will run postgres in-memory without durability.
I read this page: http://www.postgresql.org/docs/9.1/static/non-durability.html
But I didn't understand how I can set this parameters in script. Could you please, help me?
Thanks for help!
Most of those parameters, like fsync, can only be set in postgresql.conf. Changes are applied by re-starting PostgreSQL. They apply to the whole database cluster - all the databases in that PostgreSQL install. That's because the databases all share a single postmaster, write-ahead log, and set of shared system tables.
The only parameter listed there that you can set at the SQL level in a script is synchronous_commit. By setting synchronous_commit = 'off' you can say "it's OK to lose this transaction if the database crashes in the next few seconds, just make sure it still applies atomically".
I wrote more on this topic in a previous answer, Optimise PostgreSQL for fast testing.
If you want to set the other params with a script you can do so but you have to do it by opening and modifying postgresql.conf using the script, then re-starting PostgreSQL. Text-processing tools like sed make this kind of job easier.
If you're running a debian based linux distro, you can just do something like:
pg_createcluster -d /dev/shm/mypgcluster 8.4 ramcluster
to create a ram based cluster. Note that you'll have to do:
pg_drop cluster 8.4 ramcluster
and recreate it on reboot etc.