Exploring PostgreSQL’s Foreign Data Wrapper and Statistical Functions
PostgreSQL, renowned for its robustness and extensibility, offers several helpful functions for both developers and database administrators alike. Among these functions,
file_fdw_handler
, file_fdw_validator
, pg_stat_statements
, pg_stat_statements_info
,
and
pg_stat_statements_reset
stand out as invaluable tools for enhancing database management and performance optimization. In today’s blog we’ll learn how to use all of these functions as well as how Navicat can help!
File Functions
PostgreSQL’s Foreign Data Wrapper (FDW) functionality allows seamless integration of external data sources into the database. The
file_fdw_handler
and
file_fdw_validator
functions are specifically designed to handle foreign tables backed by files. The
file_fdw_handler
function serves as an interface between PostgreSQL and the foreign data source, enabling the execution of SQL queries against files residing outside the database. Let’s consider an example where we want to create a foreign table named
external_data
referencing a CSV file named
data.csv
:
CREATE SERVER file_server FOREIGN DATA WRAPPER file_fdw;
CREATE FOREIGN TABLE external_data (
id INT,
name TEXT,
age INT
) SERVER file_server OPTIONS (filename '/path/to/data.csv');
Meanwhile, the
file_fdw_validator
function ensures the integrity of the options provided when creating a foreign table. It validates if the specified file exists and is accessible. For instance:
SELECT file_fdw_validator('filename', '/path/to/data.csv');
Statistical Functions
PostgreSQL’s pg_stat_statements module provides a set of built-in functions for monitoring and analyzing query performance. Among these,
pg_stat_statements
, pg_stat_statements_info
,
and
pg_stat_statements_reset
are indispensable for identifying bottlenecks and optimizing database performance.
pg_stat_statements
is a module that records statistics about SQL statements executed by a server. It tracks details such as execution counts, total runtime, and resource usage for each unique query. To enable
pg_stat_statements
you need to add it to the
shared_preload_libraries
configuration parameter in
postgresql.conf
:
shared_preload_libraries = 'pg_stat_statements'
SELECT * FROM pg_stat_statements;
pg_stat_statements_info
provides additional information about the
pg_stat_statements
module, such as the version number and the last reset time. It can be queried as follows:
SELECT * FROM pg_stat_statements_info;
Finally,
pg_stat_statements_reset
resets the statistics collected by
pg_stat_statements
llowing you to start afresh with performance monitoring. Simply execute:
SELECT pg_stat_statements_reset();
Working with PostgreSQL's Built-in Functions in Navicat
We can access all of the above functions in Navicat for PostgreSQL or Navicat Premium 16 by expanding the “Functions” section in the Objects Pane:
To execute a function, simply select it from the Objects list and click the Execute Function button:
That will bring up a dialog where you can supply input parameter values:
Click the OK button to execute the function and view the results (or Cancel to abort):
PostgreSQL’s built-in functions, including
file_fdw_handler
, file_fdw_validator
, pg_stat_statements
, pg_stat_statements_info
,
and
pg_stat_statements_reset
,
play a pivotal role in enhancing database management and optimizing query performance. By leveraging these functions effectively, developers and administrators can streamline operations and ensure optimal utilization of PostgreSQL’s capabilities.