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

How to find the server is whether standby (slave) or primary(master) in Postgresql replication ?

-
Method 1 You can check the mode of the server using "pg_controldata". [pgsql@test~]$ pg_controldata /usr/local/pgsql/data84/ Database cluster state: in archive recovery --> This is Standby Database Database cluster state: in production --> This is Production Database [Master] Method 2 You can use pg_is_in_recovery() which returns True if recovery is still in progress(so the server is running in standby mode or slave) postgres=# select pg_is_in_recovery(); pg_is_in_recovery ------------------- t (1 row) If Return    false   so the server is running in primary mode or master postgres=# select pg_is_in_recovery(); pg_is_in_recovery ------------------- f (1 row)
Read more

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 err
Read more

How to Return a Result Set from a PostgreSQL Stored Procedure

-
Image
Both stored procedures and user-defined functions are created with CREATE FUNCTION statement in PostgreSQL. To return one or more result sets (cursors in terms of PostgreSQL), you have to use  refcursor  return type. Quick Example : -- Procedure that returns a single result set (cursor) CREATE OR REPLACE FUNCTION show_cities ( ) RETURNS refcursor AS $$ DECLARE ref refcursor; -- Declare a cursor variable BEGIN OPEN ref FOR SELECT city , state FROM cities; -- Open a cursor RETURN ref; -- Return the cursor to the caller END ; $$ LANGUAGE plpgsql; Overview : Return Multiple Result Sets Cursor Lifetime Until the  end  of transaction Auto-commit Must be  off Transaction must be active so the caller can see a result set Important Note : The cursor remains open until the end of transaction, and since PostgreSQL works
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_rel
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. Qu
Read more