Query Performance Investigator
Your application was slow. Now find out what really happened.
Query Performance Investigator (QPI) is diagnostic software for investigating SQL Server performance problems. It brings together execution plans, Query Store evidence, Extended Events, deadlocks, indexes, statistics and more to build a clearer picture of what happened and where to investigate next.
Start with the performance problem — not with a query you have already decided is guilty.
- Diagnostic, not monitoring
- For developers, accidental DBAs and specialists
- Free Alpha version available now
QPI · PLAN VIEW
The problem QPI is built for
The slowdown is over. The explanation isn’t obvious.
A user reports that the application was painfully slow for forty minutes. By the time somebody investigates, CPU has fallen back, blocked sessions have disappeared and the workload looks normal again.
There is evidence — but it is scattered. Query Store has history. Extended Events may have captured activity. Execution plans show what SQL Server chose to do. Indexes, statistics and deadlocks add more clues.
The difficult part is working out which evidence explains the incident, which issues are consequences, and which details are simply noise.
A FAMILIAR SQL SERVER PERFORMANCE INCIDENT
09:32
Users report slow screens and timeouts
The problem is visible in the application, but the cause is unknown.
09:48
Several expensive queries are identified
Are they the cause of the slowdown, normal workload, or secondary effects?
10:15
Performance returns to normal
The live evidence disappears. The investigation now depends on what was captured or retained.
10:28
Different people suggest different fixes
An index. More memory. Statistics. A plan regression. Blocking. Which explanation survives the evidence?
QPI is designed to turn that pile of clues into a structured performance investigation.
QPI · FINDINGS
Approachable without being shallow
You should not need ten years of SQL Server experience to make progress.
Query Performance Investigator can point a developer or accidental DBA towards evidence worth examining, explain why it has been highlighted and provide a route into the supporting detail.
A specialist can ignore the hand-holding and continue into the underlying plan, properties, indexes, statistics, and other evidence if they so wish.
What QPI changes
Spend less time finding the problem. Giving more time to decide what to do about it.
Query Performance Investigator Findings surface the areas most likely to deserve attention, then connect them to the supporting evidence. You spend less time searching for a starting point and more time validating the finding, understanding the cause and deciding what to test or change.
01 · FIND
See where Query Performance Investigator thinks you should look first
Findings use Query Performance Investigator’s internal rules to surface areas of concern, so you are not starting every investigation by manually searching through every plan property and data source.
02 · EXPLAIN
Understand why a Finding was highlighted
A finding is only useful if you can see the evidence behind it. Query Performance Investigator keeps the supporting plan, statistics, indexes, and other relevant detail available for inspection.
03 · CORRELATE
See related evidence together
Query Store history, Extended Events, plans, indexes, statistics, and deadlocks can provide different parts of the explanation. Query Performance Investigator is being built to bring those relationships into the same investigation.
04 · DECIDE
Move from finding to action
Use the highlighted evidence to decide whether the next step is testing a hypothesis, comparing behaviour, tuning a query, reviewing an index or collecting more evidence.
Go beyond the first finding
Follow the evidence until the explanation holds together.
Query Performance Investigator is designed to let you move from a highlighted issue into the surrounding evidence, so the investigation does not stop at a warning or recommendation.
Use Query Store to understand change
Bring historical query and plan behaviour into the investigation so a current plan is not treated as proof of what happened during the slow period.
Use Extended Events as captured evidence
Open existing evidence from a recent incident via the system health extended event session files and use captured activity as another source of context when the live problem has already disappeared.
Put index recommendations in context
A missing-index suggestion is not automatically a good change. Existing indexes and the surrounding query evidence help determine whether the recommendation deserves action.
Use internal rules to expose useful combinations
Query Performance Investigator can highlight patterns and combinations of evidence that deserve attention, giving less-experienced users a starting point without hiding the evidence from specialists.
Who QPI is for
SQL Server performance is often somebody’s responsibility without it being their job title.
Database & application developers
The application has slowed down and SQL Server is part of the picture. Query Performance Investigator provides a structured route into evidence that would otherwise require specialist plan-reading knowledge.
Outcome: investigate further before changing code or blaming the database.
Accidental DBAs & IT teams
SQL Server became part of your remit because somebody had to own it. Query Performance Investigator can help organise the investigation when there is no dedicated performance specialist on the team.
Outcome: better evidence and a clearer escalation path.
DBAs & performance specialists
Use Query Performance Investigator to reduce repetitive evidence gathering, correlate related data faster and then drill into the technical detail when a finding deserves deeper analysis.
Outcome: less diagnostic overhead, more time on the hard part.
When Query Performance Investigator is not enough
Some performance problems extend beyond the evidence in one investigation.
If Query Performance Investigator exposes a wider SQL Server, Windows, operational issue, or you just want some extra help, DatAIbase can take the investigation further.
SQL Server Health Check
Broader assessment across SQL Server and the Operating System when the concern is not limited to a single incident or query.
SQL Server Performance Review
Bring DatAIbase into a performance investigation when you need deeper analysis, wider server context or experienced technical judgement.
Fractional DBA
Add SQL Server experience when the team needs ongoing help, temporary cover or extra capacity for a project.
Try the investigation
The best way to understand QPI is to use it on a real SQL Server problem.
Use the current alpha to investigate real execution plans and deadlocks, then follow QPI as the wider diagnostic capabilities develop.