The PostgreSQL REINDEX statement is essential for recovering corrupted indexes, which can occur due to software bugs or hardware failures. Here, we will learn the syntax, usage, and a practical example to ensure you understand how to use this statement effectively in PostgreSQL.
Syntax
REINDEX [ ( VERBOSE ) ] { INDEX | TABLE | SCHEMA | DATABASE | SYSTEM } name;Parameters:
1. VERBOSE Keyword: The VERBOSE keyword is optional and provides a progress report while reindexing. It is useful for monitoring the reindexing process.
2. INDEX: To rebuild a single index, specify the index name after the REINDEX INDEX clause:
REINDEX INDEX index_name;
3. TABLE: To rebuild all the indexes of a table, we can make use of the TABLE keyword as shown below:
REINDEX TABLE table_name;
4. SCHEMA: For rebuilding all indices in a schema, one can make use of the SCHEMA keyword as shown below:
REINDEX SCHEMA schema_name;
5. DATABASE: To recover all indices in a specific database, you need to set the database name after the REINDEX DATABASE clause as shown below:
REINDEX DATABASE database_name;
6. SYSTEM: The following statement can be used to recover all indices on system catalogs from a specific database:
REINDEX SYSTEM database_name;
PostgreSQL REINDEX Statement Example
Let us take a look at an example of the REINDEX Statement in PostgreSQL to better understand the concept.
In this example we will build a REINDEX for the customer table in the sample database:
REINDEX TABLE customer;
Output:
Explanation: The command will rebuild all indexes on the customer table, ensuring they are not corrupted and are functioning optimally.
Important Points About PostgreSQL REINDEX Statement
- The
REINDEX statement is used to rebuild corrupted indexes, which can result from software bugs, hardware failures, or disk issues. - The
VERBOSE keyword is optional but highly useful for displaying progress and detailed information about the reindexing process. - Reindexing can be resource-intensive and may significantly impact database performance.
- The
REINDEX operation locks the affected table or index, preventing other operations from accessing it during the process.
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