pingcap/tidb

Expression inside window should not support legacy position indication

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#10,521 opened on May 17, 2019

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 (2 comments) (0 reactions) (1 assignee)Go (40,090 stars) (6,186 forks)batch import
help wantedpriority/P4type/compatibility

Description

Bug Report

Please answer these questions before submitting your issue. Thanks!

  1. What did you do? If possible, provide a recipe for reproducing the error.
CREATE TABLE t(i INT, j INT, k INT);
SELECT i/SUM(j) OVER (PARTITION BY kk) AS x FROM t;
  1. What did you expect to see?
ERROR HY000: Window '<unnamed window>': ORDER BY or PARTITION BY uses legacy position indication which is not supported, use expression.
  1. What did you see instead?
Unknown column 'i' in 'field list'
  1. What version of TiDB are you using (tidb-server -V or run select tidb_version(); on TiDB)?

Contributor guide

Tech stack
gomysql
Domain
backenddatabase
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
Understanding of SQL window functionsFamiliarity with TiDB's SQL parser
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
20
Research direction
The bug is that an expression inside a window function incorrectly reports 'Unknown column' instead of 'legacy position indication not supported'. The fix requires modifying the SQL parser to detect legacy position indication (e.g., using integer literals) in window function's PARTITION BY or ORDER BY clauses and produce the correct error. Look at the window function parsing logic in the parser package, likely in files like `parser/ast.go` or `planner/core/planbuilder.go`. Check the existing error handling and the condition for legacy position indication. The maintainers may have feedback in the comments.
Expression inside window should not support legacy position indication · pingcap/tidb#10521 | Good First Issue