pingcap/tidb

blob/text/int length isn't accuracy in column metadata

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#7,465 opened on Aug 22, 2018

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help wantedtype/compatibility

Description

  1. What did you do?

connection tidb with --column-type-info

create table bitest(b blob(2));
select * from bitest;
  1. What did you expect to see?
Length:     255
  1. What did you see instead?
Length:     8
  1. What version of TiDB are you using (tidb-server -V or run select tidb_version(); on TiDB)?
2.0.6

ref #7463

Contributor guide

Tech stack
gosql
Domain
databasebackend
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.
mostly clear
Prerequisites
Go programmingTiDB internals
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
40
Research direction
Investigate how TiDB reports column length for blob/text types. Compare the expected length (255 for blob(2)) with actual (8). The issue references #7463, which may contain related context. Look at the server's column metadata handling, possibly in the session or protocol layer.
blob/text/int length isn't accuracy in column metadata · pingcap/tidb#7465 | Good First Issue