We have a table with about 20 columns in a Postgres 9.2.10 DB. For better performance on some SELECT queries, we plan to add an index on one column with data type timestamp. As the index also can slow down the performance on inserts, we did the following performance test:
We inserted 5 million records into the table. That’s the max. number of records we expect in production. Then we measured the time to insert 10000 records with and without index on the timestamp column. This is the maximum number of inserts we expect per day, In peaks not more than 5 inserts per second.
Here the results:
- With index – 84 441 ms
- Without index – 78 000 ms
At least for this test, the index slowed down the performance only slightly. For our requirements, I do not see an issue to add the index.
But this was only one test in a lab environment, are there any other pitfalls when running this on a production database? Can we get into a situation, where an INSERT suddenly takes more than 5 seconds under specific circumstances?