Drop Down MenusCSS Drop Down MenuPure CSS Dropdown Menu

Differences between BDR and trigger-based replication

-

There are a number of trigger-based logical replication solutions for PostgreSQL, including Londiste, Slony-I and Bucardo. They're mature, fairly widely used and powerful, and like BDR they have the advantages (and disadvantages) of logical replication.
As with the comparison with physical replication, BDR offers advantages over trigger-based replication solutions but also has some downsides.
All trigger-based replication solutions suffer from inherent write-amplification, where each write to the database produces a corresponding write to a replication log table. Both the original write and the write to the replication log get recorded in WAL as well as the heap, so each write actually happens four times. By reading and processing WAL for data to replicate BDR avoids this write amplification, so writes to a BDR-replicated database only get written twice - like any other durable write on PostgreSQL.
Trigger-based replication also requires an external dæmon process on the sending and/or receiving side. BDR runs its management processes inside PostgreSQL itself, so there's no separate replication process to manage.
At the time of writing, systems like Londiste have a number of features for which BDR has no corresponding capability. Londiste can synchronise and compare tables between the publisher and subscriber. Slony-I supports events and confirmations. Slony-I provides infrastructure for handling DDL while also running on unmodified PostgreSQL 9.4. Bucardo supports multi-master on unmodified PostgreSQL 9.4. So while BDR offers some significant benefits it won't suit every need and every workload. Evaluate your needs carefully before choosing a technology.

Comments

Post a comment

Popular posts from this blog

PostgreSQL pgBadger

-
pgBadger is a PostgreSQL log analyzer built for speed with fully reports from your PostgreSQL log file. It's a single and small Perl script that outperforms any other PostgreSQL log analyzer.It is written in pure Perl and uses a JavaScript library (flotr2) to draw graphs so that you don't need to install any additional Perl modules or other packages. Furthermore, this library gives us more features such as zooming. pgBadger also uses the Bootstrap JavaScript library and the FontAwesome webfont for better design. Everything is embedded.pgBadger is able to autodetect your log file format (syslog, stderr or csvlog). It is designed to parse huge log files as well as gzip compressed files. See a complete list of features below. Supported compressed format are gzip, bzip2 and xz. For the xz format you must have an xz version upper than 5.05 that supports the --robot option.All charts are zoomable and can be saved as PNG images.You can also limit pgBadger to only report errors or rem…
Read more

How to Get Table Size, Database Size, Indexes Size, schema Size, Tablespace Size, column Size in PostgreSQL Database

-
In this post, I am sharing few important function for finding the size of database, table and index in PostgreSQL.
Finding object size in postgresql database is very important and common. Is it very useful to know the exact size occupied by the object at the tablespace. The object size in the following scripts is in GB. The scripts have been formatted to work very easily with PUTTY SQL Editor.

1. Checking table size excluding table dependency:
SELECT pg_size_pretty(pg_relation_size('mhrordhu_shk.mut_kharedi_audit')); pg_size_pretty ---------------- 238 MB (1 row)2. Checking table size including table dependency:
SELECT pg_size_pretty(pg_total_relation_size('mhrordhu_shk.mut_kharedi_audit')); pg_size_pretty ---------------- 268 MB (1 row)3. Finding individual postgresql database size
SELECT pg_size_pretty(pg_database_size('db_name'));4. Finding individual table size for postgresql database -including dependency index:
SELECT pg_size_pretty(pg_total_relation_size(…
Read more

ORA-01261: Parameter db_recovery_file_dest destination string cannot be translated ORA-01262: Stat failed on a file destination directory Linux-x86_64 Error: 2: No such file or directory

-
While I start my database with my initialization parameter it fails with oracle error
Solution :- su oracle
run environment variable
sqlplus / as sysdba

SQL>create pfile from spfile; Then remove or comment below line in pfile db_recovery_file_dest Save and exit su oracle
run environment variable
sqlplus / as sysdba

SQL>startup mount;
ORACLE instance started.
Total System Global Area 1068937216 bytes
Fixed Size 2166536 bytes
Variable Size 427819256 bytes
Database Buffers 624951296 bytes
Redo Buffers 14000128 bytes

it should became the mount stage then open the DB as follows SQL>alter database open;
Database altered.
Read more

PostgreSQL Pgbadger Installation On Linux

-
Image
PgBadger is a tool that analyzes PostgreSQL log files and generates reports on execution of SQL and server operation. Statistical reports analyzed from a number of perspectives can be useful not only for grasping the usual database operation but also as a hint for performance improvement.

The report output by pgBadger has the following features. Graph output in HTML format Many statistical objects Daily, Weekly unit creation possible 1.Graph output in HTML format
Many of the analysis results can be displayed in graph form by outputting the report in HTML format (output in text format or JSON format is also possible). By analyzing the log information graphed, it is much more prospective for people to see than the raw log data. So, if you do not need to handle it with another tool separately, we recommend report output in HTML format.

2.Many statistical objects A lot of data useful for database performance analysis is output in the report as shown below. Queries (total number of executions, maxi…
Read more

PostgreSQL Database startup / shutdown /restart

-
Pg_ctl Utility & Postgresql Service to do the same thing: Start the postgres server in the background. Without PGDATA set, “pg_ctl start” needs needs the additional -D /datadirargument in order to start.you can start/stop the postgresql server as root user as well as postgres userroot user: “service postgresql start““/etc/init.d/postgresql  start“, or “systemctl start postgresql-10” – this is for redhat linux above version 6postgres or edb user: Pg_ctl is only applicable for postgres user or edb user if you are a Enterprisedb su – postgres./pg_ctl start  -D /opt/PostgreSQL/9.3/data By using following anyone methods you can start,stop,reload else restart the postgresql server By using Pg_ctl UtilityPostgresl -9.3 ScriptBy using Postgresql Service1. pg_ctl utility – as postgres user:
using pg_ctl you can start/stop/reload/restart the postgresql server this utility can only permitted to access as postgres user ./pg_ctl stop -D /opt/PostgresPlus/9.3AS/data/ ./pg_ctl start -D /opt/PostgresPl…
Read more