What is PGTune?

What is PGTune?

PGTune is used to calculate configuration parameters for PostgreSQL based on the maximum performance for a given hardware configuration.

What is Checkpoint_completion_target?

checkpoint_completion_target is a configuration parameter specifying the fraction of the time between checkpoints which can elapse before a checkpoint is completed. checkpoint_completion_target was added in PostgreSQL 8.3.

What is Effective_cache_size?

effective_cache_size (integer) The effective_cache_size parameter estimates how much memory is available for disk caching by the operating system and within the database itself. The PostgreSQL query planner decides whether it’s fixed in RAM or not.

How do you change parameters in PostgreSQL?

Starting wiht PostgreSQL 9.4 you can change parameters in postgresql. conf with the “alter system” command in psql. In principle every parameter can be changed that way but not every parameter is applied immediately. Some of the parameters require a reload others require a complete restart of the instance.

What is PG bouncer?

PgBouncer is an open-source, lightweight, single-binary connection pooler for PostgreSQL. It can pool connections to one or more databases (on possibly different servers) and serve clients over TCP and Unix domain sockets. PgBouncer maintains a pool of connections for each unique user, database pair.

How do I tune a MySQL server for performance?

System MySQL Performance Tuning

1. Balance the Four Main Hardware Resources. Storage.
2. Use InnoDB, Not MyISAM.
3. Use the Latest Version of MySQL.
4. Consider Using an Automatic Performance Improvement Tool.
5. Optimize Queries.
6. Use Indexes Where Appropriate.
7. Functions in Predicates.
8. Avoid % Wildcard in a Predicate.

What is Min_wal_size?

min_wal_size puts a minimum on the amount of WAL files recycled for future usage; that much WAL is always recycled for future use, even if the system is idle and the WAL usage estimate suggests that little WAL is needed.

What is Min_wal_size Postgres?

min_wal_size is a configuration parameter determining the minimum number of WAL files to retain for reuse at a future checkpoint . min_wal_size was introduced in PostgreSQL 9.5; together with max_wal_size it replaces checkpoint_segments .

What is Pg_stat_statements?

The pg_stat_statements module provides a means for tracking planning and execution statistics of all SQL statements executed by a server. The module must be loaded by adding pg_stat_statements to shared_preload_libraries in postgresql. conf , because it requires additional shared memory.

What is Maintenance_work_mem?

maintenance_work_mem ( integer ) Specifies the maximum amount of memory to be used by maintenance operations, such as VACUUM , CREATE INDEX , and ALTER TABLE ADD FOREIGN KEY . If this value is specified without units, it is taken as kilobytes. It defaults to 64 megabytes ( 64MB ).

How do you set parameters?

Creating a parameter set

1. Enter a name and short description for your parameter set.
2. Click the Parameters tab.
3. Click the Values tab.
4. Enter a name in the Value File name field, then press Enter.
5. If a default value is not already set, enter a value for each parameter.
6. Click OK to close the Parameter Set window.

How do you pass parameters in PostgreSQL query?

The get_sum() function accepts two parameters: a, and b, and returns a numeric. The data types of the two parameters are NUMERIC. By default, the parameter’s type of any parameter in PostgreSQL is IN parameter. You can pass the IN parameters to the function but you cannot get them back as a part of the result.

What is Pgpool and PgBouncer?

PgBouncer allows limiting connections per-pool, per-database, per-user or per-client. Winner! Pgpool-II allows limiting the overall number of connections only. Connection queue. PgBouncer supports queuing at the application level (i.e. PgBouncer maintains the queue).

What is Pg_shadow?

The catalog pg_shadow contains information about database users. The name stems from the fact that this table should not be readable by the public since it contains passwords. pg_user is a publicly readable view on pg_shadow that blanks out the password field.

How do I make MySQL query run faster?

Tips to Improve MySQL Query Performance

1. Optimize Your Database. You need to know how to design schemas to support efficient queries.
2. Optimize Joins. Reduce the join statements in queries.
3. Index All Columns Used in ‘where’, ‘order by’, and ‘group by’ Clauses. INDEXES.
4. Use Full-Text Searches.
5. MySQL Query Caching.

What is the best way to Maximise MySQL query efficiency?

Optimize Queries With MySQL Query Optimization Guidelines

1. Avoid using functions in predicates.
2. Avoid using a wildcard (%) at the beginning of a predicate.
3. Avoid unnecessary columns in SELECT clause.
4. Use inner join, instead of outer join if possible.
5. Use DISTINCT and UNION only if it is necessary.

What is Max WAL size?

Maximum size to let the WAL grow during automatic checkpoints. This is a soft limit; WAL size can exceed max_wal_size under special circumstances, such as heavy load, a failing archive_command , or a high wal_keep_size setting. If this value is specified without units, it is taken as megabytes. The default is 1 GB.

What is a Postgres checkpoint?

Description. A checkpoint is a point in the write-ahead log sequence at which all data files have been updated to reflect the information in the log. All data files will be flushed to disk.

How do I read a WAL file in PostgreSQL?

Generally, there are two options in Postgres for presenting WALs in some human-readable format:

1. pg_waldump utility, but it is available only in 9.3+. You can try using pg_waldump from 9.3 with 9.2 WALs, but I am not sure in success.
2. Also it is possible to utilize logical decoding, but it is available since 9.4.

What is Pg_stat_user_tables?

pg_stat_user_tables is a statistics view showing statistics about accesses to each non-system table in the current database. pg_stat_user_tables was added in PostgreSQL 7.2.