pingcap/tidb

Percentile Function in Tidb

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#46,985 opened on Sep 14, 2023

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compatibility-oraclegood first issuesig/executiontype/compatibilitytype/feature-request

Description

Bug Report

perncentile on a column is not working SELECT PERCENTILE_CONT(0.75) WITHIN GROUP (ORDER BY column_name) OVER () AS Q3 FROM YourTable; This is the query which is supported in both postgresql and mysql but it is throwing an error in TIDB

2. What did you expect to see? (Required)

result

3. What did you see instead (Required)

You have an error in your SQL syntax; check the manual that corresponds to your TiDB version for the right syntax to use line 2 column 41 near "(ORDER BY _org_unit_id) OVER () AS Q1

4. What is your TiDB version? (Required)

7.3.0

Contributor guide

Tech stack
gosqlpostgresql
Domain
databasebackend
Issue type
feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
4
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
3-5 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
needs maintainer response
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
familiar with SQL window functionsbasic understanding of TiDB architecture
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
25
Research direction
Review the issue comments for any maintainer guidance on whether PERCENTILE CONT is planned or should be implemented. Study existing SQL window function implementations in TiDB's planner (e.g., `planner/core/plan.go`) and executor (`executor/window.go`). Look for similar aggregate functions like PERCENTILE DISC to understand the pattern. Check if there are any discussions about adding new aggregate functions in the repository's contributing guide.