Partition Size Calculator
Size table partitions and check the partition count stays manageable.
About Partition Size Calculator
Partition sizing balances two costs: partitions too large defeat pruning, while too many partitions make query planning expensive. A few dozen gigabytes per partition and under a thousand partitions is the usual sweet spot. Partitioning by time also makes retention a metadata operation, since dropping a partition is instant while deleting rows is not.
Formula
Partition Size
Partition size = rows per interval × row size; count = retention ÷ interval
- partition pruning
- Skipping partitions that cannot match the query
- planning overhead
- Cost of considering every partition when planning a query
Worked example
With the default values below, Partition Size Calculator returns Size per Partition of 5.4762. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Total rowsminimum 0
- 500,000,000
- Average row sizeminimum 0 bytes
- 280 bytes
- Days per partitionminimum 1 days
- 30 days
- Retention periodminimum 1 days
- 730 days
- Rows added per dayminimum 0
- 700,000
Results
- Size per Partition
- 5.4762 GB
- Number of Partitions Retained
- 25
- Total Partitioned Size
- 130.385 GB
- Rows per Partition
- 21,000,000
- Verdict
- Partition sizing looks balanced
Step by step
- 1Values used
- 2Partition Size
- 3Size per Partition= 5.4762 GB
- 4Number of Partitions Retained= 25
- 5Total Partitioned Size= 130.385 GB
- 6Rows per Partition= 21,000,000
- 7Verdict= Partition sizing looks balanced
Assumptions and limits
- The result is derived only from the 5 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax or fees or charges into account.
- Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
How is Partition Size calculated?
Partition size = rows per interval × row size; count = retention ÷ interval Partition sizing balances two costs: partitions too large defeat pruning, while too many partitions make query planning expensive. A few dozen gigabytes per partition and under a thousand partitions is the usual sweet spot.
Why does Partition Size matter?
Partitioning by time also makes retention a metadata operation, since dropping a partition is instant while deleting rows is not.
What values do I need to enter?
This calculator takes 5 inputs: Total rows, Average row size, Days per partition, Retention period, Rows added per day. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.