LDAP Query Calculator

Size LDAP directory load: query rate, cache offload, result bandwidth and per-connection query rate.

About LDAP Query Calculator

Directory load is a product of client count and per-client query rate, reduced by whatever the application caches locally. Result bandwidth matters separately because broad searches returning many entries move far more data than the query count suggests. Unbounded LDAP searches are a classic outage cause: a query returning thousands of entries at hundreds of queries per second saturates both the directory's CPU and the link, even though the query rate looks modest.

Formulas

LDAP Query

total qps = clients × queries per client per second; directory qps = total × (1 − cache hit ratio).

cache hit ratio: Fraction answered from the application's own cache
directory qps: Searches the directory server actually executes

Result set bandwidth

result bandwidth = qps × entries per query × bytes per entry × 8

entries per query: Search result size
bytes per entry: Serialised attribute payload per entry

Worked example

With the default values below, LDAP Query Calculator returns Total Query Rate of 1,000. Change any input above and every figure here is recalculated in your browser.

Inputs used

Application clientsminimum 1 clients: 40 clients
Queries per client per secondminimum 0.01 queries/s: 25 queries/s
Entries returned per queryminimum 1 entries: 15 entries
Bytes per returned entryminimum 32 bytes: 1,200 bytes
Client-side cache hit ratioaccepts 0–100 %: 60 %
Pooled LDAP connectionsminimum 1 connections: 20 connections

Results

Total Query Rate: 1,000 queries/s
Rate Reaching The Directory: 400 queries/s
Result Bandwidth: 144.00 Mbit/s
Queries Per Connection: 50.0 queries/s
Queries Per Day: 86,400,000

Step by step

1Values used
2LDAP Query
3Result set bandwidth
4Total Query Rate= 1,000 queries/s
5Rate Reaching The Directory= 400 queries/s
6Result Bandwidth= 144.00 Mbit/s
7Queries Per Connection= 50.0 queries/s
8Queries Per Day= 86,400,000

Assumptions and limits

The result is derived only from the 6 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 2 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 LDAP Query calculated?

total qps = clients × queries per client per second; directory qps = total × (1 − cache hit ratio). Directory load is a product of client count and per-client query rate, reduced by whatever the application caches locally. Result bandwidth matters separately because broad searches returning many entries move far more data than the query count suggests.

Why does LDAP Query matter?

Unbounded LDAP searches are a classic outage cause: a query returning thousands of entries at hundreds of queries per second saturates both the directory's CPU and the link, even though the query rate looks modest.

What values do I need to enter?

This calculator takes 6 inputs: Application clients, Queries per client per second, Entries returned per query, Bytes per returned entry, Client-side cache hit ratio, Pooled LDAP connections. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.