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2. Query not executing in a database or taking longer time to execute

In case if the SQL query is not executing

2.1. Proper Index

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When faced with issues related to SQL queries not executing or taking significantly longer to execute than usual, employing the 'Explain Analyze' keyword before the query can provide invaluable insights. This method offers detailed runtime statistics, including the total elapsed time spent within each plan node (in milliseconds) and the total number of rows returned.

Additionally, optimizing query execution often involves creating appropriate indexes, especially for tables or columns housing millions of records. Proper indexing significantly improves the efficiency of query processing, ultimately enhancing overall database performance

2.1. Indexing

You have the option to create the index manually or utilize the 'REINDEX' command to automatically generate the index on the specified table.

CREATE INDEX index_name ON table_name (column_name);

REINDEX TABLE <table> ;

The distinction between the two operations lies in their core functionalities. The REINDEX command is employed to rebuild existing indexes, a process designed to eliminate fragmentation or corruption within the database. Although this procedure can be resource-intensive, it significantly enhances query performance on the reconstructed index. On the other hand, the CREATE INDEX command is utilized to establish new indexes tailored for specific search conditions. While the creation of an index demands resources during its initialization, it offers a lasting improvement in query performance for the designated columns, optimizing database operations in the long term.

2.2. Dead Tuple

Another factor that can contribute to prolonged query execution in a database is the presence of a significant number of dead tuples, particularly when dealing with tables containing millions of records. You can assess the ratio of live to dead tuples using the following query.

SELECT schemaname,relname,n_live_tup,n_dead_tup FROM pg_stat_user_tables ORDER BY n_dead_tup DESC limit 10;

To eliminate dead tuples from tables and optimize the database, it is advisable to perform database vacuuming. This can be accomplished using the following commands, which can be applied to individual tables or the entire database.

VACUUM (VERBOSE, ANALYZE) <table_name>;

\c <database_name>
VACUUM (VERBOSE, ANALYZE);