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Why is PostgreSQL too slow to read data?
Our system writes a lots of data (kind of Big Data system). Write performance is good enough for our needs but read performance is really too slow. The primary key (constraint) structure is similar for all our tables: timestamp(Timestamp) ; index(smallint) ; key(integer).
When to use vertical partitioning in PostgreSQL?
Another candidate for vertical partitioning: If you have lots of updates on just a few columns, while the rest hardly ever changes. It might be considerably cheaper to split rows in such a case, since Postgres writes a new row version for every update.
How many lines per second in PostgreSQL read request?
A table can have millions of rows, even billions of rows, and a read request is usually for a specific period (timestamp / index) and tag. It’s common to have a query that returns around 200k lines. Currently, we can read about 15k lines per second but we need to be 10 times faster.
Which is the primary key in PostgreSQL index?
The way you have your index (primary key), you can retrieve rows without a sorting step, that’s appealing, especially with LIMIT. But retrievingthe rows seems extremely expensive. Generally, in a multi-column index, “equality” columns should go first and “range” columns last:
How can i Improve my query in PostgreSQL?
You could improve queries by better managing the table indexes. Indexes help to identify the disk location of rows that match a filter. If there is no index, Postgres will have to do a sequential scan of the whole table. The more rows there are, the more time it will take. If you add an index, the query will be faster.
When to remove indexes in PostgreSQL to improve performance?
Sometimes indexes are not used because there are not enough rows in the table. So if the table is new, you should wait a few weeks before removing them. It’s always possible to do better, and spend more time to improve performance.
Which is the best way to improve Postgres performance?
For example, for a large indexed table, the first query is much more slower than the second one. The first query is slower and has more data to load at the begin of the plan. So always prefer using NOT EXITS which is better optimized. You could improve queries by better managing the table indexes.