The pgstattuple
function provides the following useful columns:
table_len
: The length of the table.tuple_count
: The number of tuples.tuple_len
: The length of the tuples.dead_tuple_count
: The number of dead tuples.dead_tuple_len
: The length of dead tuples.free_space
: The amount of free space.
Example
How you might use this function:
SELECT * FROM pgstattuple('gin_index_name');
Interpreting Results
- If the
dead_tuple_count
is high relative to the tuple_count
, this indicates bloat. - If
free_space
is a significant portion of table_len
, the index may be bloated.
Using pg_trgm for Trigram Indexes
If you're using a GIN index with the pg_trgm
extension (for trigram indexes), you might also consider analyzing the table and index sizes directly:
SELECT pg_size_pretty(pg_relation_size('table_name')) AS table_size, pg_size_pretty(pg_total_relation_size('table_name')) AS total_size, pg_size_pretty(pg_relation_size('gin_index_name')) AS index_size;
Vacuum and Reindex
If you determine that your GIN index is bloated, you can use VACUUM
and REINDEX
to reclaim space:
VACUUM ANALYZE your_table_name;
REINDEX INDEX your_gin_index_name;
By following these steps, you should be able to detect and address bloat in your PostgreSQL GIN indexes effectively.
Hello Kam Fook
You can use pgstattuple extension, & you can use pg_trgm or gin_index_stats functions from the pgstattuple extension to check for bloat in GIN indexes.
Thank & Regards
Muhammad Affan (아판)
PostgreSQL Technical Support Engineer / Pakistan R&D
I have a GIN index. Is there a way to detect if a postgres GIN index is bloated or not? The regular select * from pgstatindex(‘indexname’); does not work because the GIN index is not btree index.
Thank you
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Any more insight on how to use those two options to actually calculate GIN bloat? From what I could tell pgstattuple didn't provide anything that could be used. I hadn't looked further into the other yet, but if you know how to do that already that info would be great.
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